Offices: DREXEL BUILDING, Philadelphia, Pa., U. S. A. LEADING MANUFACTURERS OF FINE Driers, Japans and Varnishes. Having patented, and the most advanced methods and machinery, the best equipped company in the world for filling special requirements in DRIERS, JAPANS and VARNISHES, we especially solicit the patronage of wholesale dealers. /c? The Stilwell'Bierce & Smith-Vaile Co. DAYTON, OHIO, U. S. A. MANUFACTURERS OF A “THE SMITH-VAIEE” CORN, LINSEED and COTTON OIL MACHINERY, STEAM AND POWER PUMPING MACHINERY, FILTER PRESSES, “STILWELL” Feed Water Heaters, THE “VICTOR” TURBINE. PRATT & LAMBERT (INCORPORATED.) manufacturers of Crushers' Driers, Ink Driers, Paint Driers, Oil Qoth Driers AND Varnishes for All Purposes. Offices: WOODBRIDGE BUILDING, ‘ 'JOHN & WILLIAM STS., NEW YORK. 370-378 26th ST., CHICAGO. 21 ST. ANTOINE ST., MONTREAL. Factories: LONG ISLAND QTY, N. Y. CHICAGO, ILL. MONTREAL, CANADA. II. A PRACTICAL MANUAL Linseed Oil Manufacture And Treatment. Varnish Manufacture, Superior, Medium, and Cheap Grades. By JOHN BANNON. Published by THE NATIONAL PROVISIONER PUBLISHING CO., NEW YORK AND CHICAGO. Czo/'^S tP / 'X / ^^7 MANUFACTURED BY BROOKLYN, NEW YORK. IV. THE GETTY Cti^TER UBRART 1 PREFACE. ^ I "HERB is no system in any line of manufacturing which can- * not, in some particular, he improved; nor is there any oil miller so proficient in the business that he cannot learn something of value from another of the craft. This must of necessity be the case, for the reason that there is no person who can hope to com¬ pass every known thing in any given manufacturing industry in his own personal experience, however varied or practical it may have been. Realizing this fact,, the author of this volume, during twenty years of practical oil milling, has endeavored to acquire all the information that to him seemed important relative to the busi¬ ness, same being acquired by personal experiments and close ob¬ servation. A variety of valuable points are covered and treated in this volume, and since an article is of no value unless it is un¬ derstood, the author has paid special regard to simplicity, and his aim has been to make his style of expression simple, and, there¬ fore, readily understood. Concerning the text of the work, with regard to oil milling, as already observed, same is the result of writer’s personal exper¬ ience, while with regard to varnish making, etc., the matter which appears is merely the result of research and extracts from well- known authorities. The book, in the main, was written under the most difficult conditions, and not with a view to merit encomiums with regard to its literary qualifications. JOHN BANNON, June lo, 1897. 365 Decatur St., Brooklyn, N. Y. Entered according to Act of Congress in the year 1897, by THE NATIONAL PROVISIONER PUBLISHING CO. OF New York and Chicago, ROBERT GANZ & COMPANY, PROPRIETORS, In the Office of the Librarian of Congress at Washington ROBERT OA.NZ. THE Dr. J. H. SENNER. National Profisioier Palilislii Coiaiy, ROBERT GANZ & CO., Proprietors. NEW YORK : CHICAGO : 384-386 PEARE STREET, No. 11 RIAETO BUIEDING, Cor. of Beekman. Adjoining Board of Trade. The national PROYISIONER, THE ORGAN OF THE Provision and Meat Industries OF THE . UNITED STATES AND CANADA. Chicag:o, New York, 'Roston, Philadelphia, Cincinnati, Kansas City, .^t. Eouis, Eondon, England. PUBLISHED EVERY SATURDAY. SUBSCRIPTION PRICE: In the United States and Canada, - - SS4.00 Per Annum. In Eoreig^n Countries, ----- $>6.00 Per Annum. (Postage Prepaid.) PUBLISHERS OF THE Pork Packers’ Handbook and Directory of the MEAT AND PROVISION TRADES. 440 Pages. Price, $10.(X). The Manufacture of Cottonseed Oil AND ALLIED PRODUCTS. 9.5 Pages. Price, $3.00, VII. The above cut shows our Combined Water-Cooled Mill and Mixer. Mill is entirely independent of the Mixer. Either can be stopped or started without stopping the shaft by a clutch. Made single or in gangs of two or three. It is really the most perfect mill yet placed on the market. Very substantial, neat and compact. C. W. H. CARTER. C. HARRIS CARTER. O. G. CARTER. C. W. H. CARTER, 26 Rose St., New York. ESTABLISHED OVER A QUARTER OF A CENTURY. All Kinds of Burnt Varnishes for I i Printing and Lithographic Inks* -ALSO- Burnt Plate Oils for Steel and Copper Plate Inks. Special Varnishes and Oils. Special Drier IMade Especially for Inks. viri. EDWARD CRAVEN. J. A. CAMERON. PRESS CLOTH. Sugden Press Bagging Co., ‘manufacturers of CLOTH FOR ALL KINDS OF OIL PRESSES. None but first quality cloth manufactured. Every roll guaranteed against imperfections in stock or weav¬ ing. A large stock of Linseed and Cottonseed Press Cloth constantly on hand to ensure prompt delivery. Special attention paid to the manufacture of odd widths and weights for special purposes. Represented in the Southern States by MR. HENRY CHARNOCK, 629 Gravier Street, - - New Orleans, La. Factory and Office at West Chelmsford, IMass. Telegrams to Lowell, Mass. Correspondence Solicited. IX. THE “JOHNSON” FILTER PRESS.^^^ JOHN JOHNSON & CO., Franklin Square and Cherry Street, NEW YORK aTY, N. Y. Makers and Patentees oe . . . Filter Presses For the Separation of Solids from Liquids by Filtra¬ tion and all Appliances for Working Them. SPECIAL OIL AND VARNISH FILTERS. FILTER PRESS CLOTHS and FILTER PRESS PUMPS. Send for Catalug^ue. X. THE I^ANUFACTURE OF LINSEED OIL. CONCERNING THE VARIOUS CLASSES OF FLAXSEED. Conditions Requisite in Linseed Oil to Produce Best Results. As linseed oil is a very essential constituent of a good paint or varnish, to which latter, among other features, it imparts the property of elasticity, too much care can¬ not be devoted to the selection of an article of warranted genuineness. A brief outline of the most efficient and economical method." necessary in its manufacture, together with a consideration of the requisite features which it must possess to be suited to the special requirements peculiar to varnish making, will be appropriate at this time. As pointed out in the foregoing paragraph, the primary condition essential in linseed oil intended for use in varn¬ ish or paint making of standard qualities consists in its absolute purity, that is to say, linseed oil of commerce manufactured by the most approved appliances from the purest obtainable crude material. The seed from which the oil is made should be full-grown and mature, the im¬ purities, which consist of mineral substances, grains of wheat, maize, etc., etc., and all vegetable matter foreign to the genuine linseed, whether of an oleaginous or non- oleaginous nature, should be eliminated as carefully as the circumstances warrant. The seed from which linseed oil is usually made in England, having been nurtured by the soil and clime of 1 2 THE MANUFACTURE OF LINSEED OIL. the East Indies, which region possesses elementary con¬ ditions peculiarly favorable to the cultivation of linseed, a mature and well-developed grain are some of its charac¬ teristic features. Russian or American seed in an unripe condition is not infrequently met with, and as large lots of these varieties of seed are at times imported, for the two-fold purpose of taking advantage of the low figures which occasionally rule the foreign markets and to off-set a probably high quotation with regard to the East India product, something concerning the nature of these seeds may be read with interest. However well the manufacturing process may be carried out, an inferior oil yield is always 'obtained from an unripe seed, while the quality at best is of a secondary nature. Oil of this description is unsuited to the requirements of varnish making, and should be carefully avoided. Unless sub¬ jected to extraordinary treatment in the clarification, chemical and mechanical refining, filtering, and finally in maturation, the use of an oil of this variety very fre¬ quently proves disastrous. Many reasons may be adduced in support of this averment. By reason of the fact that the mucilaginous matter, or incipient vegetable forma¬ tion of the seed, deprived of adequate time for complete development by solar and other elementary influences, or, as is frequently the case, owing to the restraining ef¬ fects of an uncongenial climate, the growth of the oil- yielding substance is retarded, and an abnormal propor¬ tion of imperceptible fibrous substance is pressed out with the oil. It is this latter substance which the varnish maker abhors as he would contagion. Its presence in an oil intended for use in varnish making is highly deleter¬ ious, and it is only after the oil has been submitted to a high temperature that this objectionable substance be¬ comes apparent. This peculiar combination of gummy or fibrous substance may be easily detected by submit- THE MANUFACTURE OF LINSEED OIL. 3 ting a sample of the oil to the fire test in a glass testing tube, and after about thirty hours’ repose, its presence will be indicated by cloudy masses suspended in the oil. Oil made from the average seed of the ripe American or Russian variety, contains a much larger proportion of natural moisture than that of the East India seed, but, subjected to skillful treatment, superior varnishes are regularly made with it. So fierfect is the manipulation made by several of the large crushing concerns in the United States, in the preparation of this oil for use in varnish making, that it is difficult even for an expert to distinguish between the genuine East India seed oil and the oil made from the domestic variety of seed. This fact is of peculiar significance when it is considered that the oil from the East India seed always commands a higher figure than that from the American product, the former commanding 20 cents per gallon over the latter at this time. Whether rightly or wrongly, it is considered that oil drawn from the most superior variety of Russian or American seed, however skillfully manufactured, or manipulated afterwards, ranks as a lower grade than oil from the East India seed, from a varnish standpoint. Nevertheless, with correct treatment, it is regularly demonstrated that very superior varnishes are made from oil of this description, unexceptionable alike in their durability and covering properties. An average sample of full-grown American or Russian seed contains from four to seven per cent of moisture and from three to six per cent of foreign matter, which in¬ cludes mineral substances, wild seed of an oleaginous or non-oleaginous nature, etc., etc. A variety of seed which is largely imported from the East Indies to England, and known as Calcutta seed, contains a high percentage of foreign matter, but the seed itself is invariably full-grown and mature, and the 4 THE MANUFACTURE OF LINSEED OIL. elimination of the objectionable matter leaves a product, which under skillful treatment produces an excellent oil, generally superior and much lighter in color than that made from seed grown in more variable climates. Seed which is imported from the district of which Bombay is the shipping port, is comparatively dear, and but little screening is required to prepare it for the manufacturing processes. It, however, contains a peculiar vegetable substance, triangular in form, as hard as flint almost, and about the size of an ordinary grain of seed, in variable proportions, which is dififlcult to remove by the ordinary mesh of the revolving screen, owing to its similarity in size to the seed with which it is intimately associated. Being of a non-oleaginous nature, its presence does not affect the quality of the oil, but in the rolling process its propensity to become wedged between a driving and frictional chilled roll—the two sides of the triangular¬ shaped substance forming the wedge, and the third side the base—very frequently clogs the entire machine and temporarily brings the crushing operation to a standstill. Another peculiarity of this variety of seed consists in the large proportion of light yellow seed always present in a parcel, while the grain is of a uniform size, plump and mature. The percentage of moisture present in the East Indian seed is fractional, and the oil yield exceeds that of the best variety of seed grown elsewhere. About thirty-two or thirty-three per cent of oil is considered a satisfactory yield from the average Russian or American variety seed, but to obtain this proportion, the seed must be ripe. and the manufacturing processes unexceptionable. The mature and well-developed seed cultivated in the East Indies yields oil more freely under treatment, the usual proportion under normal conditions being about two per cent over that of the best of other varieties. This oil THE MANUFACTURE OF LINSEED OIL. 5 being pale in color in its natural condition, when refined, and sufficiently aged, is especially prized by the varnish- maker. Cold drawn oil from any description of seed is much lighter in color than that produced by artificial heat, the latter being the only practical means, in con¬ junction with the auxiliary processes, to obtain the maxi¬ mum yield. Oil made from ripe seed and subsequently subjected to efficient treatment presents a peculiar aspect in the sample phial, at once indicative of its purity and the general properties indispensable in the production of a first-class varnish. It will appear limpid and brilliant, sweet to the taste, with very little smell, and the test will disclose the fact that it is specifically lighter than impure oil generally—although in the detection of an impure oil this is not a reliable guide—and when clarified dries quickly and firmly, and does not materially change the color of the varnish when made. In specific gravity it may be noted that even pure oil varies somewhat, the average being 0.935, but the range is from 0.932 to 0.937 at the standard temperature of 60° F. Its solidifi¬ cation is obtained by reducing the temperature to 27° C. A light-colored oil is especially desired by varnish and white lead manufacturers and to each the choice of a pure article is of the greatest moment. The growing tendency to use finely bleached oils is becoming more marked yearly. Concerning the productions of an absolutely pure oil in large quantities without containing the least vestige of foreign matter, it must be said that it is impracticable by reason of the fact that the complete removal of the im¬ purities would necessitate the employment of innumer¬ able hands, a circumstance which would involve such enormous expense that its consideration is out of the question. On a small scale, for empirical purposes, in the laboratory it is frequently done, but the tedium in- 6 THE MANUFACTURE OF LINSEED OIL. separable to the entire removal of all extraneous matter by digital means—the only possible method of ac¬ complishing the purpose—becomes almost intolerable. On a recent occasion the complete removal of about seven per cent of such matter from a sample of seed, weighing about 200 grammes, occupied the writer five hours of close application. Taking this as a basis, it would require many weeks to clean or thoroughly remove such matter from a single bushel! The oil extracted from this small sample of really pure seed, which was divested of thd slightest trace of outside matter, being filtered, and allowed two weeks’ repose, showed exceptionally light color, and its drying proper¬ ties demonstrated surpassing excellence when applied to the surface of the testing glass. The most impure seed may be screened sufficiently to meet the requirements of all practical purposes, and a high percentage of dirt and other matter in the seed may be reduced to from one and one-half to two per cent as a minimum quantity. There are on the market to-day ex¬ cellent screens, varying in capacity from 200 to 500 bushels per twenty-four hours, their use in the produc¬ tion of a superior oil being beyond question. The com¬ paratively diminutive size of the foreign seed, exclusive of maize or wheat grains, facilitates.their separation from the genuine seed, when Screens or sieves of a certain gauge or mesh are used. Seed containing these deleterious substances naturally produces an inferior oil proportionate to the percentage present, while the oil which has been extracted from pure seed, that is, seed which has been subjected to a preliminary sifting process, and from which all extran¬ eous substances have been removed, as far as modern de¬ vices will permit, is at all times an object of especial con- THE MANUFACTURE OF LINSEED OIL. 7 sideration to the practical varnish maker. A certain pro¬ portion of non-drying oil extracted from the oleaginous substances is always present in an oil made from impure seed. The product acts most injuriously on the dry¬ ing properties of the whole, unless special and prolonged treatment be accorded it. Under the most favorable treatment such oil is undesirable for the manufacture of a superior varnish by reason of the fact that, although an extended period of time be permitted for repose, during which the vegetable and fine mineral substances may be effectively precipitated, the non-drying fluid will remain irremovably in solution with the linseed oil, partly owing to the similarity of specific gravities and other affinities, the result proving a defective product. Under no circum¬ stances should oil of this nature be set aside for ultimate use in the varnish manufactory. No artificial conditions which may be superimposed on an oil of this description, can elevate it to the standard of an oil made from pure seed which has been allowed a sufficient settling period. The impure oil under the sulphuric-acid-refining process shows a large percentage of loss, the charred and pre¬ cipitated impurities being in proportion to the extent of its impure condition. When linseed cake as a feeding product commands a good price and the concurrent demand for oil is slow, and at a price where a very narrow margin of profit is ob¬ tainable, many of the small crushers improve the oppor¬ tunity by working off any variety of seed which comes their way without preliminary screening; thus the extran¬ eous substances all go to increase the weight of the cake, and the oil is sold on the market as a pure article. It mav further be added that there are oil mills which turn out just such oil right along, hence the necessity of adopting the only precautionary measure possible to insure the obtaining of a pure oil, that is, to purchase di¬ rect from a reputable crusher. 8 THE MANUFACTURE OF LINSEED OIL. ABSOLUTE REQUIREMENTS IN THE MANUFACTURE OF A PURE LINSEED OIL. Briefly, it may be stated that the general principles which govern the manufacture of a pure oil are composed of four distinct processes: 1st.—Thorough screening. 2d.—Fine grinding. 3d.—Correct manipulation of the ground material in the treating kettle, with regard to temperature, moisture, etc., etc. 4th.—Adequate pressure for the extraction of the oil from the prepared material. Subjected to from 3,500 tbs. to 4,000 tbs. pressure per square inch, the oil is squeezed out from the ground and heated material, and falls from rear of the press to suit¬ able receiving tanks beneath. At this stage—two or three hours after the oil is made —the first important step in the treatment of the oil takes place. It consists in slow filtration and is accomplished by passing the oil under light pressure through filtering material, prior to being pumped into the large storage tanks to await shipment. The filtering material referred to is held in position in the chambers of a press formed by circular-formed concave plates, between each succes¬ sive two of which cloths of different textures are placed, through which latter the oil is caused to pass, leaving the footy matter on surface of the cloths. There are various sizes and forms of filter press, particulars of which will be hereafter given in detail. A reprehensible system with regard to filtration is maintained in some instances, which consists in raising the temperature of the oil im¬ mediately after being made to about 200 degrees Fahren¬ heit to facilitate its transmission through the filtering material. The heating is effected by means of a coil of THE MANUFACTURE OF LINSEED OIL. 9 steam-piping arranged in circular form around the in¬ ner side of the receiving tank, placed immediately below the presses. In this abnormal condition the oil is forced through the filter press. A sample of oil taken as it flows from the filter press presents the aspect of a well-settled liquid; but the appearance is deceptive, owing to the fact that many substances in the oil, 'with regard to foreign matters, and that unctuous extraction of the oleaginous proportion thereof, become soluble and imperceptible in the oil when the latter is heated—although they assume the opposite physical condition when the oil is cold— and these objectionable substances are thus carried through the filtering material with the oil. Examination of a sample of oil taken under these conditions and al¬ lowed a few days’ settling will at once -demonstrate the amount of precipitated matter which under normal con¬ ditions should have been retained by the filtering ma¬ terial. Instead of eliminating from 90 to 96 per cent of the im¬ purities—the normal proportion under correct manage¬ ment—only from 60 to 80 per cent, and not infrequently a still lesser proportion, is retained by the filtering ma¬ terial, the surplus extraneous matter passing off with the oil, a circumstance which the filtering apparatus was especially designed to obviate. An equal length of time is requisite for the complete precipitation of footy matter to produce a clear oil under these conditions, as though the filtering machine were not in operation. The true solution of this difficulty consists in permitting the oil to cool prior to filtration. It is an egregious mistake not only to increase the temperature of the newly-made oil for the purpose of facilitating the filtration process, but also to permit its passage through the filter press at the temperature which it retains by reason of the heat applied to the crushed seed in heating kettle, to 10 THE MANUFACTURE OF LINSEED OIL. promote the oil yield. The licjuid should be allowed sufficient time to cool in cone-shaped receiving tanks, situated immediately beneath the hydraulic presses, the tanks to be further utilized not only as temporary recep¬ tacles for the newly-manufactured oil, but to facilitate the correct return of the regular oil yield of each watch, as well as for the deposition of the mealy matter. Sufficient pitch should be given to the cone to permit of the thick, sludgy substance working down to the point from which it may be drawn off in concentrated form at stated in¬ tervals, The accumulation of this substance may be drawn off in this manner with great facility, and a com¬ paratively clear oil is continuously passing from the upper part of the tank, through the overflow pipe, the lat¬ ter entering the tank several inches from the top. The thick, mealy substance is then slowly reworked, and much labor is saved by securing it in this practical man¬ ner, as compared with the old system, which consisted of pumping direct to storage tanks, the oil, with its ad¬ mixture of meal, thereby involving unpleasant and arduous labor in frequent tank cleaning. It is customary in ordinary mills to have small square tanks to receive the oil as it flows from the presses, and from which the meal^ is removed daily, but tlieir utility is much inferior to the cone-shaped tanks referred to. Under the most favorable conditions, a certain propor¬ tion of the mealy matter will have been taken up by the pump, and together with the oil, will be pumped to stor¬ age tanks. With ordinary care this is practically impos¬ sible in the new design, and the sum total of attention which the latter demands to ensure a very effective separation of the oil from the foots is the withdrawal of the latter twice or thrice daily by the attendant. Probably two or three pailfuls from each tank on each watch will amply suffice. In the removal of the foots THE MANUFACTURE OF LINS'EED OIL. 11 from the square receiving tanks, necessarily a large pro¬ portion of the liquid is withdrawn; also, all of which must be again worked off uniformly, and its distribution, which must be effected by the exercise of good judgment, very frequently occupies the entire time of a mill hand. The cone-shaped settling and receiving tank very mater¬ ially lessens the amount of foots to be reworked, for the reason that there is absolutely no oil withdrawn with the foots, and the solidarity of the latter facilitates its admix¬ ture with the pulverized parings, or cake trimmings, be¬ neath the small set of millers now generally used for that purpose. Mention must be made of another very desirable feature of this form of tank, which consists in the very material improvement in the filtration process superin¬ duced by its use. The precipitation of the foots in the cone-shaped tank, in the first instance, lessens the amount of work the filter press would otherwise have to perform, and lengthens the intervals between cleaning times; that is, the chambers of the filter press will not require opening for the removal of the caked meal so frequently as under other conditions, while the filtering process is maintained under less pressure and in a much more per¬ fect manner. The writer has constructed a number of these tanks within the past few years, the result proving in every instance of the -most satisfactory nature. A heated and rapidly-filtered oil requires almost as much time for repose to effect complete precipitation of the extraneous matter as though it had not been filtered, and the good results derived from filtration under ef¬ ficient management are thereby lost. The filtration of a cold oil consumes considerably more time than an oil the normal temperature of which has been increased. As previously pointed out, the heated oil passes rapidly through the filtering material under light pressure, but the cold oil, that is, oil at the normal temperature, cannot 12 THE MANUFACTURE OF LINSEED OIL. be filtered so expeditiously by reason of the fact that the retention of the almost entire proportion of the footy matter by the filtering material tends to clog the latter, and fill the chambers more frequently than is the case when the heated oil is filtered. The filtration process is therefore necessarily slower, with regard to an oil pos¬ sessing a normal temperature, but superior in quality to that treated at an abnormal temperature, while the manu¬ facturer has the satisfaction of knowing that the oil turned out under these conditions is of surpassing excel¬ lence, a circumstance which adequately compensates for the incidental expenses attached thereto. The expense involved in cleaning cloths and removing the caked substance from the clogged chambers of the press is very much more than off-set by the saving ef¬ fected in the prevention of the accumulation of the foots in the large storage tanks. Where the cone-shaped tank and filter press are operated conjointly in a seed-crushing establishment, an oil storage tank may be filled and emptied regularly for years without the necessity of tank-cleaning becoming apparent, while without their use every two or three months a removal of the accumu¬ lated foots becomes am absolute necessity. To those who know the amount of manual labor involved in the clean¬ ing of a linseed oil storage tank, the number of barrels resting on their chimes, with the heads removed, neces¬ sary to contain the foots removed therefrom, and which when filled to about three-quarters of their capacity must await their turn for weeks to be reworked, their presence lending a general air of confusion and untidiness to the entire manufacturing premises, the expense and other unpleasant incidental concomitants, it will be superfluous to add further description. These two important ad¬ juncts to oil milling—the cone-shaped receiving tank and filter press—have removed many of the objectionable THE MANUFACTURE OF LINSEED OIL. 13 features in the manufacturing processes heretofore un¬ avoidable, and no well-regulated mill can be oper¬ ated without them, A pressure up to 70 pounds per square inch may be maintained consistent with good work, at which point the pump should be shut off, the press allowed to drain, opened, and the footy matter removed. The inlet flow should be regulated so that a uniform stream of oil may be passed through, and the fact must always be borne in mind, the slower the liquid is passed through the filtering material, the more superior the filtration process will be. The temperature of the oil should not exceed 75° Fahr, The only instance where crude oil may be heated to advantage is where more than one filtration process is performed; the first run of oil depositing the thick sedi¬ ment on the filtering material and passing through, after which, when allowed time to assume its normal tempera¬ ture, is again subjected to a slow filtration, producing a clear and pure oil. In the preparation of a refined oil, and not infrequently that of a varnish oil, recourse to two or three filtering processes is regularly made. After the lapse of sufficient time for repose, say three months, the oil is specially treated for varnish making. In the treatment accorded linseed oil intended for use in varnish making, every precaution which practical experi¬ ence has found essential to adopt must be carefully ob¬ served to ensure satisfactory results. Until within a comparatively recent period the business of preparing linseed oil for use in varnish making formed a distinct and separate branch of industry from that of the manufacture of the crude product, but with the progres¬ sive spirit of the times, a number of the leading crushers in England and the United States have been constrained to enlarge their sphere of action by supplementing their original calling with that of refining, boiling and general 14 THE MANUEACTURE OF LINSEED OIL. manipulation of the oil within the confines of their indi¬ vidual manufacturing precincts. In past generations the duties of the seed crusher terminated with the manufacture of the raw product, but the modern seed crusher to keep pace with the times, must not only be conversant with the most approved ma¬ chinery and manufacturing processes, but a knowledge of chemistry is indispensable, in as far as it appertains to the oil itself, together with the ingredients used in its manipulation, to meet the various requirements essential in paint and varnish making. The underlying principles which control the diversified aspect of linseed oil in its changing physical properties must be thoroughly understood when under treatment, the exact nature of the latter, with regard to temperature, chemical and mechanical action, consistent with the use to which the product will be ultimately assigned. A thorough knowledge of this important industry in all its phases has, therefore, resolved itself into a science, in which category it may be justly placed. Very many methods of preparing oil for the needs of varnish makers diave been successively adopted and, in turn, abandoned by reason of the introduction of a more recent expedient which gave promise of better results. There are a number of methods, now in regular use, for the preparation of linseed oil well suited to the re¬ quirements of varnish making, each manufacturer hav¬ ing special processes and formulas which accord with his individual views of the necessities of the case, the knowl¬ edge of which he jealously guards as an inviolable trade secret. Linseed Oil Fecnliarities—Consideration of the Yarions I'lethods Used To-Day to Produce Best Results—The Oil Percentage in Cake. ' ^ Among the methods hereafter described, in which reference will be made to the latest and most approved known in the preparation of linseed oil for varnish pur¬ poses, many valuable hints-will be given relative to their practical demonstration of efficiency, the .careful con¬ sideration of which, it is presumed, will prove serviceable and of material consequence to the practical and progres¬ sive varnish maker. In the treatment of linseed oil for use in varnish-mak¬ ing, the primary object in view is to facilitate its assimila¬ tion with the gums, possessing good siccative properties, and other inherent qualities, characteristic of a pure oil. The first step in the manufacturing process consists in pro¬ curing an oil of pure make, of mature age, and a known brand. The chief difficulty which the operator experi¬ ences with an imperfectly prepared oil consists in the “breaking” or separating proclivity inseparable from an impure oil. In an impure or imperfectly prepared oil, the separation of the fine vegetable matter, which becomes apparent when the temperature has reached a point be¬ tween 400° or 500° Fahr., is not the only difficulty which confronts the varnish maker, for the reason that the gummy substance which assumes definite formation at this temperature, has a marked tendency to discolor the batch under treatment, and which, by the undesirable combination, is sometimes irrecoverably spoiled. It is, therefore, of paramount importance to thorough¬ ly eliminate this mucilaginous matter, by whatever means employed, if a good varnish is to be produced. If the combination of mechanical and chemical processes prove ineffective by reason of the fact that the operative may 15 16 THE MANUFACTURE OF LINSEED OIL. not be conversant with the precise and exact mode of application requisite to procure the desired results, which the least deviation therefrom will assuredly demonstrate, recourse may be had to ageing of the product, which, if not discolored by previous operations, will in every in¬ stance prove satisfactory. The fine substance which remains suspended in the oil, to the eradication of which the energies of the chemist and practical oilman have been devoted, is imperceptible in the crude oil and in many of the prepared oils, but its presence is plainly demonstrated in the test tube, in from twenty-four to thirty hours subsequent to heating. Thousands of gallons of varnish are regularly made with oil containing this substance, the presence of which may be unknown to the operator in the preliminary pro¬ cesses of varnish making, the manufactured product proving in many respects of a satisfactory nature, but it has been incontrovertibly demonstrated that the oil from which this substance has been entirely removed produces a superior product, viewed from every phase of the ques¬ tion. That proportion of the crude oil which possesses greater specific gravity than that of the pure product, is the substance which should be eradicated. The difference in specific gravity is not apparent until the lapse of a certain time subsequent to heating, when its presence becomes plainly visible, and the advantages deriving from the mechanical and chemical combination when effective, consist in the precipitation of this substance without having recourse to the usually extended period of set¬ tling, otherwise absolutely indispensable. Extended time will invariably remove this substance in an oil treated by the sulphuric acid process, but a crude oil, however long permitted to settle, will “break” when submitted to a high temperature. As previously stated, THE MANUFACTURE OF LINSEED OIL. 17 its elimination may be effectively procured by simultan¬ eous chemical and mechanical treatment. Many reasons have been advanced as to why this sub¬ stance has become more troublesome than in former years, and for the removal of which much greater pains must be taken than was heretofore necessary. Probably the most feasible reason which may be cited is.that owing to the perfection to which hydraulic pressure has been brought in its application to the crushed seed, and by means of which the uniform and maximum amount of pressure may be maintained unrelaxed during the entire pressing operation, a fine substance of a mucilaginous or gummy nature, much more delicate in formation than the ordinary vegetable matter, is pressed out with the oil. At a normal temperature its presence in a specially- prepared oil is uncertain, owing to the similarity of spe¬ cific gravity, and not until the oil has been submitted to a high temperature, and subsequent to a brief repose, is its presence indicated, the proportions of which determine the efficiency of the refining process. Less than a generation ago, the percentage of oil left in the cake, subsequent to the application of hydraulic pres¬ sure, was as high as 13 per cent, but nowadays the stand¬ ard amount is placed at 7 per cent, a very material differ¬ ence. An excess of oil over this latter amount is con¬ sidered as just so much loss—as oil—a slightly redeeming feature in the matter being the weight of the surplus oil left in the cake realizes the same market value as the cake itself, thus the difference in value between the oil and the cake is lost to the manufacturer. It is this increased amount of oil extracted by superior mechanism which contains the fine flocculent substance, the removal of which becomes of such importance in the manufacture of superior varnishes. To this circumstance is due the suggestion that the admixture of the oil which 18 THE MANUFACTURE OF LINSEED OIL. flows freely before the limit of pressure has been reached with that extracted under the maximum pressure should be obviated, thus rendering a large proportion of the newly-made oil free from the fine vegetable matter al¬ ways present in the oil obtained under the latter con¬ ditions. Several of the leading seed crushers in the United States have adopted a system by means of which the oil extracted under the light pressure may be effectually separated from that produced under the maximum pres¬ sure, and without relaxation of the latter, the results proving of such a satisfactory nature as to warrant its continuance. The oil obtained by the first flow is re¬ served for refined oil, which includes varnish oil; the resi¬ due—after the ordinary clarification and filtration pro¬ cesses have been executed—is finally utilized for boiled oil, or in the various ways in which the product is applied. Instead of one tank, which is usually placed immediately beneath a set of presses to receive the newly-made oil, two are set side by side. Into tank number one, the first run of oil yielded under light pressure is caused to flow, but as soon as the reduced volume demonstrates the fact that the light pressure has reached the limit of useful¬ ness in expressing the fluid, and prior to the application of the heavy pressure, the spout leading from the small trough which receives the oil as it falls from the press, is changed to number two tank, into which the succeeding or second run of oil is discharged. Thus, the oil which is obtained under the prolonged and maximum pressure is in no manner associated with that procured by the initial pressure, the system being maintained continuously, the volume flowing from the successive charges of the press being divided as shown. The seed being of good cpiality and thoroughly screened, and the manufacturing pro¬ cesses maintained throughout in an efficient manner, the THE MANUFACTURE OF LINSEED OIL. 19 oil from the first drawing, subsequent to the usual pre¬ liminary treatment, invariably proves to be an excellent varnish oil. ■« The oil extracted subsequent to the first run contains a high percentage of the objectionable vegetable matter, and its complete removal in the production of a superior varnish oil becomes difficult of accomplishment, even under" the most auspicious circumstances. It may be cited, as an exceptional instance, that one of the seed-crushing establishments in England, by means of fine rolling, thorough cooking and greater pressure on the material than heretofore used, contrives to reduce the percentage of oil in the cake to a point below four. The tenacity and durability of the new press bagging material, recently introduced, renders possible the fore¬ going surprising results. In the United States several of the oil mills regularly manufacture cake with a per¬ centage of oil rarely exceeding five. The increased proportion of fine vegetable matter which is unavoidably pressed out by this more perfect method, will be readily understood, and the use of pre¬ cautionary measures of separating the grades amply war¬ ranted. The adaptability of the second run to the peculiar re¬ quirements of boiled oil are readily demonstrated when applied to a surface, subsequent to suitable treatment. Unlike oil intended for use in varnish making, to suit the views of the average consumer, boiled oil must possess a deep color. This physical property is attained by the application of heat and air in conjunction with driers, the chemical ingredients of which, acting as pre- cipitants of the feculent matter, and after the expiration of about two weeks, produce an excellent boiled oil, deep in color and transparent to the view. The presence of an abnormal proportion of the extraneous substance, due ‘20 THE MANUFACTURE OF LINSEED OIL. to improper filtration or insufficient subsidence, mani¬ fests itself in an oil under treatment by discoloring- the latter. Hence the necessity of carefully avoiding the use of an oil for varnish purposes possessing the objection¬ able features referred to. It has been ascertained beyond doubt, that oil obtained during the period when the hydraulic system is strained to its utmost capacity con¬ tains a large proportion of imperceptible substances which remain in solution in the oil when cold, passing out freely with the latter from the filter press, to appear in tangible form subsecpient to the application of heat, in light fragmentary particles. A peculiarity of the latter consists in the fact that their presence is not indicated until about thirty hours after the heating process. An absolutely sure method of eradicating this substance, the presence of which is imperceptible in some prepared oils, consists in heating the latter to about 350° Fahrenheit, and after forty-eight hours’ repose subjecting them to slow filtration. About thirty hours subsequent to the heating process the fine substance assumes material form and readily deposits on the surface of the filtering medium. This additional treatment may be conducted without discoloring the oil, the reverse, a bleached oil, being produced thereby. Oil treated by the alkali or sulphuric acid process, subjected to a supplementary heating process, of brief duration, becomes bleached, but owing to the expense involved, except in special cases where fanciful prices warrant its use, it is impracticable. The Russian-made linseed oil, from thirteen to fifteen per cent of which is guaranteed to be revealed on cake analysis, with suitable treatment, is peculiarly fitted for varnish purposes. But the Russian varnish maker is slow to appreciate the advantage here presented, while the national demand for a superior product is not sufficiently pronounced to prove a stimulus to further progress. THE MANUFACTURE OF LINSEED OIL. 21 The fundamental principles which should govern the preliminary operations in the treatment of an oil intended for use in varnish making consist in thorough clarifica¬ tion and filtration in the first instance, followed by a sec¬ ondary process, by means of which the suspended matter may be eliminated, and the oil bleached concurrently. The purification and bleaching processes are effected by the use of sulphuric acid or alkali, generally, and after the expiration of a suitable period for the subsidence of the charred vegetable matter, washing is resorted to for the removal of the last vestiges of impurities. Two or three days’ additional repose is then permitted the oil, after which the water is drawn off and the clear oil pumped into a steam-jacketed kettle fitted with agitators, and submitted to the influence of a temperature not ex¬ ceeding 200° Fahrenheit. This effectually removes the moisture present in the oil, while the air which by means of forcing pumps is simultaneously blown into the mass of agitated oil, oxidizes and imparts “body” thereto by lessening its fluidity. A well-made oil treated in the foregoing manner, with correct proportions of the purify¬ ing agents, and strict adherence to the regular mechani¬ cal auxiliary processes, will produce a liquid of uniform consistency, bleached and transparent, which will not “break,” or separate, or evolve irregular action when undergoing treatment in the production of a superior varnish. Slow filtration and subsequent repose materially improve and ultimately produce a perfect varnish oil. To impart to the oil a still further bleached aspect than commercial requirements ordinarily call for, the influence of solar light is sometimes brought into requisition, sub¬ sequent to the chemical manipulation and immediately before the final filtration process. Flat copper-lined tanks placed immediately beneath extensive glass roofs are used for this purpose; the oil placed therein being of 22 THE MANUFACTURE OF LINSEED OIL. shallow depth to facilitate the action of the solar influence. The difficulties which may arise in the varnish kettle with regard to the oil are attributable to one of several causes: an impure seed, an improperly manufactured or prepared oil, immature, or a product of too recent treat¬ ment, any of which defects will suffice to give endless trouble in the manipulation of the ingredients. Linseed oil produced by the percolation of benzine, gasoline and other powerful solvents is at a discount among varnish and paint manufacturers generally. The odor of the solvent clings to the oil, its offensive nature tainting it more or less, its removal involving additional expense. The same principle which governs the removal of the chemical traces in the refining processes is applic¬ able here, but the current market prices for linseed oil are adverse to such increased expenditure in the produc¬ tion of the naturally odoriferous product. In the United States, where the process was first introduced on a large scale, the percolation system is looked upon with dis¬ favor, and the danger to life and property involved there¬ by has stimulated the legislative bodies of the majority of the respective States to pass prohibitory laws relative thereto^ which have the effect of restricting the producers to the older and safer system—that of hydraulic pressure. A few “years ago an expensively constructed percolator plant, located at Toledo, Ohio, was blown to atoms by some unfortunate blunder. A naked light was probably permitted to remain in too close proximity of the escap¬ ing fumes of the volatile fluid, and the inevitable result followed—the destruction of property and loss of sixteen lives. A small plant for the manufacture of linseed oil by this system is yet in,operation in Ohio—the only one of its kind in the United States—restrictive measures not having been enforced in that State. Several years ago, in Illinois, the writer dismantled a well-equipped plant, THE MANUFACTURE OF LINSEED OIL. 23 consisting of twenty-four large perqolators, condensing tubes, reservoirs, and all the necessary apparatus, includ¬ ing the expensive and diversified steam system, the com¬ bination, which had only been in operation a few months, costing nearly |!l50,0l)0. The proprietors resumed the manufacture of linseed oil under the old hydraulic pres¬ sure system. A simple measure which ensures reliability in the use of a pure oil consists in purchasing direct from a repu¬ table crusher. Having succeeded thus far, the next im¬ portant step in the evolution of a superior oil com¬ patible with efficient management, is the degree of care which must be exercised in the preliminary treatment of the product and in the various subsequent processes. Oc¬ casionally a batch of oil manufactured in the most ap¬ proved manner from screened and well-developed seed, warranted to have been submitted to the usual refining processes in the most skillful manner, and apparently possessing all the essential requirements of a superior varnish oil, surprises the operative by developing features decidedly repugnant to the latter, and at times causing the operation to be brought to a standstill. Investigation is set about, and very often the exact origin of the diffi¬ culty is involved in impenetrable mystery, all efforts to satisfactorily solve the problem being unavailing. In this dilemma not infrequently the crusher comes in for a large share of unmerited abuse, but the true solution of the difficulty may be traced to some irregularity of the chemical or mechanical treatment. On occasions, how¬ ever, lins.eed oil, made subject to suitable conditions and absolutely correct treatment from a mechanical and chemical standpoint, and apparently possessing all the properties of a first-class product, is nothing if not mys¬ terious in its behavior when under treatment in the varn¬ ish kettle. 