V^.''°'^ c\ ^v ^\I»A» *^ ^ ^ r'k , ^ :^^^ ^^wm&: .^' IS-- "^0^ ^:^ ^i^/ y. ,> ^' •-^#S^,* .^^ ^'M .^C>/ V' if.* <^, '" fet'- J^% : ■^^ ,^ ^>(\^^ifA:'„ "^. ^'^ .0^ . > • • ' '-m^ A <3. ; ; .'>>■-„ "^^ .^^ ^^ s'v:'. ^ ^v^ -^^ ?>^ "^ ^'^£3:ii v^'^^Xe^^.:*^^ /^V-m-\/ ^j/^J' S) cd°*. P^.^ ^^. A^ ^\w/^.w/^ ^\w-.C^'ii 'L\ ^m^., .^"•"-^^ *bp "■--..s^ :k^l&^= %/ -'^ ^^■' -'^V^' V '•Mfe- ./' .-.as^-- '*^ ■■ /% •:%€• ^^l&'- 'Mfk. \J y '>!:< J.0' ,,! ISf ; X *^ ^ /#si;\ ^^ <>* /»'•. ''c/ :M|; *" ^'* ■•**•■ /<#■ 'e, '-^^^'^ o ^"•^>.. ">^&* y < .*" --^l^ %-/ -M^ ^/ -^fc "^^^ f- y.- .'i ':i/mS:/M^^/m^/'rW'^-^'^- V vs»-„. lfe^.>^ ->«t ./^<^. .*^ •^^■' "^ '^^Sif^'- ^ NATURE aM CONTROL o/' TANNERY PROCESSES PUBLISHED BV THE Shoe and Leather Reporter Copyrighted, 1922, by Joseph R. Lorenz UNLESS the tanner "works in" the best obtainable raw materials, the most perfected tanning will be useless. Buy your hides and skins only from reliable sources able and willing to back up their written contracts. In dealing with Schmoll Fils 8 Co. you will at all times find an organization in a position to safe-guard your essential need, namely — "Hides and Skins of standard quality at origin market prices." You can obtain all these advantages, without incurring the disadvantage and risk of buy- ing from strange people thousands of miles away from you, by dealing with us. SCHMOLL FILS & CO., Inc. Scktol'Hs^CoJnc. — SINCE 1836 — International Hide Merchants Importers of Calf and Goatskins Distributors of Tanning Materials SCHMOLL-HLS BUILDING 19-25 SPRUCE ST., NEW YORK H NATURE AND CONTROL OF TANNERY PROCESSES HEMATINE CRYSTALS-i also all other DYEWOOD PRODUCTS of the STAMFORD DYEWOOD CO. ANILINE COLORS FANCY COLORS Ooze Gray Ooze Brown Ooze Black New York Color & Chemical Co. Manufacturers of ANILINE COLORS About May first we move our main office, warehouse, laboratories, etc., from 98 John Street, New York City, to our New Plant in BELLEVILLE, New Jersey, nine miles from New York City. Main Office (after May 1st), Belleville, New Jersey 164 Federal St., Boston, Mass. W. B. Carter, 1123 Columbia Ave., Clucago, lU. FACTORIES— BELIEVILLE, N. J.; PHII,.4DE1.PHI.*, PA. m \'' >922 • NATURE AND CONTROL OF TANNERY PROCESSES Nature and Control of Tannery Processes A Practical Exposition of the Purposes and Functions of the Beamhouse, Chrome Tanning, and Fat Liquoring Processes, as Revealed by the Latest Re- searches, and of the Means for the Economic Control of these Processes Within the Tannery By JOSEPH R. LORENZ PRINTED AND PUBLISHED BY THE SHOE AND LEATHER REPORTER Price $2.00 (Copyrighted, 1022, by Joseph R. Lorenz) NATURE AND CONTROL OF TANNERY PROCESSES The STAR Signifies A the SERVICE / IMPORTERS EXPORTERS HIDES and CALF SKINS CALFSKINS Dry and Green Salted HORSE FRONTS Chestnut Extract Hemlock Extract English — French — German HORSEHIDES Dry and Salted HORSE BUTTS TANNING MATERIALS Oak Bark Solid Quebracho Liquid Quebracho IMPORTERS —EXPORTERS — Russian — Danish — Swedish Holland — River Plate and Domestic CATTLE HIDES Dry and Green Salted GOATSKINS Mangrove Bark Divi Divi, Etc. Norwegian Finland The STAR Signifies the SERVICE We prefer to give Service rather than to talk about it. By its actual working out in daily transactions, customers become such champions of our organization that we frequently wonder if there is anyone in the industry who needs to be told of its resultful mechanism. Yet we are not satisfied to let our friends do all our promotion for us, w^e wish to assert that every pledge they make for us will be exactly fulfilled. The STAR Symbolizes Service — that STAR never dims because it is kept bright by accomplishment. JULES STAR & COMPANY 26-28 Ferry Street, NEW YORK 130 North WeUs St., CHICAGO )G!.A659866 '■*^^:.h M l&i ^ NATURE AND CONTROL OF TANNERY PROCESSES Author's Preface The rapid strides made witliin tlie past live years by all branches of the tanning industry, especially by that of chrome tanning, is a matter of knowledge to all leather-chemists who follow the work of such of their colleagues as Wilson and Thomas in America, and Stiasny, Pahrion. and Alfred Seymour- Jones in Europe; these names have, in fact, become as well-known to most tannery-chemists of today, as were those of Procter and Wood associated in the minds of leather-chemists of a generation ago with the pioneering work In the chemistry of tanning with which Procter and Wood are universally credited. To the investigations of our modern workers may be said to belong the distinction of having disclosed to the tanner the real nature of most Of the important processes employed today in the manufacture of leather. The effect of thirty years or more of effort on the part of the leather- chemists, as directed toward the solution of the "mysteries" of tanning, has thus been to elevate the art of leather-making from the position of obscurity in which it remained throughout the ages, to that of an exact chemical indus- try, in which it may safely be said to find itself today. This little book is addressed to the practical tanner and manufacturer of chrome-tanned upper-leather, as well as to the tannery-chemist. As its title indicates, It is an exposition of the purposes and functions of the beamhouse, chrome tanning and fat-liquoring proce sses, as revealed by the latest authorita- tive researches, and of the means for the chemical control of these processes within the tannery. It is so written that anyone having a high-school education, or its equivalent, can understand the principles set forth in it. In the subject- matter will be found a digest of the principal journal-articles bearing on leather- chemistry, as related to chrome-tanning, which have appeared to notice in the last fifteen years ; at the close of each of the descriptive chapters on the pro- cesses of tanning will be found, in addition, a guide to the analytical control of the process described, this having been prepared, to a great extent, from data gathered by the author during the term of his own experience of eight years as tannery-chemist; finally, in the chapter on "The Fat-Liquoring Process" wUl be found the principles of J. R. Blockey's recent book on the "AppUcation of Oils and Greases to Leather." The