24 THE MANUFACTURE OF LINSEED OIL. The oil which is,absolutely without defect, and which may be appropriately designated the beau ideal of the varnish maker, is manufactured by the cold-pressed sys¬ tem. The absence of artificial heat and moisture, to¬ gether with the gradual application of a pressure much less than that which now obtains, very materially lessens the amount of mucilaginous matter which abounds in the ordinary oil of commerce extracted by the simultaneous action of heat, moisture and enormous pressure. The comparatively small proportion of the latter found in an oil manufactured by the cold-pressed system is readily removed. But, under current prices of the raw and manu¬ factured products, a brief continuance of this method of manufacturing oil would speedily reduce the crusher to a condition of insolvency, the average yield varying from 18 to 22 per cent, a very considerable diminution from the present standard of from 30 to 35 or 36 per cent. The adequate price which the cold-pressed oil must neces¬ sarily command to ensure reasonable returns to the crusher is far removed from that entertained or con¬ sidered commensurate by the average varnish maker, however perfect the product may be, viewed from all standpoints; hence the impracticability of permanently producing linseed oil under such prejudicial conditions. To procure the full proportion of extractable oil by the hydraulic pressure system, heat, moisture, and pressure, suitably applied subsequent to fine rolling, become in¬ dispensable conditions. Owing to the keen competition which prevails, the trend of the times is to produce the maximum amount of oil—a circumstance which renders necessary the adop¬ tion of extreme measures in the purification of the pro¬ duct. -A^s an additional stimulus to the crusher in this respect, it has been demonstrated by agricultural chem¬ ists that the cake which contains a proportion of oil not THE MANUFACTURE OF LINSEED OIL, 25 exceeding- 7 per cent, is preferable as a stock feeding product, to that which contains the greater proportion, varying from 10 to 13 per cent. In the treatment of oil intended for use in varnish¬ making in bygone times, the only requirement con¬ sidered essential was sufficiently prolonged repose to effect perfect subsidence of the suspended impurities. But under modern conditions it has been demonstrated that subsidence and filtration are of themselves insuffi¬ cient to produce an oil suitable to the requirements of varnish making, hence the introduction of chemical treat¬ ment of various forms in conjunction with the concur¬ rent action of mechanical devices to produce the desired results. An oil which has not been subjected to the cus¬ tomary treatment, but retained for the purpose of matur¬ ing, will sometimes develop a permanent rancidity owing to the fermentation of the impurities, thus seriously de¬ teriorating the quality of the oil. The success of the re¬ fining processes and the proportions of waste are materi¬ ally influenced b)" the physical condition of the oil. The alkali method of refining is much more wasteful than that of sulphuric acid. No known substance—excepting charcoal—can so effectually bleach and purify linseed oil as sulphuric acid applied in a suitable manner. The sys¬ tem of percolation by means of charcoal is, however, im¬ practicable by reason of the great waste involved. It may be further added that no known substance so effectu¬ ally nullifies the properties essential in a good varnish oil as sulphuric acid injudiciously applied. A comparatively small proportion of the acid added to the oil in excess of the normal amount will cause the whole to vigorously attack the suspended impurities, their charred condition discoloring instead of bleaching the product, the propor¬ tion of waste being exceptionally high, while washing, however prolonged, will fail to remove the traces of the 26 THE MANUFACTURE OF LINSEED OIL. powerful chemical fluid. Although caustic alkali is some¬ times used with good results, it frequently occurs that the prolonged agitation develops an emulsion of soap and oil which render clarification subsequently a very difficult matter, the result being that the utility of the batch of oil is seriously jeopardized. R. von Wagner suggests the use of zinc chloride instead of sulphuric acid or caustic soda, as this substance clears the impurities without at¬ tacking the oil. The zinc chloride is used in concen¬ trated solution of l.(S5 specific gravity and thoroughly agitated with the oil. After the chloride solution is with¬ drawn, the oil is well washed with water and filtered in the usual manner. Tannin is used in some cases to clarify the oil, which it effects by coagulating the albu¬ men, thus facilitating its precipitation. The cheapest and by all means the most practicable method of preparing linseed’oil for use in varnish making in large quantities is by the sulphuric acid process. LINSEED OIL REFINING PROCESSES ON MANUFACTURING SCALE. A brief description of the exact forms of treatment of linseed oil in large quantities, intended for use in varn¬ ish making, as practiced in the leading refineries in Europe and the United States, may be apropos at this time. For the especial method which we now purpose describing, the apparatus brought into requisition con¬ sists of two large, open tanks or vats, one placed im¬ mediately beneath the other. Each tank should be of the capacity of 4,500 gals., about, lined with lead, and fitted with a vertical shaft, resting in a hollow step on the bottom centre. To the vertical shaft strong wings, or blades of common hard wood, are securely adjusted in a horizontal and parallel position. This constitutes the agitator or mixer, and is operated by steam power, at a THE MANUFACTURE OF LINSEED OIL. 27 speed not exceeding eighty, and not less than sixty revo¬ lutions per minute. In some establishments air only is used as a means of agitating and mixing the oil and acid, a very excellent product being the result, its super¬ iority, however, being largely dependent on the exact character of the treatment. The lower receptacle, also lead-lined, of similar formation and capacity to the upper one, lacks the interior ecjuipment essential to the former. A coil of lead piping, perforated with minute holes in the upper part, is spread over as much surface of the bottom of the vat as will uniformly distribute the steam through¬ out the oil, the pipe being closed at the end. This has the effect of producing a thorough commingling and mixing of the steam through every portion of the mass of oil. It is essential to have the vats lined with lead, and that part of the steam piping which is below the surface of the oil in the vat must also be of that metal, owing to the resis¬ tance it offers to the action of the sulphuric acid. The lead pipe is connected at the top of the vat with ordinary iron steam piping running direct to the boilers. The upper vat is filled to two-thirds of its capacity of well-set¬ tled and filtered oil. A solution of sulphuric acid of 66° Baume, previously prepared, in the proportion of about 280 tbs. of acid to 100 gals, of cold water, is now added to the 2,000 gals, of oil, the agitator being put in motion simultaneously. This has the effect of niixing the com¬ bination in a most effective manner. The introduction of the chemical solution must be carefully performed, and the agitation continuously maintained for a period of five hours. The acid attacks the yellowish coloring matter, producing a partial saponification, the subsequent pre¬ cipitation of which has a decided tendency to bleach the oil. The method of introducing the acid into the oil varies, and is carried out in accordance with the preconceived 28 THE MANUFACTURE OF LINSEED OIL. ideas of the refiners. For instance, sometimes the acid is added to the oil in its full vigor, without dilution of any kind, the chemical action on the oil being exactly similar to the foregoing method under normal conditions. It has been demonstrated, however, that this method of adding the sulphuric acid in the preparation of varnish oil is defective, by failing to produce results of as satis¬ factory a nature as that of a weaker solution process. Sulphuric acid is used in full strength, and in much larger quantities in the treatment of refined oil for use in white lead, etc., etc., and subjected to subsequent treatment of a peculiar nature and of too expensive a character to be accorded the ordinary varnish oil. In the preparation of the latter, the weak solution method is more suitable, and should be selected in every instance. The undiluted acid, while charring the impurities perfectly, that is, those impurities with which it comes in immediate contact, fails to perform the same function on the entire mass of oil, however well the agitation may be maintained, with the same degree of uniformity characteristic of the solution. The impurities held in suspension immediately beneath the surface of the oil, and which come into direct contact wdth the acid as it falls from the carboy, will first receive the full charge, and be energetically attacked and transformed into a charred condition, but the subsequent dissemination of the purifying fluid fail¬ ing to exercise a similar effect on the other portions of the oil, a defectively-treated product is the inevitable result. Owing to the increased proportion of acid and the special treatment accorded the regular refined oil of commerce, these objectionable features are obviated. In the preparation of the varnish oil, the introduction of the undiluted acid, where this method is used, may be materially modified by permitting the latter to enter the oil very slowly, and in minute streams from vessels con- THE MANUFACTUl^E OF LINSEED OIL. 29 taining the purifying liquid, placed at even distances apart over the oil’s surface, but by whatever means ap¬ plied, the results are inferior to that of the solution system. At the expiration of the specified time allotted for mixing the contents of the upper vat, the mixture is caused to run into the lower or steaming vat. The perforations in the lead pipe coil spread over the bot¬ tom of the vat enable the escaping steam to be not only uniformly distributed throughout the oil, but to enter the latter with great force; thus facilitating the continuous changing of position of the treated oil, and bringing the steam into direct contact with its every por¬ tion. The object in this steaming or washing process is akin to that practiced in the refining of petroleum, which is the eradication of all traces of the purifying factor. Subsequent to the washing process, and during the settling period, the condensed steam in the form of water facilitates the precipitation of the acid previously dissemi¬ nated throughout the oil. The steaming operation is maintained for a longer or shorter period in harmony with the established views of the refiner. Six hours is the standard time in some refineries, while others vary the continuance of the operation very considerably in periods ranging from six to forty hours. At the termination of the steaming process, the oil should be permitted undisturbed rest for at least forty- eight hours, during which the subsidence of all matter present in the oil will have been materially effected— water, sulphuric acid, and extraneous matter—while a clarified and well bleached product will float over all. I'he oil is permitted to remain in the treating tank in many cases for a more extended period, not infrequently a week or more, to still further facilitate the precipitation 30 THE MANUFACTURE OF LINSEED OIL. of suspended matter, after which the water is drawn off, and the following day the oil is pumped into temporary storage tanks, whence it is again withdrawn to be passed through the filter press, subsequent to which pro¬ cess it is finally pumped into permanent storage tanks for further settling and maturing prior to use. As an additional precautionary measure to effect the complete removal of moisture which may yet remain in the oil, subsequent to the steaming operation, the latter is sometimes submitted to a heating or drying process in a steam-jacketed kettle prior to filtration, and for a space of four or five hours maintained at a point in temperature below that which produces discoloration. By this means every vestige of moisture is driven off and the oil is very materially improved thereby. The steam- jacketed drying kettle should be equipped with an agi¬ tator to diffuse the heat throughout the oil. Another process equally efficient consists in using air as an agitating and oxidizing factor, coincident with the uniform distribution of the sulphuric acid added to the oil in the upper vat, instead of by mechanical agitation as described. The results chemically are similar, al¬ though there are refiners who maintain that the latter process is the more effective in producing a satisfactory product. A process of preparing linseed oil by bleaching and purifying through the aid of hydrate of alumina has established for itself a high reputation among consumers of refined, or varnish oils. In the treatment of linseed oil, hydrate of alumina as a purifying and bleaching factor possesses advantages over other substances peculiar to itself. Oil treated with this product is less liquefied or, in other words, possesses more “body” than that which is treated by the sulphuric acid process. The latter, while a superior bleaching and purifying agent, used in normal THE MANUFACTURE OF LINSEED OIL. 31 proportions and under suitable conditions, displays a marked tendency to reduce the specific gravity of the oil, the interpretation of which means, a greater or less liquefied condition and proportional decrease in flowing property and “body,” most undesirable features in var¬ nish. These are the chief objections to the use of sul¬ phuric acid, while the principal, if not the only objection to the use of hydrate of alumina, consists in the abnormal proportion of waste unavoidable in its use. However, where circumstances warrant the use of the latter—the consumer requiring a very superior oil and paying a commensurate price therefor—hydrate of alumina is brought into requisition among progressive varnish makers. As the waste referred to renders the general use of this system impracticable, we deem it scarcely nec¬ essary to give further particulars of the process. There are a surprising number of materials of a nat¬ ural or chemical composition, which, if applied to linseed oil in a suitable manner, will remove the jellified or gelatinous substance which becomes apparent when raw or improperly treated oil is submitted to the action of a high temperature. Ground lime, fuller’s earth in powdered form, zinc oxide, yellow ochre, alkali and very many other substances, when treated with linseed oil, produce bleaching properties coincident with the exercise of their cleansing or purifying powers. The writer has obtained excellent results by treating raw linseed wdth fuller’s earth with filtration as a final process. The drawback to this mode of treatment con¬ sists in waste, caused by the absorption of the oil by the fuller’s earth, the recovery of which would prove an expensive matter. In Germany, France and the United States, this system of refining is regularly operated, though on a somewhat limited scale, the residue of waste being used for certain classes of paint. Doubtless if a 32 THE MANUFACTURE OF LINSEED OIL. sufficient demand arose at remunerative figures for this variety of paint ingredient the adoption of the fuller’s earth system of purifying and bleaching linseed oil would become much more general. Refined cottonseed oil—the yellow variety—is treated with fuller’s earth for the purpose of producing a water- white aspect, and which product is known commercially as “Winter or Summer White.” Similar treatment will not only bleach linseed oil, but will effectually remove the gelatinous substance previously referred to and pur¬ ify it in a very efficient manner. Experiments are be¬ ing constantly made by practical cottonseed oil refiners to obviate the great waste the use of fuller’s earth en¬ tails, but so far without substantial results. To this fact is owing the relatively high price at which the “W^inter White” variety of cottonseed oil is sold. fuller’s earth as a refining agent. In the treatment of linseed oil a small percentage of fuller’s earth is mixed with the oil and briskly agitated for three or four hours, and succeeded by slow filtration to remove the impurities and fuller’s earth. Concur¬ rently with the former operation, which is sometimes accomplished in a steam-heated kettle, the mixture is submitted to a temperature of about 200° Fahr. for the space of one hour. This has the effect of bringing into operation the properties of the earthy substances, which bear a close resemblance to those of known alkaline composition, which are valuable purifying and bleaching agents, but, unfortunately, productive of anomalous waste. The best quality of fuller’s earth contains but little calcium or lime. The average analysis contains:— THE MANUFACTURE OF LINSEED OIL. 33 65 per cent silica. 20 “ alumina. 9 “ iron. 6 “ lime. 100 The component constituents of the product may vary considerably. Linseed oil improperly treated with ful¬ ler’s earth will sometimes show a greenish tinge. The writer has recently experimented successfully with ful¬ ler’s earth in linseed oil refining, by demonstrating that a well-bleached oil may be prepared by its use, together with the complete removal of the undesirable gelatinous matter. The absence of the latter became apparent on submitting a sample of the treated oil to a temperature of 550° Fahrenheit, thus producing a very superior var¬ nish oil. Ground glass and fuller’s earth intimately associated are sometimes used to effect the same object, the pro¬ portions of the earth being equivalent to three parts to one of ground glass. The use of ground lime as a purifying agent in lin¬ seed oil, in conjunction with zinc chloride, displays a wasteful saponification, even if used in very small pro¬ portions, a circumstance which renders its use imprac¬ ticable. A small sample examined several days after treatment showed a heavy percentage of loss, the sub¬ sided matter very much resembling a mass of animal grease. To still further bleach an oil which has been already submitted to any of the foregoing treatments, and by lessening the yellowish shade and producing an almost water-white oil, solar light exerts a salient influence. Probably the very best oil—that which commends it¬ self to the consideration of the varnish maker to a 34 THE MANUFACTURE OF LINSEED OIL. greater degree than any other prepared oil—is that which has been subjected to the action of solar light for a suitable period. As an essential part of the refining process, this principle demands consideration, and in the refineries noted for their uniform output of well- bleached and refined oil the system is maintained per¬ manently. In the establishment referred to, it is carried on as a supplemental or auxiliary process to the fore¬ going methods of treatment, the final one being, how¬ ever, that of filtration. It is most important that as large a surface of the oil as circumstances will permit should be exposed to the solar influence. By presenting an extended surface area of the oil and in shallow vessels, the solar rays effectively penetrate the fluid, and are materially facilitated in the bleaching functions they are expected to perform. A depth of about one foot should not be exceeded in the bleaching tanks. While it is incontrovertible that the sun’s chemical influence as an oil bleacher is of the highest order, it has also been ascertained that by ex¬ posing a very shallow proportion of oil—say four or five inches—to long-continued solar action, the heat radiat¬ ing from the latter tends to fasten the yellow coloring matter in the oil instead of eliminating it. To avoid the deleterious consequences resulting from either extreme, a depth of oil not less than nine inches and not more than twelve inches should be carried in the bleaching tanks. FORM OF TREATING TANKS AND REFINING EQUIPMENT. A modern refinery consists in having a series of large, square tanks—probably twenty feet square and about fourteen inches in depth—especially constructed for bleaching the oil, and in addition to the regular THE MANUFACTURE OF LINSEED OIL. 35 treating vats or tanks. The bleaching tanks are some¬ times copper-lined and in every instance should be sit¬ uated immediately beneath a large glass roof, so that the direct rays of light will fall upon the entire surface uninterruptedly. The oil is allowed to remain in the square tanks several weeks, after which period it should be slowly passed through the filter press, when it will be found a very superior oil, suitable for the finest variety of varnish, shall have been obtained. Tn Europe, linseed oil is not infrequently prepared for use in varnish making by this simple treatment only, the preliminary and subsequent conditions being a well-settled and thoroughly filtered oil, respectively. A method of bleaching oil is practiced in Ger¬ many, having in view that of solar light, by means of which, it is asserted, a thoroughly bleached oil is reg¬ ularly obtained, without recourse to other bleaching agents. It is well known that raw linseed oil, like other vegetable products of a like nature, if sufficiently long exposed, may be bleached by the action of solar light alone, but the length of time expedient to effect the de¬ sired object renders the adoption of this slow system, for commercial purposes, highly impracticable. The ex¬ posure of a small sample of oil in the most prominent position to the full radiance of the daylight, will probably require six months or more to lighten the natural yellow color which is characteristic of linseed oil, while the advantages derived from the German system referred to, and which will hereafter be described, consists in the fact that a well-bleached product may be obtained in as many weeks. By the aid of powerful reflectors the solar light is intensified and reflected with accumulated force on the surface of the oil in shallow tanks, similar to those pre¬ viously described. The bottom of the tank is some- 36 THE MANUFACTURE OF LINSEED OIL. times utilized by transforming it into a powerful reflector also, thus materially facilitating the bleaching process. It is alleged that better results are procured by this unique method of bleaching linseed oil than those of any other. But while a bleached oil may be obtained in this manner, it is diflflcult to comprehend how such a pro¬ duct from which the gelatinous substance has not been eliminated, and which therefore must be pronounced an inferior varnish oil, can equal from any standpoint—ex¬ cepting perhaps that of color—an oil prepared by acid treatment and which is absolutely freed from the deleter¬ ious matter referred to. A combination of the processes, each being a complemental essential in the general treatment of the oil, would seem to be the most feasible course to pursue in the production of a^ superior var¬ nish oil. It is' recognized that however long an oil may be permitted to settle, or to whatever mechanical treatment it may have been subjected, the complete eradication of the gelatinous substance which becomes apparent when raw oil is submitted to a high tempera¬ ture, cannot be effected without a material chemical treatment. Several years ago, in Chicago, the writer received a trade circular, a copy of which was distributed among varnish men and paint manufacturers generally, an¬ nouncing the fact (?) that a refined or varnish oil was placed on the market treated by mechanical means only, and which was guaranteed to equal in working prop¬ erties refined, or varnish oil, prepared by the combination of mechanical and chemical processes. Special stress was impressed on the trades, especially white lead man¬ ufacturers, that the absence of acid traces in the oil rendered its use in grinding absolutely without defect, while for varnish making it was also stated it was super¬ ior to anything previously introduced. But upon being THE MANUFACTURE OF LINSEED OIL. 37 put to the practical test, while its aspect appeared fault¬ less, the product was found lacking the essential re¬ quirements of varnish making and its ephemeral exist¬ ence was speedily relegated among the things of the past. It is a comparatively safe assumption to state that for ordinary commercial purposes all refined linseed oil is prepared by the sulphuric acid process. The practica¬ bility of treating large quantities of oil at a single opera¬ tion renders its use most economical, as compared with other methods. Probably the very best bleached oil—that which is water-white—is obtained by filtration through charcoal or animal black; but the great waste involved, together with the tediousness of the filtering operation, are insur¬ mountable difficulties in the way of its general adoption. From 40 to 50 per cent of waste is incurred, while the minute stream of oil which percolates through the filter¬ ing medium at the commencement of the operation, gradually decreases until drops descend with slowly-in¬ creased intervals between each, circumstances which un¬ mistakably point to the fact that the material is becoming rapidly gummed up—another objectionable feature char¬ acteristic of charcoal and animal black. In all methods of oil bleaching, none can produce an absolutely pure water-white oil—the charcoal process alone excepted. A slight yellow or greenish shade will be perceptible in a sample selected from the best variety on the market. Nevertheless, within the past two years a refined oil has been introduced in the United States which has attracted very considerable at¬ tention among varnish men, owing to the fact that it closely approaches the standard as set by the charcoal process, viewed from a color standpoint, while its action under treatment in the varnish kettle is all that need be desired. The process is patented in England as well as 38 THE MANUFACTURE OF LINSEED OIL. in the United States, and a brief description of its main features may prove interesting. VEGETABLE OIL REFINING BY MEANS OF THE OCHRE PROCESS, The patentee claims for his invention an improved method of refining cottonseed oil, linseed and analogous oils, rendering same of very superior quality. The pro¬ cess is carried out by the use of hematite or limonite, or any similar substance of the nature of a pigment, which does not injure the oil as an article of food, as in the case of edible cottonseed oil. By mixing and agitating the previously prepared ochre, in certain proportions, with the oil to be refined, the gum, resin and coloring matter contained in the oil are taken up and separated from the oil, thus purifying and refining it. In the prac¬ tice of the invention, the patentee further states that the ochres may be employed alone as the refining agent, or in connection with other materials, by mixing thoroughly with the ochre and treating the oil therewith, or by em¬ ploying such materials as a preliminary or subsequent treating agent, before or after the oil has been treated with the ochre. The ochre is prepared by removing all uncombined water by the application of heat, the latter maintained until an orange color is assumed. In the use of umber and siennas, the heat is continued until the former becomes a deep brown, and the latter a light red color. In some instances the ochre is dried and pulverized to fineness, and used in from four to twelve parts of oil to one part of ochre, according to the amount of impurities the oil contains. The combined oil and ochre is then briskly agitated for forty minutes, and as soon as the combination has been sufficiently agitated and the refining completed, the oil is separated from the ochre, THE MANUFACTURE OF LINSEED OIL. 39 by the use of the filter press, or left to settle twenty-four hours, and then drawn ofif, leaving only the residuum to be filtered, which, as it comes from the press, is a stiff paste of ochre, oil and its impurities in the form of a cake. Furthermore, the inventor directs, that in some classes of oil, which has undergone more or less change by taking oxygen, and is heavily charged with the free fatty acids and other impurities, the ochre is reduced to a fine powder from which ten per cent of the amount to be used is taken, and associated with from one-half per cent to one and one-half per cent of the oil, dry caustic soda, or biborate of soda (borax) in a finely powdered state. The combination is mixed with the oil to be refined and agitated briskly for from ten to fifteen minutes. Twice the weight of soda, or of chloride of calcium is then added, in just enough water to dissolve it, the agitation being continued for from ten to fifteen minutes longer. The balance of the ochre, necessary to complete the refining, is now added, agitation is resumed for a short period (about ten or fifteen minutes), the temper¬ ature of the oil being maintained at summer heat. The oil is then filtered. In the latter process the drying operation, with regard to the ochre, may be omitted. The waste unavoidable in this process, or processes, necessarily increases the cost of the prepared oil. The proportion of oil which remains in the ochre, after the latter has been utilized as the refining agent, is probably the chief objection to its use. The suggestion that the oil-saturated ochre might be utilized as a low grade paint, might be brought into operation for a short time, and thus, to a certain extent, recover the waste product, but the supply would so far over-reach the demand that the inevitable glut would accumulate instead of being appre¬ ciably relieved. 40 THE MANUFACTURE OF LINSEED OIL. In the.use of fuller’s earth the same difficulty arises, and the inventor who devises an economical method of recovering the oil absorbed by such materials will have accomplished a most progressive step in the' art of oil refining. From four to twelve per cent of oil is lost in the treatment of the various vegetable oils by the use of the foregoing materials. The application of steam to the residuum will effectually remove the oil, but the labor involved in thoroughly saturating the mass with steam and cost of separation of the oil from the water sub¬ sequently, will aggregate more than the original waste loss. The patented ochre process is sometimes applied, as in the case of fuller’s earth, to an oil already treated by the sulphuric acid process, the result proving the nearest approach to water-white linseed oil which science has so far rendered possible. In pursuit of a cheaper substance which might serve the same purpose as ochre or fuller’s earth, the writer recently experimented with sand ground to an impalpable powder, but the result, as was to be expected, proved that the fine silicious particles, lacking the calcium or lime ingredients in their composition, remained uncom¬ bined with the impurities, however persistently the agita¬ tion was maintained, and in subsidizing, when the whole was in a state of repose, failed to hasten the precipitation of any extraneous matter. By filtering a cloudy oil through sand, while the natural color will remain un¬ changed, it may be rendered bright. Press Room Operations and Their Effect Upon the Oil in Re¬ fining—Method of Testing of a Varnish Oil. It has been demonstrated that a heavy percentage of waste is unavoidably present in refining an oil which has been obtained by fine rolling and the continuity of the maximum pressure for a comparatively protracted period. The minute specks, and at times flocculent mat¬ ter, which appears suspended in the oil, subsequent to the application of the fire test, will not freely precipitate, although in the first instance the crude oil may have been subjected to the regular treatment, and in an efficient manner. It may happen that this drawback confronts the operator at a time when the product under treat¬ ment is intended for immediate use. This defect is not palpable until the expiration of a certain period subse¬ quent to the washing process, and if time were of no particular consequence the difficulty could be obviated by prolonged settling. To procure a faultless oil within the prescribed limitations, it therefore becomes essential to resort to a supplementary process. In addition to the surplus waste, characteristic of the treatment of such a product in the first instance, that which is obtained by the secondary process augments the already abnormal pro¬ portion in the same ratio. Oil extracted from the crushed and cooked seed under less exacting conditions is much more susceptible of treatment, and presents a proportional diminution in waste. To successfully meet this contingency not a few of the leading crushers in England and the United States, while manufacturing linseed oil on a large scale under the most approved conditions, for the extraction of the obtainable oil, at stated times operate a portion of the mill in the manufacture of an oil especially in- 41 42 THE MANUFACTURE OF LINSEED OIL. tended for this trade, obtained under comparatively light pressure and for which a price is procured commensu¬ rate with the cost of production. Not infrequently the cake from which this oil has been pressed, and which nat¬ urally contains a heavy percentage of oil, is ground fine and slowly added to the material in the press room, kettle or heater, and the surplus oil recovered in the regular manner. In the production of a superior varnish, it is essential that the oil possess no defective properties; but for the manifold uses to which linseed oil is subjected in the various industrial arts, a well settled oil made under any conditions, from an ordinary quality of seed, is usually suitable for all requirements. Refined linseed oil intended for use in white lead grinding must, however, possess very superior qualities, and the care essential in the removal of acid traces in the washing operation must be on a par with that intended for use in the manufacture of superior varnishes. To determine the real value of an oil as a varnish ingredient, by ascertaining its exact physical properties and general conduct in the treating kettle, together with the proportion of waste as a result of destructive distilla¬ tion of escaping vapors, the following method should be adopted, and may be looked upon as a positively accu¬ rate 'guide. From the tank in which oil is temporarily stored, take say fifteen pounds of the fluid and pour into a small copper pot. The latter should be weighed previously, so that in addition to its actual weight, fifteen net pounds of oil will be ready for treatment. With a suitable lid adjusted, having an opening sufficiently large to permit the entry of a four or six-inch pipe, the pungent vapors arising from the heated oil may be conveyed to the nearest chimney. The use of a good draught of air in THE MANUFACTURE OF LINSEED OIL. 43 the furtherance of this object is a most desirable matter. The draught pipe is indispensable if the operation is to be carried out under cover. A movable segment of the lid opening on hinges permits the stirrer, or paddle, to move freely through the oil, while it also facilitates close inspection of the fluid throughout the entire testing oper¬ ation. The exact principles which govern the manufac¬ ture of lithographic printing ink in its incipient stages are now brought into requisition. But, instead of per¬ mitting the surface of the oil in the copper pot to remain uncovered and in conflagration, as in the case of prepar¬ ing oil for printing ink, the lid and draught pipe are used. The Are should be composed of coke, or wood chemically treated, and a uniform heat maintained as far as pos¬ sible. The thermometer, which should pass through an opening in the lid, should remain suspended in the oil, about one inch from the bottom of the pot, and when 500° Fahrenheit is recorded the testing operation has actually commenced. By closely observing the action of the oil in the pot as the process advances, the varnish maker may acquire a knowledge of a definite character concerning its behavior when in greater volume subse¬ quently in the varnish kettle, and thus fortified, his pro¬ cedure is guided with a precision otherwise unattainable. The temperature mentioned should be maintained unre¬ laxed from two and one-half to three hours, according to the nature of the oils. The indications which point to the approaching termination of the process may be ascer¬ tained by withdrawing a small quantity of the oil on knife, or paddle, and when cool apply the finger, to whicli it adheres. Its adhesiveness will permit it to be drawn out to a considerable length before separating. The paddle should be continuously operated throughout the process to promote a uniform dissemination of heat in the oil, and until the desired consistency has been pro- 44 THE MANUFACTURE OF LINSEED OIL- cured. The pot is withdrawn from the fire at the suitable moment, and with its contents carefully weighed, the proportion of weight lacking the original amount being the exact percentage of loss. From ten to twelve per cent loss indicates that the oil may be treated econom¬ ically, while a greater proportion will in the same ratio present a heavier waste when submitted to treatment in the varnish kettle. In this system it will be demon¬ strated that the oil which reveals the minimum of waste is that which best receives the heat, and therefore cooks rapidly and most satisfactorily.* An impure oil proves troublesome in cooking and wasteful to a degree. While the results shown may not be accepted as an exact criterion of those which characterize the manipula¬ tion of a large batch of varnish, the maximum degree of temperature on the latter being rarely maintained for more than one hour, or two-thirds less time than that occupied by the test, it accurately serves to disclose the nature and peculiar features of the product prior to being subject to the influence of the intense heat on a much larger scale in the varnish kettle. While oil in the var¬ nish kettle is exposed to the action of intense heat for a much less duration of time, a greater proportion of vapors is evolved by reason of the fact that large bodies of oil retain heat longer than when treated on a small scale, the continuation of the heat being synonymous with that of waste; but the waste caused by treatment of a batch of oil in the varnish kettle may be approxi¬ mately estimated beforehand by the method just de¬ scribed. When the oil thus treated in the small copper pot has been allowed sufficient time to cool, it will assume a rubber-like consistency. The greasy condition character¬ istic of fixed oils will have disappeared, and from an THE MANUFACTURE OF LINSEED OIL. 45 industrial standpoint the product is of no further practical value. By being suitably applied to a surface it may, how¬ ever, be used to excellent advantage in the extermina¬ tion of vermin. Its adhesiveness to the pedal extremities of such pests being greater than their limited strength can overcome, and in this helpless condition they are speedily despatched. The radical changes which have been effected in mod¬ ern oil milling machinery, and methods in design and principle respectively, have materially changed the condi¬ tions which formerly confronted the varnish maker. Ow¬ ing to the primitive character of the old mechanical appliances, the possibility of a thorough extraction of the oil from the seed was precluded, a circumstance which ob¬ viated the presence of such a large proportion of gummy matter as is present in the crude oil as made to-day, even under the most favoring conditions. The prolonged settling allowed an oil intended for varnish purposes, to¬ gether with the protracted period invariably extended to the varnish itself, gave the refiners and varnish makers of the last generation advantages of a very superior order. But the modern consumption of varnish is in¬ creasing, having almost immeasurably outgrown the proportions of former days, while the popular taste for artistic work, in which this commodity takes such a primary part, correspondingly augments the demand. The long preliminary oil settling is inconvenient, if not impracticable, to the modern oil miller or refiner in this go-ahead age, and scientific progress has rendered prac¬ ticable the production of an oil in conformity with the needs of the hour, and in a comparatively limited time. The old system of preparing an oil for the varnish kettle by simply submitting a well-settled product to a certain temperature, about 200° Fahrenheit, for several hours. 46 THE MANUFACTURE OF LINSEED OIL. together with mechanical agitation, is utterly inadequate to meet modern conditions. The risks taken by old-time varnish makers of an oil breaking in the varnish kettle, owing to atmospheric or other conditions, cannot be tolerated by the operator of to-day, and methods are now essential for the production of a refined oil undreamed of in former times. Not infrequently the breaking of an oil was looked upon as a preliminary stage of the pro¬ cess unavoidable in varnish making. Before concluding this treatise on the treatment of lin¬ seed oil intended for use in varnish making, a few observations may be seasonably introduced with regard to sodium chloride (common salt) as a refining factor. Salt as a Refining Agent in Linseed Oil—Color Drawback Which Appears in an Improperly Treated Oil. Several years ago a patent was secured on an invention appertaining to linseed oil refining, for which the pat¬ entee claimed merits of a very superior order and of a nature hitherto unknown. The results have not been in accord with the comprehensive virtues claimed for it, nevertheless the invention is not without profitable interest to the progressive refiner and varnish maker. In the description of his patent, the inventor states that the objection to the use of linseed oil in varnish making, and in the formation of linoleums, japans, leather treatment, &c., consists in its tendency to separate—the heavier from the lighter parts of the oil—when submitted to a temperature of 400° or 500° Fahrenheit. This separation, while causing a serious loss, has the effect of producing a varnish nearly black, owing to the action of the accel¬ erated temperature on the heavier or gummy substance. In brief, the inventor claimed for his process the property of firmly uniting the heavier and the lighter parts of the oil, so that heat would not separate them when being united with the gums to form varnishes. By mix¬ ing the oil with a solution of common salt this desirable consummation was said to be accomplished. Further¬ more, the removal of the oleine is said to be effected in a practical manner in maintaining the oil at a temperature of 110° Fahrenheit and in a state of agitation for ten hours in each of from nine to fourteen days, then mixing while hot in a state of agitation a saline solution, and finally drawing off the saline and oleine precipitate and washing the oil with pure water until a further precipitate is obtained. One of the peculiar conditions of success essential in 47 48 THE MANUFACTURE OF LINSEED OIL. the prosecution of this method, according to the patentee, consists in the fact that while old and therefore well- settled oil requires fourteen days’ treatment, the new oil requires only nine days’ agitation. The really practical part of the invention deserving of the attention of the refiner is embodied in the latter part of the detailed description. Instead of using mechanical agitation, heat can be advantageously employed for ef¬ fecting the same result, in which case the saline solution is mixed with the oil at the outset, and the mixture is sub¬ jected to a heat sufficient to boil it. This heat is kept up for twenty-four hours and the precipitation of the oleine will take place on cooling. The oleine and the saline solution are then run off together, and the oil is washed with pure water and agitated for about one hour, when a second deposit is obtained and removed in like manner. An effective saline solution can be prepared by dissolv¬ ing ninety pounds of salt in sixty gallons of water for each ton of oil to be treated. To brighten the oil after being washed it is heated to about 200° Fahrenheit. This has the effect of driving off all traces of moisture, and leaves the oil in suitable condition for the final process of filtration. The proximity of a linseed oil refinery to salt water may be used to excellent advantage. The use of salt water in the natural condition, in conjunction with the sulphuric acid process in the preparation of a varnish oil is productive of more satisfactory results than can be obtained by the use of pure water. As a refining factor it is therefore apparent that salt suitably introduced in the oil to be treated plays an im¬ portant part, and its addition to the refiner’s store for more frequent use will mark a decided improvement in the general treatment of linseed oil. It is incontrovertible THE MANUFACTURE OF LINSEED OIL. 49 that this question has not received the consideration which its importance deserves. At times the refiner will turn out an oil with a greenish shade, notwithstanding the application of treatment apparently as methodical as that which marks his reg¬ ular work. The maker of fine varnishes objects to this peculiar shade, although it has never been demonstrated that an oil possessing this trait proves in the least detri¬ mental to the manufacture of a superior product. Never¬ theless its presence is objectionable, and means must be discovered to eradicate it. This will probably be found to be a somewhat difficult undertaking, and the details of the various operations may be investigated seriatim, and in the most painstaking manner, without a satisfactory solu¬ tion of the mystery. Ultimately the source of the dif¬ ficulty may be traced to the copper-lined steaming tanks, the sides of which may be coated with the accumulated deposits of numerous steamings or washings, or to exces¬ sive washings. Copper is well known to have a decided tendency to affect oil in this manner, if the latter is too long subjected to the steaming or washing process. A gallon of linseed oil heated in a small copper pot up to 400° Fahrenheit will present on cooling a much darker shade when viewed in the sample phial than a similar quantity subjected to precisely the same temperature, and for the same duration of time, in an ordinary iron pot. Further investigation will develop the fact that prolonged steaming in each of the foregoing small lots will reveal a strong green shade in the oil heated in a copper receptacle. As the purpose in steaming or washing the refined oil is to neutralize the traces of sulphuric acid, when that refining agent is used, obviously the use of an iron pot becomes impracticable owing to the corroding action of the acid. 50 THE MANUFACTURE OF LlNSEED OIL. Prolonged steaming in a copper-lined tank has a ten¬ dency to fasten the color in the oil. On the other hand, it has been demonstrated that in a coniparatively short period of steaming a greenish shade may be developed in the oil. Subsequent to filtration this defect is apparent, but careful investigation will disclose the fact that ac¬ cumulated coatings in steaming tanks are present, the removal of which will invariably remedy the difficulty. Experience is the true guide for the avoidance of the drawbacks encountered in linseed oil refining. The final treatment accorded a varnish oil consists in its filtration. This must be slowly accomplished, and, when practicable, by gravity, preferably to artificial pres¬ sure. The oil to be filtered should be tanked in an elevated position, and the chamber taps of the filter press set so that a series of minute streams will pass through the filtering medium to the trough beneath, and thence to the receiving tanks. V^ery much greater importance is attached to the shade or color of an oil, and especially its bleached aspect, than the ordinary necessities of varnish making warrant. Just why a demand should be made for a white oil, in the majority of instances, it would be difficult to deter¬ mine. For the superior varieties of colorless varnishes, however, a thoroughly bleached and oxidized oil is of peculiar value. But it is incontrovertible that however light colored an oil may be, its aspect becomes materially changed when the chemical and resinous ingredients are added to the heated fluid in the copper or iron treating kettle. The term “water-white” may be considered as simply abstract when applied to prepared oil, and the only value such a product possesses, other than that which distinguishes the regular variety, con¬ sists in its peculiar aspect being a positive warrant of having been thoroughly refined. THE MANUFACTURE OF LINSEED OIL. 51 The use of this generally expensive oil may be obviated by purchasing from an established refiner, or when the crude oil is prepared on the premises of the varnish maker. The production of a colorless oil, as previously stated, involves considerable expense, and unless sus¬ tained by exceptionally favorable circumstances will eventually prove unremunerative, principally owing to the fact that varnish makers being assured they can obtain an oil, perfect in all respects, although not bleached by extreme processes, will use it preferably to a product which costs more, and which has no better qualification to commend it other than being lighter in color. A sample of prepared oil was submitted to the writer recently, the peculiar features of which deserve con¬ sideration. The principle involved in its preparation consists in the thickening or bodying being wholly or in part governed by the heat application and general cooking manipulation. The oil in question appeared almost colorless, possessing a good body, and absolutely free from flocculent matter. Briefly, these properties were probably produced by using the following formula; By subjecting a previously prepared oil to a temperature of 600° Fahrenheit as rapidly as possible, at which point a reversion of the conditions is commenced, which con¬ sists in speedily reducing the temperature to a point below 100° Fahrenheit, or to the normal temperature— 70° Fahrenheit. Upon the celerity with which this change is brought about much of the success of the process depends. A covered kettle is the most suitable receptacle for the heating process, as better results are obtainable when the surface of the oil is not exposed to the air. The most feasible method for reducing the temperature is by passing the oil through a water-tube 52 THE MANUFACTURE OF LINSEED OIL. cooler, or the use of cooling chambers around the kettle will effect the purpose desired, while proving an excellent medium for regulating the temperature during the cook¬ ing process. The oil is then allowed to settle for say thirty hours and filtered, at which point a deep green color will pervade it. By w’ashing and subsequent settling, the process is complete, the oil being now almost color¬ less, possessing a good body and without perceptible odor. About 5 per cent of waste may be counted upon as a result of refining by this method. In the manufacture of light colored varnishes pos¬ sessing great body consistency, the oil must be rapidly heated to a high temperature and reduced as quickly as possible in the same manner as that described in the fore¬ going formula when practicable. It must be borne in mind that the superiority of the finished product mater¬ ially depends upon the rapidity with which the increasing and retrograding temperatures are carried out respect¬ ively. The removal of the coagulable substances in linseed oil by the foregoing processes, precludes the possibility of scum accumulations on surface of the oil in treating kettle—the latter being a reprehensible feature insep¬ arable to the old system. The fluid is now in suitable condition for the prosecution of the work peculiar to \arnish making. A temperature of 000° Fahrenheit may now be exerted on the oil without deleterious results, but it must be recognized that however efficiently the refining process may have been carried out, if the sub¬ sequent washings have not adequately removed all traces of the refining agent—sulphuric acid—the unavoidable reaction which takes place in the treating kettle will have the effect of generating gelatinous matter, or, in other words, the oil will break. This occurrence is an THE MANUFACTURE OF LINSEED OIL. 53 unmistakable indication that defective steaming or wash¬ ing has characterized the previous treatment of an oil, which may have been in other respects properly manipu¬ lated. Heating Kettles—Uniform Distribution of Temperature in an Oil Under Treatment Essential to Success. The complete neutralization of all acid traces becomes essential in the production of superior varnishes. On occasions, oil has been known to separate, or break, when undergoing treatment, although the principles which governed its preliminary preparation may have been un¬ exceptionable from any standpoint. Defective cooking induced by improper application of heat is responsible for this drawback. The necessity of procuring a tem¬ perature throughout the oil as uniform as modern appli¬ ances will permit, becomes otthe greatest moment. An absolute uniformity of temperature throughout the oil in the ordinary varnish kettle is impossible of attain¬ ment, and the varnish maker, however experienced, is incapable of turning out two batches exactly alike in color, body, drying properties, &c., although made from ingredients similar in quality and quantity, and subjected to the same manipulation. Owing to the nature of the prevailing methods and appliances, an insuperable difficulty presents itself in disseminating a uniform temperature throughout the oil under treatment, and modern science has failed to suc¬ cessfully grapple with the problem. By whatever device employed, having for its object the uniform distribution of heat, experience has demonstrated the impracticability of procuring a temperature alike at bottom, sides and surface of the oil in the kettle, whether of the movable or stationary variety. That portion of the oil resting on bottom of the kettle, and which receives in full force the intensity of the incandescent heat from the coke fire in a direct manner, will of necessity be subjected to a tem¬ perature very much in excess of that which the ther- 54 THE MANUFACTURE OF LINSEED OIL. 55 mometer reveals. The constantly changing position of the fluid caused by the stirring, to a material extent, pre¬ vents it from increasing in intensity until burning sets in, and the practical operative closely observing each recurring phase of the process, and guided by experience is enabled to turn out with a reasonable degree of cer¬ tainty a suitable product, the ingredients and other tech¬ nical details being appropriate. Several years ago a form of kettle was introduced, which had its origin in France, by means of which sur¬ prising results were said to have been acquired. But it must be said that experience has failed to confirm the flattering character claimed for the innovation. On the principle of the water bath the new design was operated, and its construction consisted of a double kettle, with sufficient space between to permit of the presence of melted lead, tin or wax, while even boiled oil was sug¬ gested, each being utilized as a medium for transmitting heat from the fire to the treated oil, between which elements it remained, while it absorbed and imparted the desired temperature, respectively. These substances, as is well known, melt and boil at certain specified temperatures, the melting and boiling points varying materially according to the physical com¬ position of each product. To arrive at the melting or boiling points, respectively, of the foregoing ingredients a certain temperature must be developed at top, bottom and sides in the space between the double kettle in which the fluid is placed, and maintained in that condition. It was considered that absolute uniformity of temperature could be procured by this means, with comparative facil¬ ity, and transmitted in precisely the same condition to the oil in the inner kettle. Laboratory experiments gave indications of the practicability of this desirable action, but while satisfactory on a small scale, its applicability 56 THE MANUFACTURE OF LINSEED OIL. in practical form on a manufacturing basis, proved ut¬ terly inadequate. No definite set of rules may be established for the pro¬ secution of the work peculiar to varnish making, but each operative must be guided by his knowledge of the action of the various ingredients in the several stages of the process in the production of the particular quality of varnish he has in view. It is of the greatest moment that the fire should be in that condition which best promotes a strong heat radiation, so that the latter may impinge on the lower part of the kettle uninterruptedly. Flames and smoke—the results of combustion in its incipient stages—should be exhausted prior to the intro¬ duction of the oil into the kettle for treatment. The fire should be of an incandescent character and well devel¬ oped. Coke is recognized as being the best fuel material for suitably advancing perfect combustion and maintain- • ing same in a uniform manner, the development of flame • and smoke being comparatively limited. Every varnish j maker recognizes the fact that with the advantages i derived from the use of the most superior ingredients in j the manufacture of fat varnishes—oils, gums, chemicals i and thinners—the prospect of turning out a faultless " product may be irrecoverably spoiled by neglect of these precautionary measures. The prolongation of excessive temperature, without previous treatment of a special nature, will result in . giving color to the oil, and should not be maintained more than one hour, the maximum point being about ; G00° Fahrenheit, while 570° Fahrenheit marks the limit ' with many operatives. ' J It is well-known that oxidation is developed with 1 greater effect when the oil is rapidly heated. j Reference has been made to the fact that by rapidly J heating the oil to the desired temperature, and vice versa, « THE MANUFACTURE OF LINSEED OIL. a heavy body will be imparted to the fluid. This prop¬ erty may be increased by repeating the process, but it is essential to commence the second heating under pre¬ cisely the same conditions as those which governed the first; that is, a fresh fire must be prepared for the final heating. For special purposes, where the use of an intensely oxidized oil is called into requisition, the fore¬ going heating and cooling processes may be repeated a number of times until the desired consistency is attained. In the practice of this oxidizing and bodying principle, it was discovered that the cooling of the oil very frequently delayed the progress of the work to a very considerable'extent, and to expedite matters, an excellent device, designated a heat exhauster, was introduced. The mechanically cooling process simply consists of forcing a current of cold air through a pipe, the end of which rests on the bottom of the varnish kettle, and removing the same when it arrives at the surface of the oil by a suction or exhausting contrivance. This is effected by connect¬ ing the pipe from the hood which is suspended imme¬ diately over the kettle, to a rapidly revolving fan wheel, which is conveniently situated adjoining the chimney, to facilitate the force and volume of the air draught. The fan or exhausting wheel may be operated from the most convenient counter-shaft. The rapidity with which it sweeps the ascending air from the surface of the oil renders it a valuable factor in the preparation of this quality of oil, and its use becomes indispensable when the product is treated in the stationary kettle. In the preparation of oil for lithographic ink and other special purposes where good flowing properties are essential, the use of the heat exhauster is of the greatest moment. Oxidizing Agents of Linseed Oil and Their Correct Use—Oxon- ized Air. To still further oxidize an oil, borate of manganese is brought into requisition, without detriment to the color. 1. here are a number of ingredients which effect the same object in a satisfactory manner, such as oxide of man¬ ganese, sugar of lead, sulphate of zinc, or the lead oxides, litharge and red lead. These chemicals, without excep¬ tion, impart a deep, dark color to the oil, and more espe¬ cially the two latter. In the production of boiled oils for general painting purposes, the metallic oxides re¬ ferred to stand in good favor. d'o impart intense oxidizing properties to a prepared oil without darkening it, becomes an important matter in the manufacture of superior varnishes. The oxidation of oil by atmospheric influences alone is inadequate, and the aid of oxidizing compounds to increase its drying prop¬ erties becomes indispensable. Laboratory experiments have demonstrated that hot air produces a very superior drying oil, and has the effect of rapidly thickening the fluid when uniformly disseminated throughout the oil, resembling somewhat blown rape-seed. But on a large scale the results of this oxidizing process may prove disappointing. To produce an oil having the desired body consistency, the operation must be maintained continuously to an extent —with regard to time—at variance with all factory ideas, ftom thirty to forty hours, leaving out of the question the expense involved. About five years ago a varnish firm constructed an apparatus having for its object the heating of air to be used for the oxidation of varnish oil, and costing in the neighborhood of £10,000. After five or six attempts had been made to produce the hoped- for results, the operation of the apparatus was found im¬ practicable, and in consequence was abandoned. 58 THE MANUFACTURE OF LINSEED OIL. 59 Oxonized air has been shown to impart very superior properties to linseed oil—with regard to thickening and drying—but as in the foregoing instance, the impracti¬ cability of producing the invisible fluid in its pure state, and in sufficient rpiantities, remains an insuperable bar¬ rier to progress in that direction. A method of giving body to the prepared varnish oil, and in general use in large refineries, consists of blowing air through a mass of oil, the latter being at a temperature of 200° Fahr. This also has the effect of drawing off latent moisture that may be present subsequent to the washing process, and is continuously maintained for about four hours, the ap¬ paratus consisting of a steam-jacketed kettle. By submitting refined linseed oil to further treatment, which consists of forcing oxygen gas through the mass, a very superior drying oil is obtained without changing the original color. But in tliis instance the metallic oxide used in the preparation of the oxygen—peroxide of manganese—is treated separately in a retort, and at a high temperature the fluid is conveyed to the “bottom of the treating-kettle, passing through the oil to the sur¬ face as soon as it is produced. The oil should be pre¬ viously heated to a temperature of about 300° Fahren¬ heit. Metallic oxides, such as litharge or red lead, very materially increase the absorbing properties of linseed oil for oxygen, which when applied to the surface dries hard and firm. But a dark color is unavoidably imparted to the oil thus treated, and while rendering it of great value as a boiled oil intended for painting purposes, it proves detrimental in the manufacture of the higher grades of varnish. Of all oxidizing metallic substances, probably borate of manganese takes the lead as being the most powerful. The rule which is generally adhered to, in the ma- 60 THE MANUFACTURE OF LINSEED OIL. jority of instances, with regard to the oxidation of oil, consists in combining lead and manganese driers. The quantity and nature of the driers incorporated with oil, the mode of application and extent of temperature, ma¬ terially govern the quality of the finished product. Umber, in the preparation of boiled oils, finds con¬ siderable favor, and is valuable according to the propor¬ tion of manganese it contains. Its propensity to darken the oil limits its use in the preparation of varnish oil. By conducting the boiling operation in a closed vessel, having first withdrawn the air, thereby removing the atmospheric influence, an oil may be boiled without the usual discoloration which a boiling in the open kettle presents. In order to thicken the oil, if necessary, air could be blown in subsequent to the incorporation and blending of the drying ingredients with the oil. A safety valve will permit the escape of the accumulated vapors and gases when the pressure has reached the releasing point. According to Van Wagner, borate of manganese be¬ comes an excellent siccative when added to raw linseed oil, one part to a 1,000 of oil. In the preparation of a superior drying oil, the combination of lead and man¬ ganese oxides is desirable. It readily unites with the oil and renders very excellent drying properties in the fin¬ ished product. In the preparation of driers various bodies, which comprise salts of iron, lead, manganese and zinc, are called into requisition, and Prof. Hurst’s comprehensive list, which includes the compounds most used in oils, paints and varnishes, may be here cited: red lead, lith¬ arge, lead acetate, lead borate, manganese oxide, man¬ ganese sulphate, manganese borate, manganese oxalate, zinc oxide, zinc sulphate and ferrous sulphate. There are other substances, however, such as borax and salam- THE MANUFACTURE OF LINSEED OIL. 61 nioniac, which possess the properties of promoting a per¬ fect assimilation of the oxides and oil, and lessening the fluidity of the latter, respectively, which are utilized on special occasions. The combination which uniformly gives the most satis¬ factory results in the preparation of driers and japans consists in the use of black oxides of manganese, of which there are two varieties. It is conceded by compe¬ tent authorities that the black manganese contains a larger proportion of oxygen than other varieties of that oxide, and is, therefore, a powerful drying factor in the composition of boiled oils, paints and certain classes of varnish. Unfortunately, its proclivity to darken the oil precludes its use in the preparation of light-colored varnishes. FILTERING MEDIUMS-MODE OF RENOVATING, ETC. The combination of cloth and paper will prove very effective in the production of a perfectly clarified linseed oil, and may be strongly recommended in the case of prepared oils and as well for varnishes. To produce an absolutely clarified oil by means of a filter press, with, say, fifty plates, thirty-two "inches square, 400 gallons per day should be the maximum output; while if the cir¬ cumstances permit, from 250 to 200 gallons would be preferable. When practicable, the pressure should be by gravity, otherwise the feed pump should be operated with the slowest movement possible, which will be found ade¬ quate to keep up supply. Laboratory experiments by the writer have also con¬ clusively established the impracticability of utilizing paper as a filtering medium when the oleaginous fluid contains moisture. Several small sheets of filter paper were placed in a large glass funnel, and in the cavity thus formed, one quart of oil, to which a fractional percentage of water had been previously added, was poured. The 62 THE MANUFACTURE OF LINSEED OIL. first rim of oil was perfectly bright, thus demonstrating that, to a certain point, the paper retained the moisture, but subsequently the fluid became cloudy, exhibiting no further improvement until the operation was termi¬ nated. A close investigation revealed the fact that after the first run of oil had passed through the paper in a clarified and transparent condition, the latter became charged with moisture retained from the same, while the succeeding flow of oil from the filter press contained the original and full proportion of moisture, the filtering medium being disqualified for further use as a clarify¬ ing agent. In the case of crude or prepared oil filtration, the pro¬ cess may be maintained uninterruptedly for weeks, con¬ ditional upon the fluid being free from moisture, and until the increased pressure shown on the press gauge indicates the necessity of removing the accumulations in the chambers, and washing the filtering material, when textile fabric is used if necessary. In the case of varnish filtration, also, when the operation is regularly maintained during the day, the filtering material, if paper, can be used similarly, but in the event of the press standing inactive for twenty-four hours, it will be necessary to change the paper for the succeeding opera¬ tion, by reason of the varnish having dried and closed the pores of the paper, rendering it unfit for further use. To avoid this drawback it is necessary to keep the filter¬ ing medium saturated with oil, which may be effected by passing a continuous stream through. In the filtration of superior oil, intended for special purposes, fine filter cloths are sometimes used, the pro¬ cess being slow, but results are invariably of a satisfac¬ tory nature. In the ordinary work of crude oil filtration, when cloths have been scraped several times, it will be dis- THE MANUFACTURE OF LINSEED OIL. 63 covered that the intervals in which good work may be effected will become gradually diminished until removal and washing become necessary. Not the least important function devolving on those whose duty it is to keep the filter press or presses in thorough working order con¬ sists in their possessing a correct knowledge of how to prolong the duration of service of the filtering fabric to the possible limit. On more than one occasion the writer has seen an excellent set of lamb’s wool filter cloths utterly ruined by mismanagement. The same objection which is made to permitting the filtering material, when paper, to become dried up, causing the pores to become clogged, is applicable with greater force when the medium is cloth. The latter should not be allowed to remain in the press longer than ten or twelve hours without being moistened with oil; other¬ wise, where a perfect system of washing is not thor¬ oughly understood, the cloths are rendered unfit for fur¬ ther use. Washing by means of the most approved sys¬ tem will not fully restore cloths which have been neglected and allowed to gum up; hence, the necessity of judicious treatment in the care of same. In several of the forms of varnish filter press pre¬ viously described, after removal of the filtering medium the interior is thoroughly cleansed by continuously pass¬ ing through benzene or turpentine for a fixed brief period, but experience has demonstrated that this is an expensive, as well as an ineffective, method. An alkaline solution composed of caustic soda and hot water will be found more economical and serviceable. The solution, caused to pass through the machine in the foregoing manner, will remove the adhering matter by saponifica¬ tion, after which a strong stream of water forced through the pump and filter press will effectually remove all loose particles of gumming matter and other impurities. Care 64 THE MANUFACTURE OF LINSEED OIL. must be exercised in allowing ample time for the ma¬ chine to dry before being again put in operation. Cloths which need restoring should be washed singly in benzene to effect a thorough cleansing. This is ef¬ fected, where no better appliances are available, by tak¬ ing each cloth singly and, after submersion in benzene, subjecting them to a thorough scrubbing by means of an ordinary scrub-brush on any conveniently-arranged plat¬ form. The adhering wax-like substance, which clogs the texture, may by this means be thoroughly removed, the cloths, after sufficient time has elapsed for the com¬ plete evaporation of the volatile fluid, being in good or¬ der again for the execution of satisfactory work. This cleansing process is arduous and tedious, as well as be¬ ing expensive—objections, however, which may be ob¬ viated by the use of an excellently-constructed hand¬ washing machine, especially designed to meet the re¬ quirements of the case. The machine referred to will cleanse one heavy or two light filter cloths in a rapid and effective manner. The rapid movement of a lever subjects the fabric to a thor¬ ough churning or agitation in benzene. This is pro¬ duced by wooden projections on the under surface of a movable cover, the latter being actuated by the lever referred to. By the aid of this machine two men can re¬ move a set of thirty-six heavy and light filter cloths, thoroughly wash and replace them in the press ready for use, in from ten to twelve hours. In the event of steam heat being used to hasten the evaporation of the ben¬ zene which the washing-machine wringer has left in the cloths, this period may be considerably abridged. The location selected for drying the cloths should be one in which air freely circulates. The escaping vapors must be unconfined; otherwise disastrous results may ensue. Probably the best method of heating the cloths after THE MANUFACTURE OF LINSEED OIL. 65 washing for the purpose of drying consists in the use of a specially-constructed heater, composed of two oblong sheets of boiler iron, connected at ends and sides, form¬ ing a two or three-inch chamber between. Steam is permitted to enter at one end and exhaust at the other, the heat radiating therefrom rapidly drying the cloths, which latter are placed on the heater. Care must be ex¬ ercised in changing the cloths at the proper time to avoid over-heating. In the event of time not being a consideration in the prosecution of this work, the cloths will dry very thoroughly if exposed to the sun or left over during the night in a suspended position. Another excellent device in the form of a filter-cloth washing machine consists of an apparatus which auto¬ matically raises the rubbing surface free from the cloths and benzene at the end of each revolution, returning, pounds and turns them, taking a new hold each time and rubbing in a new place. This combination, or triple action, resembles the process of hand-rubbing, with a reduced percentage of wear and tear, and requires but little physical effort to actuate it. Before proceeding further on the subject concerning the filter press, a few more hints of a practical nature concerning filtration will be in order. To procure best results varnish or linseed oil should be filtered when cold. This applies with equal force in the case of prepared oil, and for the reason that in these products fatty sub¬ stances are present, soluble at a temperature above 140° Fahrenheit, which, when filtered at the normal tempera¬ ture, are retained by the filtering medium; but when filtered at an accelerated temperature, equivalent to, or in excess of, the foregoing limit, will pass in solution with the oil through the closest medium—paper, cloth or felt—to subsequently reappear in the oil after a brief period of repose. In the treatment of superior oils and 66 THE MANUFACTURE OF LINSEED OIL. varnishes best results are attainable by securing the use of fine filtering material—whether lambskin, felt, or paper—the inferior filtering mediums being more ap¬ propriate, if used at all, in the filtration of new oil, as previously referred to. The oil or varnish manufacturer, or those identified with oils in a practical way, without the use of the filter press, is behind the times, and neglectful of his best interests. Here are a few of the advantages gained by the filter press over the old-time methods of separat¬ ing impurities from oleaginous fluids: 1. Economy of space. The method adopted of dis¬ tributing the filtering surface in the filter press secures an enormous filtering area within a comparatively small space. 2. Saving of time. What formerly took months to ac¬ complish by subsidence in the settling tank can now be done in a very brief period by the filter press. 3. Under suitable treatment, a complete separation of the impurities from the oil or varnish. In the case of cottonseed oil refining, as well as in lards and greases, fuller’s earth is used as a refining agent. The latter during filtration is collected in the form of compact cakes, containing a certain proportion of the oil or grease, which latter can be thoroughly re¬ moved and secured by steaming the cake before taking it from the press, no subsequent handling being neces¬ sary. The filtering area of round metal plate press, 18 inches in diameter and containing 20 chambers, is 43 square feet, the thickness of cake permissible by width of cham¬ bers being 1 inch, while with plates and extension rings the thickness of cake can be more than quadrupled -A. 36-inch plate press of 40 chambers contains 534 square feet, the size of the cake being in THE MANUFACTURE OF LINSEED OIL. 67 the ratio of increase, with or without extension rings. In the square-plate press the increased area over the circular, almost within the same compass, is deserving of consideration. The IS-inch plate press, square, contains 80 square feet of filtering area, as compared with 43 square feet of the circular variety, each having 20 chambers. THE SETTLING TANK OR CLARIFIER. As an auxiliary to the filter press, and a valuable ac¬ quisition to modern oil milling, the use of a small settling tank, or clarifier, immediately beneath each set of presses, may be strongly recommended. By its aid the necessity of frequent cleaning of receiving tanks is en¬ tirely removed, the foots being secured in concentrated form and in a most convenient manner. Recently the writer designed and set up six of these excellent clarifying tanks, and it is a safe assumption that no linseed or cottonseed crusher, knowing their value, would be without them longer than the necessary time to construct and put them in operation. Its utility is practically unknown, and it is a matter for surprise that such a valuable and economical factor should have so long remained dormant. The first form of clarifier was introduced in a Chicago mill, and is circular and conical. It is estimated that by means of this clarifier about nine pounds of thick, mealy matter may be obtained from 500 gallons of oil. How¬ ever, the quantity of foots obtained depends considerably on the form of the hydraulic press plate? and the general cooking system of the crushed seed which obtains. This proportion may be exceeded in certain cases, and vice versa. It is evident that if, by any means, the heavy sedi¬ ment or foots is separated from the oil immediately after it falls from the presses and prior to filtration, the latter 68 THE MANUFACTURE OF LINSEED OIL. process will be very materially facilitated, while protect- . ing and lengthening the duration of service of the filter¬ ing material correspondingly. The tank is simply a huge funnel-shaped vessel. The capacity is 140 gallons, and the dimensions are 7 feet long and feet wide at top, and 9 feet deep over all, the material be¬ ing ^-inch steel, and may be readily constructed in any boiler-making establishment. A 3-inch plug cock must be adjusted at the bottom, and not a valve, the steep pitch of the apparatus carrying the mealy matter direct from the top to the point of discharge. By means of in¬ terior top flanges the tank may be suspended from the ceiling immediately beneath the presses, and one of the foregoing dimensions will suffice for a set of five or six presses. In the centre, also suspended, but in a slightly , more elevated position than the settling tank, a capacious funnel of tin or galvanized iron receives the several streams of oil as they flow from the respective presses. Of necessity, the fluid and mealy matter are carried down, the clear oil rising from beneath and encircling the exterior of the funnel, until the Overflow is reached at the point indicated. Nothing but comparatively clear oil thus escapes to the filter-press tank, while at stated in¬ tervals—say twice each week—the attendant will re¬ move the mealy matter in a pail by opening the cock partially, shutting it off sharply the instant the liquid ap¬ pears. The operation may now be maintained in¬ definitely, the cost of construction being the first and only expense involved by the introduction of the system. The overflow pipe must lie four or five inches below the top of the tank. The first, or circular, form of clari¬ fying tank was operated with a coil of one-inch steam pipe running around the interior, but for the reasons previously considered—that an accelerated temperature THE MANUFACTURE OF LINSEED OIL. 69 has the effect of assimilating the mucilaginous or gummy matters with the oil during the period said tem¬ perature is maintained. A series of these clarifiers could be constructed for a large mill, or a single one, with cor¬ respondingly increased capacity, would produce similar results, if the character of the surroundings necessitated the measure; the former should have the preference, however, when practicable. In the event of the circular cone-shaped tank being selected, care must be exercised in giving sufficient pitch to the cone; otherwise the foots will lodge on the sloping sides instead of working to the bottom as desired. With suitable pitch, as de¬ scribed, no apprehension need be entertained of the pos¬ sibility of the foots failing to pass out upon the partial opening of the three-inch cock. To lessen or increase the size of the latter will be harmful. The triangular¬ shaped tank has many advantages over the circular one. not the least being the fact that the greater part of the apparatus—the bulky and unwieldy portion—presents no obstacle to the regular mill operations by being in an elevated position, the lower part, tapering to a point, giving ample clearance. STORAGE TANKS—LATEST METHODS OF STORAGE. In addition to the appliances heretofore described con¬ cerning the equipment of a boiling and refining plant, it will be necessary to refer, for a brief period, to the de¬ sign of the various makes of storage tanks, together with the material of which they are composed—attach¬ ments, etc. Covered tanks, made of bright tinned iron, hooped when of large capacity, and furnished with screw bung, together with gauge-glass, similar to the regular furnace- boiler water gauge-glass, with index, will be found economical, as well as convenient, in the storage of vola¬ tile fluids. Similarly constructed tanks, complete with 70 THE MANUFACTURE OF LINSEED OIL. dipper, fitted with lock or other taps—in both varieties— together with wooden under-supports to carry the weight of oil or varnish, in addition to the usual metallic bottom, are very desirable acquisitions. The lids are, in some in¬ stances, made half open or fitted with screw bung. For raising the temperature of water, for oil refining (especially in the preparation of varnish oils), and for other purposes where a steam pressure not exceeding ten or twelve pounds per square inch is needed, the double¬ case heating tank fills a long-felt want. The heating tanks referred to are made on an improved principle, being especially adapted for heating and mixing pur¬ poses. The inner and outer shells are riveted and hooped at the top, and at the bottom are two inches apart. The bottom of the inner shell is concave, and the outer casing convex, and, meeting in the centre of the bottom, form a cavity for the steam, while being peculiarly well adapted to resist pressure of the latter. At the point where the two bottoms meet in the centre they are securely riveted. They are strongly hooped and provided with flanges for steam inlet and outlet, draw-off cock for condensed water, and flange for main draw off tap or tube.' They are made in various sizes, the capacity ranging from 50 to 200 gallons. The double-cased or steam-jacketed high-pressure kettle is deserving of special mention. P'or rosin melt¬ ing, or mixing of various substances where a compara¬ tively high temperature is imperative, it is peculiarly well adapted. The tank or kettle is made from the best selected mild steel plates, and is constructed to stand a steam pressure of 60 pounds per square inch. Standing on three or four strong angle-iron feet, riveted on, the in¬ side casing is all solid welded, and free from the objec¬ tionable rivet heads. There are also two-solid wrought- iron blocks securely riveted to the pan, one for outlet of THE MANUFACTURE OF LINSEED OIL. 71 condensed steam, and the other for inlet, while the cas¬ ings are stayed from inner to outer shells, both on the sides and bottom. The capacity, in gallons, of the various sizes ranges from 35 to 150 gallons. The Anderson improved jacket kettle of Cleveland, Ohio, possesses advantages of a very superior charac¬ ter. The kettle is fitted with a special steam trap, which removes steam condensation as soon as formed, prevent¬ ing loss of steam. The kettle is guaranteed not to leak or get out of order, requiring but little attention, for the reason that, as soon as steam is turned on the jacket, the trap will regulate the blow-off. For this reason it has gained very considerable popularity, while the economy established by its use is directly traceable to the fact that the very best possible results are obtained by means of the least possible supply of steam. A comparatively recent innovation in the method of storing varnish, at once simple and possessing decided advantages over the older system, is deserving of the con¬ sideration of those unfamiliar therewith. As the latter has been introduced by a very limited number of manu¬ facturers, and is, therefore, not generally understood, not¬ withstanding its simplicity, detailed particulars at this time will be in order. As a means-of rapidly developing the desirable properties of a fat varnish, prepared oil, and drier of all varieties, the new system is without a com¬ peer, and no varnish plant may be considered completely equipped lacking this invaluable adjunct. A double- bottomed, steam-heating tank is all that is necessary to accomplish the results referred to. By increasing the temperature of the stored fluid, whether oil or varnish, in a comparatively short period a clarified product will be obtained, the subsidence of the impurities, or inert materials, with which the product may have been pre¬ viously treated being very materially expedited by 72 THE MANUFACTURE OF LINSEED OIL. rendering the contents of the tank increased in fluidity, due to the accelerated temperature. As a preliminary step to the filtration of raw oil, of whatever variety, by thus effecting a thorough subsidence of the mucilagin¬ ous and other impure substances, a brilliant oil is pro¬ duced, while the duration of service of the filtering medium, whether paper, felt or cloth, is correspondingly prolonged. The elimination of the objectionable matter prior to filtration obviously protects the filtering medium, and, as previously stated, the oil should be allowed suffi¬ cient time to cool before being filtered, if best results are to be obtained. In the storage, therefore, of all varieties of treated oils results are obtained in two or three weeks by means of the double-bottomed, steam-heated tanks, which require five or six months when stored in the ordinary settling-tank. In the latter variety of storage tank, it will be readily understood that when a treated oil, after it has been allowed the necessary time to cool in the cooking kettle, has been run into said tank, the chemical ingredients which were used as oxidizing agents, and which render the product turbid, precipitate slowly, thus indefinitely prolonging the clarification pro¬ cess. On the other hand, by prolonging an increased temperature the oil is thinned, thus facilitating the sub¬ sidence of the impurities, otherwise held in suspension when the oil is cold and, therefore, of increased viscosity. It is well known that treated oils, after having been placed for cold storage in the old tanking system, thicken in twenty-four hours, thus proving a barrier to rapid and effective subsidence—a drawback which is obviated by the system described. The advantages obtained by the use of storage tanks constructed of material such as previously referred to over those in ordinary use, such as large ones constructed of boiler-plate, are manifold. The two most important are THE MANUFACTURE OF LINSEED OIL. 73 low prime cost, as compared with other systems, and ex¬ cellent facilities for re-arrangement. A series of tanks of 500 gallons each—ten in number, holding in all 5,000 gallons—complete with index, cover, taps, and pipe con¬ nection, may be constructed at a comparatively small cost. The system permits of almost endless varieties of arrangement—a matter of great consideration and utility in the varying requirements and changes in trade. An individual tank can be instantaneously cut out of circuit for repairs. They can be arranged in places of irregular form that longer and square tanks would not fit into, and by means of the index the quantity of liquid con¬ tained therein may be ascertained at a glance. For oil, petroleum, spirits, and other fluids, the use of this form of tank may be strongly commended. FILTER PUMPS. With regard to the design of pump best adapted to the requirements of thorough oil or varnish filtration, the duplex variety will be found very superior to the single pump. In fine filter-press work, the fluid must be uni¬ formly pushed, not punched, in the press—an occurrence which is unavoidable in the use of the single pump. Messrs. Stilwell-Bierce & Smith-Vaile Company, of Dayton, Ohio, have designed an excellent pump of the duplex variety for filter-press work. The pump is made of all iron, brass, or bronze on liquid ends, according to the views of the manufacturer. The plunger is packed on the outside, and is, therefore, easily accessible, while re¬ movable cylinders, brass or copper lined, are also special features of this form of pump. There are several other makes of filter-press pump, each of which possesses pecu¬ liar and advantageous features, well suited to the re¬ quirements of the case. 74 THE MANUFACTURE OF LINSEED OIL. AIR PUMPS. Improved blowing or air engines are now largely used for agitating oils, acids, and chemical preparations, as well as for ventilating purposes. They are usually con¬ structed on the direct-acting system, compact and simple. The machine is now ranked among the indispensable requirements of a well-equipped plant. In the admixture of the sulphuric acid with the oil in the refining process, no system known can compare with the thorough agita¬ tion and commingling of the fluids as obtained by the use of a reliable air pump. No costly foundations are neces¬ sary when setting, while the expense for attendance and maintenance is but a fractional item. The Henry R. Worthington Pump Works have a very excellent form of air pump on the market. A feature of the pump deserv-- ing of special mention consists in the compensating valve motion, enabling the length of stroke to be readily and finely adjusted, so that the pistons can be made to travel close up to the heads of the air cylinders, thus combining greatest economy in use of steam, together with efficient work. The air valves are not liable to derangement, and are of very durable form. The air pistons are made light and strong, and are furnished with adjustable pack¬ ing of improved design. The pump is made in various sizes and capacities, the steam and air cylinders ranging in diameter from 4 and 4^ inches to 24 and 48 inches, re¬ spectively. An air pump liable to become deranged at the critical period when the acid is introduced to the oil, or at any period during the agitating or mixing process, is a very dangerous appurtenance to a varnish plant. Its use is most reprehensible, and is equivalent to a di¬ rect invitation to disaster. On several occasions the writer has seen batches of oil charred and utterly spoiled for the intended purpose, owing to this cause. Having THE MANUFACTURE OF LINSEED OIL. 75 these circumstances in view, the value of a reliable ma¬ chine will be more fully appreciated. FILTER PRESSES. Since the use of the filter press is finding its way into almost every branch of industry, a short account of the machines manufactured by the original maker may be in¬ teresting. The present style of filter presses was intro¬ duced into this country in 1860 by Mr. A. L. G. Dehne. Since that time he has made constant improvements in them, and has so perfected them that they now enjoy a wide reputation for high efficiency and irreproachable workmanship. The principal advantages of the filter press are: 1st. The largest possible filtering surface in the small¬ est possible space. 2d. The facility for forcing the material through the filtering medium (cloth) by the most suitable pressure. This varies from a slight hydrostatic pressure to 140 tbs, per square inch. 3d. The ease with which the filter press may be handled. THE FILTER PRESS—CORRECT MODE OF OPERATION, ETC. The introduction of the filter press in oil milling and varnish manufacture filled a long-felt want by removing many of the inconveniences coincident thereto, while be¬ ing an economical factor of material import. A patent was first obtained by the Messrs. Johnson, of London, on the filter press, about fifteen years ago, since which time its use has become widespread in lines where its introduc¬ tion became practicable throughout the manufac¬ turing world. IN'Iessrs. John Johnson & Co., of 59 Franklin street. New York, was formerly a branch of the London house, but the business 76 THE MANUFACTURE OF LINSEED OIL. of filter press making, in all its forms, is car¬ ried on by the New York house as a distinct and separate firm. The house has a national reputation, and the business, as conducted to-day, is in a most flourishing condition. The form of press originally introduced con¬ sists of eighteen chambers, each of eighteen inches diam¬ eter, but subsequently larger ones were constructed, and are now in general use in the leading oil mills. In var¬ nish manufactories, however, a press is used having simi¬ lar measurements to the former, but with increased num¬ ber of chambers. The original form has been altered to suit special recjuirements, and many varieties and makes of filter press are now on the market, differing in design, though identical in principle, each presenting advantages peculiar to themselves. There are a large number of filter press manufacturers in England and the United States, to the best makes of which, coming within the scope of this treatise, we purpose extending consideration. It must be conceded that the makers of the filter press in the United States have made very considerable progress with regard to efficiency, durability, and simplicity of construction. In the various industrial arts in which fil¬ tration, or percolation, advances manufacturing interests, the modern filter press must be accorded the highest posi¬ tion. This applies with peculiar emphasis to oil milling and varnish making. For the removal or separation of solids held suspended in liquids, such as mucilaginous and other objectionable impurities in crude linseed oil, the adaptability of the filter press is peculiarly advan¬ tageous. In the clarification- of oils and varnishes, the fil¬ ter press has a wide application, while being rapidly ex¬ tended, mechanical filtration having very largely super¬ seded the old system of subsidence effected by protracted settling, the only method heretofore available for the separation of objectionable matter present in oleaginous I THE MANUFACTURE OF LINSEED OIL. 77 THE JOHNSON filter PRESS. or Other fluids. The loss of time necessary to procure the desired results, together with the concurrent expense attached thereto being considered, the merits of the filter press as an economic factor in the production of a per¬ fectly clarified product in a comparatively brief period, will be more fully appreciated. The use of the filter press removes probably the most objectionable feature in oil¬ milling, heretofore unavoidable. The retention of the “foots,” or mealy matter, in the filter cham¬ bers, precludes the necessity of frequent storage- tank cleaning, while the practicability of their be¬ ing reworked in the kettle in an expeditious and effective manner is very materially improved, owing to their being in concentrated form. The waste involved in the practice of the old system, whether 78 THE MANUFACTURE OF LINSEED OIL. in the protracted period essential for the removal of the foots from the storage tanks—a circumstance of frequent occurrence—the inconvenience experienced by loss of the storage room occupied by the casks and barrels of foots awaiting their final disposition, together with the cost of preparing same in the form of a suitable admixture with the regular material from the rolls, or ground cake, for the purpose of being suitably reworked in the kettle, taken collectively, amount to a very large item of ex¬ pense annually in an average-sized oil mill. It is palpable, therefore, that an oil mill of whatever capacity, and however well equipped in other respects, cannot be considered to be complete, with regard to suitable ap¬ pliances for the prosecution of economical work, lacking this most useful adjunct. Until within the last few years the form of filter press designed for oil milling consisted of a thirty-six-inch fil¬ ter with thirty-six chambers, which is in operation to-day in many manufactories; but in the event of additions be¬ ing needed to the filtering capacity, or the installation of new plants, later and improved presses are selected preferably. In the old form of filter press the plates are covered with suitable filtering cloths, which consist of two sets of fabrics held in position by three adjustable fastenings on the centre and sides of the upper edge of the plates. The equipment, with regard to the filtering medium, is comprised in one set of heavy texture, being next to the plate, and an outer set of lighter material. Not the least important condition in the attainment of satisfactory results consists in the filtering material being of the correct grade and texture. The fabric must be strong, yet woven closely, so that while producing a clear fluid, it must be sufficiently tenacious to successfully withstand the extra pressure always exerted where the joints are formed. In the filtration of raw linseed oil, the THE MANUFACTURE OF LINSEED OIL. 79 writer has used for years a fabric specially prepared, and by means of which impurities are removed from the oil in a most perfect manner, and which, with judicious treat¬ ment, may be kept in practical operation for at least a year, the Johnson filter press having been used. Further along in this treatise instructions will be given concerning the treatment which should be accorded the filter cloths, whether in or out of use, the best mode of cleansing and removing the gummy accumulations which clog the fabric, together with other important details con¬ nected therewith. With the cloths suitably adjusted, the plates are forced together by the follower, which is actuated by a screw operated by the lever-wheel. The plates are recessed, so that a chamber is formed between each two plates, the rim or outer edge of the latter being finished to a uniform thickness, while being of sufficient width to form tight joints and prevent tearing or rending of the cloths. The concave surfaces of the plates have vertical grooves, in which the liquid may pass off, the drainage being in¬ creased by several short, straight grooves, running laterally across the first ones, at stated distances apart, toward the plate bottom, in which is located the outlet. The plates being forced together the press is now ready for work. The oil is pumped into the press and, passing through the cloths, courses down the grooves referred to, and through the outlet into the receptacle beneath, a perfectly clarified product, the residue or mealy matter being retained in the chambers by the filtering medium. The capacity of this press is about 20 tons of oil daily, al¬ though this quantity may be exceeded under certain conditions. Presses without accompanying engine, and pump fitted and geared thereto, are preferable, the direct steam-acting pump usually producing best results, with regard to being less prone to get out of order. Practical Points Concerning the Filter Press, Whether for Oil or Varnish Filtration, and Where the Best Form of Filtering IMedium May Be