author is indebted to Mr. Irving W. Skilton, president of the North- eastern Leather Company, tor valuable counsel given in the preparation of this treatise. J. R. L. NATURE AND CONTROL OF TANNERY PROCESSES nfiliiiiiiiiiiiiiiiii^ :>iiiijLii m Retanning of Chrome Leather During the war the United States Government, as well as the Gov- ernments of the Allies, placed orders for large quantities of retanned Chrome upper leather. This leather was found essential for soldiers* trench shoes, being practically waterproof with excellent wearing qualities. Do you know that about 90 per cent of this leather was retanned with Quebracho? That of this about 75 per cent was retanned with Liquid Quebracho Extract, and the remainder with Argam (Crown Brand) Solid Quebracho Extract. That the bulk of the liquid used was S. M. brand of Liquid Extract of Quebracho made "direct from the wood." Liquid Quebracho Extract S. M. and S. M. S. Brands "made direct from the wood" are manufactured only at our Brooklyn factory. Greenpoint, New York. These extracts cannot be imitated by dissolving and treating chemically Ordinary Solid Quebracho Extract For particulars and information regarding these and other vegetable tanning materials, write to THE TANNIN CORPORATION Main Office: 80 Maiden Lane NEW YORK, N. Y. REPRESENTED AT TORONTO, CANADA 13 Wellington St., East NATURE AND CONTROL OF TANNERY PROCESSES Contents SOAKING OF HIDES Page Soaking Process, Analytical Control of 9 FIRST FLESHING Chemical Behavior of Acids, Alkalies, and Salts Employed in Tanning 11 THE LIMING PROCESS Analytical Control of 15 DELIMING AND BATING Deliming and Bating Process, Analytical Control of 21 Method of Ascertaining Weight of Dry Substance in Wet Hides,. 23 Diagram of Sections of Raw Hide Before and After Liming and Bating, Respectively 23 THE PICKLING PROCESS Analytical Control of 23 THE CHROME - TANNING PROCESS Analytical Control of 27 Method for Finding the Capacity of Tannery Paddle-Vats, Tanks and Pits 33 RETANNING OF CHROME LEATHER 35 "NEUTRALISING" OF CHROME - TANNED LEATHER Neutralising Process. Analytical Control of 35 THE FAT - LIQUORING PROCESS Analytical Control of 37 Copyrighted, 1922, by J. R. Lorenz NATURE AND CONTROL OF TANNERY PROCESSES COD OIL Pure Tanked Newfoundland Fifty Years' Experience Insures Satisfaction MARDEN-WILD CORP. FRANK W. MARDEN, Pres. Somerville Station BOSTON, MASS. NATURE AND CONTROL OF TANNERY PROCESSES Nature and Control of Tannery Processes A Practical Exposition of the Purposes and Functions of the Beamhouse, Chrome-Tanning and Fat-Liquoring Processes, as Revealed by the Latest Researches, and of the Means for the Economic Control of These Processes Within the Tannery By Joseph R. Lorenz Soaking of Hides The purpose of the first tannery process, namely, the soaking in water of the green salted or dry hides, is two- fold; it may be stated as follows: (1) By causing the hides to absorb water, to permit the semi-dry condition of the raw stock to return to the original moist (and therefore workable) condition of the hide in which it was removed from the animal. (2) To remove by mechanical action the blood, dirt, and dung adhering to the hides, and to dissolve the salt and any other soluble curing — or pre- servative-substances used in the preparation of the hides at the slaughter-houses. The softening action of the soak is hastened in the case of dry hides by the addition to the soak-water of caustic soda or sodium sulfide (in the amount of one-tenth per cent of either material on weight of stock in the soak) ; these materials, by giving rise to alkaline swelling acceler- ate the absorption of the liquor by the hides. Adhering blood, dung and salt removed from the hides remain in the soak-pit; the blood and dung are partly dis- solved, while the salt is completely dissolved by the soak- water. Those portions of blood and dung dissolved by the water (collectively termed "dissolved organic matter") fur- nish a medium (i. e., a vehicle) for the propagation of the micro-organisms (namely, bacteria, bacilli, etc.,) that are carried into the soak-liquor by the hides. The majority of the micro-organisms originally in contact with the hides belong to species which — while possibly including some of pathogenic (i. e., disease-producing) origin, — are harmless in character insofar as their action on the hides is con- cerned. Accompanying the various harmless types, how- ever, are other micro-organisms known as "liquefying bacteria" which, through the action of enzyme-substances' which they secrete, indirectly have the power of dissolv- ing protein-bodies (such as albumin, hide-substance, etc.), especially in weakly alkaline media. In a freshly-used soak-liquor the number of liquefying bacteria present is generally small; the nutrient-substances in the form of the blood and the dung introduced by the hides, however, cause a rapid multiplication of the original few; at the same time, the enzymes secreted by these bacteria are actively at work digesting the said nutrient-substances, and further, in splitting up the complex chemical struc- ture of these into products of a simpler chemical construc- tion. In the course of a few days, where repeated use is made of the same soak-liquor, the family of liquefying bac- teria will have grown to such dimensions that the supply of ' Enzyme: The active principle of digestive fluids secreted by living body cells; examples of enzyme-substances are pepsin and rennin (found in gastric juice), and ptyalin (amylase) — the diges- tive principle of saliva. blood and dung furnished them becomes inadequate; at this point, therefore, the enzyme-bodies produced will at- tack the hides in the pit, and, in the process of supplying their mother-bacteria with additional nutrient-material, they will cause a loss of hide-substance, and, ultimately, the total destruction of the hides. It follows from this that the more or less common practise of using the same soak- liquor for successively treating a number of packs of goods is, by nature, a wasteful process; for, as the "mellow" property of an old soak-liquor is seen to depend on the activity of the bacterial enzyme-bodies which it contains so will the extra softening-effect be gained only at the ex- pense of much hide-substance lost in the process. Except common salt, many of the curing — and pre- servative substances dissolved from the hides during soak- ing are known to have a solvent action on hide-substance, especially in medium dilutions'; if allowed to accumulate (as in the case of an old or "mellow" soak-liquor), their presence, including that of common salt, will interfere with the proper swelling of, and absorption of liquor by the hides. (See the role of salts in the Pickling and Chrome- Tanning Processes.) Analytical Control. The analytical control of the soak- ing process is ordinarily confined to those eases which, for any reason, require the use of the same soak-liquor over and over again. The determination of the quantity of dis- solved organic-matter accumulating in such liquors should be made from time to time, as indicating the extent to which the liquefying organisms present are being encour- aged to thrive. (It might b© suggested here that by the judicious use of germicidal materials which are also capable of acting as anti-ferments, all the micro-organisms present In the liquor might be rendered innocuous, and further de- structive action by the enzyme-bodies stopped. The possi- ble hardening or "tanning" effect upon hide-substance of any germicidal substance emplo.red should, of course, be taken into consideration.) The nature of the salts, and the quantities of these and of common salt dissolved by the soak-liquor may also be determined, if desired. \\Tien- ever the concentration of the salts is found to interfere with the proper swelling of the goods, it may be reduced by the addition of fresh water to the liquor in the pit. = II. i:. rrooti.T— "Leather Industries Lahoratnrv 11. ...l;." J. BRISK « COMPANY SODIUM SULPHIDE ALUMININA SULPHATE SODIUM BICROMATE POTASH CH ROM E ALU M GLAUBER SALTS EPSOM SALTS Tanners' Chemicals of all kinds. 155 N. Clark St.. CHICAGO 10 NATURE AND CONTROL OF TANNERY PROCESSES It takes them As they come! Model "F" Heavy Duty FleshiDg Machines handle heavy or light sides with utmost precision. The evenly balanced shaft automatically sets the bed roll against the cylinder — a new feature. Other features: Hyatt Roller Bearings, Clutch Mechanism set high. Moving parts guarded. Grinding Bar can be ground without removing from machine. Two sizes — 72" and 84". Shipped on trial. Write us for further information. BuUders CHAS. H. STEHLING CO. of Cor. 4th and Poplar Sts. Tanning Machinery MILWAUKEE - -- WISCONSIN Designers of Tanneries FOREIGN HIDES And CALFSKINS ARMAND SCHMOLL INCORPORATED 4 1 Park Row, corner Spruce St. NEW YORK Cable Address: PROMPTER, New York -Service- that connects the continents Whether it comes from South America or from far away New Zealand, we supply you immedi- ately — and to your satisfaction. - HIDES — So. American Frigorifico — New Zealand Freezers New Zealand Pickled Skins So. American Pickled Skins Pulled Wools THE TUPMAN THURLOW CO. fXCORPORATED 1 54 Nassau Street, New York NATURE AND CONTROL OF TANNERY PROCESSES 11 First Fleshing Hides having much surplus flesh and tallow attached require a thorough fleshing before being placed into the lime liquors. The importance of ridding the hides at this stage of every trace of tallow, especially, is evident from two considerations; namely, (1) that the action of lime upon the fats is to produce insoluble soaps, and that lime cannot, therefore, be depended upon to remove the fats; and (2), that the form of blemish known as "fat-spue" ap- pearing on the surface of the finished leather has been ob- served by W. Fahrion' to arise most frequently in the pres- ence of the "crystalline" fats (stearin and palraitin), of which tallow is composed, rather than from the constitu- ents of the fish oils normally used in the fat-liquoring of the leather. Chemical Behavior of Acids, Alkalies, and Salts Employed in Tanning For the purpose of enabling the non-technical reader to form a true mental picture of the coui'se of action of the liming, deliming, pickling and chrome-tanning processes, an explanation will be attempted, first of all, of those fundamental chemical principles upon which the mechan- ism of these processes rests. The reader (assuming he is not already familiar with the subject) is therefore asked to consider, briefly, the chemical structure or "make-up" of the simpler acids, alka- lies (or "bases"), and salts. It would be found, first, that every acid, alkali, and salt is chemically constructed of two principal components, consisting of groups of certain chemical elements examples of which are hydrogen, oxy- gen, sulfur, chlorine, calcium, sodium and potassium, these groups being known as "radicals;" secondly, that these groups exist within every acid, alkali, and salt, irrespective of the number or variety of indivldua! elements which the substance may contain. Now, when any acid, alkali, or salt is decomposed (i. e., caused to he "broken-up" into its constituent parts), it will be evident that the immediate products of the decomposi- tion wiU consist, — not of the individual elements of which the substance was composed. — but, instead, of the two groups or radicals, in which these elements may still be found residing. In other words, the first step of the "breaking-up" process, in general, will do no more than separate the groups in the compound, the groups them- selves remaining intact. For the purpose of this discus- sion, the foregoing principle, upon which the course of chemical reactions, in general, may be said to depend, may be stated as follows: The behavior of the chemical groups or radicals composing any chemical compound Is, In gen- eral, that of primary, or elementary bodies. Taking for consideration the principal acids, alkalies and salts employed in the tanner>-, it is possible to estab- lish a connection between the physical properties (e. g., taste) of these and their chemical structure. Thus, acids are familiarly associated with a sour taste, alkalies with a "caustic" or "soapy" taste, and salts with a saline or bitter taste; again, the chemical formula of sulfuric acid, for example, is H.SO, (meaning the combination of two parts of hydrogen with one of sulfur