Obtained. In the event of the press being required to remain idle for a few days, a simple but effective method of keeping the cloths moistened, and thereby preserved, without the necessity of removing them from the plates for submer¬ sion, consists in charging the press with oil, the outlets being shut. This is impracticable, however, where shut¬ off taps are not fitted to the plates; but the liquid may be slowly pumped through, the oil continuously coursing from suction tank to press, and return. By repeating this operation at frequent intervals, the material is preserved. When through omission, or from any other cause, fil¬ ter cloths used in the clarification of linseed oil are per¬ mitted to dry up during a temporary cessation of the fil¬ tering operation, the damaging effect on the material is more serious than in the case of cottonseed oil filtration. The drying properties of linseed oil act very deleteriously on the surface of the cloths by gumming them, thus blocking the minute openings between the woven threads, rendering them impervious to the oil, and con¬ sequently valueless as a filtering medium. Cottonseed oil, which possesses drying properties to a comparatively trifling extent, is not so injurious to the cloths when permitted to remain thereon; nevertheless, complete submersion guarantees preservation of the fab¬ ric when out of use for any extended period. The cloth used in the filtration of lard oil, being of the same texture, requires similar attention under like cir¬ cumstances. The coagulation of the albuminous de¬ posits characteristic of animal oils displays a tendency to clog the filtering material when not submerged in the 80 THE MANUFACTURE OF LINSEED OIL. 81 liquid. This has the effect of damaging them equally with that of the gumming tendency of linseed oil under similar conditions. Impressed with the fallacious supposition that a saving is effected in cost of filtering material, some of the cottonseed crushers and refiners have substituted several plies of cotton-duck cloth on each plate of the filter press for the closely-woven and substantial fabric especially manufactured for that purpose. The use of such material is most reprehensible; and viewed from a practical and economical standpoint, should not be maintained under any condition whatsoever. To obtain an oil from which the ordinary proportion of vegetable matter has been eliminated, as is the case where a suitable filtering me¬ dium is utilized, by means of such flimsy material as the common fabric referred to, becomes a practical impossi¬ bility. The tendency of the duck cloth to rend at the joints augments the difficulty by permitting the oil to pass out unfiltered, thus materially contributing to the defective principle involved; that is, the attainment of perfect filtration by inadequate means. Not infrequently leaks occur by reason of the im¬ practicability of forming permanently tight joints, the cheap material separating under the pressure essential to form a perfect joint. At this juncture the screw is set up, thus bringing the plates closer, the object being to stop the leak or leaks; but while this expedient may for the moment prove effective, aided probably by the dis¬ lodged foots in the filter chambers forced to the leaky point by the escaping fluid, and blocking the aperture or apertures temporarily, the extra pressure exerted at the joints, as a result of the latest movement of the screw, will eventually manifest itself by still further increasing the undesirable oil exit, until perforce the operation is brought to a standstill. The press is then permitted to 82 THE MANUFACTURE OF LINSEED OIL. drain off its fluid contents, the fragmentary cloth or cloths are removed, to be substituted by whole material, which, in turn, is destined to be similarly cast aside, prob¬ ably before the expiration of forty-eight hours. The use of filter cloths of suitable texture is much more economical, actually costing less in the end, with¬ out reference to the very superior product obtained by its use as compared with that of the frailer material. Under skillful treatment, a set of soiled and clogged filter cloths can be restored to their original usefulness, or so closely approaching it, that the difference is not perceptible; and this may be successively repeated as occasion re¬ quires, until they are worn out by prolonged usage. Lack of adequate knowledge to effect a thorough cleansing of the soiled cloths, in nine cases out of ten is the prim¬ ary cause of their being irrecoverably spoiled, thus pre¬ cipitating their premature abandonment. It is oppor¬ tune to observe at this point that the house of J. H. Lane & Co., 110 Worth street. New York, handles a line of filter cloths which are of a very excellent charac¬ ter. The writer has used their cloths for many years with uniform satisfaction, and takes pleasure in recom¬ mending them. OIL-BOILING AND VARNLSH THERMOMETERS. A perfect thermometer may be rendered absolutely un¬ reliable by injudicious treatment during a single opera¬ tion. Among the primary causes which induce defects in a varnish thermometer may be mentioned the repre¬ hensible system of permitting the instrument to rest on the kettle bottom during the whole, or part, of the period essential in the preparation or treatment of an oil or var¬ nish. In the position referred to, the instrument is brought into close proximity with the fierce heat, always most intense in that particular location, especially when the material requires heating quickly to a high tempera- 83 THE MANUFACTURE OF LINSEED OIL. I ture. A temperature of 600° Fahrenheit, registered at a point near the surface of a body of oil or varnish, in the treating-kettle, indicates a very much increased tempera¬ ture at the bottom, where the intense and unobstructed heat of an incandescent fire impinges most forcibly. With certain makes of thermometers, the sudden transition from the normal temperature to this highly intensified heat has the immediate effect of agitating the measur¬ ing liquid in the tube, and, in its rapid and spasmodic as¬ cent, causing separation. On the other hand, by deposit¬ ing the thermometer in an atmosphere of low tempera¬ ture, or on the surface of a cold or damp floor, immedi¬ ately subsequent to the completion of a batch of oil or varnish, the results, with regard to their bearing on the instrument, are equally pernicious. The thermometer or thermometers should be carefully introduced into the heated liquid, or, better still, the instruments should be suspended in the oil before the application of heat, the mercury gradually ascending in the tube, together with the rising temperature. The effect of a high temperature on the thermometer is not injurious by impairing its ac¬ curacy when handled in this manner. An excellent form of thermometer now in use in many American varnish manufactories, and of comparatively recent construction, may be subjected to the sudden change from low to high temperature without apparent deleterious results, but the foregoing method is, never¬ theless, to be commended in all instances. A distinct clearance of six inches should obtain be¬ tween the lower point of the instrument and the kettle bottom. The exact temperature necessary to procure a certain oil or varnish being absolutely arbitrary, it fol¬ lows that an accurately defined scale of readings, which is engraved on the tube or facing of the instrument, when undergoing the process of calibration, becomes an in- 84 THE MANUFACTURE OF LINSEED OIL. dispensable condition in modern varnish making. The most perfect type of thermometer will, however, exhibit inaccuracies if used regularly for a year, even under favorable conditions, thus demonstrating the necessity of regular tests. The most serviceable type of varnish thermometer consists in the lower part of the column or bulb, which contains the mercury, and which is, in turn, enclosed in a metallic shell, being protected by a small frame composed of six arms extending downwards, and uniting at a central point beneath, the frame being about 4^ inches in length. This affords effective protec¬ tion to the most vulnerable part of the instrument, and being simply screwed to the bottom, may readily be re¬ moved for cleaning or other purposes. In other designs, a perforated metallic guard is attached to the bottom, re¬ movable in a similar manner. Complaints from varnish makers are of frequent oc¬ currence with regard to the unreliable character of their thermometers and frequent proclivity to get out of or¬ der, the fault in the majority of instances resting with themselves. On the completion of a batch of oil or var¬ nish instead of handling with the greatest care, the heed¬ less operative will seize the instrument and throw it into an obscure place as a valueless object, repeated treatments of this character not only causing twists and bends in the frame, but also displacing from its central position the metallic shell which immediately protects the bulb. Fur¬ thermore, neglect of a thorough renovation or cleaning after each operation will, like the foregoing censurable methods, undoubtedly impair the sensitiveness of the in¬ strument, however perfectly constructed. Recently the writer examined a thermometer which the oil boiler com¬ plained of as being misleading, and found that the in¬ terior of the perforated guard was entirely filled with burnt resinous and other substances, the accumulation THE MANUFACTURE OF LINSEED OIL. 85 of numerous operations. The radiating rays of heat, in this instance, were obstructed by the accumulations re¬ ferred to, and, failing to act upon the mercury in the bulb in a direct manner, the scale readings were necessarily in¬ accurate. A thorough cleansing should succeed each operation, and this is most expeditiously and satisfac¬ torily prosecuted by the aid of benzine. Partially cal¬ cined gum or resinous accumulations are by this means removed with facility, thus maintaining the sensitive¬ ness of the instrument unimpaired for the succeeding operation. In the preparation of oils and varnishes, it is, there¬ fore, imperative that an accurate instrument be used, the best interests of the manufacturer being subserved by a recognition of the fact. The writer has used for a number of years, with entire satisfaction, a design of thermometer peculiarly adapted for the needs of oil boiling and varnish making. The design referred to has been invented by the Hohmann & Maurer Manufacturing Company, with offices at 123 Liberty street. New York, and works at Rochester, N. Y. This well-known house has experimented for eighteen years with thermometers for use in oil boiling and varnish making, Vv^ith the result that it is beyond question, the most reliable and practi¬ cal thermometer on the market to-day for its various uses. The construction of the design of thermometer referred to is essentially substantial, thus lessening the chances of breakage. The scale case, which is graduated from 212° to 700° Fahrenheit, is made of pure aluminum casting, and in triangular form, thus imparting strength and facility for hand¬ ling. The scales or dials are hermetically sealed by a removable glass joint, secured by screws to the body of the frame, the joint being grooved 86 THE MANUFACTURE OF LINSEED OIL. and packed. The figures and graduations are a dead white against a jet black background, which greatly facilitates reading, the dimensions of the scale case be¬ ing 14 by 2f inches, the entire length being under 40 inches. The thermometer tube, with the long cylindrical mercury bulb, is encased in a metallic shell, and held in position by means of a suitable packing screw and stuff¬ ing box, the packing material being asbestos. For pre¬ parations which do not require a temperature exceed¬ ing 500'^' Fahrenheit, the conductmg medium differs from those which require a higher temperature. In the lower portion of the copper sterii in which rests the bulb, the latter is immersed in a mercury bath, which instan¬ taneously transmits the slightest variation in temperature to the mercury within the bulb, indicating the circum¬ stance simultaneously on the scale. The bath system insures great durability to the thermometer, as the glass bulb and tube never come into contact with the hot liquids. In the application of temperature ranging from 100° to 500° Fahrenheit this form of thermometer is most superior, being unexceptional from any standpoint. The manufacturers of this form of thermometer have also, for higher temperatures, an instrument which is unique and without a compeer in its line, the scale reach¬ ing 850° Fahrenheit, to which point the temperatures of gases or liquids are accurately indicated, while it is the ultimate intent of the makers to increase the scale to 1,000° Fahrenheit. This thermometer has been subjected to protracted and continuous use at temperatures rang¬ ing between 700° and 850° Fahrenheit, at the end of which time the variation was insignificant, as demon¬ strated by a careful test. When it is recognized that the temperature which this thermometer is capable of indi¬ cating is largely in excess of the mercury boiling point, together with the fact that the fluid metal, when sub- THE MANUFACTURE OF LINSEED OIL. 87 jected to a heat equivalent to 680° Fahrenheit, boils and is converted into vapor, the achievement attained will be more fully appreciated. The ebullition of the mer¬ cury is obviated by means of nitrogen gas, its method of application and operation being patented. In this in¬ stance the mercury bath is substituted by copper dust, specially prepared by a secret process, and, as a conduct¬ ing medium and protection to the bulb, is in all respects equal to the mercury at the lower temperatures. The scales or dials, which are hermetically sealed by a re¬ movable glass front, are slotted and held in position at either extremity by small brass screws, thus permitting their adjustment when occasion requires. MACHINERY FOR THE TREATMENT OF OILS WITH FUL- ler’s earth. Following the most improved method, and that em¬ ployed by some of the most successful refiners, in Eng¬ land and France, the mixing kettles are now constructed in the form of cylindrical steel tanks, with dished ends, and constructed necks at the top. The bottoms are made double, so as to provide a steam-jacket for heating; and the apparatus is further provided with a patent vortex disc agitating gear, which effects a very powerful and rapid admixture of fuller’s earth with the oil. The tank is filled to the underneath part of the neck with the oil, or fat, to be treated, previously heated to a temperature of 150° to 180° Fahrenheit. The temperature is important. The vortex mixer is kept in motion while the tempera¬ ture of the oil is being adjusted, and as soon as it ar¬ rives at 150°, the fuller’s earth is added, care being taken that the proper quantity is employed. It should be ground to a VERY FINE POWDER (we can refer prospective purchasers to reliable New York houses who hold in stock specially prepared material for this pur- 88 THE MANUFACTURE OF LINSEED OIL. pose) and ought to be quite dry and free from moisture. This is most important. Three to five per cent is the amount generally used, but, of course, the quantity would depend on the amount of color to be extracted. This the refiner can test by experiment, by heating a small quantity and filtering it through filtering paper in a heated tin funnel before commencing. When treating oils or lard which are to be used as food, it is very important to remove the fuller’s earth from them as quickly as possible after the mixing, and also that the mixing should be effected as rapidly and thoroughly as possible. For this reason, and so as to keep up a constant supply of the oils and fats and keep the filter at work, it is preferred to have the kettles worked in pairs on the twin system, i. e., whilst one kettle is being used to feed the oil filters, the other is being pre¬ pared and treated with fuller’s earth. If the fuller’s earth remains any length of time, say over fifteen minutes, it commences to impart a taste to the oil or lard, and is objectionable. Such oils, etc., should be kept at a lower temperature. The best tem¬ perature to employ can be readily found by experiment. After the proper quantity of fuller’s earth is thoroughly mixed, the whole of the contents of the mixer are pumped by a steam pumping engine into the filter press. It should be noted that kettles made to hold very large quantities are objectionable, as the fuller’s earth remains too long in mixture with the oil, and imparts an earthy taste by the time the filter is. filled with cake. The filter is so proportioned to the work to be done, as to have a cake that will not be quite formed—a hollow cake. Steam is admitted into the centre feed channel of the press, and it finds its way into each of the hollow cakes. All the cocks are shut off, except the one farthest away from the head. The steam passes through the centre of THE MANUFACTURE OF LINSEED OIL. 89 the press, and first steams out the cake next the follower. When the steam has blown through this cake so as to free it thoroughly from oil, it is shut off, and the next one opened; and so on, until all are steamed. When the press is opened to remove the fuller’s earth it falls out in powder on the floor, little or no oil being left in it. In the case of some oils, such as castor oil, fuller’s earth does not answer as well, and in such cases finely powdered animal charcoal or else wood charcoal, in fine powder (willow charcoal being preferred) is used. It is important also that the temperature should be raised to about 150° to 180° in these cases also; in fact, the ani¬ mal or wood charcoal miay be used in lieu of fuller’s earth, the same precaution as to dryness and fine powder being observed in these cases. Care should be taken where the oils are viscid, such as castor oil, linseed oil, etc., that the room where the filter is situated be artificially warmed, so that the whole mass of metal in the filter may be heated up to the tem¬ perature at which it is found best to work. In the case of linseed oil, this should not be less than 90° Fahrenheit. With castor oil it should be higher still. Filters are also made with each of the plates steam- jacketed, so that the contents of the oil filter can be main¬ tained at any temperature required. These are used for testing solid fats, such as wax, paraffin, vaseline, etc. Economic Oil l^iliing—Practical Hints and Suggestions to Oil IMillers. The fundamental principles of oil milling are fine grinding and adequate cooking and pressing. To the practical oil miller it would appear, needless to say, that it pays handsomely to keep the rolls in good order. That is, they should be perfect cylinders. The writer has operated a most excellent lathe, which automatically grinds and trues up worn rolls in a surprisingly short space of time, an emery wheel * working on each side of the revolving roll. You can build the lathe readily and at a low' cost. May add that this system of grinding precludes the possibility of metallic particles floating about,' which are so injurious to human lungs. No well-equipped mill can afford to be without this valuable machine. . It will pay for itself in a very short time. What kind of belting do you use for your rolls? If they are not double, they should be -by all means. HEATING OR COOKING THE CRUSHED SEED. Under the writer’s supervision was constructed a form of kettle within the past three years, which is, beyond, doubt, the most effective for the intended purpose— a thoroughly cooked material—that has ever been intro¬ duced. They are now being put up in first-class mills. The use of this kettle rendei's it possible to turn out uniformly well-cooked charges continuously. In twelve minutes the kettle will prepare a batch ready for withdrawal, it being very susceptible to heat. It con¬ sists simply of two jacketed kettles, 15 inches apart, a disc on top, upon which the meal from the rolls is dis¬ charged, thus making three bottoms. 90 THE MANUFACTURE OF LINSEED OIL. 91 They can be made of any desired capacity. Those referred to are 6 feet inside diameters, 6 feet 4 inches outside, f inch and f inch steel bottoms, ^ and 5 1-16 inch shells. The com¬ bination turns out a press charge of twenty cakes, weigh¬ ing, when trimmed, 12^ pounds, every 7^ minutes, the^ agitation being of a very superior order. The jacketed kettle, such as referred to, will cost about $400, the at¬ tachments being fitted thereto on the mill premises. Two openings at bottom of each kettle, on opposite sides, are made for the entrance of live 'steam with the meal, while at top of the kettle three descending steam jets are also furnished, passing over kettle top and inserting themselves into the upper layer of meal. The agitation here .caused by the revolving sweep causes a thorough mixing of the Steam and dry heat with the seeds. In the first place the seed falls upon the disc, which is about 4 inches less in diameter than the two other bottoms be¬ neath. A sweep drops a certain portion of crushed seed continuously over the entire circular edge of the disc to the u^per section of the double -kettle immediately be¬ neath. -Here it is again mixed,-the real cooking opera¬ tion now commencing. The material falling to that part of the kettle beneath which is furthest from the centre, in which latter location a small hatchway is located, close to the vertical shaft, gradually works its way by reason of the mixing and agitating process to the central dis¬ charge gate referred to. The extent of this opening is readily governed by the operative. The treated seed again falls, this time into the central part of the bottom kettle, whence it works its way downward and gradually further from the centre, where it falls to the discharge gates at the end of the diametrical line beneath. A most thorough and perfect mixing and heating system is thus assured. For cottonseed it is also of great value. 92 THE MANUFACTURE OF LINSEED OIL. as surplus moisture may be readily eliminated by the great dry heat which may be radiated throughout the mass. American cottonseed, which at times contains a large percentage of moisture, is readily cooked to the proper consistency in this manner, the live steam being shut off and the dry heat thus disseminated. PRESSURE APPLICATION. In the event of your not having in operation the latest system of pressure application, with whatever form you may now use, the introduction of the latest and most approved method referred to is practicable. By the in¬ sertion of a small steel plug (writer has a number on hand) in the high-pressure orifice, the new system, by means of which the pressure is applied to the material in the press in such a gradual manner that the press cloth fabric is capable of being used for a very much longer period than under the old system. A minute hole is perforated through the centre of the plug, which has the effect of obviating the sudden change from the low to high pres¬ sure, which is productive of so much destruction to the press fabric and the cause of breaks in the presses. The use of this plug will keep pressure so uniform that even in a large mill the accumulator system does not be¬ come necessary. AUTOMATIC CHANGE OF PRESSURE. In oil mills, heretofore, it has been the custom to de¬ pend entirely upon the pressman to shut off the low pressure and turn on the high at a certain moment. At times, especially on the night watch, the careless em¬ ployee, rather than bend his back to shut off the low and turn on the high pressure at the proper time, will allow the low pressure to remain on during the entire pressure period. A very heavy oil percentage is thus THE MANUFACTURE OF LINSEED OIL. 93 left in the cake and the manufacturer is by so much the loser. This suggested to the writer the idea of overcoming this difficulty, which was successfully accomplished, and in the following manner. It is now in use in a 24-press mill, and from the time the system was first introduced three years ago, it has given great satisfaction, while re¬ quiring not the least attention at any time. It simply consists of this: By means of a small gear wheel, which is between and affixed to the upper parts of the low and high pressure stops, the act of opening one simultaneously opens the other stop. Therefore, when the pressman turns on the low-pressure pump to start the press ram, the high-pressure pump is connected * or turned on at the same time. Without the use of another device this operation would be impracticable, ' for the reason that in some hydraulic systems the high pressure would force the oil into the low-pressure pipes, unless latter were shut off, thus causing disaster. This suggested the idea of a small tumbling valve to the writer. This small tumbling valve is placed in the low- pressure orifice, and most effectively shuts off the low- pressure system when the high-pressure in its ascent ex¬ ceeds the latter. To be more explicit, this small tumbling or retaining valve is placed right beneath the low-pressure stop in the reversing chest. Let us suppose the press is charged and ready to ascend. The pressman opens the stop. The moment the pressure exerted by the high-pressure pump exceeds that of the low-pressure pump, which takes place an instant or two after the oil commences to flow, the retaining valve is forced into the low pressure orifice, thus completely closing off that system, auto¬ matically, and in the most complete manner possible. You are not depending upon the pressman to do this. 94 THE MANUFACTURE OF LINSEED OIL. and all that he does is to shut off the pressure when the full pressure period has expired, open the lever and the ram descends. This is a most excellent system, and can be introduced for a mere trifle. Have you in operation an automatic announcer in your mill which notifies the pressmen when to charge their presses while registering the work done, so that at any time during the week you can learn exactly how many pressings have been made/ BOILING BY STEAM. The steam-boiled oil has a very large consumption in the United States. A mixing of 2,000 gallons is boiled at a time, the steam-jacketed kettle hay¬ ing a capacity of 2,500 gallons. • The system of mixing is most perfect. A rotary pump placed close to the kettle is continuously and rapidly withdrawing the treated oil from bottom part of the kettle and discharging it at the. top, thus obtaining a sys¬ tem of mixing which cannot be equaled. The liquid drier is most thoroughly mixed and incorporated with' the oil and very excellent results are obtaine*d, all other conditions being correct. Air is also blown'into the oil and maintained during the operation. LIQUID DRIER MAKING-FOR ST^AM-BOILED OIL. Into a small kettle, or iron pot of suitable capacity, of, say about 100 gallons, put in 48 gallons raw oil. When 250° F. has been reached, add under'constant stirring’60 pounds manganese, 10 pounds sugar of lead, 6 pounds borax and 3 pounds of sulphate of zinc. All must be added very slowly, and to be constantly agitated and mixed by two persons, one on each side of the kettle, furnished with long stirrers. Heat is increased to 500°, the agita¬ tion being maintained unrelaxed until the entire opera- THE MANUFACTURE OF LINSEED OIL. 95 tion is completed, the stirrers being alternately passed along the bottom of the kettle so as to prevent the chemi¬ cals from settling and facilitate their incorporation with the oil. The chemicals must be added a little at a time, and, as already stated, the agitation must be continued until the fire is withdrawn. At any time, when the preparation threatens to rise in the kettle, pour in a pail of raw oil. Raw oil to the extent of 30 gallons must be poured in during the op¬ eration. making 78 gallons of raw oil in all. The temperature of 500° must be maintained in the preparation for 3| hours. • Twenty-eight gallons of this drier, suitably thinned with raw oil, will be needed for 2,000 gallons of oil by the steam-h-eating or boiling process. FIRE-BOILING SYSTEM. ’ This boiling may be accomplished in a casting of any desired capacity. We will suppose the boiling to con¬ sist of 750 gallons of oil, the casting or kettle for which should have the capacity of, say, 1,000 gallons. When the furnace heat has sent the temperature in the oil up to 250° F., 30 pounds of litharge and 10 pounds of umber are added. From the moment the fire is started a verti¬ cal shaft, which runs down the centre of the kettle, with arms attached with suitable sweep at bottom, is set in motion and continued until one hour after the fire is withdrawn. A temperature of 475° is maintained in the oil for three hours. The resultant product is a most excellent boiled oil drying, with a rich gloss and varnish-like surface, in 5 or 6'hours. The pot or kettle is built up by masonry and suitably covered, the vapors being carried oft’ by a large pipe to the boiler chimney. 96 THE MANUFACTURE OF LINSEED OIL. The element of danger inseparable from this system of fire-boiling has tended to increase the steam-boiling sys¬ tem with regard to the amount of oil turned out. TREATMENT OF CALCUTTA SEED OIL FOR VARNISH. Several of the leading crushers make a specialty of this oil, and there is a very large demand for it from varnish makers. But the fact is, that in some instances, it is composed to a ver}'^ large extent, probably one- third of the whole, of common American raw. It will stand the fire and water test without breaking, and present the natural aspect of well-settled oil. The method of procedure is as follows: Seven quarts of sul¬ phuric acid are measured into a lead-lined tub, then 56 quarts of water are added to the acid, the latter being 66° B. The mixture of acid and water is now allowed to stand •> over night. The treating tank must be ready, and in this case 2,800 gallons of oil are treated at a time in each tank, and six tanks of oil under treatment at one time. The air-pump is started and the oil is set in commotion at once. Across the top of the tank there are three small wooden runways, upon which stone jars are placed. To these jars are secured a long wooden handle, or stick, by means of which the refiner can push the jars with their contents backward and forward over the top of the tank at pleas¬ ure. In the jars, three in number, the acid and water, mixed the previous day, are poured in. At the bottom of each jar a small hole, which has been carefully drilled through previously, permits the solution to fall into the agitated oil beneath in minute streams. This has the effect of causing the acid and water to be associated with every portion of the mass of agitated oil THE MANUFACTURE OF LINSEED OIL. 97 beneath. When the oil has been in agitation for three- quarters of an hour 1,500 or 1,600 gallons of hot water, preferably sea water, which must be ready, are run into the 2,800 gallons of oil under treatment. The water should be heated in an elevated tub or vat with direct steam connection with the boilers. When the water is all in the treating tank the temperature of the oil and water should be about 130° F. From the mo¬ ment the air-pump is first started, prior to the addition of the sulphuric acid dilution, two hours’ agitation should intermittently be maintained. The air is forced through a lead pipe coiled in cir¬ cular form around the bottom of the tank, with perfora¬ tions closely together on the upper end of same and the end closed. The preparation is now left to repose, and on the third day it is pumped into a large jacketed kettle and dried by heat, so that the moisture will be thoroughly elimi¬ nated. This usually takes four hours, but sometimes to procure the correct color it will take longer. The air pump is operate’d in conjunction with the dry¬ ing by heat, and the oil is pumped from bottom to top continuously by rotary pump as already shown. Tem¬ perature should be about 170° F. When the oil has been properly dried and aired it is pumped into a large tank temporarily, from which it is afterward slowly filtered and finally placed in stock ready for delivery. The per¬ centage of water in this system is so small that it does not exceed one per cent. Filtration makes it a beautiful bright oil. METHOD OF REFINING. Here is an excellent system as carried out in several of the leading mills. The oil has no equal in America, and it commands a ready sale. Two thousand eight hundred gal- 98 THE MANUFACTURE OF LINSEED OIL. Ions of oil are awaiting treatment in the tank, and the air is turned on, causing the oil to be in commotion at once. In three jars placed over the top of the tank on the wooden runways 28-| gallons of sulphuric acid, 66° B, is poured. The acid runs out in minute streams and be¬ comes thoroughly mixed with the agitated oil beneath. In this mode of introduction the acid will not char the oil, which it comes in contact with, which, under other conditions, it would do. It should take 20 minutes for- the acid to run in. When all the acid is in 1,500 or 1,600 gallons of cold water, preferably salt or sea water, is at once run in. The air agitation is kept up for one hour, at the expira¬ tion of which the cold w'ater is run in, and the agitation is now continued for three hours longer. The oil and water are now allowed to settle for two weeks at least, the longer the better. It is then with¬ drawn, a thousand gallons at a time, and steamed in a copper-lined tank. It is steamed for six hours. The following day the water is drawn off and the succeed¬ ing day it is pumped into storage tanks to be delivered. EXTRA REFINED OIL, AND FOR WHICH A FANCY PRICE IS OBTAINED. The same operations are pursued as in the foregoing process until the steaming is executed. In this instance, after the steaming and proper settling period have transpired, the oil is pumped into a shallow tank (copper) immediately beneath a large glass roof, where the sunlight may have unobstructed play thereon, the oil depth not exceeding 14. inches. It is left here as long as possible, a week at least, from which place it is caused to run through a pipe to a filter press. It is filtered very slowly and by gravity only. The re- THE MANUFACTURE OF LINSEED OIL. 99 sultant oil is perfectly bleached; it is water white, and its brightness is remarkable. The cost of a refining plant is not great. Two large vats, one for mixing and agitating the oil and the acid and water, and the other for steaming, both being lead lined. CAKE-PACKING MACHINE. This machine is a most useful adjunct to a mill which exports its cake. It will pack 400 or 500 bags of cake in a day. The workman simply fills the bag with enough cake to make the bag stand. The bag with the loosely put in cake is now trucked into the machine. The ma¬ chine operative, seizing two cakes, inserts the lower ends between the tops of the cakes in the bag and the upper ends are pushed back until they stand vertically. The ram or arm of the cake-packing machine is now caused to descend, and, in a quicker time than it can be told, it presses the two cakes clear down into position and again comes down to press two more cakes and repeated until the bag is packed. It will not break the cakes if man¬ aged as instructed, and no cake chips or fragments strew the packing-room floor, everything being clean. The bags are packed firmly. The gear shaft is 2| inches diameter and 7 feet 2| inches from the floor. The arm extends about 14 inches, and is secured to a movable rack running in a slot in an upright hardware beam or stout stick. The iron arm has a face large enough to drive two cakes. It should be flanged. The small gear wheel for running the rack should be 6 inches in diameter, teeth 1 inch; rack 54 inches long by 2 inches wide and speed of the pulley 66 revolutions. A system of oil drawing from storage tanks for deliv¬ ery, which is valuable, is deserving of notice. By sim- 100 THE MANUFACTURE OF LINSEED OIl! ply turning a cock the oil flows from the desired tank, without belt changing or starting the pump. A rotary pump, always in operation, together with a simple con¬ trivance, produces the convenience referred to. Boiled, raw, refined or varnish oil can be drawn instantly from the various tanks' concurrently or separately. The use of this system is a very great convenience, its intro¬ duction or cost of same being unimportant. CAKE TESTING. The method of analyzing cake is as follows: In a mill of large capacity it is customary to select a cake from each set of presses for each watch of analysis. A cake may be selected from each press, or more than one from each other, if desired. The apparatus needful is simple and inexpensive, comprising glass tubes and porcelain dishes sufficient for each test of meal made; a pestle and mortar, fine screen and balance complete the outfit, the solvent used being bisulphide of carbon. A small wooden stand will be needed to hold tubes in a vertical position, with perforations in lower cross-piece to permit the pointed ends to be inserted therein, so that the solvent and oil may drop unobstructedly into the small recepta¬ cle beneath. Take the cake to be tested and saw through diagonally, the fine meal and fragments falling on a previously spread out paper. Avoid passing the saw through the oily edges of an imperfectly trimmed cake. This is accomplished by breaking off one or two inches from each end. Raise the meal dust and cake fragments and pass through a fine screen. The frag¬ ments may be reduced by the pestle and mortar to a mealy consistency, the finer portion being secured as be¬ fore. Lumpy matter or fragments, however small, must not be permitted in the meal to be tested, and as an ad¬ ditionally precautionary measure the pestle and mortar THE MANUFACTURE OF LINSEED OIL. 101 are again brought into requisition, and the meal pulver¬ ized into an impalpable powder. Five grams of meal are now carefully weighed by the balance, the weighing being conducted with delicacy and exactness, so that re¬ sults will be accurate. The tube or tubes are in readiness, each having a small piece of cotton pressed firmly to the bottom. By means of a small tin or glass funnel, which is inserted into the upper part of the tube to be charged, the weighed meal is now introduced, over which another small piece of cot¬ ton is pressed down, the whole being subjected to a mod¬ erate strain to secure compactness. When removing the meal from balance dish to the tube, carefully dis¬ place from same adhering particles, or dusty matter which remains on sides and bottom when the dish has been inverted. This may be done with the cotton, which is intended to press over the 'meal, the funnel being carefully cleaned down with same and the whole pressed into position. A small wire rod and wooden pin, the latter made of a suitable diameter to enter the tube, will be found useful adjuncts in this connection. The small porcelain dish is now placed immediately under the charged tube and the solvent poured in. The same funnel which introduced the meal will answer this purpose, when the top is closed with a small piece of cotton. The bisulphide of carbon will be observed pass¬ ing through the compressed meal and a few minutes later falling into the dish beneath, together with the oil. The bisulphide of carbon is added in the following man¬ ner: To place this phase of the testing operation before the prospective analyst in the most simple manner it will be necessary to give the dimensions of the glass tubes, which, for other reasons, it is also essential to ex¬ plain. I'he tube should be about 15 inches long and one-half 102 THE MANUFACTURE OF LINSEED OIL. inch wide and blown to a point at one end. Bisulphide of carbon sufficient to occupy 6 inches of the tube space will suffice for the first charge, when, at the expiration of two or three hours, about 2 inches more are poured in, and in an hour or so afterward the final addition is made —about 1 inch. A good plan is to have this accom¬ plished late in the day, allowing the solvent and oil to re¬ main over night, when the former will have been almost completely evaporated. However, this is not essential, as when the last charge of solvent has percolated through the meal, the small dishes may be placed over a heater or stove, when the solvent or moisture that may be pres¬ ent is removed with facility, leaving the pure cotton oil in readiness for weighing. Under any circumstances it is necessary to place the dishes with their contents on the heater or stove, so that possible traces of solvent or moisture may be assuredly eliminated. The dish and oil are now weighed and the result jotted down, the oil is carefully wiped out, the weight of the empty dish ascertained, which, deducted from the original figures or gross weight, gives the exact percentage of the oil left unextracted by hydraulic pres¬ sure. A good plan is to have the weight of the empty dish beforehand, a distinguishing mark, or number, still further simplifying matters. Of the 5,000 grams of meal we will say for illustration 430 grams of oil are obtained or equal to 8.6 per cent of the weight of the meal, which is the exact percentage of oil left in the cake. The wooden stand or stands may be made of sufficient capacity to hold 6, 12 or 20 tubes, or as many as will be required for a regular testing operation, according to mill capacity. A record book should be kept show¬ ing results, which may be referred to for purposes of comparison at any time. The method is simple and ab¬ solutely accurate, the last vestige of the oil being effect- THE MANUFACTURE OF LINSEED OIL. 103 ively withdrawn from the meal. In this connection ether is generally supposed to be a more powerful and effective solvent, but by following the particulars here laid down a much more simple and practicable factory method will be secured, while being uniformly reliable. Bisulphide of carbon may be purchased at 9 or 10 cents per pound, while there is many times this price. A pound of bisulphide will suffice for 12 or 14 tests. One point should always be borne in mind. Bisul¬ phide of carbon is extremely inflammable; its vapor, even when confined, is explosive. No light or fire should be brought into its vicinity. With care in this respect, how¬ ever, it is easy and safe to handle, and it is not dangerous to inhale a reasonable amount of the vapor, in spite of its offensive odor, to which, by the way, one soon be¬ comes accustomed. The writer has used this system regularly for twelve years in preference to all others and with uniform satis¬ faction. EXTRACTION OF OIL WITH ETHER. In most factories working on a large scale with bi¬ sulphide of carbon, experiments on a small scale are gen¬ erally made with ether. It has been shown by numerous experiments that the seed is completely exhausted with ether, and the oil after evaporation is of excellent quality. But, notwith¬ standing that the advantages of ether over bisulphide of carbon and canadol are known, its use on a large scale never proved a success. The loss by evaporation in an incompletely closed ap¬ paratus was feared, and the use of water, as with bisul¬ phide of carbon, was not possible, the specific gravity of bisulphide of carbon being 127, and that of ether only .072.8. Consequently the latter would not sink in water. 104 THE MANUFACTURE OF LINSEED OIL. Very recently O. Braun has proposed the extraction of seed oil on a large scale by ether. It is claimed that the properties of ether, as well as its low specific gravity and low boiling point, are not hurtful but rather ben¬ eficial in an entirely closed vessel or apparatus. On account of the low specific gravity one pound of ether occupies nearly double the space of one pound of bisulphide of carbon, and as the solvents are used by measure and not by weight, the difference in price is al¬ most annulled. The low boiling point allows of a rapid and complete distillation of the ether from the oil and the residue. (Braun’s work.) Extractors 3^ feet high and feet wide, 550 pounds capacity of crushed seed and in 40 minutes the process is complete, and the last vestige of ether odors removed by steam, driving the ether into the distilling vessel. The consumption of ether, it is claimed, does not exceed one per cent of the oil extracted. AUTOMATIC CHANGING FROM LOW TO HIGH PRESSURE— HOW TO FACILITATE THE MAXIMUM OIL YIELD WHILE SAVING THE PRESS CLOTH. The automatic change from low to high pressure without breaking into the hydraulic pipes was success¬ fully experimented upon by the writer in 1891, and is now in regular operation. By means of a small tumbling or retaining valve placed in the low-pressure orifice in reversing chest, right under the screw stop-cock, the seat must be trued up, so that when the upper part of the retaining valve receives the pressure from the high-pressure pump, no oil can pass around or beneath it. Let us suppose the press is charged and ready to ascend; the two stops, high and low, must be swung wide open; the ram then ascends. The THE MANUFACTURE OF LINSEED OIL. 105 moment the pressure exerted by the high-pressure pump exceeds that of the low-pressure pump, the retaining valve is driven into its seat, as the pressure strikes the head of the retaining valve equally with any part of the ram, thus stopping the pressure from going below it. When the time has arrived for emptying the press the two stops are shut, the relief valve opened and ram de¬ scends. The uniformly good results obtained from running the mill on above principle would be difficult to over¬ estimate, as compared with old principles. The small plug in the high-pressure orifice and retaining valve in the low-pressure orifice make this a beautiful piece of work. The small plug prevents the pressure from com¬ ing too suddenly on the bags in presses, causing the pres¬ sure to slowly and gradually increase, a saving of 25 per cent, and saving very considerably in press bag¬ ging. The retaining valve insures the full length of time under high-pressure “nip” without depending on the pressman, who at times neglects to make the change, which causes a high percentage of oil to go off in the cake nearly all the time. The uniform good yield of the mill since the above principles were put in regular opera¬ tion bears undoubted testimony to the fact. The high pressure now being regulated by the small plug with the No. 12 core also prevents the meal from being squeezed out from between plates on each side of the press, causing it to run down and fill up the troughs below every few days. F ormerly the troughs under the presses were cleaned out twice a week; now they are cleaned once in two weeks. On old principles the pressure coming suddenly on bags and meal ripped and burst the former and caused the lat¬ ter to rush out, filling troughs and causing lots of work in the pressroom. The percentage was regularly from 8 to 10 per cent, many times up to 11 or 12 per cent. 106 THE MANUFACTURE OF LINSEED OIL. Before this important change was made in the mill re¬ ferred to the general average was about 9 to 9^ per cent. It was thus brought down to 6 per cent, and it rarely reached 7 per cent, the general average being in the neighborhood of 6^ to 6f per cent. The percentage of oil left in cake is always less in Cal¬ cutta seed than in American. METHOD OF ANALYZING CALCUTTA SEED BY WEIGHT. The following explanation supposes the use of the Marseilles system of sieves, which are in number from 1 to 6 inclusive, being placed over each other: To weigh an average sample of, say, 100 grams, pass from No. 5 sieve about 9-10 of this. That remaining will mostly contain large non-oleaginous matter mixed with linseed, etc. Separate this into two parts; the non- oleaginous lay aside, the remainder re-mix with seed now in sieve No. 3. Work the seed in No. 3 lightly with the hand for a short time, when it will be found con¬ siderably smaller oil seed, and dust will enter into No. 2. Rub the contents of No. 2 and afterward No. 1 with wash leather in order to crush into dust the non-oleagi¬ nous matter, returning to and re-mix in each case with the linseed now in No. 3 the oleaginous and non-oleagi¬ nous too large to pass through Nos. 1 and 2. First dust: The fine dust now formed to be added to that first sepa¬ rated from No. 5, which together constitute the first dust to be afterward weighed and percentage taken. Of the seed cleaned from the first dust, take an average sample by weight of, say, 25 grams, separate in three parts, namely, linseed, oleaginous matter, other than linseed and non-oleaginous matter. Second dust: This last dust is called the second dust, in order to THE MANUFACTURE OF LINSEED OIL. 107 arrive at a percentage or per cent of second dust to first, obtained for total non-oleaginous matter ad¬ mixture. In the same way obtain the percentage of oleaginous admixture in the 25 grams taken, which must be divided by 2, and is, therefore, assumed as being one- half the value of linseed. Add the oleaginous and non-oleaginous together. The difference between the total and 4 per cent will show the allowance to be made; if less than 4 per cent to the seller, if more to the buyer. A MORE SIMPLE METHOD OF ANALYZING CALCUTTA SEED. Weigh 100 grams dead fine. Shake up the seed well in a circular covered tin sieve, divided into about six chambers, the perforated holes in the top chamber being largest, the size of the holes decreasing in each successive chamber until the bottom one is reached, the bottom of which is similar to cover on top, a plain tin surface. The agitation of the seed in the chamber greatly facilitates the separation of the dirt and foreign matter from the pure seed. The oleaginous matter must be carefully separated from the non-oleaginous matter, wdien the three ingre¬ dients must be accurately weighed. The result gives at once the proportion of dirt and foreign matter in the seed. When the oleaginous matter exceeds 2 grams, no more than one gram is allowed to be added as pure seed, for instance: 97.000—Pure 1.000—Oleag. -Non-oleag. 97.000 2.200 .750 98.000 or 2 per cent. 108 THE MANUFACTURE OF LINSEED OIL. METHOD OF ANALYZING AMERICAN OR EUROPEAN SEED. Capacity of scale must be one pound, having two rows of graduating figures. The upper row should be from ^ to 16 ounces. The lower row from .0 to 100. The man¬ ner of using is to weigh one pound of seed in the scoop, v and next sift in a double sieve, then place the dirt in the scoop and the lower row of figures will indicate the per¬ centage of dirt; or, by placing the clean seed in the scoop, the percentage of clean seed will be ascertained. In connection with the scale, the Chicago Board of Trade adopted as standard sieves one having a mesh 3x16 and one with a mesh 16 x 16—Fairbanks. COLD-PRESSED OIL. Fine linseed oil is always obtained by pressing it at an ordinary temperature— cold pressing; by heating the pressed pulp to about 170° or 180°—hot pressing—a larger percentage of oil can be obtained, but it is always inferior in quality to the cold-pressed oil. Cold-pressed oil has a very light-yellow color, very lit¬ tle, but a peculiar taste and odor; the hot-pressed oil has a much darker color, golden-yellow to amber; tastes much stronger and more disagreeable than the former. CURIOUS FACTS CONCERNING THE OIL EXTRACTED FROM FOREIGN SEEDS. Oil made from Bombay seed does not make good sweetmeats, although the latter is unusually clear. This is owing to its excessive fatty properties; it makes an excellent refined oil nevertheless. In the cooking of a small quantity of this class of oil, when the desired rubber consistency was arrived at, the loss in waste equaled 35 per cent. The explanation would appear to be, that the fatty and volatile ingredients under the influence of high temperature disappear, re¬ ducing the weight of the whole accordingly. THE MANUFACTURE OF LINSEED OIL. 109 A peculiar feature of the Argentine seed oil consists in the fact that it also makes an unprofitable varnish oil, from the varnish maker’s standpoint; the waste being abnormal in its cooking. The writer tested a ten-pound lot of well-settled oil, cooking same 3^ hours, at a tem¬ perature of 507° Fahrenheit, the loss being 22 per cent. A second sample showed a similar loss, the finished sample resembling molasses rather than the ordinary linseed oil caoutouche. This class of seed makes a very dark or dark reddish oil, while the cake, which sells read¬ ily on the foreign market, is of a light color. The oil may be used to excellent advantage for boiled oil, whether by the fire or steam operation, LINSEED OIL AND CAKE MACHINERY, It has already been stated that in order to procure a really pure oil the first important step in the manufac¬ turing process is that of seed cleaning. There are ex¬ cellent seed screens now on the market, their cost being in the neighborhood of |250, They perform their work effectively, the capacity being about 500 bushels of seed in twenty-four hours. There are other screens of a much larger capacity. Where a fair quality of seed is operated on, the use of this machine entirely obviates the chances of an oil showing “fattening” proclivities. It must be conceded, however, that the use of these screens is uncommon and only operated on special oc¬ casions. SEED CRUSHING ROLLS, The rolling, or seed-bruising, machine is next in order, and consists usually of a stack of chilled iron rolls, the number and proportions varying according to the nature and amount of work they are called upon to perform. Undoubtedly the best -kind in use is the five-stack variety, the rolls being placed on top of each other, all no THE MANUFACTURE OF LINSEED OIL. the shafts excepting those of the bottom roll having boxes accurately fitted to them, so that they are held firmly in position by the strong iron frame which con¬ tains them. The journals of the bottom roll rest in brass bearings, and the whole machine is usually operated by belts. Gearing is sometimes used to actuate them, but it has not been found as economical as the former. The modus operandi is as follows: Three of the five rolls revolve in one direction, while the remaining two, which are placed between the first and third, and third and fifth rolls, respectively, are moved the reverse way by fric¬ tion. The seed from the hopper first passes a small cor¬ rugated feed roll, which distributes it uniformly over the entire length of the topmost roll, and by means of a guide-plate, it is directed between the first and second rolls, the inward motion of the revolving cylinders rapidly drawing and crushing the material, and causing it to pass out on the opposite side; here it is again guided by the slanting position of a plate which causes it to fall along the face of roll number three and to pass between the latter and roll number two, thus crushing it again in its passage and facilitating the process by the weight of the two upper rolls. In a similar manner, the seed is carried through the lower rolls. When passing between the lower rolls, which termin¬ ates its winding course through this machine, the seed receives the added weight of the four upper rolls, which pulverizes it to a degree of fineness which materially promotes the flow of oil when subjected to hydraulic pressure. This method of grinding seed is the most effi¬ cient ever devised. The guide-plates also act as scrapers or cleaners to remove the pulpy substance which sometimes forms on the rolls’s surfaces, and which, without the use of these plates, would render friction abortive. THE MANUFACTURE OF LINSEED OIL. Ill Rolls of this class are usttally four feet long and from fourteen to sixteen inches in diameter. There are other rolls smaller in size and fewer in number, some consist¬ ing of four, some of three, and in some remote localities the old method of operating two rolls of similar or dif¬ ferent diameters, bound together laterally, yet holds sway. The work performed by these is very inferior, its efficiency being very little advanced by the use of stone-edge runners, which usually enter into the combin¬ ation; but this system of linseed oil milling will soon have become a thing of the past. COOKING OR HEATING KETTLE. Next in order comes the heating kettle. These are usually jacketed throughout; steam pressure is obtained directly from the boilers used for heating purposes. Small apertures are tapped in the side at various points to permit the entrance of live steam into the mass of meal in the kettle in order to admit the moisture necessary to cook it to the proper consistency. A vertical shaft runs through the centre, the* arms attached to which cause increasing commotion in the meal, thus thoroughly mincing all its parts and permitting the heat from the jacketed sides to come in contact with as much as pos¬ sible of the agitated mass. There are several forms of kettles in use; some having three chambers; the ob¬ ject aimed at in this design is to procure a uniformly cooked meal. The upper chamber receives its charge direct from the rolls continuously and gives the seed a preliminary treatment, after which, by the withdrawal of a slide, it is permitted to fall into the second chamber, in which the cooking operation is always proceeding, and when sufficiently treated, is permitted to fall to the lower or delivery chamber. The latter at all times con¬ tains a charge ready for withdrawal to the mold on its 112 THE MANUFACTURE OF LINSEED OIL. passage to the hydraulic press. There are other ket¬ tles consisting of two chambers, and good results are sometimes obtained from those containing only one chamber, conditional upon proper attention being be¬ stowed on this very essential part of oil milling. Experi¬ ence has demonstrated that where more than one cham¬ ber is in use, more uniform and satisfactory results are obtained. CAKE FORMER OR MEASURING FRAME. We now come to the cake former or measuring com¬ pressor. Of this indispensable machine there is also a variety in use; but a description of one of the latest im¬ proved patterns will suffice for all practical purposes. From an economical point of view, as well as from its superiority of design and its efficiency in execution, the hydraulic cake former unquestionably stands in the highest rank. Its purpose is to measure correctly and to compress into convenient and compact form the cooked material from the heating kettles, so that it can be placed with facility between the plates of the great hydraulic presses for the final process. The introduction of the power and steam formers, similar in design to the hydraulic former, made possible the abolition of the old box system in oil milling, and completely revolu¬ tionized the cumbersome methods which prevailed some twelve years ago. While the capacity of this style of mechanical former or measuring compressor is many- fold, that of the old system of gauging by hand the quan¬ tity of crushed seed each press sack shall contain, it also effects a saving of from 40 to 50 per cent in the cost of labor. The machine is about three and one-half feet in height, the head and base plates being firmly connected by three stout iron bolts, one at each angle at one end and central THE MANUFACTURE OF LINSEED OIL. 113 at the other end. The base and head plate form a parallelogram, and are about four feet four inches in length. lo the underside of the head piece is securely adjusted a plunger. This is a projecting block of iron, the sides of which being beveled to a point, give it a depressed surface across, so that when a cake is formed, the edges being thin and hard, the meal will not drop to the floor in its passage to the press; the ends being protected by the cloth. The meal is formed slightly smaller than the cake, also to facilitate its handling. On the base plate rests a small hydraulic cylinder, having a ram, say, eight inches diameter, operated by the low pressure hydraulic power, which exerts a pressure of about 500 pounds per square inch. This pressure is uniformly distributed and forms the meal into a compact cake about one and one- half inches thick. The machine itself can be operated with precision and despatch at each pressing. On each side of the cylinder a small trackway is provided for the travel of the molding box, which contains the meal to be compressed. The exact method of procedure when the machine is in motion is as follows: The machine being at rest, the molding box is in exact line with the delivery plate pro¬ jecting beneath the kettle. Mounted on the delivery plate and beneath the kettle is the measuring box, open at the top to receive meal from the kettle by withdrawing a slide, and open at the bottom to deliver the meal into the molding box. The flapper frame and appendage to facilitate the handling of the pans and trays and cloths being up, a tray is placed in position in the molding box, and over this is placed a cloth, the centre of the cloth be¬ ing at the centre of the tray. The flapper frame is now brought down, forming a continuous track on which the measuring box travels. This box is mounted on wheels 114 THE MANUFACTURE OF LINSEED OIL. and provided with scrapers, so that when it is drawn forward and backward on the track and over the molding box, the meal is dropped into the molding box and the flapper frame and delivery plate are scraped clean, so that the operation is a “tidy” one. The measuring box is now pushed back beneath the kettle to be filled for the next cake. The flapper frame is raised and the ends of the cloth are folded over the top of the meal, slightly overlapping. The entire molding box with its load consisting of pan, cloth and meal is pushed forward until it stops at a point exactly beneath the plunger, on the under side of the head plate. Pressure is now turned on; the cylinder ascends, raising the molding box with its load above the trackways and compressing the material against the plunger into proper shape firmly, and into its smallest compass, suitable for the operation of pressing. After a few seconds, pressure is released, the cylinder descends and the wheels of the molding box fall smoothly to the • tracks; a perfect cake has been formed and the machine is again at rest. The molding box is drawn back until it stops. The cake to be pressed for oil is taken up with its cloth and slid between the plates of the powerful hydraulic press. The pan is now withdrawn. The whole operation oc¬ cupies only a small fraction of the time required to de¬ scribe it. The moment the loaded pan is removed from the molding box, another pan is placed in position with a new cloth, the flapper frame is brought down and the measuring box, which is already filled with another charge, is again drawn over the molding box; and the -operation proceeds thus continuously. This cake former or measuring compressor is built single or double. When built double, for two operators, it is provided with a simple mechanism which renders THE MANUFACTURE OF LINSEED OIL. 115 the one operator entirely independent of the other. Its pressure niav be easily regulated, and it is adjustable as to the weight of the cake. Eighty cakes in eight minutes, weighing 12| pounds when pressed, are molded on this machine in routine work. The cakes so molded are the most perfect that have been produced, which point greatly facilitates their adjustment in the hydraulic presses, saves cloth, and guarantees more oil. In mills provided with the accu¬ mulator system of the Buckeye Brass and Iron Works, Dayton, Ohio, the low pressure is utilized to operate the cake former, and in the absence of this, suitable pressure is provided for its operation'by a single plunger power hydraulic pump and small accumulator. The Stilwell-Bierce & Smith-Vaile Co., of Dayton, Ohio, are makers of an excellent cake former which is operated by compressed air. Writer has seen one in use in a leading cotton oil mill in Texas, the superintendent of the mill giving the machine a high character during inspection. This well-known house also makes a com¬ plete line of oil mill machinery, as does the Buckeye Brass and Iron Works, of which Mr. Charles E. Pease is president. PRESSURE PUMPS. With regard to the steam hydraulic pump, the Worthington make presents features deserving of the oil miller’s consideration. When the greatest efficiency is desired with the least consumption of power, this steam hydraulic pump may be used to advantage. Its first cost is con¬ siderably more than a first-class belt pump, but it uses no steani that is not required for effective work, and “follows up” without loss of power. In a belt pump the sur¬ plus water must overflow through the safety valve, con- 116 THE MANUFACTURE OF LINSEED OIL, J THE MANUFACTURE OF LINSEED OIL. 117 suming power, and wearing the valve rapidly. In run¬ ning a number of presses with an accumulator a steam hydraulic pump is particularly desirable. The pump ends and plungers are made of forged steel, and the valves easily accessible. A safety valve may be pro¬ vided, and the whole set on a base in the form of a saucer, which catches any drip and conducts it through a Avater-pipe where desired. Any desired size can be furnished. Realizing the fact that any form of cast metals is not safe under high pressure, unless it is of such a shape that it can be lined with copper or steel, this hydraulic pressure pump is constructed of forgings. Further¬ more, the pump is one in which the water ends, in- steadl of being made of castings, are forged solid with all openings, plungers, etc., drilled out of the solid forgings. This makes it absolutely safe, and pumps constructed in this way operate satisfactorily at a pressure up to 10,000 pounds per square inch; but after the pressure exceeds 5,000 pounds there is so much difficulty with the valves, and they need regrinding so often that the company does not recommend anything higher than 5,000 pounds pressure for ordinary services. This really is very much in excess of the pressure which the oil miller requires, and, therefore, the pump referred to is admirably adapted for oil milling purposes. The accompanying cut will convey an idea of the gen¬ eral outline of the pump we have endeavored to de¬ scribe. THE HYDRAULIC PRESS, In the complex system of machinery indispensable to oil milling, to the hydraulic press must be assigned a most essential part. Here the manufacturing process terminates; that is, with the exception of the cake-trim- 118 THE MANUFACTURE OF LINSEED OIL. ming after the pressed material has been withdrawn from the press. Great changes have been made in the design of this machine within the past twenty-five years, but the last step in its evolution has proved to be by far the most important advance yet made. The change from the box system to the plate press is the particular step referred to. Of this class of machinery there is also a varietv of makes, each manufacturer claiming distinct and separate virtues peculiar to his own design. Comprehensively speaking, the modern hydraulic press is well constructed and peculiarly adapted to the nature of the work it is called upon to perform. The columns, cylinders, rams and heads are usually planed and turned accurately to gauges, so that each part will bear its due proportion of the strain and no more, thus materially lessening the liability to breakages. The rams are usually sixteen inches in diameter, and an ag¬ gregate pressure of about 400 tons, or 4,000 pounds to the square inch, is exerted on them by the high-pressure pump, the latter operating conjointly in many instances with an accumulator as in the low-pressure system. The accumulator system is to be recommended for mills op¬ erating one or two sets of presses and upward. The au¬ tomatic shut-off arrangement, between the accumulator and the pump, effectually shutting down the latter when the maximum pressure is reached, is undoubtedly a great protection against breakages and a most excellent ap¬ paratus in every respect. . A number of new features have been introduced in the plate-press system within recent years. A 16 or 18- cake press, the former with hair mats, has excited con¬ siderable interest in oil-mill circles of late, innovations from the ordinary flat plate having been introduced. This press is fitted with appliances, resembling minia¬ ture boxes, based somewhat upon the old principle, but THE MANUFACTURE OF LINSEED OIL. 119 compact and perfect in ill respects. It is fitted with drainage bars, and the formation of the boxes reduces very considerably the amount of fragmentary or oily edges always present in the flat-plate system. A number of mills use presses with hair mats adjusted to the plates, while others have the steel corrugated plates bare, and in some cases steel mats or drainage bars are used with the flat plates. The consensus of opinion, based on years of practical experience with re¬ gard to the relative merits of the bare and the mat-plate systems, is decidedly in favor of the former. The trimming or paring machine necessary to trans¬ form the cake into presentable shape to facilitate pack¬ ing and shipment, is also an essential feature in oil mill¬ ing. After pressure the cakes are withdrawn, pared and placed in racks to cool. Some machines are constructed so that when the cake to be pared is placed on the iron slab or table, a single stroke of a side or end knife, actu¬ ated by steam pressure, trims the overlapping edges of one side and end of the cake, the same action of the knives performing a similar function on the two remain¬ ing sides of the cake when reversed by the operator. Some paring machines are operated by belts, but the cakes taken from the new system of presses previously alluded to require but little paring, and are merely slid along a grooved box by hand and against the edge of a knife, the fragments falling through an aperture to be worked over again. The leading American houses in this line are the Stil- well-Bierce & Smith-Vaile Company, of Dayton, Ohio, and the Buckeye Brass and Iron Works of the same town. The machinery of each of these houses can be found in all vegetable oil producing centres in the United States, as well as abroad, and it is safe to say that the 120 THE MANUFACTURE OF LINSEED OIL. great reputation which they have acquired is well nicrited. THE FUNCTIONS OF THE ACCUMULATOR. The load on the plunger is usually such as to produce a pressure in the cylinder equal to 4,000 pounds to the square inch or two tons, and the apparatus is made suf¬ ficiently capacious to contain the largest quantity of liquid which can be drawn from it at once by the simul¬ taneous action of all the hydraulic machines with which it is connected. Whenever the engine pumps more liquid into the ac¬ cumulator than passes into the cylinder which contains the larger plunger, the loaded plunger in the accumula¬ tor rises and makes room in the cylinder for the surplus; but when on the other hand the supply from the engine is less for the moment than the desired quantity, the plunger, with its load, descends and makes up the defi¬ ciency out of store. The accumulator also serves as a regulator to the en¬ gine or force pumps, for when the loaded plunger rises to a certain height it begins to close a throttle-valve in the steam-pipe, so as to gradually reduce the speed of the engine or pump until the descent of the plunger again calls for an increased production of power. ROBERT GA.NZ. Dr. J. H. SENNER. THE Nalleiil Frovisiomr Mllslis Gmv, ROBERT GANZ & CO., Proprietors. NEW YORK : CHICAGO ; 284-286 PEABE STREET, No. 11 RIAETO BUIEDING, Cor. of Beekman. Adjoining Board of Trade. The national PROVISIONER, THE ORGAN OF THE Provision and Meat Industries OF THE UNITED STATES AND CANADA. Chicag:o, New York, 'Boston, Philadelphia, Cincinnati, Kansas City, St. Eouis, Eoodnn, England. PUBLISHED EVERY SATURDAY. SUBSCRIPTION PRICE: In the United States and Canada, - - $4.00 Per Annum. In Foreign Countries, ----- $6.00 Per Annum. (Postage Prepaid.) PUBLISHERS OF THE Pork Packers’ Handbook and Directory OF THE MEAT AND PROVISION TRADES. 440 Pages. Price, $10.00. The Manufacture of Cottonseed Oil AND ALLIED PRODUCTS. 95 Pages. Price, $3.00. XI American Linseed Cake Versus English and Other Foreign IMakes in the English and European IMarkets (with Analyses). There are probably few, if any, American manufac¬ tured products or by-products, which, in proportion to the output, are so largely exported for consumption abroad as linseed cake. The annual output of linseed cake in the United States may be estimated at 300,000 tons, while of this immense quantity probably nine- tenths are exported, chiefly to Great Britain. The quality of American linseed cake is of a diversified character, and as a stock-feeding product each brand is rated on the English market in accordance with its known properties, as disclosed by the analysis of the ag¬ ricultural chemist. Sales in England and Germany of American and other linseed cakes are effected on a basis of certain oil percentages, the proportion of the latter being usually accepted as the standard of commercial value. Within the recollection of many who have not yet arrived at the meridian of life linseed cake had but few competing factors in stock-feeding centres, while the price per ton has at times reached £17, which is equivalent to |85. A change has come over the situation; the number of stock-feeding pro¬ ducts now in actual competition with linseed cake appears to be increasing, with unavoidable decline in values as a natural sequence. Cottonseed cake is prob¬ ably the most powerful and successful competing feed product which the world’s manufacturers of linseed cake have encountered. The rapid and unprecedented devel¬ opment of the cottonseed cake and meal industry has proved decidedly detrimental to the distribution of lin¬ seed cake. The differential quotations for the respective 122 THE MANUFACTURE OP LINSEED OIL. 123 products are immaterial, while but a few years ago lin¬ seed cake, even of the most inferior make, readily com¬ manded a much higher price. Certain brands of American cottonseed cake to-day command a higher, price than many makes of linseed cake, while rice meal, feeding treacle, cocoanut meal, palm-nut meal, locust meal and fenugreek meal each add their quota, at lesser value, in their restricting influence on the development of linseed cake consumption. In addition to the fore¬ going array of products competing with American lin¬ seed cake abroad we have also in the field Russian, Polish, French, Spanish, Egyptian, East Indian, Peru¬ vian, Chilian and Argentine linseed cakes, the quality and general composition of each being considered fur¬ ther on. While the quantity of American linseed cake is very superior to that made twenty years ago, whether from the crusher’s or consumer’s standpoint, there is yet much to be done in many mills before the standard of efficient work has been attained. Twenty years ago imported seed contained a very high percentage of extraneous matter, averaging as high as 15 per cent, which, un¬ screened, necessarily made a very inferior stock-feeding material. To-day, thanks to the efforts of the Linseed Association, a very much better variety is imported, while the regular domestic product is all that can be desired in its freedom from dirt. With 95 per cent of pure seed of whatever variety—East India, La Plate or Western—subjected to suitable treatment, an excellent feeding material, friable and nutritive and containing a proportion of oil not exceeding 7 per cent should be the invariable result. An examination of many of the brands of American linseed cake reveals the fact that as high as 12 per cent of oil is regularly disposed of in the cake, while in some instances this figure is exceeded. On the 124 THE MANUFACTURE OF LINSEED OIL. other hand certain makes of linseed cake are regularly exported containing an oil percentage not exceeding 7, while in one or two exceptional cases only from 4^ to 5^ per cent of oil is left in the cake. The primary cause of the high oil percentages referred to may be attributed to defective rolling, while hardness, always a highly ob¬ jectionable feature in feeding cake, is superinduced by the presence of an abnormal proportion of moisture. Not a few of the American brands of cake, otherwise de¬ sirable, are pronounced inferior by the English importer and consumer, owing to this cause. Cake of this char¬ acter is of necessity sold at a material reduction, while the American manufacturer by force of circumstances must accept the estimated valuation as based on the ana¬ lytical report. The price obtained for cake containing the heavier proportion of oil, while a few shillings per ton higher than that which contains the normal pro¬ portion, is far from being adequate to compensate for the loss of the surplus and unextracted oil. Aijother peculiar phase of this important export industry and which redounds to the pecuniary disadvantage of the manufacturer, consists in the anomally that not infre¬ quently a cake which contains a lesser proportion of oil commands a higher commercial value than that which contains a much heavier oil percentage, primarily owing to the latter variety’s possessing a degree of hardness not present in the former. It will be inferred from this that the presence of a high percentage of oil in cake does not always imply a desirable feeding product, or the softness of the material necessarily a result. In the cooking pro¬ cess which the crushed material is subjected to prior to the pressing operation, surplus moisture will, of neces¬ sity, produce a hard cake with a comparatively light pres¬ sure, but when the application of the latter is maintained at a uniformly high standard—customary in linseed oil THE MANUFACTURE OF LINSEED OIL. 125 mills for a thorough extraction of the oil—the material is compressed into an almost impenetrable substance by that force which is essential for the procurement of the oil. Imperfectly crushed seed, cooked with excessive moist¬ ure—two most reprehensible and destructive processes— will necessarily produce a hard cake, together with a heavy percentage of oil as a result of normal pressure application, superinduced by the foregoing conditions. The manner in which improperly rolled seed is obtained, and which should be carefully avoided, is owing to the operation of rolls, which, by reason of their protracted use, cease to be perfect cylinders, causing the seed to pass through partially crushed, or by causing a few to be carried to the rolls beyond their capacity of grinding thoroughly. A set of rolls com.prising five, forty-eight inches, will effectively grind 400 bushels of seed per day, conditional upon the latter being distributed uniformly in quantity and longitudinally on the upper roll. It thus becomes possible for a mill well equipped in all the modern appliances, to turn out a very inferior grade of cake, although made from a fair quality of seed, by neglecting the condition of rolls, or defective cooking. The term “inferior,” which may be appropriately ap¬ plied to cake containing a high percentage of oil made from improperly rolled seed, or defective cooking, is transposed when viewed from the standpoint of the Eng¬ lish stock feeder. There are few things, if any, which gladden the heart of the average stock feeder more than linseed cake which is soft, heavily charged with oil, and the strata of which are turned with facility by the blade of an ordinary pocket-knife, disclosing partially crushed seeds, and occasionally whole seeds which have escaped the rolls. Cake of this variety is designated “choice” and commands a ready sale. Within a very recent 126 THE MANUFACTURE OF LINSEED OIL, period, the writer has analyzed a sample of American cake similar in all respects to the foregoing, the oil per¬ centage being 13.10. Hard cake and low oil percentages are looked upon as synonymous terms, but it should be recognized by the American crushers, that it is possible and practicable regularly to turn out cake, soft and unobjectionable from any standpoint, and containing about 7 per cent of oil. A cake containing 12 per cent of oil by reason of exces¬ sive moisture will be harder than a cake containing only 7 per cent of oil, made from well-ground seeds and suit¬ ably cooked and pressed. To many the imperfectly understood conditions which govern the value of the respective grades of cake in the English markets seem paradoxical, but it is nevertheless an established principle that hard cake, although possess¬ ing more oil, and, therefore, really more valuable to the consumer (based on the principle laid down by the latter that the value is increased with the proportion of oil), sells for a lesser figure than a variety of cake which is more friable, but contains a lesser percentage of oil. Agricul¬ tural chemistry has, however, demonstrated that the de¬ ductions, with regard to the value of cake being in¬ creased in the same ratio as the percentage of oil it contains, are misleading, and for all purposes a 7 per cent cake produces a uniformly superior result. There is clearly room for improvement here, and it behooves the manufacturer, in these times of sharp com¬ petition and astonishingly low prices, to induce radical changes in appliances, or methocls, where necessary. Doubtless if the cake exported were in the pulverized form of meal the objection to hardness would be ob¬ viated, but the English agriculturalist has a decided pre¬ judice against using the disintegrated product, owing to the facility with which adulteration may be carried THE MANUFACTURE OF LINSEED OIL. 127 on, and also to the liability of the wind carrying off the fine substance when stock are feeding in the open. We are thus perforce constrained to accept the situation as it is, and meet the requirements of the case in the most feasible and economical manner, fortified in the.knowl¬ edge that the difficulty may be permanently removed thereby. In the procurement of a low oil percentage, fine seed grinding becomes absolutely essential, but the application of excessive moisture in the heater to the crushed material, while facilitating the flow of oil, pro¬ duces an extremely hard cake, as previously pointed out. To obtain a marketable product, containing a propor¬ tion of oil not exceeding 7 per cent friable, and in all respects a faultless stock-feeding material, the following conditions must be arbitrarily observed; Seed, 95 per cent pure; fine grinding; material in heater cooked so that a few ounces when compressed in the palm of the hand will form into a compact mass, temperature being maintained at 160°Fahrenheit, and finally, hydraulic pres-' sure to the extent of 3,800 to 4,000 pounds pressure per square inch or ram maintained until the oil drainage ceases. - In the event of the material being dry, the pressure of the hand will be insufficient to form a paste, and when withdrawn from the hydraulic press a crumbling condi¬ tion will be apparent, while analysis will assuredly dis¬ close a heavy oil percentage. The hand test for the de¬ termination of proportion of moisture present, may be relied upon, but by reason of the elevated temperature in the material it must be performed rapidly. To deter¬ mine the exact temperature of the meal, the writer has designed a conveniently constructed thermometer, which, when inserted into the mass in any part of the heater, or withdrawing box beneath, instantaneously re¬ veals the actual caloric condition. As it is recognized as 128 THE MANUFACTURE OF LINSEED OIL. one of the fundamental principles of oil milling, that a certain temperature must be attained in the material under treatment, failing which, the oil will be only partially extracted, the necessity for such a device is ap¬ parent, and its use may be commended in the attainment of uniform work in linseed and cottonseed oil mills. Ir¬ regularity in cooking will affect the oil yield to the ex¬ tent of 2 or 3 per cent, although the previous and suc¬ ceeding consecutive methods may have been faultless, while the sale of the cake at current quotations may be characterized as being problematical. Crushed seed withdrawn from the heater with insufficient moisture, but possessing the current degree of heat, will result in a decreased oil yield, or, the conditions reversed will pro¬ duce similar results. Excessive moisture, however, in conjunction with the normal cooking temperature, will assuredly produce a cake, which subsequent to storage for a few days, becomes as hard as stone and impervious to ordinary force, the fracture being accomplished at the expense of extreme physical effort. A few bags of this variety of cake are sufficient to condemn an entire con¬ signment as being of inferior quality; the interpretation of which must be construed as pointing to a very ma¬ terial reduction from ruling market quotations for that especial brand. The necessity of perfectly dry storage for cake, sub¬ sequent to being thoroughly cooled when withdrawn from the press, for the avoidance of the mouldy and sour conditions referred to, together with the removal of the faulty manufacturing methods, which have been shown to conduce to hardness, is palpable. Within the past two months the writer has analyzed twenty-two distinct makes of cake manufactured in the United States, the highest oil percentage being 13.10 and the lowest 4.75, with an average of 10.65. THE MANUFACTURE OF LINSEED OIL. 129 Here are several copies of the certificates of analysis of as many brands of American cake, certified to by a well-known English agricultural chemist; TRADE-MARK AMERICAN LINSEED CAKE. Oil. 9.14 Moisture.11.23 ^Albuminous compounds.33.60 Mucilage, sugar, digestible fibre, etc. . . 35.23 Phosphates, etc. (bone producers). 4.72 Woody fibre (cellulose). 6.08 100.00 ^Containing nitrogen, 5.36 per cent. (Signed) T, Williams, F. C. S., etc. AMERICAN LINSEED CAKE. Oil.12.80 Moisture. 7.80 ^Albuminous compounds.33.05 Mucilage, sugar, digestible fibre, etc. . . . 36.93 Phosphate, etc. (bone producers). 4.77 Woody fibre. 7.10 100.00 * Containing nitrogen, 5.27 per cent, (Signed) T. Williams, F. C. S., etc. N. W. L. O. CO. AMERICAN LINSEED CAKE. Oil. 8.83 Moisture.10.06 ^Albuminous compounds.33.50 Mucilage, sugar, digestible fibre, etc. .. . 35.59 Phosphate, etc. (bone producers). 4.92 Woody fibre (cellulose). 7-10 100.00 *Containing nitrogen, 5.34 per cent. (Signed) T. Williams, F. C. S., etc. 130 THE MANUFACTURE OF LINSEED OIL. AMERICAN LINSEED CAKE. Oil.. Moisture.^ * Albuminous compounds. Mucilage, sugar, digestible fibre, etc... Phosphates, etc. (bone producers) . . . . Woody fibre (cellulose). 8.59 9.70 33.46 36.00 5.06 7.18 100.00 * Containing nitrogen, 5.33 per cent. The foregoing data will be sufficient to convey a fairly accurate knowledge concerning the general character of linseed oil milling as it exists in the United States to-day; and, while there is urgent need of mechanical and methodical reformation in too manv instances, it must be conceded that we are still in advance of the work of other nationalities, as demonstrated by the following analyses. The following certificate of analysis repre¬ sents a sample of English-made cake of 95 per cent pure seed: AD (branded on surface OF CAKE). Oil.12.88 Moisture.13.52 Albuminous compounds (flesh formers). 30.57 Mucilage, sugar, digestible fibre, etc. . . 31.88 Woody fibre. 6.03 Ash. 5^ 100.00 Nitrogen, 4.83; equal to ammonia, 5.86 per cent. (Signed) . M. D. Penney, F. C. S, Hull, April 21, 1895. A sample of “A D,” analyzed by the writer recently, exceeded 14 per cent of oil, while the stipulation covering sales of this brand calls for an oil percentage between 12 and 14. A sample of 'S' linseed cake of English make revealed 13.05 per cent of oil. While the percent¬ ages of oil are heavy in these instances, the gravity of the THE MANUFACTURE OF LINSEED OIL. 131 case is not of such moment as in the case of American makes, for the well-known reason that oil and cake values in Great Britain are viewed from a standpoint at decided variance from that which we attach to the products here. Oil being valued at a higher commercial standard here, its thorough extraction becomes a matter of material consequence, while lesser importance is attached to the question in English and other foreign manufactories, the cake being the primary product, and the oil the by-product. A brand of Russian linseed cake, H. O. C., now offered on the English market, contains the extraordinary per¬ centage of 16.28 of oil guaranteed, while the “Harbur- ger” brand (Russian), like the former is sold on a basis of 12 per cent of oil. German cake of Bremen make is offered to-day on the English market with a guaranteed percentage of 10 to 14 of oil; also, round Polish cakes at 14 to 15 per cent of oil, and square French cakes (Marseilles) at 12 per cent of oil. East Indian and Egyptian lin¬ seed cakes are guaranteed to contain from 12 to 14 per cent of oil, and Chilian, Peruvian and Argentine cake from 12 to 15 per cent of oil. The following copy of certificate of analysis will further confirm the analytical work of the writer, who has tested each of the foregoing varieties of cake: TRADE-MARK “s.” CHILIAN LINSEED CAKE. Oil.13.18 Moisture. 9-07 *Albuminous compounds.28.90 Mucilage, sugar, digestible fibre, etc. . . 30.39 Woody fibre.12.66 Mineral ash. 5.80 100.00 *Containing nitrogen, 4,62 per cent. (Signed) ^ T. Williams, F. C. S., etc. 132 THE MANUFACTURE OF LINSEED OIL. There are several small mills in operation in England which are rarely without a supply of lin¬ seed cake of American, Russian, or other makes, and which are known to contain a high oil per¬ centage. These cakes are reduced to meal and gradually worked off in various proportions, with the regular charge of crushed seed in the cooking kettles, and from them 6 to 8 per cent of oil is obtained, the cake being ultimately disposed of at a price actually higher than that paid for the reworked material. It is by these means that the enterprising English oil mil¬ ler turns many an honest penny at the expense of the American and other manufacturers. The moral is ob¬ vious. COMPOUND cake: a new outlet for mill-feeding PRODUCTS. The bulletin recently issued by the Secretary of Agri¬ culture concerning the practicability of increasing the consumption of American stock feeding products, whether of the artificial or unmanufactured varieties, alike in domestic and foreign consumption, is fraught with in¬ terest to the seed crushing industry. The introduction of a system in oil mills by means of which a feeding cake could be compounded of various constituents, the rela¬ tive quantities of each being proportioned to meet cer¬ tain arbitrary requirements in stock feeding, which is lacking in pure mill-feeding products, such as oil cake, should prove a welcome and profitable innovation or adjunct to the ordinary seed crushing business of the country. While the in¬ troduction of a system such as referred to would partake of a novel character in the list of American manufactured products, the principle is not new, how¬ ever. In English oil milling centres the manufacture of THE MANUFACTURE OF LINSEED OIL. 133 a mixed, or compounded cake, of which cot¬ ton cake meal forms an important constituent, is carried on to-day on a most extensive scale. It is this circumstance, more than all else, which has contributed to the decline in price of mill feeding products of the unmixed or pure variety, such as standard brands of cotton and linseed cakes. During the past twenty years the latter material has declined in value at a rate exceeding 100 per cent, while at times sales are difficult with regard to either feeding product, even at such abnormally low prices which have marked the course of the current season. While in the aggre¬ gate the consumption of mill-feeding products has gradually increased, preference is given in numerous in¬ stances in Great Britain to the compounded feeding cake, of which American decorticated cake meal forms a component part. Mill-feeding stuffs—linseed, rapeseed and cottonseed cakes—are largely exported to Germany and England from Russia, Poland, Spain and Egypt, while Peru, Chili and Argentine add their respective quota to the whole. Although American feeding stuffs are of a superior quality, cotton cake especially being in¬ comparable, low-priced feeding stuffs manufactured in the countries mentioned affect the demand for same to a greater or less extent. It is a significant fact that the compound cake which stands highest in favor abroad is that which contains a substantial proportion of Amer¬ ican decorticated cake meal. The progressive American manufacturers should bear this important fact well in mind, the necessity of devising adequate means to im¬ prove the occasion being palpable. It is recognized among agriculturalists who resort to artificially-prepared stock-feeding materials that in near¬ ly all instances American cotton cake is too concentrated for feeding alone, its consumption being usually accom- 134 THE MANUFACTURE OF LINSEED OIL. plished in association with certain proportions of farin¬ aceous substances. This circumstance resolves into a powerful argument in favor of the compound cake. It must not be forgotten, however, that owing to the risks involved in feeding to live stock unknown or @heap brands of feeding cake, not a few of the prominent British agriculturalists are in favor of purchasing the pure cake and adding the dilutent themselves. As the cheap adulterated stuffs—of which there is always a supply abroad—are being more readily recognized than heretofore, they are carefully avoided by the leading cake consumers; while, on the other hand, certain brands of mixed cake of known properties are also becoming more widely known, and are in correspondingly increased de¬ mand. Were an American compound cake placed on the foreign markets possessing the essential qualifica¬ tions, the possibility of trade expansion, with especial reference to cotton cake, would be practically unlimited, while that of other feeding substances would also be very appreciably increased. Nearly twenty-four years ago the late Dr. Augustus Voelker, of the British Agricultural Society, recognizing the need of a combination of feeding materials in con¬ venient form, possessing to the fullest extent practicable the essential nutritive attributes, while modifying the ex¬ cessive nitrogenous properties characteristic of mill products, formulated the idea now suggested to the American trade, the merit of cheapness being an addi¬ tionally attractive feature. Experiments on a small scale were made of various combinations—the primacy of American decorticated cotton cake among the mill or unmanufactured feeding stuffs being an invariable guar¬ antee of its presence therein—results proving uniformly successful. In some instances, Indian corn and cotton cake in disproportionate quantities were jointly com- THE MANUFACTURE OF LINSEED OIL. 135 pressed, while linseed cake, cocoanut, palmnut, rice, rape cake, all in ground form, were variously added, while also wheat bran, oats and feeding treacle were tried simi¬ larly. The nitrogenous element in certain materials being thoroughly incorporated with other nutritive in¬ gredients of a less concentrated character, a “balanced ration” was the resultant product. Within the past ten years in England the manufacture of compound cake of the character described has assumed enormous propor¬ tions. The first to appropriate Dr. Voelker’s recipes on a manufacturing scale was the Waterloo Mills Cake & Warehousing Co., Limited, Hull. The present output of this concern, which is not equal to its capacity, consists of 350 tons of compound cake, 150 tons of undecorticated cotton cake and 120 tons of linseed cake weekly, figures which adequately represent the relative appreciation of the consumers for the respective products. In Liverpool the Bibby compound feeding cake is manufactured to the extent of 800 tons per week, while at this writing so great is the constantly increasing demand, that'^e Bibby mill capacity is being increased 300 tons per week. Im¬ mense quantities of cotton meal are annually used in this mill, which is operated exclusively on this form of feed¬ ing cake. The demand for compound cake is of such a character that the manufacturers are taxed to execute their orders. The business in this form of cake, notwith¬ standing the dimensions it has already assumed, is only in its incipiency, and as the number of manufacturers are comparatively few, the fringe of the market has been touched only. Without reference to the practically illimitable agricultural districts within the confines of the United States where the introduction of such a valuable commodity would prove a veritable boon, there are yet vast sections in Europe and Great Britain where this class of cake has yet to be introduced. English seed 136 THE MANUFACTURE OF LINSEED OIL. crushers, to protect their languishing cake trade, are real¬ izing the necessity of adding to their regular mill work the manufacture of a compound cake. A number have already done so, while many more are contemplating a similar step. There are a number of well-known brands of com.pound cake on the English markets which are preferred before other forms of cakes by the stock feeders, the slightly reduced price being but a second¬ ary consideration. Here are the names of several popu¬ lar brands: “H. & C,” “One and All,” “Mayon,” “Dairy No. 1,’* “Waterloo,” “Grindall,” “Eagle Champion,” etc. Several years ago the writer suggested the practicabil¬ ity and ultimately the necessity of this movement as an increased outlet for American mill products, while ex¬ tending trade in corn, etc. The demand for compound cake in England has diminished the consumption of our feeding stuffs very materially; nor may we expect a per¬ manent betterment of existing conditions until the reme¬ dial measures within our reach are energetically pur¬ sued. American compound cake, placed on the English and Continental markets, would unquestionably receive a similar recognition as that formerly accorded the concen¬ trated foods or mill products, which at all times success¬ fully compete with the makes of other countries. As in the case of the pure cakes, it can be laid down at any prominent distributing point abroad at a lower rate than is possible to manufacture same outside the United States, the supply of ingredients of all classifications be¬ ing cheap and plenteous. As no feasible argument may be advanced showing why a compounded American cake would not have an excellent prospect of success in being disposed of abroad in competition with English-made compounds, every¬ thing bearing on the situation unmistakably indicating the contrary result, it behooves the American seed THE MANUFACTURE OF LINSEED OIL. 137 crusher to adopt measures with the object of expedit¬ ing such a movement. The languishing stock-feeding trade of the country urgently needs a stimulating resto¬ rative to secure the former position it held in foreign markets. To attain this, suitable machinery must be procured. This latter is free from complexity, the manu¬ facturing operation being of a much more simple charac¬ ter than that which is involved in the manufacture of the pure cake, the necessity of oil extraction being pre¬ cluded. The apparatus or plant necessary is of a com¬ paratively inexpensive character. A set of presses com¬ prises two, upon which a heater rests, the cake being usually circular. The heater (jacketed) increases the temperature of the material, as its name implies, and in which it also receives a certain amount of moisture, so that when pressure is applied a compact substance, or cake, is formed with facility. The pressure needed is comparatively light, and the duration of same to produce a batch of suitably pressed material is brief. This