and four of oxygen), while that of hydrochloric (or "muriatic") acid is HCl (or, one part of hydrogen combined with one part of chlorine). In each of the formulae of the two acids named it will he noted that the element hydrogen is written first; if the whole list of acids were surveyed It would be found that hydrogen is a common constituent of all. Hydrogen is, therefore, a "group-element" with respect to the acids. To the "hydrogen-radical"*, as this group is called, then, is due the "acidity" or sour states of the acids. In the case of the family of alkalies, of which ordinary slaked lime (or calcium hydroxide), caustic soda (or sodium hydrox- ide), and aqua ammonia (or ammonium hydroxide) are some of the best known members, that particular chemical radical which determines the "causticity" (or "alkalinity") of these substances may, on inspection of their chemical formulae, be readily identified; the formula of lime is Ca(OH), (meaning the combination of two parts of the oxygen-hydrogen group with one part of the metal cal- cium) ; that of caustic soda is NaOH (wherein one part of the oxygen-hydrogen group is united to one part of the metal sodium, whose symbol is Na) ; while that of aqua ammonia is NH^OH (wherein the oxygen-hydrogen group is attached to the ammonium-radical, the latter being con- structed, as the formula shows, of one part of nitrogen, and four parts of hydrogen). Clearly, then, the common radical of the alkalies, and the one to which these bodies owe their caustic property and "soapy" taste, is the oxygen- hydrogen group, or better known as the "hydroxyl-radical." To consider, finally, the remaining class of substances, namely the "salts." A salt is produced whenever an acid combines with an alkali, or vice versa, the process being the familiar one of "neutralization." The following equa- tion, which is typical of all neutralization reactions, shows how a salt is produced. H,SO,-f2(NaOH)=Na3SO,+2(H,0) Acid-fAlkali=Salt-(- Water In this equation it will be noted that the SO,-radical of the acid has united itself to the Na^-radical of the alkali, these together forming the "neutral" salt Na,So, (sodium sul- fate, or "Glauber's Salt") ; simultaneously, the hydrogen- radical (Hj) of the acid has attached itself to the hydroxyl- radical (20H) of the alkali, the two thus combining to form water. (The fact that might be pointed out as of interest here is that the two last-named groups, to which the power of all acids and alkalies respectively, is due, are merely the constituent parts of that well-known substance — water.) Compared with either the acids or the alkalies, the salts are much the more stable (i. e., chemically inac- tive) substances, a firmer union existing between the groups that compose a salt; again, the saline or hitter taste of a salt is not due to any one of its two significant groups, but resides in the combination of these as a whole. It now remains to be explained why some acids are chemically more powerful or "stronger" than others, or why the alkali lime, for instance, is so much weaker in action than the alkali caustic soda. As any one who has ever experimented with chemicals knows, a perfectly dry sub- stance is entirely without action upon another perfectly dry substance; on dissolving the first substance in water, however, and adding to it the second substance also dis- solved in water, chemical combination between the two group of the alkalies. NATURE AND CONTROL OF TANNERY PROCESSES TANNERS SAY: Our Liquid Quebracho Extracts — Q. P. PICKLE SHEEPSKIN SPECIAL and SNOW WHITE Will produce more leather and of a better quality than any other Quebracho Extract on the market. Try it! QUEBRACHO PRODUCTS CO., Inc. Manufacturers of Clarified and Decolorized Liquid Quebracho Extracts 39-4 • CORTLANDT STREET NEW YORK CITY Factory, Staten Island. N. Y. MATURt AND CONTROL OF TANNERY PROCESSES 13 substances may be at once effected. That water must be tion, and this limit is, therefore, a measure of the chemical present in order to cause two chemicals to combine is, power or "strength" of that substance. Thus, for Instance, therefore, evident". Now, the part that water plays when the number of hydrogen-radicals (or acid-groups) that be- any acid, alkali or salt is dissolved in it is simply this: come released when the different acids are dissolved in Water causes the two chemical groups or radicals com- water (and. hence, the relative "strengths" of these acids) posing the compound to disunite and become separated". has been determined for each of the acids named in the Only when thus separated, or "released for duty," as It appended table, as follows: were, are the radicals of one chemical compound able to ^^.j^ Relative Strength combine with the radicals similarly released from another Hydrochloric 200 (approx.) chemical compound. Plainly, then, once a chemical com- Sulfuric 200 (approx.) pound is dissolved in water, it must exist in that first stage Oxalic 0.1 of decomposition to w-hicli reference was made at the be- Formic 0.0214 ginning. For illustration, taking the composition of sul- Lactic 0.0138 furic acid as H,SOj, that of a solution of this acid in water Acetic 0.0018 would read : Butyric ' 0.00115 (Hj) + (30.) + (Water) + (Unchanged HjSOj) °a. Boracic 0.0000001 Thus, while a portion of the total quantity of acid dls- •, ,• ^ ^ ., , • ^u i . *i, ■ ^ .... ^ „^ The acids listed are thus arranged in the order of their solved becomes dissociated, yielding its H, — and SO. — .. ^ „ „ ,* -,i u * j ^i, * *i, * • , „ . , " . . ,. "strengths. It will be noted that the two mineral acids, groups to the water, the remainder escapes dissociation: , , j ,, ■ , ,^ ■ ,_ . . , namely, hydrochloric and sulfuric, are each approximately that is, its H, — and SO. groups remain united in the pres- ^ ^, , ^. „ ^ ,, ^, ., „ . * " ^ ^ ^ two thousand times "stronger" than the "strongest" or- ence of the water. Disregarding this latter portion, there . ., , ,.,.., . ., . . game acid, namely, oxalic; formic acid comes next, then are found in the dissociated portion the "active gi-oups; , ^. .. , , ^ . ., u-, i_ ■ -j i , . , . , lactic, acetic, and butyric acids, while boracic acid, al- that is, those groups capable of entering into chemical ,, . -j „ • 4. ,, .i, .. , 1,. -j ,, , , . though a mineral acid, is seen to be the weakest acid union with other substances. Now, the number of groups . „ j ..u ,■ j i, of aU; compared with oxalic acid, boracic acid possesses that water is capable of releasing vanes with every chemi- . „ . but one-millionth the strength of oxalic acid! cal substance; in other words, irrespective of how concen- ,1-1 ^, ^-^ ■ x, ,. x xt „ , ' „ , , X. , ,x In like manner can the difference m the "strengths" trated or strong the solution of an acid, alkali or salt „ ,, . ,, ,- v , . j . x, ,. of the various alkalies be explained. In the absence of might be made, for every such substance there is a fixed x , „ 7 -x 1, x x j x, x * x, actual figures', it may be stated that, of the common alka- limit to the niiiiili. !■ i.f "active" groups present in the solu- ,. ,. x , , x ■ u j . , > . x,. ., x lies, caustic potash (potassium hydroxide) is the strong- ch™ica!"re/,.',V:, ^ V .'''a 'o^dim-TrAempera^m^^^^^^^ ""'"'' °^ ^st"; caustic soda is next in order, then slaked lime, and, » This sfii, 11,11 : I .l^ase" by water of the chemical groups finally, aqua ammonia. iu a dissolvefl sulistaiioe, is technically known aa "dissociation." "a Sulfuric acid actually dissociates into H-I-H.S04. For prac- : See. however, "Tabulation of Hydrogen and Hvdroxvl-ion tieal purposes, however, the dissociation products of this acid may concentration of Some Acids and Bases."— xiithur W Thomas he regarded as consisting of H,— and SO.— groups. Jour. A. L. C. A.. 15, 133 (1920). New York Hide and Skin Merchants NEW YORK - BOSTON - CHICAGO I. DOERFLINGER BROKER Foreign arid Domestic Hides and Skins Tanning Materials Tribune Building New York City FEARON, BROWN COMPANY CHINA GOATSKINS AND HIDES 96 Wall Street New York Phone, John 4(l:;(( FREDERICK TAUBER FOREIGN HIDES AND SKINS 100 Gold Street New York Phone, Beel ■'■ "limiting point" the degree of swelling pro- dui-.(i I i.roportion to the number of hydroxvl-groupg relc:iM : lil ii: ,i:„s have not the same power to swell hide: thus, caustir i,,,i,.ii, Miiirh im solution yields the greatest number of these groups, possesses the maximum swelling power of the alka- lies, while ammonia— giving rise to the least— is weakest in swell- ing action. hairing — that of the bacterial enzyme-products formed in the lime-liquor soon after the hides are introduced. Again, taking the case of the alkalies in general, plumping may be said to be more distinctly influenced by the nature of the metal-group of the alkali; thus — while the plumping and swelling produced by "pure" solutions of the alkalies are known to occur simultaneously, both in diminishing ratio, from the "strongest" alkali down — plumping is not a necessary accompaniment of swelling nor is swelling always accompanied by plumping. The unhairing power of the alkalies, on the other hand, increases as the alkali becomes "weaker"; in other words, caustic potash and caustic soda — although exhibiting the strongest swelling action — cause least unhairing, while ammonia — possessing minimum swelling power — is most rapid in unhairing ac- tion. It must not be supposed, however, that this increase in depilatory power is gained as a result of the lesser hydroxyl-group concentration of the "weaker" alkali: on the contrary, the hydroxyl groups, as will be seen, play a very important role in the unhairing process; moreover, the unhairing power of any alkali will increase in propor- tion to the concentration of its solution (e. g., the unhair- ing effect of caustic soda may be made to equal that of ammonia simply by employing a relatively "stronger" so- lution of the soda). The explanation of this paradoxical behavior of the alkalies with respect to unhairing rests — as it does in the case of plumping — upon the difference in the nature of the metal-group by which one alkali is dis- tinguished from another. In the case of liming, the mechanism of unhairing may be described as follows": The hydroxyl-groups in the lime- liquor first soften the epidermis (or "outer skin") of the hide, and then dissolve it, together with the coriin (or ce- menting substance of the hair roots) ; the dissolved epi- dermis and coriin, in turn, furnish, a nutrient-medium for the bacteria present, enabling these bodies to secrete en- zyme-substances, by whose solvent action the hair is still further loosened. The process is thus seen to consist of a cycle of operations, and it wUl be apparent that the longer it continues, the richer must the lime-liquor become in enzyme-content, and, hence, the more powerful in unliair- ing effect'^. Now, as the lime-liquor grows "mellow," the solvent action which it normally exerts upon the hide itself be- comes greater and greater. A "mellow" lime-liquor thus compares with a "mellow" soaking-liquor both causing losses of hide-substance. By reason of its alkali-content, however, the lime-liquor will be the more destructive of the two; in other words, a certain loss of hide-substance occurring in the liming process may result from tlie purely chemical action of the alkaline liquor. Tbus, in general, the greater the concentration of hydroxyl-groups (i. e., the more "alkaline" the liquor), the greater will be the loss of hide-substance. The one exception to this rule, how- ever, is ammonia; far from exhibiting the minimum sol- vent action, ammonia causes instead the greatest loss of hide-substance". Besides giving rise to tbe foregoing phenomena, a fur- ther function of the liming process is to remove the seba- " The unhairing enzymes are secreted freely in media other- wise unfavorable to the rapid growth of the bacteria, such as, for instance, lime-liquors. -Edmund Stiasny- 16 NATURE AND CONTROL OF TANNERY PROCESSES Cable A(l nud," »n- York FREDERICK FARAONE & CO. Direct Importers of HIDES. SKINS — Gl. Produep from CHINA, JAVA. INDIA, NO. AFBICA, SPAIN. ITALY. BAXKANS, ETC. 74-76 Gold St., New York (I'.vruiiiid lUdg.) W. L. MONTGOMERY « CO. HIDES AND SKINS lo High Street, BOSTON Cable Address: "Winsmout," Boston EDWARD H.BILL 8 CO. Specialize in FOREIGN HIDES '^i SKINS }:y. 79 South Sf. Boston, Mass. /,' PERSSON & CO. NEW YORK TANNERS' CHICAGO RAW STOCK