will be readily understood when it is stated that with a set of cornpoimd-cake presses from 500 to 800 cakes per hour are turned out when regular work is being maintained. Oblong, square, tapering cakes are also distinguishing features of some brands, the form of press being accord¬ ingly designed. The material descends through openings in the press heads in quantities sufficient to form a single cake, the operation being simple, and, as already implied, being susceptible of being continuously repeated in rapid succession. When sufficient time has elapsed for the cake to cool, its storage or transportation, even on prolonged sea voyages, may be effected with less risk of decomposition or moldiness than that which is inseparable from the shipment of pure feeding cakes. According to the mate¬ rials employed in compounding cake, the grinding and 138 THE MANUFACTURE OF LINSEED OIL. reducing machinery varies, the necessary screens and mixers in like manner. The dimensions of the various brands of compound cake are about as follows: Sixteen inch( s diameter; 26 x 11 inches; 21^ x 12^ inches; 26^ X 12^ inches; 23^ x 13 inches, etc. CAMEL-HAIR PRESS CLOTH. Concerning the use of press cloth in oil milling, there is much to be said. However perfect the material may be, with improper pressing or cooking the fabric will undoubtedly be destroyed long before its usefulness should have expired under normal conditions. As is well known there are various makes of press cloth on the market. It is a notorious fact that at times a new press bag will be destroyed on the first day of service. This is invariably due to defective material or improperly made goods. The writer has used the Perkins press cloth for twelve years, and can testify to its uniformly good quality and general satisfaction under normal treatment, excepting in the case of an irresponsible or biased judgment which has happened on one occasion, to the writer’s knowledge; otherwise we have never heard of a complaint. The firm of J. T. Perkins Company conscientiously and consistently offer a reliable press cloth, and it is the company’s boast that under no conditions will anything in the way of crude material be allowed within their fac¬ tory precincts which is not of the very best quality. Concerning the Sugden press cloth, which is manu¬ factured at West Chelmsford, Mass., we have this to say: It is singularly well adapted for the use of linseed and cottonseed oil mills. The writer has given their material a severe test, and it has stood same in a very satisfactory manner. It will be interesting for the oil mill fraternity to know that a THE MANUFACTURE OF LINSEED OIL. 139 good camel-hair press cloth, well made from sound mate¬ rial, same being sufficiently long 'staple, should last, with fair treatment, six weeks, the mill running twenty- three hours out of the twenty-four, and the system and pressroom being six pages per hour. The writer takes pleasure in recommending the two firms mentioned as being, as far as his knowledge goes, the only reliable camel-hair press cloth manufacturers in the United States. OIL boiler’s driers. Oil boiling by the steam process has rapidly grown in favor within recent years. The old system of boiling by fire is rapidly dying out, and is inadequate to meet mod¬ ern demands. The advantages of the steam process, when compared with the older system referred to, are generally admitted by those who have tried both sys¬ tems, and we would strongly recommend manufacturers who, at considerable inconvenience, boil by the old style, to give proper consideration to the subject upon which we propose to dwell. The advantages deriving from the new system may be ascribed to various causes. In the first place, no apprehensions may be entertained of con¬ flagration caused by the oil swelling while under treatment. A uniformity of temperature may be obtained thioughout the process with ordinary attention; and, lastly, science has made the opera¬ tion practicable and profitable by the blending and solution of various siccative compounds pre¬ pared in linseed oil in consistent proportions, and which are included under the designation of liquid drier. In these days of sharp competition it devolves upon the seed crusher to give consideration to this im¬ portant branch of his business, and select the most eco¬ nomical method of bringing about a satisfactory result; 140 THE MANUFACTURE OF LINSEED OIL. that is, a good drying oil for all practical purposes at a minimum of cost. The liquid drier is especially adapted for use in the steam-boiled process. The covered and jacketed pot or kettle in which the oil is treated confines the objec¬ tionable odors, always present in oil boiling, in a much more perfect manner than is possible in the fire system of boiling. The intensity of the heat, which is a prom¬ inent feature of the latter process, has doubtless much to do with this result, as whatever means have been de¬ vised to restrain or destroy these injurious odors, none has been found effective. Where an oil is boiled by steam heat the pungent odors are more readily conveyed through conveniently ar¬ ranged vapor pipes to the furnace chimney and dis¬ charged high in the air, out of reach of human eyes and lungs. The same appliances for the removal of the ob¬ noxious substances may be in operation with the fire- boiled system, but, as stated, without success. Despite all precautions, the deadly fumes and vapors will slowly curl from each chink, or smallest aperture visible, either in or around the iron hood which usually covers the boiling caldron, much to the discomfort of the attend¬ ant. Where the latter’s duty calls for frequent removal of the small movable side covering to watch the process of the operaton, or to agitate the mass by hand in the % absence of mechanical power, matters are much worse. The comparative absence of these conditions, where the liquid drier of genuine quality is used, whether by the fire-boiled or steam-heating process, is a powerful argu¬ ment in favor of that form of drier as compared with the solid variety. That this impression is gradually gaining ground among oil boilers is unquestioned, and the logic which superinduces the change is unassailable. Where a good liquid drier is used in oil, heated in the THE MANUFACTURE OF LINSEED OIL. 141 Steam-jacketed kettle to a temperature varying between 230° to 280° F., in conjunction.with a blast of air forced into the oil, a good body is given to the latter, a satisfac¬ tory color is obtained (although on this latter point it is impossible to suit the views of all), while for all practical purposes its main features bear favorable comparison with the older system, possessing fully what must be ad¬ mitted to be the most essential characteristic property of a boiled oil, viz., the property of drying quickly. A siccative material is any compound which, added to linseed oil, either hot or cold, hastens its drying qualities, which are naturally slow, and renders its use in painting and varnishing practicable and efficient. Liquid drier is simply a concentrated boiled oil. The most reliable form of drier is a compound of bases having the property of several oxides and series of salts. Formerly oil was boiled by simply adding red lead, and even at the present advanced stage of the business not a few crushers in the Central and Western States adhere to this primitive method. While red lead unques¬ tionably possesses a considerable proportion of oxygen, and therefore gives to the oil with which it is treated su¬ perior drying qualities when added at a high tempera¬ ture, its use in the majority of instances is reprehensible. The necessity of an effective drier in oil boiling is of the greatest importance, and too much attention cannot be bestowed on the selection of same. There are liquid driers on the market to-day which are undeserving of the name. On the other hand, there are driers made in similar form, which are admirably adapted for the steam- boded process and unexceptional in their results. The practicability of making a good drier of oil by means of this form of drier at a medium temperature, say, 260° to 280°, renders the use of the steam-boiled, or new process oil, especially advantageous. The writer has 142 THE MANUFACTURE OF LINSEED OIL. witnessed the use of the Pratt & Lambert drier for ten years with uniform satisfaction. Very excellent boiled may be regularly made with this form of drier in the pro¬ portion of 10 per cent of drier to the weight of oil. This is a well-known and reliable house, and, therefore, will place on the market nothing but that which is absolutely genuine, and the author takes pleasure in commending them to the attention of the seed-crushing trade of the United States. The necessity of efficient driers in oil boiling is, there¬ fore, apparent, and too much attention cannot be be¬ stowed on the selection of a drier which is not misnamed. There are liquid driers on the market to-day which are undeserving of the name; on the other hand, there are driers made in similar form, admirably adapted for either the fire or steam-boiled process, and unexceptionable in their results. The practicability of making a good dry¬ ing oil by means of this form of drier at a medium tem¬ perature, renders the use of steam-boiled or new-process oil especially advantageous, although equally good re¬ sults may be obtained by the use of the same form of drier in the older process, with this difference in its favor that a moderate temperature is sufficient. Anhydrous binoxide of manganese, which contains a large propor¬ tion oxygen, is a valuable ingredient in a well-prepared* drier. The transition of oil on a level plane from a fluid condi¬ tion to that of a dry and glossy surface is hastened by the absorption of oxygen due to the inherent properties of the presence of acetate of lead, minium, manganese, or other compounds. The use of litharge in oil boiling has long been known, but the few who are familiar with its use zealously guarded the knowledge. The super-addi¬ tion of red lead or of binoxide of manganese is of more recent date. THE MANUFACTURE OF LINSEED OIL. 143 Some of the ingredients of a good drier, that is, those which are not oxides, are capable of discharging their peculiar functions at moderate temperature. Their especial utility consists in their direct action on the mucilaginous and vegetable matter present in the oil, thus materially aiding the latter in its absorption of the oxygen from the metallic oxides. But this property of the non-oxidizing ingredients, with regard to tempera¬ ture, is of little avail, because, as previously pointed out, a high temperature is essential in the preparation of a drier to render the oxides efficient. The complete nulli¬ fication of the action of vegetable or mucilaginous mat¬ ter, which is a well-known preventative of the drying of an oil, is one of great significance. Sulphate of zinc ranks among the most important of all substances for this office. When a manganese compound is used, a high tem¬ perature is not essential when oil boiling is progressing. It should not be forgotten that the correct temperature necessary to render a liquid drier potent has been main¬ tained during the process of its manufacture, so that its full powers are capable of development when added to the oil at a temperature varying between 175° and 260° Fahrenheit, but when an intense heat is maintained (which is indispensable when a solid drier is used), con¬ siderable precautions are necessary to guard against the danger of swelling and conflagration. Unremitting at¬ tention must be given in the latter system and grave risks are incurred, all precautions and devices to that end notwithstanding. No possible precaution can guard against the possibility of a crack or flaw in the casting widening when a batch of oil is under treatment. At any moment during the period when the heat is at its maxi¬ mum point, a crack may develop, when deplorable con¬ sequences are inevitable. In this system such risks can- 144 THE MANUFACTURE OF LINSEED OIL. not be obviated, as an intense heat is required for proper fusion of the solid drier with the oil. The liability of the caldron casting to cracking sug¬ gested the feasibility of increasing the thickness of the metal at the bottom, where the heat is most intense; but castings, however carefully molded, are not to be at all times depended upon, and this is especially so with re¬ gard to their use in oil boiling. The oxygen in the liquid drier, always assuming it to be the genuine article, is freely given out to the oil at the temperature named. To procure the desired dark- brown shade, which the views of the consumer sometime demand, a lead salt is added in variable quantities—the correct proportion the practical drier-maker can readily solve to suit the respective needs of each case. The Atlantic Drier Co., Drexel Building, Philadel¬ phia, manufacture a drier for the especial use of oil boilers, which has also become very much in demand for the seed crusher’s purposes. Writer has given this brand of drier numerous tests under all conditions, and, from the point of economy for the procurement of de¬ sirable results, its use on a manufacturing scale is all that can be desired. This drier will mix perfectly with linseed oil, turpentine or benzene without curdling or separating. It is a very strong, heavy-bodied drier; its chief mission is making boiled linseed oil. Contain¬ ing, as it does, the most approved boiling and drying agents in greatly concentrated form and entirely free from volatile matter, it does not thin the body of lin¬ seed and it is only necessary to mix a small amount with raw linseed to obtain an oil having all the char¬ acteristics, properties and power of the best boiled oil. Such a mixture may be made in tanks or barrels and at the most convenient temperature from 200° Fahrenheit THE MANUFACTHRE OF LINSEED OIL. 145 down to 80° Fahrenheit. Heat is unnecessary if the raw linseed is well settled and free from moisture. Ten per cent or five gallons of this drier to the barrel of raw linseed oil, makes a full strength boiled oil, and a moment’s calculation on their prices will prove this done without any advance in cost. This firm manufactures another form of drier, differ¬ ing from other oil driers, as it sets quickly alone; it gives a fine gloss and hard finish, almost replacing varnish. Like the latter variety, it may be used for boiling linseed oil, and will give a stronger drying oil used in the same proportions; it has, however, another and equally valu¬ able field: because of its great concentration and strength, it may be thinned or reduced with turpentine or benzene and a japan or liquid drier produced, ranging in cost from forty-five cents down to twenty cents, equal in drying power to the usual fifty-cent and seventy-five cent driers. Should very quick drying be desired, Indiglos—a special form of drier thus designated and made by the A. D. Co.—may, of course, be used in its original state. SUGGESTIONS AS TO THE VALUE OF TESTS AND THE MAN¬ NER OF TESTING DRIERS AND JAPANS. All tests should be by comparison; no test that is not so is of any value. To judge any drier, japan or varnish, it should be tested side by side (on the same piece of glass, if pos¬ sible) with goods whose qualities are already known. A test of japan or drier, in its natural state, may not exhibit its true properties. No drier sets and dries hard so quickly alone as “Lightning Drier,” and none con¬ tains so little real merit. 146 THE MANUFACTURE OF LINSEED OIL. TO TEST JAPANS. Use a clean test tube or bottle; mix the article to be tested with raw linseed oil, in any desired proportion (one part drier to nine parts linseed is a good rule); in a similar vessel and the same proportion, mix the stand- dard for comparison; agitate, or stir, until the mixtures are complete, then allow to stand a few moments. The two compounds may then be tested for drying strength, either alone, or rubbed up in any desired pigment. Zinc IS one of the best to test with as it is not easy to dry. All oil driers should be tested in a similar manner. In some cases it is best to heat the materials slightly in mixing oil driers, but do this cautiously, because of the turpentine or benzene which may be present. Boiled linseed oils should be tested pure on glass and also rubbed up in lead or zinc, and always in compar¬ ison with another oil OIL BOILING. It has been demonstrated by Mulder that linseed oil is a glyceride of a peculiar acid called lineoleic acid, and according to a recent analysis, lineoleic acid has the com¬ position in chemical formula CisHsiOiOH; so that the composition of the glyceride would be rep¬ resented by Water, mucilaginous and coloring matter abound in the crude oil, which, together with the lineoleic acid form its component parts. The primary principle incorpor¬ ated in practical oil boiling is the elimination of the moisture and mucilaginous matter in conjunction with a thorough oxidation of the oil. The destruction of the impure substances, and com- THE MANUFACTURE OF LINSEED OIL. 147 plete removal of the moisture present in all crude oil, are of necessity an essential preparation to produce a good drying oil. It has been shown that in a pure oil, that is an oil made from full-grown mature seed, tanked for months, in order to procure a thorough precipitation of the “footy” or objectionable substances, there are twenty parts of a non-drying nature. This proportion is increased when the oil is not given a sufficient length of time for repose and in the ratio to the quality of seed used. This fact illustrated the necessity of efficient oil boiling, by which means, in conjunction with suitable driers in correct proportions, a good drying oil is ob¬ tained. Submitting the oil to an intense heat has the effect of destroying the glycerine present, the non-dry¬ ing qualities of which render it unfit for economical or practical work. This destruction is materially facilitated and the drying properties of the oil increased by the ad¬ dition of metallic oxides in conjunction with heat, whether by the direct application of fire, or by steam, and, when the latter method is used, by the introduction of air into the mass of oil in the treating cauldrons. Oil boiling is now carried on with much greater precision than formerly. To the scientific achievements acquired by long ex¬ perience, this desirable result is attributable. There are various methods of boiling, each having a stated max¬ imum and minimum degree of temperature, to procure a certain color or grade of oil. The length of time allotted for the various methods differs largely, whether by the fire or steam process. As the process of boiling by fire has right of priority by reason of its time-honored usage, we shall proceed to treat on that system first. The oil selected for boiling should have the characteristic color of pure raw linseed oil, a more or less yellowish green, its brightness being 148 THE MANUFACTURE OF LINSEED OIL. a guarantee that it is well settled, which qualification is only acquired by being left for a considerable period for repose in the settling tank. SETTLING TANKS. The settling tanks, in which oil is placed prepara¬ tory to be being boiled, should be in every instance cov¬ ered, and the tanks into which the oil is pumped after having been boiled, should be also covered, as a pale color is not so much an object; except where a pale boiled oil is especially desired, the deprivation of oil from light is of no consequence. These conditions are devised in case of an oil prepared for white lead or varnish man¬ ufacture, where it should be stored as much as pos¬ sible exposed to the light in order to bleach it. Where a boiled oil is stored in open tanks the .oxygen and surface of the oil combine in forming a thick coat¬ ing or skin, which frequently clogs pipes, and in some cases is drawn off in fragmentary portions with the oil and only discovered when being bleached with the pig¬ ments for immediate use. As previously stated, it is of the utmost importance that a well-settled oil should be chosen for the reason that if an oil be used which has been recently made, sufficient time not being allowed for the precipitation of the plant flesh and mucilaginous matter, the latter becomes charred, which in turn dis¬ colors the oil when subjected to the high temperature usual in fire boiling, rendering it of an inky and non¬ transparent appearance, not only at the conclusion of the boiling operation, but for a permanency, repose, however prolonged, being inadequate to produce a blight oil. Where an oil is chOsen which has been sub¬ jected to filtration, immediately after being made, and prior to being pumped in settling tanks, precipitation of the vegetable matter, together with its anhydrous THE MANUFACTURE OF LINSEED OIL. 149 properties, are materially facilitated. It is a well-known fact that a certain proportion of fine plant flesh is present in all ciude oil, notwithstanding the attention bestowed in the matter of filtration, repose, etc. The specific grav¬ ity of this objectionable substance is so light and of such similarity in its density to that of the oil itself that it remains suspended. An examination of a sample of such oil, when subjected to the first test, will readily disclose the previously invisible substance. The more thorough the filtration and the greater the period of time allotted for repose, the less vegetable matter and other impurities will be necessary to be eliminated when boil¬ ing, thus materially aiding that process. Where it is possible, the oil selected for fire boiling should be per¬ mitted a longer period of repose than that which is cho.sen for steam boiling, say, several weeks. The greater the heat an oil is subjected to, the darker will be its color; so that a pure oil boiled by the fire process will be much darker than that boiled by the steam process; therefore the ad¬ ditional discoloration consequent upon the selection of an oil for fire boiling which has not been well settled <» is apparent, and should be carefully guarded against. Should an opaqueness be discernible when the oil is viewed in the sample glass, however slight, it should be rejected; it is an indication that it is not settled, and therefore contains a larger proportion of moisture and of impure substances than should be present in oil for boil¬ ing. The writer has seen an instance where an oil was boiled a few hours after being made, which, as should have been known, retained its inky appearance, and gave the consumer, at least in this case, solid grounds for complaint. To sum up: The indispensable preliminary treatment of an oil for boiling is simply sufficient time for re-. pose. 150 THE MANUFACTURE OF LINSEED OIL. A fire-boiled oil may be said to be efficiently treated which possesses the desired color, usually a deep old port wine hue, and drying properties, which, when the oil is applied in a thin surface, will harden and become bright and glossy in from five to seven hours. Imme¬ diately after a parcel of oil has been boiled its dry¬ ing qualities should be ascertained. A reliable method of accomplishing this is to cover the surface of a small piece of glass thinly, placing the latter in a vertical position against some object, and if at the end of six or seven hours it shall present a dried and uni¬ formly glossy surface, it may be classed as a good boiled oil. If, on the other hand, the upper part of the glass is greasy and tacky to the touch, the lower being covered with a heavier body of the oil, which has slowly worked down in streaks, it is an indication that it is an im¬ perfectly boiled oil. This method resembles Messrs. Pratt’s paper rule, but as glass is a slower test the result is more reliable. Extreme care is essential to maintain a uniform heat in the oil when boiling. The usual temperature for fire boiling averages between 500° Fahrenheit and 600° Fahrenheit. By means of the proper fuel, with the other necessary appliances, this heat can be steadily main¬ tained without serious fiuctuation for several hours. The exact temperature can be accurately ascertained at any stage of the process by a glance at the elongated ther¬ mometer suspended in the oil. The utility of the thermometer is apparent, as any sudden change in the temperature is at once perceived by the oil boiler and the neces.sary remedy applied promptly. If the thermometer should suddenly rise when in the proximity of 550° Fahrenheit, imminent danger is present of its swelling and running over the THE MANUFACTURE OF LINSEED OIL. 151 lop of the kettle, in which case a prompt withdrawal of the fire with cold oil poured in will avert. This action of the mercury would indicate that a regu¬ lar fire had not been maintained, or the difficulty may have arisen from the nature of the oil. Oil made from Ea.st India seed has a tendency to swell and froth when subjected to heat, consequently is more dangerous in boiling. just now, however, when there is such a material difi’eronce in the relative values of the oil from the for¬ eign and that from the domestic seed, the former com¬ manding a higher commercial value, it is rarely, if ever used for boiling. If, on the contrary, the mercury descends in the tube, the fire needs prompt attention by being increased in in¬ tensity. The modern system of oil boiling in efficiency and pre¬ cision becomes more apparent when compared with the old rule of thumb method in vogue, when the only sys¬ tem known was that of submitting the oil with a certain proportion of red lead to an unknown temperature, the entire operation being gauged by the individual fiat of the crude oil boiler. Boiling linseed oil with chemical compounds added thereto and known as driers, facili¬ tates the thorough diffusion of the latter throughout the mass by imparting to it the oxygen absorbing and dry¬ ing jjroperties which are characteristic features of the combination of lead salts and manganese known as litharge, acetate of lead, sulphate of lime, and other basic lead oxides. To the painter, the thoroughness of oil boiling is of peculiar consequence. Pure linseed oil, well boiled in conjunction with a judiciously selected drier, correct in quality and propor¬ tion, possesses the requisites absolutely indispensable 152 THE MANUFACTURE OF LINSEED OIL. to form a good covering surface as the component part of an applied paint. A good boiled oil should not run into streaks, leaving remnants of the coloring matter be¬ hind, but should form a smooth, but hard surface, im- liermeable for a prolonged period to atmospheric in¬ fluences. This is what practically constitutes a good boiled oil. A uniform system of boiling all varieties of linseed oil would be inapplicable. A pure, well settled oil made from ripe seed, containing a small proportion ot natural moisture, does not require as much drier or as long a period for boiling, as an oil made from a stunted and impoverished seed. The treatment neces¬ sary to the latter, if applied to the former, would spoil the entire batch. Oil from inferior seed should be per¬ mitted a much longer period for settling, and when boil¬ ing, more drier and longer time is necessary. Red lead and umber are used in boiling by fire, both ingredients imparting color to the oil. Red lead pos¬ sesses powerful drying properties, materially oxidizing the oil, as well as imparting color to it, but it has been largely superseded within recent years, and it is not used so extensively as formerly. Umber is not used to the extent it formerly was, but old oil boilers • have great faith in its virtues. It contains a certain proportion of manganese and alumina, about 12 per cent of the for¬ mer and 2 per cent of the latter, the properties of which are so essential to a good drying oil. It also imparts a rich hue to the oil, some consumers basing their esti¬ mate on the quality of the oil by this color. It is, there¬ fore, apparent that umber is a good coloring agent and contains elements in the form of manganese and alu¬ mina, which if carefully ground, is valuable in propor¬ tion to the above properties it contains. It also imparts a good body to the oil and thoroughly assimilating with it. I THE MANUFACTURE OP LINSEED OIL. 153 The following are the names of the chemicals used as driers in various proportions: litharge, lead acetate or sugar of lead, manganese dioxide, sulphate of zinc, red lead, umber, borax, etc., etc. Driers of the metallic nature usually aggregate in weight when used in the oil from five to eight pounds for each 300 gallons. Prof. Hurst states that litharge is the monoxide of lead and has the composition shown by the formula PbO. Mixed with drying oils, a slow action sets in, resulting in the formation of lead soaps which are insoluble in water and many solvents. This action occurs with linseed oil. The lead linoleate so formed dissolves in the rest of the oil, forming a kind of varnish, which, on drying, forms a lustrous coat. This is a marked feature of lead salts, which renders their use of especial value to the oil boiler. Litharge being a powerful drier, it should be borne in mind that it should not be used extravagantly in oil boiling, but in the pro¬ portion of about ten pounds to the ton of oil. Sugar of lead or acetate of lead has not the drying or oxygen imparting qualities which are features of litharge, man¬ ganese, or red lead, but when added to the oil in cor¬ rect proportions, readily assimilates without discoloring it. The latter qualification renders its use desirable where a pale boiled oil is needed. The black oxide of manganese is the most powerful of all driers, and is now extensively used. It possesses a greater proportion of oxygen than any other drier, which feature renders it invaluable for oil boiling. When added to the oil, and the proper temperature arrived at, a small proportion of its weight dissolves slowly, the whole transmitting to the mass its oxidizing or drying properties, and the residue precipitating the moment the mechanical agitation in the boiling caldron ceases. The precipitated manga¬ nese matter has the peculiar faculty of re-absorbing the 154 THE MANUFACTURE OF LINSEED OIL. element which it has in part lost during the boiling pro¬ cess. By proper treatment, it will again absorb oxygen and become as powerful a drier as before. A formula will be described later on by the observance of which the once-used manganese can be restored to its pristine use¬ fulness. The proportion of this drier used should not exceed six pounds to a ton of oil. A greater amount would not only darken the oil, but would, when the lat¬ ter is applied as the constituent part of a paint, mate¬ rially afifect the surface, cracking, and proving unsatis¬ factory generally. Its drying qualifications, under such conditions, are all that could be desired, but the excess of manganese deteriorates the durability of the paint, to¬ gether with imparting a rough surface to the whole, by reason of its cracking and separating. Sulphate of zinc, which is commonly used in this country, is considered by some chemists to be of little value, its virtues as a drier being problematical. The prevailing opinion among oil boilers in Europe, as well as in the United States, in regard to the inherent properties of sulphate of zinc, is, that when added to the oil at the proper moment, and a high degree of tem¬ perature has been reached, it renders the impurities— mucilaginous substances, etc.—insoluble, and thus, by increasing their specific gravity, aided by the charring effects of the heat, hastens their precipitation after the boiling process has ceased. Its action in this respect is co-incident with that of sulphuric acid, when a crude oil is being manipulated for white lead or varnish manu¬ facturing. Livache, in investigating the process of oxidation of drying oils, has shown that when treated with metallic lead, or with litharge, and shaken up with a solution of zinc sulphate, all the lead is precipitated from the oil and the zinc passes into solution therein. THE MANUFACTURE OF LINSEED OIL. 155 It has. however, been demonstrated that the action of salts of zinc exerts no chemical action on the drying (lualities of the oil when cold, but when added thereto nt the seasonable moment and the increasing tempera¬ ture slowly proceeds, its action on the suspended impuri¬ ties is believed by many to hasten their destruction, thus materially increasing the drying qualities of the oil. Buckheister shows that zinc linoleate and lead linoleate do not act as driers when simply added to the oil; he has also shown that though the former is soluble in heated oil, it is insoluble in cold oil, and it, therefore, separates from the oil as it cools. The exact action of lead salts is, however, somewhat uncertain, but it may be accepted that to a certain ex¬ tent they tend to precipitate the impure substances, caus¬ ing the oil in co-operation with the heat, to become more fluid at the time of boiling, thus facilitating the precipi¬ tation of the impure matter when in repose and impart¬ ing to the whole a good body. The function which borax performs is of the absorption of muriatic and sulphurous gases, but no others, and it promotes a fusion of the other ingredients. Reference has been made to the peculiar quality of manganous oxide by means of which the elements which it has been deprived of can be restored. In Europe the practice of restoring the oxygen to the already utilized manganese is common. The precipitated matter is taken from the bottom of the boiling caldron and burned in the furnace until the vestige of chemical and fatty mat¬ ter is destroyed. It is then placed in an exposed place, spread efut thinly, so that as much as possible of the pulverized metal will be accessible to the atmosphere and left for a period extending from four to twelve months, when it can be again used to as much advantage as be- m Tll£ MANtlfACTURE 0£ LiNSEEt) OIL. ■fore. This process can be repeated for a nnnil^er of times before the utility of the manganese shall have ceased. In many oil boiling establishments in Europe, and in several in the United States, the precipitated manganese is again used, with the addition of fresh material and with¬ out exposure to the atmosphere. It is well known that after having passed the boiling process, it still contains a proportion of oxygen which is further utilized in con¬ junction with the new material, as has already been stated. A GOOD DRIER FORMULA. The writer has frequently made a drier in the follow¬ ing proportions for fire-boiled oil with satisfactory re¬ sults : About 80 gallons of clear raw oil are poured into the drier caldron and gradually heated. When the first froth or effervescence subsides., the following ingredients are slowly added: 20 pounds of manganese, 4 pounds of red lead, and 2 pounds of sulphate of zinc. This is boiled for the space of 3^ or 4 hours, or until the whole shall have assumed a sirupy condition. Great care is required to guard against the mixture boiling over, in the event of which disastrous results will ensue. There is great danger attached to drier making, and unremitting care is needed to establish a uniform heat during the entire process, and a close watch kept on the action of the contents of the boiling pot. The mass must be constantly agitated by two attend¬ ants provided with paddles, which alternately sweep around the bottom and sides of the pot, thus distribut¬ ing the heat more uniformly and rendering the admix¬ ture and assimilation of the chemicals with the oil more perfect. The fire is now withdrawn, and the drier ready for use proportionate to the grade of oil required. We now proceed to use the precipitated manga- THE MANUFACTURE OF LINSEED OlL. 157 nese, when the following course is pursued: After hav¬ ing emptied the kettle of its contents in the matter of drier, which is conveyed to a proper receptacle for future use, the precipitated manganese, with the lead and other chemical and sooty matter, is not removed, and 80 gal¬ lons of new oil added thereto, which in conjunction with the following proportion of new driers, and operated exactly similar to the one described is repeated. Ten pounds of new manganese, 2 pounds of red lead, and 1 pound of sulphate of zinc, gradually added, will make as serviceable a drier boiled with the residue of the first process as the latter under similar conditions. Another combination of driers which has proved satisfactory in turning out an oil suitable for all practical work, is made as follows: Twenty-four gallons of crude oil are placed in the drier pot and heat slowly applied, when 30 pounds of manganese, 5 pounds sugar of lead (or acetate of lead), 3 pounds of borax and about 2 pounds of sulphate of zinc, are slowly added, the whole being in a state of commotion the while. The same precautionary measures are necessary as in the previous operation, two attend¬ ants being required to be paddling the mixture without exertion until the process is completed.. The three latter ingredients must be added in small cjuantities so that the whole will be thoroughly mixed, the agitation being kept up until the drier is made, and for the space of one- half an hour after the fire is withdrawn, when cooling sets in. In addition to the above, a few gallons of raw oil poured in from time to time, especially if the mass at any stage of the process attempts to swell or rise. This has the effect of causing it to subside at once, and should be used in the proportion necessary to bring the mixture to the consistency of thick molasses. When a drier pot is emptied it should be thoroughly 158 THE MANUFACTURE OF LINSEED OIL. scraped and cleaned; the sides and the bottom, especially shall be divested of any metallic scaling- adhering to it. lloiling oil by the aid of this drier is usually carried on as follows: The full amount of drier made by the last described method would be sufficient for ordinary pur¬ poses, to be added to from 1,200 to 1,500 gallons of oil. The quantity cf drier made at a single operation, or the amount of oil boiled, varies in proportion to the capacity and number of pots used. In the case of the latter, a row of pots of boiling oil can be properly attended to by two persons, which would be impossible in the case of drier making. From 1,000 to 8,000 gallons of oil are boiled at one time. The usual course of procedure consists in first starting the fires after the oil has been placed in the pots and slowly heated. When the temperature has reached that point that when the finger is placed in the oil it becomes painful, the drier is slowly poured in. The oil is then frequently stirred by the attendants until the process is completed. In some large concerns a driving or agitat¬ ing gear is operated by a separate engine, as in the case of steam-boiled oil. The revolving motion of the vertical shaft running down the centre of the kettle with the ex¬ tended arms attached works well, and much more uni¬ formly than when the agitation is dependent on the muscles of the attendants. The entire mass is thor¬ oughly mixed; the revolutions of the agitators should not exceed four or four and one-half per minute. The quality of the oil will largely depend on the uni¬ formity of the heat applied, any fluctuations having a tendency to spoil the batch. The process should not be terminated under 5^ hours, the temperature averaging as nearly as possible about 55° Fahrenheit. Where the fires are withdrawn, a certain proportion of red lead (about 10 pounds usually) is added to the oil, THE MANUFACTURE OF LINSEED OIL. i:.9 but sometimes in amounts sufficient to procure the de¬ sired color. The capacity of the boiling pots varies from 200 to 1,000 gallons, and sometimes even a larger vessel is used. In formation they should be about the same depth and breadth. As the heat strikes the bottom of the pot with more or less intensity, the metal will contract or expand if the temperature is changed rapidly, thus causing cracks, and rendering the pot unfitted for further work. For a slight additional cost, extra thick bottoms can be made when casting, and with ordinary care will last with regular use for many years. Some boiling pots are made in France and England of wrought-iron boiler-plates of a uniform thickness, and the bottom, which is made separate, is riveted to the outer sides. By a sy.stern of fines encircling the boiling pot, heat can be more evenly distributed, thus avoiding the infringement of the intense heat on any particular spot, and lessening its liability to crack. Where the quantity of oil boiled at a single operation in one large caldron amounts to 1,(M)() gallons, the sys¬ tem before alluded to, having a driving gear, should be adopted. The commingling of the mass is better per¬ formed, and fusion is thus materially facilitated. Where circumstances permit, a flagged floor having a slight pitch towards the door of the building or shed should be constructed, extending around the pot, and between the top of the latter and the furnace beneath, thus effectively shutting off all chances of the oil, should it flow over, coming in contact with the fire beneath. By this means the boiling can be carried on with comparative safety, the risk of conflagration being entirely removed. As an additional precautionary measure, the oil boiler should have at hand 40 or bO gallons of the raw oil, so that any suspicious movement of the oil could be 160 THE MANUFACTtJRR OF LINSEED OIL. immediately checked by pourings a quantity in and then promptly withdrawing the fire. Sufficient room should be left between the surface of the body of oil and the top of the boiling pot to prevent any slight swelling or effer¬ vescence from causing the mass to flow over. By a system of weights and movable sheet-iron hoods which descend and completely cover the pot when the boiling operation is progressing, the operative is spared the suffering of inhaling the pungent vapors of the seething mass. These hoods are connected by means of a large pipe with the main chimney of the steam boiler furnaces, and the abominable odor is thus con¬ veyed into the atmosphere. In some instances where oil boiling is carried on in the centre of a large city, the vapor is drawn to the boiler furnaces and passed through the fires, thus completely destroying them by the in¬ tense heat before reaching the atmosphere. The flying and obnoxious vapors which would other¬ wise linger in the vicinity where oil boiling is carried on, attacking the eyes and the lungs of all coming within reach, rendered the adoption of this method an abso¬ lute necessity in populous centres. The hoods alluded to have at their lower extremity, and at various places around, small doors or hatchways, which open and shut by means of hinges, so that the oil boiler can at any time observe the action beneath; these small,doors also give sufficient room for the working of the paddles, where such are used, and which can be worked when the hood is closed all around. It may be stated that in the event of the oil boiling over, where no intervening floor is placed between the top of the pot and the furnace fires, no better means can be adopted in such an emergency than by throwing sand on the burning fluid. For this reason, it is always desirable to have an available supply THE MANUFACTURE OF LINSEED OIL. 161 of sand on hand where the boiling is done in the above manner. Where oil is in conflagra¬ tion, water should be studiously avoided; its use would bring about ten-fold more trouble. In some methods of oil boiling by fire, and in drier mak¬ ing especially, risks are taken of necessity, so that every possible precaution should be taken to avert a conflag¬ ration, and when such should occur, the means referred to should be readily available to effect the extinction of the flames of the burning oil. In some large European boiling concerns, the large pots are completely bricked in with arched covering, the agitating shaft descending through a stuffing box in the arch, placed immediately over the centre of the spot, and in the event of the oil rising over the pot, it could only flow through one small opening, the burning fluid being conveyed by means of a large, shallow iron trough well out into the open at¬ mosphere. Having described the method of oil boiling by fire, we now come to the steam boiling process which is in use in many parts of the United States. Oil boiled by fire in conjunction with lead salts is detrimental to good work when mixed with zinc white. It is only due in part to this fact that the idea of boiling by steam was first for¬ mulated shortly after the introduction of the latter as a pigment. However, the desire to avoid the odors when oil is boiling (the effective methods which have been de¬ scribed for the destruction of these vapors and odors were unknown at the period of the introduction of the steam boiling system) has doubtless played an import¬ ant part in the new departure. Sufficient heat can be imparted to the oil by this means to drive off the hydro¬ genous conditions present, and, by its prolongation, with the addition of suitable driers, drying and hardening qualities are superinduced. 