GOATrKlNr" DEER/KINJ J-HEEPXKINJ-- HIDEr= DEERJKINi-'GOAJJKINJ- HIDEJ" 'i XHEEPJKINJ"'^ COATrKINJ-^DEER-TKINJ- '-JHEEPJ"KlNr '- HIDEJ * DEERJ-KIN-r«GOATJKINJ J-HEEP-TKINJ-'- HIDEJ"5 GOAT-TKI N J-s DEERJKIN J- sJ'HEEPJ'KINi' >HIDE-r a CABLE ADDRESS "BABAN Complete Outfits of Leather Working Machinery Send for Catalog and Price L'ut G. W. Baker Machine Co. Wilmington, Delaware, U. S. A. Fleshing Machine Wilmington Automatic Rollei NATURE AND CONTROL OF TANNERY PROCESSES 17 ceous (or fat) glands situated at the roots of the hair on the hide; the removal of these glands is effected by the mild saponifying action which lime exerts upon the fats. The removal of these glands should be complete, else "spueing" of the finished leather may result. Thus far, the action of a "straight" lime-liquor has been considered. In modern practise, however, the period In which the hides remain in contact with the lime-liquor is shortened as much as possible by the employment of liquors containing in addition to lime, certain materials designed to accelerate the unhairing process. Such so- called "sharpening" materials may be divided into two groups": (1) Those serving to increase the "alkalinity" of the lime-liquor. (2) Those which form hydrosulflde (SH)-groups. The first group of sharpening materials may be fur- ther divided into two classes, viz.: (a) Substances which in solution yield a greater num- ber of hydroxyl-groups than lime alone can pro- duce; e. g., caustic potash, caustic soda, ammonia, etc. Of ammonia a word may be said here; am- monia enters into a loose combination with lime, forming a calcium-ammonium compound similar to the corresponding barium and zinc compounds; in so doing, the "alkalinity" of the liquor becomes actually lowered, in consequence of which the swelling and unhairing power of the liquor will be inhibited. In the presence of lime, therefore, ammonia is quite without value as a "sharpening" agent, and the belief long held that the ammonia- content is a measure of the unhairing power of a lime-liquor is, therefore, unfounded. (b) "Neutral" salts of bases "stronger" than lime. The manner in which these render the lime-liquor more "alkaline" may be illustrated by taking the case of sodium sulfate (or Glauber's Salt), Na^So,; in contact with lime, sodium sulfate re- acts with it, becoming itself converted to caustic soda, and changing the lime to calcium sulfate, or, Ca(OH),+Na,SO,=.2NaOH-|-CaS04; thus, in place of the lime will remain the "stronger" alkali, caustic soda. 0£ the second group of sharpening materials, sodium sulfide (Na^S) is the most prominent member. Notwith- standing the loss of the hair which it ordinarily causes (for sodium sulfide attacks keratin — the substance of which hair is composed), this material finds favor in the tannery on account of the rapidity of its action in loosening the hair when employed either alone or in combination with lime. Dissolved in water, sodium sulfide releases its two chemical groups, Na^ and S. which, however, immediately combine with the two water-groups, H and OH, to form the substances NaOH (caustic soda) and NaSH (sodium hydrosulfide), in accordance with the following equation: Na,S-fH,0=NaOH+NaSH. The caustic soda and sodium hydrosulfide, m turn, be- come dissociated into metal groups (Na.), hydroxyl-groups (OH), and hydrosulfide-groups (SH). In the presence of ■' Ecliiu.nd Stiasny— Loc. Cit. lime a second metal-group, namely Ca, is further intro- duced as a dissociation-product of the calcium hydrosulflde (Ca(SH)j) that is formed when lime reacts with sodium sulfide". The most prominent characteristics of the various chemical groups present in a sulfide, or sulfide-lime liquor, as enumerated above, have been brought to light by Sti- asny", and may be summarized as follows: (1) The hydrosulfide-group alone possesses neither swelling, plumping nor unhairing properties. (2) Only by the combined action of the hydrosulfide- and hydroxyl-groups is the powerful unhairing effect exhibited by a sulflde-liquor produced. (3) The extent to which the swelling, plumping and unhairing effects manifested by a sulfide-liquor occur depends on the proportion of hydrosulfide- groups to hydroxyl-groups present, the most favorable ratio being 1 : 1". (4) An excess of hydroxyl-groups (i. e., an increase in alkalinity) has little effect on the action of the liquor. A preponderance of hydrosulfide- groups, on the other hand, adversely affects the action of the liquor. In presence of an excess of hydrosulfide-groups, swell- ing, plumping and unhairing are all markedly inhibited. In practise, a sulfide-liquor may suffer loss of alkalinity through the use of "hard" water in preparing the liquor. "Hard" water uses up the hydroxyl-groups, leaving the hydrosulfide-groups in excess. The deficiency in alkalinity thus produced can, however, be restored by the use of a small quantity of lime in admixture with the sulfide. It will be noted that the active alkali of both sulfide- liquors and sulfide-lime liquors is caustic soda. By reason of the ready solubility and powerful action of this alkali compared with lime, greater care is necessarily required in the use of sulfide-liquors, in general, than would be de- manded of a "straight" lime-liquor. Thus, in the repeated use of the same sulfide-liquor, the excess caustic soda which accumulates in the liquor must be removed. For this purpose, prohably the best means Is calcium chloride (CaCL)". Added to a sulflde-liquor, calcium chloride de- stroys the caustic soda by converting it into common saltr (NaCl), at the same time regenerating caustic lime in ac- cordance with the following equation: CaCL+2NaOH=2NaCl-|-Ca (OH),. The action upon hide of a sulfide-liquor has been ob- served to differ from that of a lime-liquor In one important respect, to wit, that sodium sulfide attacks the keratin of the hair, upon which, on the other hand, lime exerts little or no solvent action. From this it may be inferred that the sweat ducts of the hide, being keratinous in structure, would also be dissolved by treatment with sulfide-liquor; a "straight" liming treatment, on the other hand, would leave the sweat ducts intact in the hide. Analytical Control. The following considerations >■■ The reaction is as follows: ra(OH),-f2.\aOII-f2NaSn=Ca(SH)2-|-4XaOH. The fouvcrsion of the lime into the strong alkali, caustic soda, explains the increased swelling and plumping action exhitiited by a lime-snlHde mixture. »« Loc. Cit. "Or. the ratio in which these groups are found to exist in the material, sodium sulfide. " Payne-Pullman Process. In practise, one part of calcium chloride to three parts of crystallized sodium sulfide are employed. 18 NATURE AND CONTROL OF TANNERY PROCESSES ilors for I^eatl A Supplementary Text-Book on Leather Dyeing Every leather dyer should have his copy of "Colors for Leather." This loose-leaf volume describes those Du Pont Dyestuffs w^hich are suitable for the dyeing of leather. Complete directions for application, with samples showing the results obtainable, are given for each dyestuff. E. I. du Pont de Nemours & Co., Inc. Dyestuffs Department WILMINGTON. DELAWARE Branch Offices New York Boston Proviilenfe l*liiladel]>lua Chicago rliarlotte, N. C. STANDARD ^VE5TLJFF3^ ^^N gFORMl^^ W^ NATURE AND CONTROL OF TANNERY PROCESSES 19 should govern the procedure employed for the analytical control of any particular form of the liming process": (1) That the "alkalinity" of a pure lime-liquor in con- tact with solid lime remains at a practically con- stant point throughout the liming treatment'; thus, the alkali-content of iifty cubic centimeters of a saturated lime-solution, measured at 60° Fahrenheit, will be found to correspond to 23.6 cubic centimeters of a tenth-normal acid solu- tion. A higher figure will indicate the presence of one or more of the "stronger" bases, viz., caus- tic potash or soda; a lower figure, on the other hand, may mean (a) that the liquor holds in solution "neutral" salts, or decomposition-products of hide-sub stance and lime, or both, or (b) that the liquor contains tion with lime, or in combma- (c) that the liquor has been insufficiently agitated. (2) That the influence of ammonia, formed by the action of lime and bacteria upon the dissolved organic-matter, is positively detrimental. Where the conservation of hide-substance is of any im- portance, a lime-liquor that has become strongly ammoniacal through repeated use had best be drained into the sewer. (3) That dissolved organic-matter accumulating in the liquors consists of both epidermal matter (which it is the function of lime to remove from the hides), and portions of the hide itself. In the absence of analytical means permitting the differentiation of the products of the normal action of the lime, on the one hand, from the dissolved hide-fibres, on the other. It will be evident that the estimation of dissolved organic-matter in lime-liquors is of limited usefulness only. For control purposes, however, the quantity of or- ganic matter normally dissolved by the liquors under any given set of conditions during the lim- ing treatment may be determined, and losses of hide-substance made possible of detection, by any Increase which the value thus established may show In subsequent runs. (4) That the unhairing power of a lime-liquor in- creases with the age of the liquor, the age of the liquor, in turn, being measured by the amount of ammonia and dissolved organic-matter which it contains. (5) That the unhairing power of a sulfide-liquor, or a sulfide-lime liquor, depends principally on two factors, viz.: (a) the strength of the liquor in terms of sulfide (SH); and (b) the proportion of sulfide to alkali (SH : OH) present. In the analysis of siilfide-liquors, therefore, the im- portant determinations to be carried out are (1) Sulfide as NRjS" and (2) Alkali in combination with the sulfide-" WASHING OF LIMED HIDES The first step In the removal of lime fi'om the hides " See "Tlie Determination of Alkaline SuUiiles in Lime Liquors."— Fiui G. A. Enna.— Jour. S. L. T. C, 5, 131 (1921). M sge "The Analysis of Lime Liquors."— Donald Burton— Loc consists in washing the limed goods, after unhairing and fleshing, for a period of one-half hour or longer, in a re- volving wheel supplied with a stream of water. The maximum washing effect is gained (1) when the water used Is quite free from "temporary hardness." and (2) when the temperature of the water is kept at the proper (or "optimum") point. The effect of "temporary hardness" (consisting of calcium and magnesium bioarbonates dissolved in the water) is exceedingly detrimental. In tlie presence of "temporary hardness," the caustic lime, with which the hides are impregnated. Is immediately converted into in- soluble calciium carbonate (chalk); once formed in the hides, calcium carbonate cannot be removed by further washing, but will require an acid treatment for its re- moval. The question of what is the most effective temperature of the wash-water cannot, in the absence of specific data, be answered definitely. 'WTiile it is true tliat cold water will dissolve more lime than warm water, it must be re- membered that cold water will also produce the greater swelling of the hide, and by thus allowing the hide to re- tain more lime-liquor, the action of oold water is to actual- ly decrease the effectiveness of the washing. The choice of temperature, hence, would appear to be one of compro- mise, and luke-warm water, it would seem, should remove in a given space of time the greatest quantity of lime from the hides. The passage of the limed hides througli the unhairing and fleshing machines serves to rid the goods of about thirty-five per cent of the lime; another thirty per cent, is dissolved out during the one-half hour period of washing, the lime-content of the washed hides being thus reduced to about thirty-five per cent of the original amount. HIDES and SKINS FOREIGN AND DOMESTIC E. F. CASsIdY & CO. 1 70 SUMMER ST. BOSTON, MASS. HIDES AND SKINS Careful Selections — Satisfactory Service U. S. BROKERAGE CO. H. J. ElSENDRATH GEO. H. ELLIOTT 130 N. Wells St., Chicago 20 NATURE AND CONTROL OF TANNERY PROCESSES B:(III!TIimi!TIIIIII!!!I!!I!I!T!I!IITII!IIITtI!TmTiq KAFCO As Good on Calfskin as Wax Enamel is on Sheep You are Not "Painting" Your Kidskins When You Use KIDCO application of all on Finishes gladly sent request. WAX ENAMEL An Excellent Finish for "Blotchy" Skins