1G2 THE MANUFACTURE OF LINSEED OIL. There are decided advantages in using steam as a means of boiling oil; the risk of fire is reduced, and the oil is in accordance with the nature of the drier used, much lighter in color. Colorless driers, such as acetate of lead in solution, being largely used, and in proportion to the color and general qualities required. For very many purposes an oil boiled by steam is equally as good as that boiled by fire, while for special work its proper¬ ties with regard to light color, etc., are indispensable, the latter feature being, as is well known, entirely for¬ eign to the fire-boiled oil. The steam jacketed kettle in which the oil is treated has various forms and sizes, but a brief description of one will give a general idea of the design of all. Through the centre of the domed kettle a shaft descends, hav¬ ing projecting arms and serving the same, purpose when in motion as that which has been previously described. Pipes are connected to the top, and run to the furnaces or chimney as described, and, as before described, when treating on the fire-boiled system. By this means the odors and vapors are similarly removed. Through the jacketed bottom a pipe is laid and ex¬ tended across the entire bottom of the kettle. By means of this pipe, which is thickly perforated with small holes, finely divided currents of air are forced into the oil. This has a tendency, in conjunction with the drier used, to oxidize and impart a body to the oil, as Avell as keeping the mass in constant commotion in co¬ operation with the heat. In some instances circular coils of air piping are arranged around the bottom of the ket¬ tle. A blowing engine supplies and forces the air through during the entire process. The heat applied varies from 35 to 40 pounds of steam pressure per square inch on the kettle. In some instances the oil before be¬ ing pumped into the treating kettle is heated prelimin- THE MANUFACTURE OF LINSEED OIL. 163 arily by means of a steam coil and np to 200 or 210 cubic feet. This preliminary heating greatly facilitates the boiling. The jacketed portion is two-thirds of the size of the kettle. By the means described, ample facilities are afforded to produce a good boiled oil. The quantity of driers does not equal in weight that which is used by the fire¬ boiling system. It is frequently added in fluid form, and the perfect system of uniform heat and agitation by steam and air, procures as thorough a diffusion of oil and drier as can be achieved, bringing the particles into intimate contact with each other, and at the same time thoroughly oxidizing the oil. Prof. Hurst describes the method of procuring a drying oil recently patented. A manganese linoleate is made by preparing a soap of linseed oil by the following process: The manganese linoleate is dissolved in twice its weight of turpentine and from two to five volumes of this solution are added to 100 volumes of linseed oil. Insoluble matters are separated, the mass raised to a temperature of 212'' Fahrenheit in a special apparatus, and a current of air or oxygen passed through the oil until it has attained the desired degree of thickness; for example, a clear, transparent oil of a pale amber color, having a specific gravity of 0.007, can be obtained from a linseed oil of specific gravity 0.037. This thickened oil may be used in painting, and in the manufacture of floor cloth, linoleum and similar materials. It must, however, be borne in mind that this especial treatment only refers to oil from East India seed. Mulder found that when raw oil, especially if old, was kept for twelve or eighteen hours at a temperature of 100° Fahrenheit, it acquired the property of boiled oil. According to C. W. Vincent, a body of oil heated so that no air can reach it except on the surface, as in a 164 THE MANUFACTURE OF LINSEED OIL. jacketed kettle; such oil heated for several days became thicker, more greasy, and had decidedly less drying power, and out of many hundreds of samples taken at various stages of heating and boiling, not one dried more rapidly than a sample of raw oil from which it had been taken. Between these conflicting results, an intermediary course is pursued which is productive of a pale boiled oil. The application of heat is only permitted to a limited extent in conjunction with a suitable colorless drier. In some instances the light colored fluid drier is simply mixed with the oil for a short period without the application of heat. When the operation has terminated in the fire-boil¬ ing system, where it is possible the oil should be allowed to remain in the pot for at least forty-eight hours. This gives ample time for cooling and precipitation of the footy matter. The longer the period of repose in the boiling pot, the better and more thoroughly the sus¬ pended impurities will descend in conjunction with the fine metallic particles. After an oil has been boiled, whether by the fire or steam process, it is not necessary to subject it to filtra¬ tion; three or four weeks’ repose in the settling tanks prior to shipment is all that is necessary. The Filter Press in Oil Milling—Further Details Concerning Its Workings, Etc. The introduction of the filter press marks a new era in modern oil milling. In many of the industrial arts, especially those which require the separation of solids from liquids when held in suspension, the work was here¬ tofore accomplished by the hydraulic press or centrifugal machine, and, according to the nature of the work, by evaporation and concentration; the filter press has relegated all these among the things of the past. Its adaptation to the special requirements of chemical and color works, paraffine wax, china clays, stearine, dex¬ trine, yeast, paper, whiting, plaster, sugar, graphite, etc., has been most momentous. In every art where filtra¬ tion or percolation is brought into requisition in the various manufacturing processes it has proved of the greatest value. In the clarification of liquors, such as linseed, cottonseed, lard and castor oils, glycerine, var¬ nish, chocolate, water, ink, chemical and pharmaceuti¬ cal preparations, it is widely used. For extracting and washing powdery substances, as in the manufacture of bicarbonate of soda, cream of tartar, etc., its efficiency is recognized. Hot presses for wax and candle manu¬ facturing, and close filtration presses, in which naphtha, alcohol, ether or other volatile fluids are used, are also in general use. Some of these latter are of great size, the plates being set together by means of hydraulic pressure. Although of comparatively recent origin, its wide¬ spread recognition as an invaluable factor in the ad¬ vancement of the respective arts where its use becomes practicable is abiding. Its utility has been demon¬ strated by a decade of practical experience, and owing to 105 166 THE MANUFACTURE OF LINSEED OIL. the general approval with which its functions are re¬ garded, the wonder is that this latest and most important innovation in many of the manufacturing industries was so long deferred. To the oil miller and varnish maker the filter press is of peculiar consequence. No well regulated and equipped mill can afford to di.spense with the use of this invaluable auxiliary in the manipulation of crude and re¬ fined oils, by reason of the fact that no pretentions to the possession of either cpialification can be entertained while lacking this important adjunct to efficient oil mill¬ ing. The use of the filter press renders practicable the transformation of the crude oil into a marketable product within a few hours subsequent to its extraction from the crushed seed, a circumstance heretofore impossible of attainment, owing to the prolonged period requisite for the precipitation of the foots and fine vegetable matter in the production of a clarified oil. The separation of the mealy substance from the oil is effected in a very excellent manner by the use of the filter press. The modus opcrandi consists in forcing the fluid through the press, the plates of which are covered with textile or other material, permitting the oil to flow through in a clarified condition while retaining the foots. This mealy substance—in oil mill parlance recognized as “foots”—slowly accumulates until the chambers become clogged, a condition which makes itself apparent by the labored efforts of the jnimp, and the consequent in¬ crease of pressure as indicated by the press gauge. The filtering process must now be stopped until the foots within the press chambers have been removed and the cloths carefully scraped, where such are in use, when the plates are set together again by the screw and the regu¬ lar work resumed. THE MANUFACTURE OF LINSEED OIL. 167 By securing the foots in this concentrated form—that of caked meal impregnated with oil, in width and thick¬ ness proportionate to the filtering area of the chambers —a great saving is effected. The unpleasant and arduous duties which devolve on the mill hands of removing the foots from the bottom of storage tanks at frequent in¬ tervals a.re by the use of the filter press wholly obviated, d'he characteristic feature of tank cleaning—that of a sloppy and greasy condition permeating the floor and every object in the surrounding vicinity, together with its unavoidable and wasteful concomitant, a greater or less loss of oil—are now, thanks to the filter press, be¬ longing to the past. A pressure exceeding eighty pounds should not be maintained, and if the process be stopped at this point, and due time allowed for the oil in the chamber to run oft prior to drawing the plates apart, it will be found that sufficient meal will have accumulated to form a fairly-sized cake. By placing the limit of pressure at fifty pounds instead of eighty pounds, better results are obtainable. Any good pump of sufficient capacity to supply from 100 to 300 gallons per hour will suffice, but if fitted with change speed or of the duplex variety, the filtering pro¬ cess is maintained more uniformly, the latter being an indispensable feature in the production of a perfectly filtered oil. The first form of pump used for the purpose was fitted with a relief valve, and while a full charge of oil was continuously delivered to the filter press, the surplus oil was permitted to flow out freely. The up¬ ward movement of the valve caused the surplus oil to escape and return to the suction pipe. A spring valve with stuffing box on the adjusting stem and placed in a I)ipe connecting the suction and forcing pipes of the pump worked satisfactorily. By setting the valve to the 168 THE MANUFACTURE OF LINSEED OIL. desired pressure it was constituted a sort of safety valve, preventing an excessive strain on the press. In the filter press of recent construction the valve is sometimes di¬ rectly attached thereto, and meets the requirements of the case in a more suitable manner, the surplus oil fall¬ ing to the expansive pan beneath, and by gravity slowly moving to the suction pipe. In scraping the waxy substance from the surface of the filter cloths a smooth-edged plate of steel should be used; or hard wood champfered to suit, in size, say, about three or four inches long, five inches wide and about one-six¬ teenth of an inch thick. In the case of the steel, the edges must not be sharp or the textile material, where such is in use, will be cut. In the event of paper being used as the filtering medium, and the increase of pres¬ sure indicating the formation of a cake in the interior, the outer ply of the eight or ten which may be in opera¬ tion is removed, the foots or caked substance falling to the pan, after which the press is closed and the operation resumed. Recourse is made to this simple method until the number of sheets of filter paper has been reduced to three or four, when a fresh lot is added. With regard to the cloths, it must not be forgotten that when not in use they should be submerged in oil. Neglect of this precautionary measure will assuredly ruin the fabric, more especially in the case of linseed or lard oil filtration. A new set of cloths of the very best ma¬ terial may be thus irrecoverably spoiled. In the event of the press being required to remain idle for a few days, a simple but effective method of keep¬ ing the cloths moistened, and thereby preserved, without the necessity of removing them from the plates for sub¬ mersion, consists in charging the press with the oil, the outlets being shut. This is impracticable, however, where shut-off taps are not fitted to the plates; but the r THE MANUFACTURE OF LINSEED OIL. 169 liquid may be slowly pumped through, the oil con¬ tinuously coursing from suction tank to press, and re¬ turn. By repeating this operation at frequent inter¬ vals, the material is preserved. When through omission, or from any other cause, fil¬ ter cloths used in the clarification of linseed oil are permitted to dry up during a temporary cessation of the filtering operation, the damaging effect on the material is more serious than in the case of cottonseed oil filtra¬ tion. The drying properties of linseed oil act very dele- teriously on the surface of the cloths by gumming them, thus blocking the minute openings between the woven ! threads, rendering them impervious to the oil, and con¬ sequently valueless as a filtering medium. 1 Cottonseed oil, which possesses drying properties to a comparatively trifling extent, is not so injurious to the cloths when permitted to remain thereon; nevertheless, complete submersion guarantees preservation of the fab¬ ric when out of use for any extended period. The cloth used in the filtration of lard oil, being of ' the same texture, requires similar attention under like circumstances. The coagulation of the albuminous de- posits characteristic of animal oils displays a tendency to clog the filtering material when not submerged in the liquid. This has the effect of damaging them equally with that of the gumming tendency of linseed oil under similar conditions. Impressed with the fallacious supposition that a saving is effecte^J in cost of filtering material, some of the cot¬ tonseed crushers and refiners have substituted several plies of cotton-duck cloth on each plate of the filter press for the closely-woven and substantial fabric especially manufactured for that purpose. The use of such mate¬ rial is most reprehensible, and viewed from a practical and economical standpoint, should not be maintained 170 THE MANUFACTURE OF LINSEED OIL. under any condition whatsoever. To obtain an oil from which the ordinary proportion of vegetable matter has been eliminated, as is the case where a suitable filtering medium is utilized by means of such flimsy material as the common fabric referred to, becomes a practical im¬ possibility. The tendency of the duck cloth to rend at the joints, augments the difficulty by permitting the oil to pass out unfiltered, thus materially contributing to the defective principle involved; that is, the attainment of perfect filtration by inadequate means. Not infrequently leaks occur by reason of the imprac¬ ticability of forming permanently tight joints, the cheap material separating under the pressure essential to form a perfect joint. At this juncture the screw is set up, thus bringing the plates closer, the object being to stop the leak or leaks-; but while this expedient may for the mo¬ ment prove effective, aided probably by the dislodged foots in the filter chambers forced to the leaky point by the escaping fluid, and blocking the aperture or aper¬ tures temporarily, the extra pressure exerted at the joints, as a result of the latest movement of the screw, will eventually manifest itself by still further increasing the undesirable oil exit, until perforce the operation is brought to a standstill. The press is then permitted to drain off its fluid contents, the fragmentary cloth or cloths are removed, to be substituted by whole material, which, in turn, is destined to be similarly cast aside, probably before the expiration of forty-eight hours. The use of filter cloths of suitable texture is much more economical, actually costing less in the end, with¬ out reference to the very superior product obtained by its use as compared with that of the frailer material. Under skillful treatment a set of soiled and clogged fil¬ ter cloths can be restored to their original usefulness, or so closely approaching it that the difference is not per- THE MANUFACTURE OF LINSEEO OIL. 171 ceptible; and this may be successively repeated as oc¬ casion recjuires, until they are worn out by prolonged usage. Lack of adequate knowledge to effect a thor¬ ough cleansing of the soiled cloths in nine cases out of ten is the primary cause of their being irrecoverably spoiled, thus precipitating their premature abandonment. In adjusting the cloths, care must be taken that they do not overlap, for the reason that when the plates are set together by the motion of the screw, an imperfect joint will have been made, a circumstance which is de¬ monstrated the moment the pump is put in motion by the rush of unfiltered oil from the defective point. Under these circumstances, the pump must be stopped at once, the screw relaxed, and after the press is drained, the dis¬ placed fabric is restored to its normal position, when the work can be resumed. The correct management of the cloths, in adjusting them to their respective positions, is a matter of considerable importance. By overlapping, however slightly, an exit is made for the oil through the imperfect joint which is thereby formed. A stream so thin that its presence is not made perceptible may flow for hours undetected. This has the effect of producing a cloudy oil, and in a proportionate degree rendering abortive the functions which the filtering apparatus is expected to perform. A reliable system consists in view¬ ing a sample of the oil hourly in a glass test-tube as it flows from the press. Any defect in the operation, not plainly discernible, is thus promptly detected, and the usual remedies at once brought into requisition. .If the oil is bright and transparent, the work is progressing satisfactorily; but a cloudy condition is indicative of an irregularity requiring immediate investigation. The necessity of this regular examination of the oil will be apparent when it is understood that not infre¬ quently a leak manifests itself when least expected, al- 172 THE MANUFACTURE OF LINSEED OIL. though the filtering medium may be of suitable tex¬ ture and in good condition. This is owing to the yield¬ ing or stretching of the cloths at the joints, thus causing slight leaks by slacking. This drawback is easily reme¬ died by setting up the screw, pressing the plate rims with the fabric between firmly together, and thus form- ing tight joints. With good material there need be no apprehension of rending the cloths by thus taking up the slack, as in the case of the common duck cloth. From the time a new set of cloths are first put into operation, it is necessary, at proper intervals, to take up this re¬ laxation, thus lessening the risks of leaks. The success of the filtration process, together with the period of time which it may be permanently maintained, very materially depends on treatment accorded the me¬ dium used, whether felt, paper, or woven material. Sev¬ eral years ago the writer saw a valuable filter press prac¬ tically abandoned, owing to insufficient experience in maintaining the cloths in proper condition. A set of good cloths, comprising the heavy and light variety for each plate, under careful management, should give satisfactory results for six months, working night and day. There are various forms of filter presses especially constructed to suit the respective requirements of the industrial arts. The original form of press was fitted with plates of circular shape, but other designs have been adopted, and are now in general use. The concave surface of the circular plates forms cham¬ bers in which the foots are retained. The press of later construction consists of a series of square plates, the chambers being formed by intermediate frames, and the oil inlet differing in principle as well as in design. The plates and frames rest on suitable side-bars, the centre screw forcing the head block plates and frames together. THE MANUFACTURE OF LINSEED OIL. 173 As previously shown in the case of the circular-cham¬ bered variety, the joints are made by the filtering me¬ dium, which is adjusted to each side of the plates. The plates vary in size from eighteen to thirty-six inches, while for such material as ochre, fuller’s earth, etc., a smaller size of the square-plate kind is constructed. The varnish makers of Europe and America realizing the utility of the filter press, have very generally adopted it. In the form of press used for the production of paraf¬ fine wax and other materials requiring high pressure, the hydraulic ram is used. Wood plate presses are used for filtering substances containing acids, the iron press, owing to the corroding action of the latter, being un¬ available. ' The entrance of the substance to be filtered into the press chambers, varies according to the nature of the work to be performed, centre, bottom, corner, and sometimes upper portion of the plate are used, the volume filtered varying from one to two thou¬ sand gallons, according to size of the press, per twenty-four hours. During this period they must be scraped and washed as occasion requires. After three or four removals of the caked foots, the secondary treatment of washing becomes indispensable. A very excellent patented machine, especially constructed to facilitate the cleansing of the soiled fabric, has been on the market for several years, its use proving effective and economi¬ cal. The practice of rapidly pumping the fluid through the press is highly deleterious. A slow speed, maintained under uniform pressure, is most desirable, and other con¬ ditions being normal, satisfactory results are obtainable in every instance. A force pump which is irregular in its motion should not be used. Jerks or sudden movements of the pump plunger rapidly force the oil through the 174 THE MANUFACTURE OF LINSEED OIL. filtering material, the proportion thus hurriedly passed through being imperfectly clarified. A steady pushing motion, characteristic of the duplex variety, is a require¬ ment of perfect filtration. Pumps are specially designed for this service, and efficient work will be best subserved by their use. The temperature of oil intended for filtration should not exceed 70° Fahrenheit. This temperature is obtained by permitting sufficient time to elapse subsequent to the extraction of the oil, during which period the precipita¬ tion of the heavy foots is effected simultaneously. The use of the filter press materially facilitates sys¬ tematic work in the regular manufacturing processes, while as a labor-saver and preventative of waste and primarily as a means of clarifying a newly made oil, it is incomparably superior to old-time principles. The principle involved in the use of substantial mate¬ rial for filtering purposes in oil mills, has equal bearing on the various industries where the filter press is oper¬ ated. , BUCKEYE Iron and Brass Works, DAYTON, OHIO. Manufacturers of f Linseed and Cotton¬ seed Oil Machinery. Engine Builders. Steam and Water Fitters. Brass Goods for All Purposes. WRITE FOR CATALOGUE. XII. WILLIAM H. SCHEEL, Importer Gums and Necessaries for the making of Varnishes, Lacquers, Etc. 172 Pearl Street, NEW YORK, N. Y. THE MANUFACTURE OF VARNISHES. MANUFACTURE OF OIL VARNISHES, Oil varnishes are divided commercially into two groups, coach varnishes and cabinet varnishes, although there is very little difference between them in either the method of making, or the materials from which they are made. The former are the best and most durable var¬ nishes made, the best materials and workmanship being employed, while less care is taken with cabinet var¬ nishes. The process of manufacture is, however, the same for all the oil varnishes. The materials used are resins of various kinds, linseed oil (rarely any other kind of oil), turpentine, shale-petroleum, or resin-spirit, and, for some special sorts of varnish, other ingredients. The process usually adopted for their manufacture will be first pointed out; then, any special process which is, or has been used; then, important points of detail in the pro¬ cess will be noticed, and recipes given for various kinds of oil varnishes, followed by a section dealing with their general properties, application, etc. 176 THE MANUFACTURE OF VARNISHES. 177 MANUFACTURE OF OIL VARNISHES.—The method and plant used in the manufacture of this class of varnishes are comparatively simple, but the process it¬ self, while being so simple, is one that requires very great care and experience to carry out to a successful end. The process in outline consists of the following stages: 1st. Melting (or “running” as it is known in the trade) the resin or “gum”; 2d, boiling the oil; 3d, mixing the melted gum and boiling oil; 4th, boiling the varnish; 5th, thinning the boiled varnish; 6th, clearing. 1st. “GUM RUNNING.”—This* is, perhaps, the most delicate operation in the whole process of varnish mak¬ ing, as unless it is well done, varnish cannot be made, no matter how well the rest of the process be carried out. “Running” is done in a large cylindrical copper vessel, the “gum pot;” there are two forms of this gum pot in use; one, known as the London pot, is shaped like a silk hat, and is made in two pieces, viz., the bottom formed of a solid piece of cast copper with a flange cast on it; and the body, which is a cylinder of sheet copper, riveted to the bottom piece. There is a very consider¬ able wear of the bottom part, as it comes in contact with the fire, and hence has to be replaced from time to time; usually a bottom will last about three months. The gum pot usually measures about 26 inches in depth by 10 inches in diameter, the body being about 9 inches deep. This is large enough to run about 8 pounds of gum at one time, but the pots are often made large enough to hold 50 pounds of gum. In the north of England the gum pot is made of a different shape, from which it will be seen that it differs principally in the shape of the bot¬ tom, which is made conical. The main advantage of this form lies in the fact that the gum runner can more read¬ ily ascertain when the whole of the gum has been melted 173 THE MANUFACTURE OF VARNISHES. by probing with his stirrer; in.the London shape parti¬ cles of unmelted may lodge in the bottom corners, into which it is difficult to work the stirrer, whereas in North¬ ern shape, any unmelted gum must settle down to the point of the conical bottom, and its presence there is easily ascertained. The “gum pot” rests by flange in a suitable hole in the top of a furnace. In modern varnish works the top of the furnace forms the floor of the gum¬ running shed, the furnaces themselves being fed with fuel from the outside. The pots are also fitted to a pair of wheels, by which they can be wheeled from the gum¬ running shed to the mixing shed; sometimes rails are laid, on which the pots are run. As a very considerable quantity of vapor of rather an acrid character is given off during the process of gum running, it is necessary to lit the pots with a hood connected with a flue, by which means all the vapors are carried into a chimney, and so away out into the atmosphere. It would be better, how¬ ever, to take the vapors into a large condensing cham¬ ber to allow as much as possible of them to condense into a liquid form, for which some uses (if only as fuel for the furnaces) could be found. This would prevent a considerable amount of nuisance being generated during the process of varnish making. In some large places where they have steam boilers, the vapor is carried by means of a pipe to the ash-hole of the fire-place, and thus passed through the fire; the mouth of the pipe must be covered with wire gauze. Prior to the gum being run, it is broken up into small pieces about the size of a walnut. At one time this used to be done by hand with a ham¬ mer, but is now effected by a machine known as the breaker, usually consisting of a pair of rollers fitted with teeth, by which the gum is broken up as it passes be¬ tween the rollers. THE MANUFACTURE OF VARNISHES. 179 2d. OIL BOILING.—While the gum is being ‘'run” the oil to be used is boiled. This is done in what is known as the boiling pot, which is the same in shape as the oil boiling pots described when dealing with the boil¬ ing of linseed oil. The oil is heated to about 500° Fah¬ renheit for one or two hours, when it is ready for mixing with the melted gum. The boiling of the oil is a com¬ paratively simple operation, and there should be no dif¬ ficulty in carrying it out. 8d, MIXING.—When the gum has been properly run by being heated in the gum pot until it is in a cjuiet state of ebullition, and there is no more frothing; which al¬ ways occurs when a gum is first heated, and which is a source of trouble in the operation of gum running by causing the gum to boil over and to become a source of danger by being liable to take fire if it finds its way into the furnace, as well as being a loss to the varnish maker. This frothing is probably due to the water which the resin naturally contains being driven off, as well as to the escape of the more volatile constituents of the resin; when this frothing happens, the best thing to be done is to lift the pot from the fire and beat down the froth as much as possible; when it has subsided, the pot may be replaced on the fire, and the gum again heated, these proceedings being repeated until all frothing ceases. With the object of preventing accidents from boiling over, the gum pot is made deep, and to hold a much larger quantity of gum than is run at one time. When the runner considers that the gum has been properly melted (on which point experience is the only reliable guide), the necessary quantity of boiling oil is taken from the boiling jjot in the coi)per jack and poured into the melted gum, which is stirred energetically all the time. When properly mixed, the contents of the gum pot are poured into the set pot (see below); the gum pot 180 THE MANUFACTURE OF VARNISHES. is then ready for another run of gum. What has here been described is called a “run;” usually a large number of runs are made and put into the set pot for treatment at one time by the next operation. In the early days of varnish making the usual quantity of gum run at one time was 8 pounds, and all recipes for making varnish are based on this figure; but nowa¬ days quantities of 50 or GO pounds are commonly run at one time. 4th, BOILING.—For the purpose of boiling the mix¬ ture of oil and gum so as to cause them to combine to¬ gether properly and to increase their drying properties, what is called a “set pot” is used. This is an iron ves¬ sel, in shape resembling a washing boiler, having a capacity of about 600 gallons, and set in a suitably con¬ structed furnace. Several runs of gum are poured into it, and the whole heated or boiled at from 450° to 500° Fahrenheit. The duration of the boil varies with differ¬ ent kinds of varnish, and may range from half an hour to 4 or 5 hours. When sufficiently boiled, the liquid has a certain amount of stringiness. When the gum and oil are first mixed they will not string, that is, if a drop be taken between the finger and thumb, and these be ex¬ tended, the varnish will not extend in the form of strings;» by boiling, it obtains this property, and the longer it is boiled the more extensible does it become; some varnishes only require a moderate amount of stringiness; others require a great deal; instructions on this point will be given when dealing with each indi¬ vidual varnish. Another effect of the boiling is to make the varnish clear and transparent; the mixture of gum and oil, when first made, is usually rather cloudy, but clears up on boiling. The set pot should be so placed in the furnace that it can be readily lifted out at the end of the boiling, and be THE MaNUEACTURE of VARNISHES. 181 taken out of doors away from the proximity of the fur¬ naces for the next operation. As a further precaution, a shallow concave cover, filled with sand, should be slung by chains over the pot. Should the oil take fire during the operation of boiling, this cover is quickly lowered down onto the pot, and the fire smothered out before it has taken too great a hold of the oily mass. Water is perfectly useless for this purpose, and should never be used to put out burning oil; there is nothing better for this purpose than sand. Varnish making is always sub¬ ject to the danger of the material firing; hence, every precaution should be taken to have means at hand to provide the promptest extinction of the flames. It would be advisable to have the floor of the running and boiling shops made of sand, so that if any oil does boil over it will be absorbed by the sand and would not in¬ flame. A heap of sand should always be kept in a con¬ venient position, so that it may be thrown on any oil that may by chance boil over. The fireplace should be so built as to be fed from the outside. 5th, THINNING.—After the boiling operation de¬ scribed above is completed, the set pot and its contents are removed from the fire and taken out of doors, if the weather permits, or into a shed specially used for this purpose, and which is at some distance from any fire; here it is mixed with turps, to thin it down to a working consistency. Turps is so volatile a body that if poured at once into the hot varnish mass it would be almost entirely driven off as a vapor, which is readily inflam¬ mable by contact with a fire or light. This thinning operation should, therefore, always be done at some con¬ siderable distance from a fire or light. Turps vapor, be¬ ing heavy, travels along the ground, and may even reach a fire 20 feet away. Although it is necessary to mix the turps with the varnish mass at as high a temperature 18-2 THE MANUJ'ACTURE OF VARNISHES. as possible, yet it is advisable to allow the hot varnish mass to cool down somewhat before adding the turps;' this should also be added in small quantities at a time, and each lot well stirred in before adding the next lot; by these means the mixing will be properly done without too great a loss of turps. (ith, CLEARING AND AGEING.—Freshly-made varnish is most unsatisfactory to use, and all the best qualities are subjected to an ageing and clearing process before they are sent out. This process consists simply in putting them into large iron tanks or cisterns, where the varnish is kept (free from exposure to the atmos¬ phere) for periods varying from six months to one and a half to two years. During this time the particles of in¬ soluble matter fall down, and the constituents becom¬ ing more thoroughly amalgamated, a clearer, more trans¬ parent, lustrous and more easily worked varnish is ob¬ tained. Such is a brief description of the usual method of mak¬ ing oil varnishes. The quality of the varnish made de¬ pends upon a number of factors. The gum must be good and as free as possible from particles of vegetable matter, which, in the running, are apt to char and thus discolor the resulting varnish. For pale varnishes, clear, pale gums must be used; and the running must be both thorough and carefully done, since there is no remedy for any defect due to a bad run; while one such run will spoil a whole batch of varnish. It should always be borne in mind that any gum left unmelted will not dis¬ solve on adding the oil. Again, the temperature of run¬ ning should not be too low nor too high; the former in¬ fluences the bloom of the varnish, while the latter tends to make the varnish too dark. The boiled oil should be hot, about 500° to 550° Fahrenheit, so that on being poured into the melted gum it will mix freely and not THE Manufacture of varnishes. 183 cool down the latter too much; after mixing it is advis¬ able to boil the mixture for about ten minutes before pouring it out into the set pot. The best practical guide to all these and other points in varnish making is experi¬ ence. The linseed oil used should be of the very best quality, as good.varnish cannot be made from poor oil, and it ought to be kept in covered tanks for some months before using. The turps should also be of good quality; it is improved by keeping. Another method of making varnishes, which was much advocated by Tingry, is to melt the gum in the usual way; then to run it out on to a cold surface, so that it would solidify in sheets; when cold, the solid gum is roughly powdered, put into the boiling pot with the oil and boiled up as described above. In mixing, 3 pounds of melted gum should be reckoned as equal to 4 pounds; in other respects, the same quantities of oil, etc., may be taken. The varnishes made by this method cannot be distinguished from those made by the old method. Tingry advised keeping the gum melted until it had lost 25 per cent of its weight, and he devised a special form of melting apparatus by which this could be done; but the process was (for several reasons) a rather unpractical one. It is stated in many accounts of varnish making that oil varnishes may be made by boiling the gum in oil. As a general rule, this is not correct. A few gums may be dissolved in this way, but most of the oil varnish gums obstinately refuse to be transformed into varnishes by this method. RECIPES.—Oil varnishes are divided by the trade into coach varnishes and cabinet varnishes; but there is no essential difference between them; they are made in the same way and often from the same materials; the dif¬ ference is due to the carriage varnishes being made from 184 THE MANUFACTURE OF VARNISHES. better qualities of gums and oil and a little more care being taken in their preparation. The following recipes are taken from the most reliable sources and give par¬ ticulars for preparing all the varieties of oil varnishes now in use. The preparation of varnishes is considered a trade secret; and it is difficult to obtain reliable infor¬ mation on the subject. What is here given and what is to be found in most accounts is based on a lecture on varnish making given by Mr. J. Wilson Neil to the So¬ ciety of Arts many years ago, and published in an early volume of their Transactions, which is difficult to obtain now. The proportions are generally given as for a run of 8 pounds of gum. 1. FINISHING BODY VARNISH FOR COACHES.—Run 8 pounds of the best African animi, pour in 2 gallons of the best oil well boiled, set very slowly (by boiling 4 to 5 hours until it strings well), al¬ low to cool and add 3^ gallons of turps; strain and allow to age. This varnish is considered to be the best varnish made, but it requires considerable care in making it to obtain it of good quality; the best and palest gum and the best oil must be used. 2. HARD DRYING OR FLATTING VARNISH. —This is made by running 8 pounds of gum animi, mix¬ ing with 2 gallons of oil, and, after boiling for 4 hours, thinning with 3^ gallons of turps. This varnish dries rather harder than the above and quicker— i. e., in about 8 to 10 hours. It is ,chiefly used for the under coats of varnish on a coach body. This varnish is used for the surface coats of carriages, is pale in color, and dries with a brilliant surface in about 12 hours. It is a very durable varnish, and will resist the destructive action of the atmosphere very well. THE MANUFACTURE OF VARNISHES. 185 3. ELASTIC CARRIAGE VARNISH (1).—Run 8 pounds of good quality gum copal, mix with 2^ gallons of oil, add | pound of dried copperas and ^ pound of litharge, boil until it strings, then allow to cool and thin with 5^ gallons of turps. Run 8 pounds of second sort gum animi, mix with 2-| gallons of oil, add ^ pound dried sugar of lead and ^ pound of litharge, boil until it strings, allow to cool and thin with gallons of turps. The two lots are mixed together, strained, and allowed to mature. This varnish dries hard with a fine polish in about 5 hours in summer and in about 7 hours in winter. It is used for varnishing common carriages, and also for cabi¬ net work. 4. ELASTIC CARRIAGE VARNISH (2).—Run 8 pounds of first quality gum copal, mix with 3 gallons of oil, boil for 4 hours until it strings, then, after cooling, add gallons of turps. Run 8 pounds of best gum animi, mix with 2 gallons of oil, and, after boiling until it strings, thin with 3| gallons of turps. Two pots of this running are mixed with one pot of the first running, and the whole is strained and allowed to mature. This varnish is much used as the finishing varnish for com¬ mon coaches, and for the under parts of superior coaches. It dries brilliant and is durable. It is rather quicker in drying than No. 1, taking about 10 hours in summer and 12 hours in winter. 5. ELASTIC CARRIAGE VARNISH (3).—Run 8 pounds of gum copal, mix with 2 gallons of oil, boil until it strings, then thin with 3^ gallons of turps. Run 8 pounds of gum animi, mix with 2 gallons of oil, boil as before, and thin with 3| gallons of turps. Mix one pot of this running with one pot of the previous running, strain, and finish in the usual way. As good a quality of gums is not used in making this varnish as the last, so 186 THE MANUFACTURE OF VARNISHES. that it is usually rather darker, although it is quite dur¬ able. It dries in about the same time. 6. ELASTIC HARD CARRIAGE VARNISH.— Run 8 pounds of gum copal, mix with 2 gallons of oil, add I pound of dried sugar of lead, and boil until stringy; thin with 3^ gallons of turps. Run 8 pounds of gum animi, mix with 2 gallons of oil, add ^ pound of dried copperas, and boil until it strings; thin with 3^ gallons of turps. Both runnings are mixed together and finished in the usual way. This varnish is used for the under coats in varnishing carriages; it dries hard in about 5 to 6 hours, and gives a smooth surface. 7. CARRIAGE VARNISH.—Run 8 pounds of sec¬ ond quality gum animi, mix with 2| gallons of oil, add I pound each of litharge, dried copperas, and dried sugar of lead, boil until it strings; then thin with 5^ gallons of turps, and finish in the usual way. This varnish is used for varnishing dark-colored carriages, the iron-work of coaches, and for ordinary cabinet work. It dries quickly in about 4 hours in summer and 5 hours in win¬ ter, with a hard and glossy surface. It is not so durable as the other varnishes described above, 8. PALE OAK VARNISH.—Eight pounds of gum copal are run and mixed with 3 gallons of oil; | pound each of dried copperas, dried sugar of lead, and litharge are added; the mixture well boiled and thinned with 5^ gallons of turps, and the varnish strained and finished in the usual way. This varnish is used for all kinds of best cabinet varnish; it dries in about 4 hours with a hard and durable surface. 9. OAK VARNISH.—Made in the same way as the last, but from a poorer quality of gums. 10. HARD CHURCH OAK VARNISH.—Run 8 pounds of gum kauri; mix with 3 gallons of oil; boil until it strings well; then, after cooling, thin with gallons THE MANUFACTURE OF VARNISHES. 187 • of turps. This varnish dries with a hard, glossy surface I in from 6 to 7 hours. It is not a durable varnish if used ; in positions where it is exposed to the weather, but for all interior work it stands well, and resists a great deal of wear and tear. 11. No. 2 HARD CHURCH OAK VARNISH.— This is made in the same way as the last; only poorer qualities of gums are used. 12. PALE COPAL VARNISH.—Carefully select 8 pounds of the palest gum copal; run well, and mix with 2 gallons of pale boiled oil; boil the whole until it strings, then allow to cool down a little, and thin with 5^ gallons of turps. Strain and finish as usual. When well made this varnish is very pale, and dries with a lustrous, dur¬ able coat, in from 8 to 10 hours. 13. JAPANNERS’ GOLD SIZE.—Run 10 pounds of gum animi and mix it with 2 gallons of hot oil; prepare two runs of this. In the set pot place 10 gallons of oil and boil it well for 2 hours; then add 7 pounds of red lead, 7 pounds of litharge, and 3 pounds of copperas; the addition of these driers is best made in small quan¬ tities at a time, the whole mass being kept boiling all the time; when all the driers have been added, the boiling should be continued for about 3 hours longer. Some¬ times the addition of the driers causes the boiling oil to froth up very much; in such cases it is best to reduce the fire somewhat, and to take some of the oil out of the pot, adding it again as the frothing subsides. When the oil has been boiled for 3 hours the two runs of gum are j added, and the boiling is continued for 5 hours, when it ? will begin to string; the boiling is continued until the I mass drops off the ladle or stirring rod in large drops, I and strings well. Then allow to cool, which will take 1 about 2 hours; pour in, in small quantities at a time, 30 I gallons of turps; as this is being poured in the whole * 188 THE MANUFACTURE OF VARNISHES. mass must be thoroughly stirred up, so as to get the turps and varnish well mixed; the mixing with the turps must not be done too quickly, or otherwise there is too great a liability to boil over; in fact, this applies to the rnixing of turps in making all these oil varnishes. This gold size will dry in about 10 minutes, if well made; al¬ though sometimes it may take 25 minutes to dry. 14. BLACK JAPAN (1).—This is made in a very similar manner to the gold size just described. Into the set pot put 6 gallons of linseed oil, boil it on a slow fire for 2 hours, then run in a gum pot 10 pounds of asphal- tum, and mix with 2 gallons of oil; when mixed, pour into the set pot; then run three more lots, pouring each one as it is run into the set pot; then add 7 pounds of red lead, 7 pounds of litharge, and 3 pounds of copperas, in small quantities at a time; keep the mixture boiling slowly for 4 hours longer; then allow.to stand till the next day, when it is boiled until a small quantity taken out on a glass will, when rubbed or rolled in the fingers, set hard; it is now allowed to cool, and when sufficiently cold, 30 gallons of turps are added. If after the japan has become cold it is found to be too stiff, then it* can be warmed up and more turps added until it attains the right consistency. This japan is used for all kinds of ironwork about carriages which are to be black; it dries with a hard, durable, lustrous coat in about 8 hours. 15. BLACK JAPAN (2).—A better quality of black japan which will dry harder and more glossy, is made as follows: Melt 48 pounds of asphaltum in the set pot, and, when melted, add 10 gallons of oil; run in the gum pot 8 pounds of common gum animi, and mix with it 2 gallons of oil; pour the mixture into the set pot; then run 10 pounds of common amber, and mi.x with 2 gal¬ lons of oil; this running is also added to the set pot, the .contents of which are boiled for 3 hours longer, during THE MANUFACTURE OF VARNISHES. 189 which time 7 pounds of red lead, 7 pounds of litharge, and 3 pounds of copperas are added, and the boiling continued until the mass sets between the fingers into a hard mass. Allow it to cool; then thin with 30 gallons of turps, as before. 16. BLACK VARNISH FOR CARRIAGE IRON¬ WORK.—Run 48 pounds of asphaltum in the set pot and add 10 gallons of boiled oil, 7 pounds of red lead, 7 pounds of litharge, and 3 pounds of copperas; run 8 pounds of copal, mix with 2 gallons of oil, and add to the set pot; boil the whole for 4 hours; place on one side till the next day, and then boil until it sets hard between the fingers; then, after cooling, thin with 30 gallons of turps. This dries hard, with a good surface, in about 3 hours. 17. BRUNSWICK BLACK (1).—This very useful black varnish is made in several ways. Run 45 pounds of asphaltum for 6 hours in a set pot. Boil 6 gallons of oil with 6 pounds of litharge until it strings well; pour into the set pot with the asphaltum, and boil the whole until it will set hard between the fingers; then allow to cool, and thin with 25 gallons of turps. This dries in about 4 hours, with a good surface, having a brilliant gloss. 18. BRUNSWICK BLACK (2).-^ A commoner Brunswick black is made as follows: Twenty-eight pounds of coal-tar pitch and 28 pounds of asphaltum are boiled together in the set pot for 6 hours; the mixture is allowed to stand all night, after which it is boiled up and 8 gallons of boiled oil are added; 10 pounds of litharge and 10 pounds of red lead are added, in small quantities at a time, and the mass boiled until it will set hard be¬ tween the fingers; it is then allowed to cool, and is mixed with 20 gallons of turps. This will dry in about 1 to 2 190 THE MANUFACTURE OF VARNISHES. hours, and is a good black varnish for all kinds of iron¬ work. 19. BLACK LEATHER VARNISH.—A very good black varnish is made by boiling 10 pounds of linseed oil with 4 pounds of litharge for about 5 hours, and then coloring with lamp-black. Other leather varnishes will be found described under spirit varnishes. 20. AMBER VARNISH.—Run 6 pounds of the palest amber, mix with 2 gallons of oil, and boil until it strings; then thin with 3^ gallons of turps. This forms one of the most durable varnishes known; it is much used for varnishing pictures. 21. COPAL PICTURE VARNISH.—Run 8 pounds of the very best and palest copal, mix with 3 gallons of oil, and boil until it strings well; then thin with 3 gallons of turps. When good materials are used, a pale, durable varnish is obtained. 22. OIL VARNISH.—Boil 6 gallons of linseed oil with 1 pound of sugar of lead for 5 hours. Other driers may be used instead of the sugar of lead, such as sulphate of zinc, borate of lead, and borate of manganese. Only a very small quantity of the last is required, or about 1 pound to 70 or 80 gallons of oil. 23. GOLD SIZE.—Run 8 pounds of gum copal, mix with 2 gallons of oil, boil until it begins i-o string, then add () gallons o.f boiling oil, and thin with turps to the required consistency. This does not dry as (juickly as japanners’ gold size, and, as its name indicates, is used for fastening gold leaf to glass and other objects. GENERAL CONSIDERATIONS.—The following general features concerning oil varnishes and their manufacture should be noted. An oil varnish should possess the following properties: 1st, good and free working; 2d, drying hard and rulibing freely; 3d, giv¬ ing an elastic coating not liable to crack or bloom, and THE MANUFACTURE OF VARNISHES. 191 which is resistant to the destructive action of the atmos¬ phere. It is difficult always to secure these features of a good varnish especially to combine the second and third, as hardness and elasticity are somewhat opposed to one another. In the preparation of these varnishes too much care cannot be exercised in carrying out the various opera¬ tions. The materials should be carefully selected; good varnish cannot be made from a poor quality of gum, and, no matter how good this may be, the use of a bad sample of oil will spoil any varnish made from it; the quality of the turpentine used also has some influence. In the sections referring to these materials will be found information as to the qualities required in good materials. The better the gum or resin is run, the larger will be the quantity of varnish obtained, and this will be stronger and better for working. The boiling of the oil and resin together must be well done; if not sufficiently boiled, the resulting varnish does not work freely, and is sometimes liable to bloom. This latter defect also occurs in var¬ nishes made from badly-run gums. The stringing or boiling should be done slowly, and at as low a heat as possible; if brought forward too quickly by the use of too much heat, then the resulting varnish is liable to be discolored. It takes more turps to thin it down, and the varnish neither works so freely under the brush, nor gives such a smooth, brilliant surface as a good oil var¬ nish should do. The more oil there is used in the com¬ position of a varnish, the more elastic and less liable to crack is the coat formed by the varnish. On the other hand, the drying is retarded by using too little oil. The more gum there is put into a varnish, the thicker, firmer, more quickly drying, and more brilliant when dry, is the coat formed; on the other hand, it is more liable to crack if there is too little gum. The varnishes made by the 192 THE MANUFACTURE OF VARNISHES. French method (which contain little oil) are rather liable to these defects of cracking because of the want of elas¬ ticity in the coat they form. Driers, especially copperas, when added to varnishes have a tendency to make the varnishes opaque, and to harden them. An oil varnish made with quick driers forms a coat which is hard, non-elastic, liable to crack and of short duration. The usual proportions of resins are,for body varnishes, about to pounds per gallon; for carriage and cabi¬ net varnishes, from 1 to Ij pounds per gallon; for gold size and japans, from ^ to f pound per gallon. If, after making and cooling, the varnishes are found to be too thick, they can be reduced to the required consistency by warming (so as to render them more fluid) and adding turps. Varnishes should be kept at least six months after making before they are used; this ageing causes a bet¬ ter amalgamation of the constituents of the varnish, in¬ creases the ease with which it works under the brush, and causes it to form a smoother and more lustrous coat. Lacquers and Varnishes. MANUFACTURE OF FAT COPAL VAR- NISFIES.—Violette, who has thoroughly studied the ac¬ tion of copal subjected to high temperatures, and its solu¬ bility, recommends the following process for the manu¬ facture of copal varnish: The copal is first heated to 680° Fahrenheit until it has lost 20 to 25 per cent of its weight, when a suitable mixture of linseed oil and oil of turpen¬ tine is dissolved in the melted copal at 212° Fahrenheit. The melting and distillation of copal is an operation which, as a definite temperature must be kept up, is very difficult to execute on a large scale. The following ap¬ paratuses have been tested and approved by Violette. THE MANUFACTURE OF VARNISHES. 193 The arrangement consists of a clay crucible about 8 inches in diameter and 12 inches deep, resting in a fur¬ nace. The crucible is heated to such a degree that zinc will just melt in it. The balloon is then brought into the crucible. It contains f pound of copal and is suspended from a balance, the right scale pan of which contains the tare of the balloon and the copal, while upon the left scale pan is placed a quarter of the weight of the copal. The vapors from the copal escape through the opening in the chimney. When 25 per cent of the copal has been distilled off, the beam of the balance assumes a horizon¬ tal position, and the balloon is lifted from the crucible, the distillation being finished. The melted copal is dis¬ tributed on the sides of the balloon by swinging the lat¬ ter, when it is allowed to cool off somewhat, and then 1 pint of oil of turpentine and 5 ounces of linseed oil are added. A cast-iron block weighing about 300 pounds, which can be easily kept at a definite temperature, is used. It is heated to 750° Fahrenheit, and then a little box containing If ounces of copal, is placed in the hollow space. A moderate fire is kept up to prevent the block from becoming cool. The vapors evolved from the copal escape from the space closed with the cover through a pipe, are condensed by the cooling apparatus, and col¬ lected as a yellow, clear fluid in a conveniently situated vessel. The operation is interrupted as soon as a quan¬ tity corresponding to the fourth part of the copal has been collected, when the box is taken from the cavity in the block and the copal poured out. Another modification of the distilling apparatus is represented by a copper sphere, silvered inside, and hav¬ ing a diameter about 20 inches, which can be turned by means of a handwheel around a horizontal shaft. After 194 THE MANUFACTURE OF VARNISHES. 10 pounds of copal have been placed in the globe and the opening closed, a moderate fire is started and the globe slowly turned. Varnish prepared in this manner is soluble in ether. Violette recommends the following proportions for copal: One pound of copal and 2 pounds of sulphuric ether. The resin is powdered, placed in the flask, and the ether gradually added with vigorous shaking, and the flask hermetically closed. Solution takes place readily. The varnish thus prepared is cleared by allowing it to stand, and before using it, filtered through paper or linen. SPIRIT LACQUERS are especially adapted for polishing fine woods and coating maps, book-covers, etc. The only objectionable point in using them for metal is that they do not adhere tightly. This can be remedied by using crystallized boracic acid, ^ part of which is dis¬ solved in 1,000 parts of the respective lacquer. When this is applied to a bright metal surface it forms a hard, glassy coating which cannot be scratched off with the finger-nail. IRON LACQUERS are all prepared in a very simple manner by melting pitch with various products of the dis¬ tillation of tar. The pitch is melted, with an addition of the oil, in an open iron boiler heated from the outside. The oil accelerates the melting of the pitch and prevents it from congealing too rapidly. After the pitch has become liquid it is advisable to al¬ low it to cool somewhat before adding the oil, to prevent the latter from boiling. Add the oil gradually, and stir each portion thoroughly into the pitch before adding the next. To see whether the varnish has the right con¬ sistency take occasionally a sample from the boiler, al¬ lowing it to cool. An exact statement as to the quantity of oil to be used cannot be given, since the consistency of tHE MANUEacTUrE of VaRNISHES. 195 the varnish depends on the purpose for which it is to be used, and the demands of the consumer. CLARIFYING VARNISH.—A method of clarifying varnishes and other liquids and removing impurities in 48 hours is as follows: Mix with every 10 gallons of var¬ nish 8 ounces each of powdered marble-dust and burnt oyster-shells. All the impurities in the varnish will be attracted by and adhere to the oyster-shell dust, and the weight of the marble-dust mixed therewith precipitates every floating particle to the bottom of the vessel con¬ taining the varnish. This process may also be applied to the clarification of turpentine, oils and molasses. FILTERING VARNISHES.—The apparatus pre¬ vents a loss of solvent, as spirit of wine, benzole, etc., by evaporation. It consists of a large flask, either of glass or tin, closed by a doubly perforated stopper. In one of the holes is placed the neck of the glass funnel, the upper rim of which is ground smooth, and the other is fitted with a glass tube, bent at a right angle. A thick wooden cover, with a ring of rubber on the lower side, is placed upon the funnel, closing it air-tight. In the centre of the lid is fitted a glass tube, also bent at a right angle, and connected with another tube by a rubber hose. Either filtering paper or fine cotton is used as a filtering sub¬ stance, of which a plug is formed in the lower part of the cone of the funnel, and lightly pressed into the tube of the funnel. The air in the bottle is displaced by the fluid dropping into it, and escapes into the funnel, where it absorbs the vapor of the fluid, but absorbs nothing after it is once saturated. While evaporation goes on con¬ stantly when an open funnel is used, it is entirely checked by using this apparatus. When it is observed that the pores of the filter become very much choked up, the contents of the filter are allowed to run off and the fil¬ tering material is changed. 196 THE MANUFACTURE OF VARNISHES. SPIRIT GOLD-LAC VARNISHES.—L Pulverize 66 parts of shellac and 133 parts of gamboge. Rub up the powder with 8 parts of dried saffron, and dissolve the whole in 266 parts of alcohol in a flask tied up with a piece of perforated bladder, by placing it in a water bath, II. Treat the following ingredients in the same man¬ ner as above: Thirty-three parts of shellac, 16 parts of dragon’s blood, a like quantity of turmeric, and 8 parts of gamboge dissolved in 200 to 266 parts of alcohol. III. Thirty-three parts of shellac, 4 parts of dragon’s blood, and 2 parts of saffron, are digested in 800 to 1,200 parts of alcohol for 8 days in the sun, and then filtered. GOLD-LAC VARNISH WITH SHELLAC AND OTHER RESINS.—1. Mix 133 parts of seed lac, a like quantity of sandarac, 66 parts of turpentine, 16 parts of dragon’s blood, and 2 parts each of gamboge and tur¬ meric, with 133 to 166 parts of pulverized glass, and digest the whole in 1,600 parts of alcohol. H. Pour 500 to 600 parts of alcohol over 30 parts of seed lac, 60 parts of sandarac, a like quantity of elemi, 30 parts of dragon’s blood, 20 parts each of turmeric and gamboge, 1 part of saffron, and 60 to 100 parts of pul¬ verized glass. HI. Take 133 parts of shellac, 50 parts of sandarac, 33 parts of mastic, in grains, 100 parts of yellow resin, 33 parts each of yellow amber and dragon’s blood, 24 parts each of-gamboge and turmeric, and, if a deeper color is desired, 30 parts of aloes, and pour 2,000 parts of alcohol over the whole. GOLD VARNISH WITHOUT LAC.—Dissolve 33 parts of copal, 16 parts of white boiled turpentine, and 4 of camphor in alcohol. Then prepare a solution of 33 parts of sandarac, 16 parts of mastic, 8 parts of dragon’s blood, 16 parts of gamboge, 8 parts of annotto, and 4 ROBERT GAN2. Or. J. fct. sENNER. THE Nalional Prayisioier Palilisliii Coiaay, ROBERT GANZ & CO., Proprietors. NEW YORK : CHICAGO ; 384-386 PEARE STREET, No. 11 RIAETO BUIEDING, Cor. of Beckman. Adjoining Board of Trade. The national PROVISIONER, THE ORGAN OF THE Provision and Meat Industries OF THE UNITED STATES AND CANADA. Chicago, New York, 'Roston, Philadelphia, Cincinnati, Kansas City, St. Eouis, Eondon, England. PUBLISHED EVERY SATURDAY. SUBSCRIPTION PRICE; In the United States and Canada, - - $4.00 Per Annum. In Foreign Countries, . _ . _ _ $5.00 Per Annum. (Postage Prepaid.) PUBLISHERS OF THE Pork Packers’ Handbook and Directory OF THE MEAT AND PROVISION TRADES. 440 Pages. Price, $10.(X). The Manufacture of Cottonseed Oil AND ALLIED PRODUCTS. 95 Pages. Price, $3.00. XIII. 198 THE MANUEACTURE OF VARNtSkES. parts aloes in spirit of wine, and mix the two solutions together. GOLD-LAC VARNISHES WITH OIL OF TUR¬ PENTINE AND OIL OF LAVENDER (from Lavan¬ dula spica).—1. Without Linseed Oil Varnish. Boil 66 parts of mastic, a like quantity of sandarac, and 4 parts of turpentine, with 100 parts of oil of lavender over a coal fire; then add 33 parts of aloes and some resin, and heat the whole until a small feather dipped into the mixture ignites. H. With an Addition of Linseed Oil Varnish. 1. Dissolve, with the aid of a water-bath, 16 parts of amber, 33 parts of shellac, 16 parts of sandarac, 33 parts of aloes, 4 parts of gamboge, and 2 parts of dragon’s blood, in 266 parts of oil of turpentine, and then add a few drops of strong linseed-oil varnish. 2. Pulverize 266 parts of amber and 66 parts of stick lac. Dissolve the powder in 266 parts of hot linseed-oil varnish and 400 to 533 parts of hot oil of turpentine, pre¬ viously colored with 66 parts each of gamboge, dragon’s blood and annotto, and 16 parts of saffron. 3. Mix 133 parts of stick lac, a like quantity of sanda¬ rac, 16 parts of dragon’s blood, 2 parts of gamboge, and 166 parts of pulverized glass, and digest the mixture in 500 parts each of oil of turpentine and linseed-oil varnish. All the foregoing recipes have been tested and can be highly recommended. WALTON’S PROCESS OF PREPARING LIN¬ SEED-OIL VARNISH consists mainly in exposing the linseed oil to the action of air, whereby it is converted into a resinous mass, which, dissolved in wood spirit or alcohol, furnishes a quickly drying varnish. Clear lin¬ seed oil is mixed with a siccative, 5 to 10 per cent of ace¬ tate of lead being the most suitable. The mixture is then passed through a tube in which the oil is conveyed by THE MANUFACTURE OF VARNISHES. 199 means of a force pump into the reservoir provided with a perforated bottom. The oil passes down through this bottom, and falls in jets or drops through the column, whereby it comes in contact with air forced in by means of a blower. Two sides of the column are constructed of glass to allow the entrance of light, which exerts also a bleaching effect upon the oil. The object is to distribute the air in the apparatus over the hollow column, while the other is to allow the air to pass out and to retain par¬ ticles of oil. The current of air need not be very strong, but a constant renewal of the air in the apparatus is ab¬ solutely required. The oil falls into the reservoir be¬ neath which is a space heated from 212° to 300° Fahren¬ heit by the introduction of steam; the higher the tem¬ perature the quicker will be the conversion of the oil; there is a pipe through which the oil is re-conveyed to the pump, by which it is again forced into the reservoir, drops down through, and so on until it has become suffi¬ ciently changed. On the upper end is a small cylinder containing a valve, which is connected with a lever loaded in proportion to the pressure which is to be exerted in the reservoir. The rod is connected in such a manner with a cock on the pipe that, when the valve rises too high, in consequence of too strong a pressure, communi¬ cation between the pump and the reservoir is interrupted. SEVERAL UNIVERSAL FURNITURE VAR¬ NISHES.—I. Dissolve 240 parts of sandarac,^60 parts of seed lac, and 120 parts of resin in 1,500 parts of spirit of wine, and compound the solution with 180 parts of Venetian turpentine. II. Compound 180 parts of naphtha with 30 parts of virgin wax. Apply the varnish warm and polish with a woolen rag. III. Boil 500 parts of white wax in a solution of 750 parts of potash in warm water for ^ hour, and, when the 200 THE MANUFACTURE OF VARNISHES. lye has become cold, skim off the wax which floats on the surface. Apply the wax to the furniture, and by rubbing it an hour afterwards with a woolen cloth, a beautiful lustre will be the result. IV. Melt 120 parts of yellow wax and a little pulver¬ ized resin, and compound this with 60 parts of warm oil of turpentine or spirits of turpentine. Rub the furniture with this by means of a woolen rag, which will give it a beautiful lustre. BALLOON VARNISH.—Cut up 500 parts of caoutchouc, and let it digest in 3,000 parts of oil of tur¬ pentine for 7 days, putting the vessel in a warm place; then heat the mixture in a water-bath until it is entirely homogeneous, add 2,000 parts of warm drying oil pre¬ viously boiled, mix intimately, and strain the compound as soon as it is cold. The above recipes have been tested, and can be highly recommended. COPAL VARNISH WITH SPIRIT OF SAL-AM¬ MONIAC.—Convert copal into a coarse powder and gradually pour spirit of sal-ammoniac over it until the whole is swelled up to a thick, transparent mass. Heat this to 100° Fahrenheit, then mix it gradually with alco¬ hol, 75 to 80 per cent strong; shake it thoroughly, and finally add more alcohol to give the mixture the requisite consistency. CHINESE VARNISH.—Dissolve 60 parts of shellac and a piece of camphor the size of a hazel-nut in 1,000 parts of spirit of wine, by placing the vessel containing it in the sun or in hot ashes for 24 hours, shaking the bottle from time to time; then strain the fluid. Let the varnish stand quietly for 24 hours, and then pour it off carefully from the sediment; the latter may be used for the first coat. INCOMBUSTIBLE VARNISH FOR WOOD.— An application of a solution of equal parts of alum and THE MANUFACTURE OF VARNISHES. 201 isinglass to the place exposed to the flame prevents igni¬ tion, but not the transmission of heat. By coating a wooden vessel with this varnish, fluids may be boiled in them over an ordinary fire. VARNISH FOR WOOD NOT ACTED UPON BY BOILING WATER.—Boil in an untinned copper boiler 750 parts of linseed oil. Suspend in this, in a bag, which must not touch the bottom, 150 parts of lith¬ arge and 90 parts of pulverized minium. Let the oil boil until it has assumed a dark-brown color; then remove the bag, and replace it by one containing 7 to 8 bulbs of garlic. Now melt 500 parts of pulverized amber in 60 parts of linseed oil over a strong fire, add it while boiling to the prepared linseed oil and let it boil for 2 or 3 min¬ utes longer, stirring it vigorously. Then take it from the fire, allow it to settle, pour off the clear liquid, and, when cold, put it in bottles, which should be hermetically. closed. To use this varnish, polish the wood first and give it the desired color; for instance, nut-brown, by laying on a thin coat of a mixture of lampblack and oil of turpen¬ tine. When the stain is dry, apply four coats of the var¬ nish with a fine sponge, allowing one coat to dry before laying on the next. VARNISH FOR EARTHEN-WARE VESSELS.— Mix equal parts of pulverized glass and soda; dry the mixture over a strong fire, and spread it upon the surface of the burnt vessels while they are still hot. JAPANESE TRANSPARENT LAC VARNISH.— Dissolve 30 parts of copal ajad 2 parts of camphor in 120 parts of oil of turpentine and 30 parts of oil of lavender. JAPANESE BLACK LAC VARNISH.—1. Take 120 parts of burnt umber, 60 parts of genuine asphaltum, and 3,000 parts of boiled oil. Dissolve the asphaltum in a small portion of the oil with the aid of heat, then add 202 THE MANUFACTURE OF VARNISHES. the umber, previously rubbed up with oil, and, finally, the remaining oil; mix the whole thoroughly, allow it to cool, and thin with oil of turpentine. This varnish is very elastic. II. Dissolve 1 part of shellac in 4 of wood spirit, and color with lampblack. VARNISH FOR FANS, FANCY BOXES, ETC.— Dissolve 60 parts of mastic and 240 parts of sandarac in 1,500 parts of spirit of wine, and compound the solu¬ tion with 120 parts of Venetian turpentine. VARNISH FOR UMBRELLAS.—Boil 2 parts of turpentine and 1 of pulverized litharge in 2 to 3 of lin¬ seed oil. This varnish is applied with a brush and dried in the sun. BLACK VARNISH FOR TINSMITHS.—Mix fine lampblack or Frankford black with a solution of shellac, or with a solution of 1 part of asphaltum in 3 of oil of tur¬ pentine, and then add some linseed oil and minium. GOLD VARNISH ON IRON.—Boil in an earthen¬ ware pot 90 parts or more of linseed oil, 60 parts of tar¬ tar, 60 parts of hard-boiled yelk of egg, 15 parts of aloes, ^ part of saffron and 1-10 part of turmeric, and apply the fluid to the iron. PITCH VARNISH FOR BUILDINGS. — One pound of linseed oil, 150 parts of pitch, and 120 parts of litharge are boiled over a coal fire and stirred until they are intimately mixed. Apply one, or, if. necessary, sev¬ eral coats of this varnish to the weather side of the build¬ ings, which will render them impervious to moisture. The above quantities suffice to give 4 coats^ to 18 square feet of surface. Shingle roofs coated with this varnish last at least twice as long as ordinary. SPIRIT VARNISH FOR VIOLINS AND OTHER MUSICAL INSTRUMENTS.—Dissolve over a moder¬ ate fire 120 parts of sandarac, 60 parts of shellac, a like THE MANUFACTURE OF VARNISHES. 203 quantity of mastic, and 30 parts of elemi, in 1,500 parts of highly rectified spirit of wine, and after the solution has boiled up several times, add 60 parts of Venetian turpentine. BLACK VARNISH FOR ZINC.—Equal parts of chlorate of potassium and blue vitriol are dissolved in 36 times as much warm water, and the solution allowed to cool. If the sulphate of copper used contains iron, it is precipitated as a hydrated oxide and can be removed by decantation or filtration. The zinc castings are then im¬ mersed for a few seconds in the solution until quite black, rinsed off with water, and dried. Even before it is dry the black coating adheres to the article so that it may be wiped dry with a cloth. If copper-colored spots appear during the operation, the solution is applied to them a second time, and after awhile they turn black, when the article is washed and dried. On rubbing, the coating ac¬ quires a glittering appearance like indigo, which disap¬ pears on applying a few drops of linseed-oil varnish or “wax-milk,” and the zinc then has a deep-black color and gloss. The “wax-milk” is prepared by boiling 1 part of yellow soap and 5 of Japanese wax in 21 of water until the soap dissolves. When cold, it has the consist¬ ency of a salve, and will keep in closed vessels for an in¬ definite time. It can be used for polishing carved wood and for waxing ball-room floors, as it is cheaper than the solution of wax in turpentine, and does not stick or smell disagreeably like the latter. PARISIAN WOOD VARNISH.—This celebrated varnish is prepared by dissolving 1 part of shellac in 3 or 4 of alcohol of '92 per cent, on the water-bath, and cautiously adding distilled water until a curdy mass separates, which is collected and wrapped in linen. The liquid is filtered through paper, all the alcohol removed by distillation from the water-bath, and the resin re- 204 THE MANUFACTURE OF VARNISHES. moved and dried at 212° Fahrenheit untif it ceases to lose weight. It is then dissolved in double its weight of alcohol, of at least 96 to 98 per cent, and the solution perfumed with lavender oil. FURNITURE VARNISH.—Heat gently, with con¬ stant stirring, 8 parts of white wax, 2 of resin, and ^ of Venetian turpentine; pour the mixture into a glazed stone pot and add, while it is yet warm, 3,500 parts of rectified oil of turpentine. After standing for 24 hours the mass forms a soft, buttery substance, and is ready for use. The articles to be varnished must be carefully cleansed with soap and water, and then dried before ap¬ plying the varnish. The polish obtained is not quite as brilliant as that obtained by shellac varnish, but has a peculiar chaste appearance. TO LACQUER FLOWERS.—Pulverize 40 parts of sandarac, 15 parts of mastic, and 2 parts of camphor, and put the powder into a long-necked flask; then pour 1,000 parts of rectified spirit of wine over it, and place the flask in a moderately warm place, shaking it at first frequently, and then allowing it to stand quietly so that the fluid may settle. Flowers, plants, and herbs may be coated with this varnish. Flowers retain not only their beau¬ tiful colors, but are also protected against the ravages of insects. This varnish is also adapted for coating maps, playing-cards, copper prints, and pictures. WHITE UNCHANGEABLE LACQUER FOR LEATHER.—Artificially prepared carbonate of baryta is rubbed up with very light linseed-oil varnish, and the compound applied to the leather. On this is laid a coat prepared from carbonate of baryta and white copal var¬ nish, When dry, the lacquer is pumiced with elutriated pumice-stone and a piece of felt, and then polished with elutriated bone-ash. The white color of this lacquer THE MANUFACTURE OF VARNISHES. 205 is not changed in the least by sulphuretted or other ex¬ halations, which, as is well known, darken white lead. TO POLISH CARVED WOOD.—Dissolve 1 part of seed lac and 1 of transparent resin in 9 of spirit of wine. This polish must be applied warm, and the article to be polished must be heated if possible. A beautiful French polish is obtained by using the fol¬ lowing ingredients: 700 parts spirit of wine, 15 parts of copal, 7 parts of gum-arabic, and 30 parts of shellac. The resins are first pulverized and bolted through a piece of muslin. The powder is placed in a flask, the spirit of wine poured over it, and the flask corked. By putting the flask in a moderately warm place, the solution will be accomplished in two or three days. It is then strained through a piece of muslin and kept in hermetically closed bottles. This polish gives a beautiful appearance to the carvings, and a gloss and richness of color which cannot be obtained by any other means. It is especially adapted for polishing fine furniture, dnd for this purpose is to be preferred to all other polishes. To give to articles polished with this lacquer the finest finish possible, the following preparation is used: Put 8 parts of shellac and a like quantity of benzoin, and 350 parts of rectified spirit of wine into a flask, keep this in a warm place until all the gum is dissolved, and shake it vigorously. To the cold solution add a small portion of the best poppy-seed oil, which should be as clear as water; mix all intimately together and keep it for use. PARISIAN BRONZE LACQUER.—Dissolve 1 part of shellac in 8 to 10 of alcohol, and add to the solution ^ part of camphor, rubbed up with a few drops of lavender oil. BLACK POLISH ON IRON AND STEEL.—A beautiful black polish is obtained by boiling 1 part of sul¬ phur with 10 of oil of turpentine, but it has a disagreeable 20(5 THE MANUFACTURE OF VARNISHES. odor. A coat as thin as possible is laid on the article to be polished, which is then held over the flame of an alco¬ hol lamp until the black polish makes its appearance. A NEW VARNISH (patented in Germany), which serves as a substitute for linseed oil or oil of turpentine, is prepared in the following manner: 100 parts of resin free from oil of turpentine, 20 of crystallized soda, and 50 of water are heated together, and then intimately mixed with 250 parts of water, containing 24 of aqua ammonia. The coloring substances are rubbed up with this prepara¬ tion without an addition of linseed oil, or oil of turpen¬ tine; they , dry easily without a siccative, and can be coated with lacc|uer. This varnish becomes very hard; resists the action of water and atmospheric influences, and is about one-third cheaper than ordinary varnish. PARISIAN BOOKBINDERS’ LACQUER.—Dis¬ solve on the water-bath 360 parts of shellac and 2 parts each of camphor and loaf sugar in 3,000 parts of alcohol of 66 per cent. Eilter the solution through blotting- paper; distill off one-half of the alcohol, and add to the residue, while yet warm, a trace of oil of cinnamon. EXCELLENT GLASS-LIKE VARNISH.—Dis¬ solve, at a moderate heat, 4 parts of camphor, 60 parts of sandarac, 15 parts each of Venetian turpentine and oil of turpentine, and 4 parts of white sugar, in 400 parts of spirit of wine of 96 per cent, and clarify the solution by allowing it to stand for some time. In using the varnish expose the article to be coated to a gentle heat, and then apply the solution, which, when it becomes dry, will form a beautiful, glass-like coat. VARNISH EOR WOOD NATURALLY COL¬ ORED OR STAINED.—Pulverize and dissolve 3 parts of light-colored shellac, 2 of sandarac, 2 of white resin, and I of camphor, in 24 of alcohol of 80 per cent. Put, first, the shellac, sandarac, and camphor in the alcohol, THE MANUFACTURE OF VARNISHES. 207 tie up the vessel with a piece of wet bladder and shake it for half an hour; then add the resin, and let the mix¬ ture boil up several times in a suitable vessel. Filter the ready varnish, while yet warm, throug^h cotton or felt, and to clarify it, let it stand for 12 hours in a well-closed bottle. No more varnish than is to be used in two or three days should be prepared at one time, since age im¬ pairs its beauty and hardness. COLORLESS VARNISH.—Boil 500 parts of linseed oil with 1,000 parts of water for two hours; then add 60 parts of silver litharge, 45 of sugar lead, one onion, and a small piece of pumice-stone, and then heat the mix¬ ture for some time longer. FRENCH LEATHER LACQUER.—Boil 15 parts of logwood shavings in 120 of ordinary water until but half the quantity'remains; dissolve in this 2 parts of sugar and 12 of gum arabic and compound the mixture with a solution of ferric sulphate until the previously brown-red color of the decoction has changed into a violet-blue tint, and finally add some spirit of wine. CHEAP LACQUER FOR HARNESSES AND CARRIAGE TOPS.—Soak 2 parts of glue and then liquefy it over a moderate fire. Then dissolve 3 parts of ordinary soap over a moderate fire, and add this to the solution of glue. About 120 parts of water are used for dissolving both ingredients. After the two solutions have been intimately mixed, add 3 to 4 parts of spirit var¬ nish, and finally stir into the mixture 2 parts of good wheat starch, previously triturated with some water. Now place the pot containing the mixture over a moder¬ ate coal fire, and let it evaporate, although it may also be used before evaporation. The evaporated mass, when to be used, is liquefied by adding beer or water. The thin¬ ner the coat the more beautiful will be the gloss. 208 THE MANUFACTURE OF VARNISHES. LACQUER FOR DRAWINGS.—Dissolve 30 to 40 parts of dammar in 180 parts of acetone and then mix 40 parts of this solution with 30 parts of thickly-fluid collodion. TRANSPARENT LACQUER FOR CLOSING BOTTLES.—A process of closing bottles, which is more elegant and effectual than with tinfoil, has recently been introduced in France. The neck of the bottle is dipped into a tenacious mass and quickly withdrawn with a rotary motion. It is in this manner covered with a trans¬ parent mass, which can be given a still more beautiful ap¬ pearance by placing the monogram of the firm, or other label, on the neck of the bottle or on the cork. The pre¬ paration consists of 20 parts of resin, 40 of ether, 60 of collodion, and any desired coloring matter. TAR VARNISH.—Tar is intimately mixed with equal parts of hydraulic lime and Roman or Portland cement, by heating the ingredients to 158° Fahrenheit. The mix¬ ture remains thinly fluid and when dry, soft and flexible. This varnish is not acted upon by acids, and protects the wood from rotting. It is especially adapted for wood under water, shingles, and water-pipes. POLISHING OF WOOD.—The former practice of pumicing furniture with oil is now supplanted by Ross- bach’s patent (now expired), of pumicing dry and coat¬ ing with a mixture of 285 parts of copal, 57 of oil of tur¬ pentine, 628 of infusorial earth, and 28 of umber, prin¬ cipally used for walnut and chestnut; for rosewood, car¬ mine is used in place of umber; for oak, ochre, etc. A solution of 3 parts of shellac, 2 of copal, and ^ of oil of rosemary in 10 of alcohol is used as a ground lacquer. ELASTIC LACQUER.—Slake 15 parts of lime with 20 parts of water, and add, while the lime is yet warm, 50 parts of the melted crude caoutchouc. When cold. the MANUTACTURE of VARNtSHES. 209 the lacquer is in the form of a paste. It is best applied warm. black harness lacquer.—D issolve 40 parts of best shellac, 10 parts of sandarac, and 5 parts of mastic in 500 parts of spirit of wine. To prevent the lacquer from becoming brittle, add to the solution 20 to 30 parts of pure Venetian turpentine, and finally sufficient aniline- black (nigrosine), dissolved in water or spirit of wine. PARCHMENT ELUID is prepared from gutta¬ percha soaked and swelled up in ether. It is used for coating pictures, maps, etc. The coat, if stained or soiled, can be washed with a moist sponge. Crayon and char¬ coal drawings can be fixed by coating them with this lac¬ quer. TO PROVIDE BARS OE SPRING STEEL WITH A COATING NOT ACTED UPON BY ACIDS, AL¬ KALIES, CHLORINE, AND STEAM.—The bars are first coated with copal or asphaltum lacquer and dried at a high temperature. They are then wrapped in several layers of strongly-pressed . paper, impregnated with chromium glue, and subjected to a very strong pressure, and finally receive a coat of the following compound: Fifty parts of China clay, 10 of shellac, 8 of sandarac, 3 of elemi, 2 of gun-cotton, 0.5 of camphor, and 5 of oil of lavender (from Lavandula spica), dissolved in 100 parts of alcohol. When half dry,'the bars are again subjected to pressure, and when entirely dry, ground. ALUMINIUM PALMITATE AND ITS USES IN DIFFERENT BRANCHES OF INDUSTRY.— Aluminium palmitate, a combination of alumina and palmitic acid, is a resinous substance of remarkable pro¬ perties, making it useful for many purposes. It melts at a higher temperature than dammar and copal resin, and is easily soluble in oil of turpentine and benzene. A so¬ lution of 1 part of it in 5 of a solvent retains a lacquer- 210 tHE MANUFACTtrftE OF VAftNISHES. like, thickly-fluid consistency. The lacquer obtained in this manner does not soak through paper, never becomes brittle, but remains flexible and dries quickly. It has a beautiful silky gloss, bears an addition of any amount of dammar and copal, obtaining thereby greater gloss and depriving the latter two resins of their brittleness. Alum¬ inium palmitate will, without doubt, be of great import¬ ance in the manufacture of wall paper, lacquers, artificial leather, water-proof substances, etc. Lacquer prepared from it will be of great value in manufacturing gold wall papers, and for coating genuine and imitation leather hangings, giving to the latter the characteristic gloss of stamped leather, and preserving it in the first. It fur¬ nishes also an excellent vegetable glue which does not spoil; is, and remains, entirely neutral, and consequently exerts no injurious influence upon the shades of the colors. This makes it especially useful in the manufacture of velvet wall paper. If used as a sizing on cotton fabrics, it imparts to them a silky gloss, which does not entirely disappear even after frequent washings. This sizing, on account of its neutrality and entire indifference, can be used for fabrics printed with the most critical colors with¬ out injuring them in the least. Palmitate lacquer is not acted upon by water, and can, therefore, as it remains perfectly flexible, be advantageously used in the manu¬ facture of artificial leather, rubber tissues, and water¬ proof fabrics, its property of being inodorous when dry deserving special commendation. NEW METHOD OF PREPARING FAT. LAC¬ QUER AND VARNISH, PATENTED IN GER¬ MANY BY ZIMMERMANN & HOLTSWICH.— The resins are melted by a current of air heated above the melting point of the resins and circulating in the melting apparatus. The products escaping in melting are collected in a cooled and closed receiver. The warm •tme manufacture of varnishes. ^11 current of air, after it leaves the melting apparatus, serves to convert the linseed oil into varnish. The addition of litharge is saved by the use of lead vessels or lining them with sheet lead. The linseed oil flows slowly down in an apparatus through several boxes placed above each other, from whence it reaches a reservoir (a kind of montejus), is pumped up by compressed air into another vessel, and flows from this again through the boxes; the operation being repeated until it is converted into var¬ nish. With this apparatus, a light-colored, fine varnish, of excellent consistency, equal to the best English var¬ nish, is prepared in about one-quarter of the time used in the ordinary process. LIGHT COPAL VARNISH WITH COAL-TAR VARNISH OIL.—Light copal 2 parts, light resin 1, sandarac and Venetian turpentine each -J, varnish oil 10. Pulverize and melt together the copal and resin, then add the sandarac, and finally the turpentine; stir until all are dissolved; let it cool somewhat and then add the varnish oil, first in small portions and finally the remainder. Fil¬ ter the varnish through cotton. LIGHT PARISIAN VARNISH WITH COAL- TAR VARNISH OIL.—Light sandarac 3 parts, light resin and mastic each 1, Venetian turpentine cam¬ phor and oil of lavender each 1-10, varnish oil 12, abso¬ lute alcohol 2. jMelt the sandarac, resin and mastic to¬ gether, and then add the turpentine. Dissolve the cam¬ phor and oil of lavender in the absolute alcohol, and add finally to the varnish. LIGHT VARNISH FOR LACQUERING PHO¬ TOGRAPHIC NEGATIVES.—Dammar 1 part, mas¬ tic sandarac chloroform and varnish oil each 10. Pulverize the resin, pour the chloroform over them, then add the varnish oil, and digest the whole in a sand-bath until all are dissolved. Filter the varnish through clean 212 THfi MANUFACTURE OF VARNISHES. cotton and keep it in well-closed bottles. It dries very easily. ENGLISH METHOD OE VARNISHING COACHES.—The superiority of English work is largely due to the fact that though the same materials are used, more care is exercised in preparing the varnishes, and greater attention paid to preparing the woodwork for the reception of the varnish. PUMICING.—Grind a smooth face on a piece of pumice-stone, then sift some pulverized pumice-stone through a hair sieve, and dipping the ground face of the stone into this powder, pumice the panels of the coach; then cleanse thoroughly with a brush and finish them with a cloth. PUTTYING.—Before laying on the ground color, all holes, cracks, and indentations must be puttied up. The putty used is prepared by mixing white lead, red lead, umber and a little silver litharge with thick boiled linseed oil varnish, and adding a little amber varnish. Press the putty into the holes and cracks by means of a wooden spatula. When the putty is dry, dip a piece of pumice- stone in water and grind the puttied places down so that they become even with the panels. SATURATING THE PANELS WITH OIL.—For this purpose a mixture of equal parts of linseed oil and linseed-oil varnish is used. Pour both into a pot, mix thoroughly, make the mixture boiling hot, and then satu¬ rate the panels. When the first coat is thoroughly soaked in, repeat the operation, and then allow it to dry thor¬ oughly. LAYING ON THE GROUND.—The ground color is prepared by rubbing 1,500 parts of white lead, 6G parts of red lead, 16 parts of litharge, and 83 parts of burnt umber with oil of turpentine, and diluting it with amber lac varnish. Do not lay on the ground color too thick THE MANUFACTURE OF VARNISHES. 213 at one time, but apply several thin coats. Care should also be had that the color shows no lustre; should this be the case, add some oil of turpentine. PUMICING THE GROUND.—Moisten two pieces of pumice-stone with water, and rub them against each other until they have a smooth surface; use one of them for pumicing, dipping it frequently in water. The pumic¬ ing must be done in a circular direction, so that no place remains untouched. The color adhering to the pumice- stone is removed by rubbing with the other piece after both have been dipped in water. While pumicing wash the panels frequently, with a large, wet sponge, and finally dry them with a white linen cloth. LAYING ON THE PAINT.—Proceed in the same manner as for ground, with the exception that, if the color is light, pale amber lac varnish must be used. FIRST PUMICING OF THE PAINT.—Pulver¬ ize some pumice-stone and pass the powder through a hair sieve. Roll a piece of well-fulled felt and tie it to prevent its unrolling during pumicing. Then, with the felt moistened with water, and dipped into the sifted pumice-stone powder, pumice the paint as smooth as possible, rubbing always with a circular motion. SECOND PUMIcInG OF THE PAINT.—Calcine pumice-stone by placing it on a coal fire, then rub it to a fine powder with water upon a stone, and allow it to dry. Then rub it very fine once more, and with a piece of felt, but not rolled together as before, moistened and dipped into the powder, rub in every direction until a glossy surface results. THIRD PUMICING OF THE PAINT.—For this purpose white prepared buck’s horn is used. The work is done with a piece of felt moistened and dipped in in the same manner as for the second pumicing. The paint is then cleansed by washing with a sponge and water. 214 THE MANUFACTURE OF VARNISHES. dried with a soft linen cloth, and finally rubbed with a piece of chamois, until the paint has a mirror-like lustre. LAYING ON THE LAC VARNISH.—In doing this the following rules must be observed. 1. Use only the best brushes, and apply the lacquer in long perpendicular strokes, taking care that the coat is everywhere of equal thickness. 2. The lacquer must be applied cold, and the second coat only laid on after the first is thoroughly dry. 3. Lacquering should only be done in a room pro¬ tected from dust and. vermin; when the lacquer is no longer sticky the carriage may be brought into the air. 4. When the carriage has been placed in the sun, it must be frequently turned, so that the sun does not beat too steadily against one place. 5. The lacquer should be contained in a wide-mouthed vessel so that the brush can be dipped into it without hindrance. Do not take too much of it on the brush; after dipping it in, turn the brush several times, and strike it against the side of the vessel. 6. Prepare your own lacquer, for which several tested recipes will be found below, or buy it only from a well- known firm. POLISHING THE LACQUER.—Use a piece of very soft, clean felt. Dip it first in a little olive oil, and 4hen in prepared white buck’s horn, and rub the lacquer until it has a lustre equal to a ground mirror-plate; and iinally rub it with a soft linen or silk cloth dipped in fine .-starch flour. ORDINARY BODY CARRIAGE LACQUER.— .Boil for four hours 2 parts of the best African copal, 7 parts of clarified linseed oil, and 8 parts of turpentine. Mix thoroughly and strain. On the other hand, boil as usual 2 parts of the best gum anime, 5 parts of clarified linseed oil, and 7 parts of turpentine. Strain while hot, THE MANUFACTURE OF VARNISHES. 215 and put into the pot used for preparing the copal varnish. Mix 2 parts of the anime varnish with one of copal var¬ nish; it will dry quicker and harder than’the best body copal varnish, and will polish very soon. QUICK-DRYING BODY COPAL VARNISH.— Boil 200 parts of best copal, 500 parts of clarified linseed oil, 6 parts of dry sugar of lead, and 800 parts of turpen¬ tine until viscid, and then strain. Boil in another pot 200 parts of gum anime, 500 parts of clarified linseed oil, 6 parts of sulphate of zinc; strain while hot, and mix equal parts of the two varnishes. This varnish will dry in 6 to 7 hours in winter, and in 3 to 4 in summer. NEIL’S CARRIAGE LACQUERS.—I. Melt 2 parts of best copal, add gradually 10 parts of clarified linseed oil; boil until viscid, then reduce it with 6 parts of oil of turpentine, and filter. 11. Melt 2 parts of gum anime, add 5 parts of clarified linseed oil, boil until viscid, reduce with 7 parts of oil of turpentine, and filter. The two lacquers can be used either by themselves or, in case a quick-drying lacquer is required, mixed in equal parts. Water Varnishes. This group comprises but few and little used varnishes. 1. LAC WATER VARNISH.—Shellac 6 ounces, borax 14 ounces, water 1 pint. Boil together until the lac is dissolved. If bleached lac is used a white varnish will be made; if the orange shellac, the varnish will have a pale brown color. This varnish makes a fair vehicle for water colors; it is a good paper varnish, and dries with a fair lustre, and with a hard coat, which is water¬ proof. By adding any of the soluble coal-tar colors col¬ ored varnishes can be made. 2. GLAZING VARNISH.—Mix 1 pint of white of egg with 1 pint of water. A little carbolic acid or salicylic 216 THE MANUFACTURE OF VARNISHES. acid, or, better, thymol should be added to preserve this varnish. This varnish or glaze dries with a fair amount of lustre. If, after being applied, it be placed in a hot room, to dry, the coat will be made more waterproof. Dried albumen may be used instead of the white of egg by dissolving 1 ounce in 1 pint of water; only the color of the glaze is not so good. 3. GLUE VARNISH is made by dissolving 1 pound of good, pale glue in 2 gallons of water. The color of this varnish depends very much on the quality of the glue used; if the best gelatine, then a white varnish will be made; if a brown glue, then a brown varnish. This var¬ nish is not very good, because of the sticky coat it gives, which is not waterproof; by adding just before using a small quantity of bichromate of potassium (1 ounce in 2 gallons), the coat becomes nearly waterproof. It is im¬ portant that the bichromate be added only just before use, as it would act on the varnish and cause it to set into a gelatinous unworkable mass. This varnish forms the basis of some leather varnishes. A little thymol or borax may be added as a preservative. 4. CRYSTAL WATER VARNISH.—One pound of good white gum arabic and 1 pound of glucose are dis¬ solved in 3 pints of water. This dries hard, with a gloss. How to Lace a Belt. Punch two rows of holes in each end, placed zig-zag. In a three-inch belt there should be four holes in each end—two in each row. In a six-inch belt, seven holes— four in a row nearest the end. A ten-inch belt should have nine holes; the edges of the holes should not come nearer than three-quarters of an inch to the sides, nor seven-eighths of an inch to the ends of the belt. The second row should be at least one and three-quarter THE MANUFACTURE OF VARNISHES. 217 inches from the end. On wide belts these distances should be even greater. Begin to lace in the centre of the belt and take care to keep the ends exactly in line, and to lace both sides with equal tightness. The lacing should not be crossed on the side of the belt that runs next to the pulley. In taking up belts, observe the same rules as in putting in new ones. Care should be taken that the ends of the belts, if to be butted, are cut square across, else a crook may be made in the belt. Hints to Users of Belts. Horizontal, inclined and long belts give a much better effect than vertical and short belts. It is asserted that the grain side of a belt put next to the pulley will drive 30 per cent more than the flesh side. THE END. A Practical Manual ON THE MANUFACTURE OF Linseed Oil and Varnishes. TABLE OF CONTENTS. THE MANUFACTURE OF LINSEED OIL. PAGE. Concerning the Various Ceasses of Feaxseed—Con¬ ditions Requisite in Linseed Oie to Produce Best Resuets . i Linseed Oie Pecueiarities—Consideration of the Various Methods Used To-Day to Produce Best Resuets—The Oie Percentage in c.ake. 15 Press Room Operations and Their Effect Upon the Oie in Refining—Method of Testing of a Var¬ nish Oie . 41 Saet as a Refining Agent in Linseed Oie—Coeor Drawback Which Appears in an Improperey Tre.ated Oie. 47 Heating Kettees—Uniform Distribution of Temper¬ ature IN an Oie Under Treatment Essentiae to Success. 54 Oxidizing Agents of Linseed Oie and Their Correct Use— OxoNizED Air. 58 Practicae Points Concerning the Fieter Press, Whether for Oie or Varnish Fietration, and Where the Best Form of FTetering Medium May Be Obtained . So Economic Oie Mieeing—Practicae Hints and Sugges¬ tions TO Oie Mieeers. 90 American Linseed. Cake Versus Engeish and Other Foreign Makes in the Engeish and European Markets (with Anaeyses). 122 The Fieter Pre.ss in Oie Mieeing—Further Detaies Concerning Its Workings, Etc. 165 Manufacture of Oie Varnishes. 176 INDEX TO ADVERTISEMENTS. PAGE. Atlantic Drier Co., Philadelphia, Pa .. .Inside Front Cover Bartlett, C. O. & Co., Cleveland, O. VIII Buckeye Iron & Brass Works, Dayton, O. 175 Carter, C. W. H., New York..... VIII Devoe, F. W. & C. T. Raynolds Co., New York. XVI Dopp, H. Wm. & Son, Buffalo, N. Y. XVIII Enequist, Erik, New York. XX Feuchtwanger, D. & Co., New York.XVIII Hohmann & Maurer Mfg. Co., Rochester, N. Y. . -. XV Imhauser, E., New York.. . . XX Johnson, John & Co., New York.. X Keasbey, Robert A., New York ..XVII Lane, J. H. &Co., New York .Inside Back Cover Listers Agricultural Chemical Works, New York.. . XIV Manhattan Spirit Co., Buffalo, N. Y. XX National Provisioner Publishing Co., New York, VII, XVII, 121 and 197 Niles Tool Works Co., Hamilton, O. XIX Patterson, G. W. S. & Co., New York...XVIII Perkins, J. T. Co., Brooklyn, N. Y. IV Pr.att & Lambert, New York. II ScHEEL, William H., New York .. 176 Sperry, D. R. & Co., Batavia, III. XIX Stilwell-Bierce & Smith-Vaile Co., Dayton, O. I Sturcke, H. E. & Co., New York .Inside Back Cover SuGDEN Press Bagging Co., West Chesterfield, Mass. . IX Taber Pump Co., Buffalo, N. Y. XVI Winterbourne, S. & Co., New York. XX Worthington Pump. 116 Do You I'lake Black Varnish? IF so Listers Agricultural Chemical Works, 159 Front Street, New York, Can furnish you with ASPHALTUM of abso¬ lute purity, admirably suited for making the HIGHEST GRADE Black Varnishes and Japans. ADDRESS, LISTERS AGRICULTURAL CHEMICAL WORKS, 159 Front Street, New York. XIV. THERMOMETERS For Oil Boiling and Varnish Making. The HoIiinann& Maurer ROCHESTER, N.Y.. U. S.A. MANUFACTURERS OP THE ‘ H Special Thermometers FOR Linseed Oil Crushers and Refiners, Cotton Seed Oil Mills, Oil Boiling, Gum Melting, Mfgrs. Varnishes and Paints, Patent and Fancy Colored Leather, Oil Cloth and Linoleum, Printing Ink, etc. Hand Thermometers for Testing Meal, etc. XV. TABER ROTARY PUMPS. SPECIALLY ADAPTED TO PUMPING Oils, Fats, Brine, Glue, Soap, Etc. Put in on Positive Guarantee and Long Trial Before Pa3dng. PUMPS Hot, Cold, Thick, Thin FLUIDS. TABER PUMP CO., WRITE FOR CATALOGUE AND PRICE LIST. BUFFALO, N. Y, F.ff.DEVOE4C.T.RAYllOLD!iCO ESTABLISHED 1753. Thj Oldest and Largest Paint Manufacturing Concern in the W ild. NEW YORK, CHICAGO, 101-103 Fulton Street. 176 Randolph Street. Manufacturers of House Paints, Fine Varnishes, Brushes, Artists^ Materials. XVI. MAGNESIA SECTIONAL COVERINGS. 54 WARREN ST.. Telephone, 1515 Gortlandt. New York, A superior non-con¬ ductor of heat for Steam Pipes and all heated sur¬ faces. There is Only One MAGNESIA COVERING. - BEWARE OF IMITATIONS. Robt. A. Keasbey, The Manofactare of Cottonseed Oil -AND- ALLIED PRODUCTS. 95 Pages. Price, $3.00. PUBLISHED BY THE National Provisioner Publishing Co. NEW YORK: 284-286 Pearl Street, Corner of Beekman. XVII. CHICAGO: No 11 Rialto Building, Adjoining Board of Trade. THE LEtDING HOUSE. SEIMLESS JICKETED GtST-IROG KETTLES, With and Without Agitators. Steam Jacketed Vacuum Pans, Ex¬ tract Kettles, Lard Drier, Mixer and ( ooler. Full line of Soap-Makers’ Machinery. H.WM.DOPP&SON, MANUFACTURERS OF Soap-Makers’ and Butchers’ Machinery. 462 Ellicott Street, Buffalo, N. Y., U.S. A. Write for Descriptive Circular and Catalogue. Mention this advertisement. By buying from the Producer, the Consumer saves the profits of the Middleman. G. W. S. Patterson & Co., kauri gum. GUM FIELDS AND PACKING AMERICAN OFFICE: WAREHOUSES: 204 Pearl Street, cor. Maiden Lane, Kaikohe, New Zealand. New York. TELEPHONE, 2728 CORTLANDT. A Full Line of Standard Gradings Constantly on Hand. CORRESPONDENCE SOLICITED. ALBERT UEL TODD. ESTABLISHED 1835. WILLIAM H. OSCANVAN. L. FEUCHTWANGER & CO.. Manufacturers and Importers of Miners of and Dealers in CHEMICALS. MINERALS. High Class of Driers for Oil Boilers and Varnish Manufacturers. Oxide of Manganese, Borate of Manganese, Chlorides, Sulphates, Etc. Publishers of Treatises on Gems, Soluble Glass and Fermented Liquors. Factories: West Avenue, First and Flushing Streets, Long Island City. Salesroom and Office; No. 191 Fulton Street, Cor. Church Street, - - New York. XVIII. FILTER PRESSES. .I ATeI For the Filtration of All Kinds of Product. Write for Catalogue. THE NILES TOOL WORKS CO., Hamilton, 0. BRANCHES—New York, Philadelphia, Boston, Pittsburgh, Chicago, St. Eouis, New Orleans. m CDCDDV CIITCD DDCQQ superior in efficiency OrCntll rlLICn rnLOOi and construction. The Patent Plate saves cloths, produces a drier cake and is altogether better than the old form. Write for Information. D. R. SPERRY & CO.. Batavia, Ilf. Manufacturers of VACUUM PANS, STEAM-JACKET KETTLES. CALDRONS, Etc. XIX. ERIK ENEQUIST, IMPORTER OF High-Grade MANGANESE OXIDE, Granulated or Powdered. MANUFACTURER OF MANGANESE Borate, LINOEEATE, CARBONATE, CHLORIDE, Etc. DEALER IN SODA ASH, CAUSTIC SODA, LITHARGE, ACETATE OF LEAD and CHEMICALS for Varnish Makers, Oil Boilers, and Color Makers. Manhattan Spirit Co., BUFFALO, N. Y. MANUFACTURERS OF Columbian Spirit and Refined Wood Alcohol. Perfect Substitutes for Grain Alcohol for use in the Arts and Manufactures. Varnish Gums. All Descriptions. S. WINTERBOURNE & CO., 94 PINE STREET, ALFRED MASON, Agent. NEW YORK. Samples and Information on Application. WATCHMAN’S IMPROVED TIME DETECTOR. This instrument is supplied with 12 and 24 keys, cover¬ ing either 12 or 24 stations. Contains all modern im¬ provements. SEND FOR CIRCULAR. E. IMHAUSER, 206 B’way, New York, U. S. A. XX. FILTERING FABRICS BAGS Of All Constructions for SUGAR, OILS AND OTHER PRODUCTS. J. H. LANE 8i CO., 110 Worth Street, - - New York. H. E. STLRCKE & CO., National Provisioner Analytical Laboratory. Chemical Analyses of all Raw Materials, Supplies, Products and By- Products in the Manufacture of Linseed Oil and Varnishes. PROCESSES INVESTIGATED AND TESTED. 284 Pearl Street, GETTY CENTER LIBRARY 3 3125 00140 2599 New York.