feiiiiiinnmiii i iiiiiiiiiiiii n iiiiiiiiiiiim^^ Established 1848 D. LOVEJOY & SON LOWELL, MASS. ANDERSON, IND. NEW ORLEANS, LA. High Grade Knives of Every Description FOR THE SHOE TRADE All Kinds of MACHINE KNIVES for Shoe Factories. Cut Sole Fac- tories, Wood Heel Factories, etc., are made by this, the oldest plant manufacturing machine knives ex- clusively. Try our DOUBLE BEVEL SPLITTING KNIVES all lengths and sizes; also knives for counter cutting machine — or send to us for anything required in Machine Knives. FOR THE LEATHER TRADE We have full line for Tanneries — Belt Knives, Union Splitting Knives. Shaving and Fleshing Blades. Bark Mill Knives. CHIPPER AND HOG KNIVES etc. High Quality, Reasonable Prices and Prompt Shipments As- sured. BELT KNIVES Write foe Catalog E and full particulars NATURE AND CONTROL OF TANNERY PROCESSES 21 Dclimin^ and Bating The final beamhouse operation, by which the last ot tho non-essential portions of the hide are removed, and the hides are made ready for tanning, Is that of bating. Bating has for its object ", ": (1) The reduction of the swelling of the limed hides. (2) The digestion (a) of the elastin fibres present in the outer layers of the hides, and (b) of the cementing substance surrounding the fibres of the main body of the hide. In the present-day production of chrome-tanned upper leather, deliming and bating are generally carried out In one operation by the use of some proprietary preparation of the tj-pe of "Oropon," of which the active ingredients are (1) ammonium chloride ("Sal Ammoniac"), and (2) the digestive principle (tryptic enzymes) extracted from the pancreas of hogs and cattle. The reduction, in the first place, of the swelling of the hides is of prime importance, for hard leather would otherwise result were the hides tanned in a swollen state ". The first essential of bating, therefore, is the removal of the caustic lime producing the swelling, and this is brought about by the chemical action of the ammonium chloride present in the bating material. Ammonium chloride finds preference over a host of other deliming materials be- cause (1) (3) it foi-ros with caustic lime one of the few lime- salts that are readily soluble in water, namely, calcium chloride; its base, namely ammonia, which is set free by the action of the lime, is known to produce less swelling of hide than any other alkali, and ammonia can, moreover, be readily washed out of hide: ammonium chloride is comparatively low in cost. The fact should be stated, however, that ammonium chloride will not attack any calcium carbonate that may have been formed in the hide by the action of "hard" water, if the latter was employed in the washing of the limed goods. Calcium carbonate, however, being a "neu- tral" substance, has no swelling power, and may be con- veniently left in the goods until these are placed into the pickle, when, by the solvent action of the acid liquor, the hide win be freed of the carbonate. So far, tlie purely chemical action of the bate in re- moving the lime from the hides has received mention. True "bating," however, commences when the digestive principles in the form of the pancreatic enzymes contained in the bate-liquor begin to act upon, and to dissolve the " "The Mechanism of Bating." — John Arthur Wilson — Jour. Ind. Eng. Chem., 12. 1087 (1920). " "The Removal of Elastin During Bating."— Robert H. Mar- riott—Jour, S. L. T. C, 5, 280 (1921). " Cf. Sole Leather, which receives no bating. elastin fibres present in the outer layers of the hide. The elastin fibres form the chief support of th grain structure of the lilde, and their slow removal causes the grain-mem- brane to gradually collapse, producing what is known as the "hated-effect." The hide thus becomes flaccid — a de- sirable condition, from the standpoint of the tanner, as productive of "silky-grained" leather. A further function of bating, however, has been described by Robert H. Mar^ riott '-' to consist in dissolving the cementing substance surrounding tlie fibres of the main body of the hide. A portion of this cementing substance is removed during liming, and the effect of its complete removal by tlie sub- sequent action of the bate would be to cause the hide- structure to fall together a little, — thus contributing to the "bated-effect" as a whole. The last-described action would e.xplain the characteristic effect which bating has upon the appearance of the grain-side of the hide, the grain showing up pix)minently once the liair-holes and sweat- ducts thereon have been opened up and cleared ot gummy matter. In the modem short-time method of bating with arti- ficial materials, destructive tendencies — well-known as a feature of the earlier drug bates — may be said to scarcely enter. Indeed, it is to be questioned whether any true "bated-effect" at all is gained during the extremely short period in which the hides are left, for instance. In an "Oro- pon"-liquor. Wilson ■'■■ has thus shown that in order to de- prive a calf-skin of its elastin fibres it must be digested for a period of twenty-four hours in a liquor containing trypsin. That the action of the modern bate-liquor is practically confined to that of the ammonium chloride present in re- moving lime from, and in reducing the swelling of the hide, seems, therefore, most likely. Analytical Control. The actual measurement of the "bating-power" of a bate-liquor cannot be performed by any simple means. For this reason, the analytical control of the bating process is but seldom practised; the delim- ing power of a fresh or used bate-liquor, however, may be readily ascertained by chemical analysis. In the beam- house, the test for the presence of caustic lime remaining in the bated hides may be conveniently made by moisten- ing a freshly-cut edge of the hide with phenol-phthalein solution, which will turn red in the presence of the free alkali. " Loc. Cit. " Loc. Cit. WALTER S. LAPHAM Foreign and Domestic HIDES I Park Row New York ALBERT HEYMANN & CO. 41 PARK ROW NEW YORK FOREIGN HIDES AND SKINS 22 NATURE AND CONTROL OF TANNERY PROCESSES ! i YOUR GUARANTE E | j - ^ ^ j I i Weighed and Selected by j I i i Wm. Harkin & Sons | I i [ "We Tell You WHAT You're Getting!" j i ! I Let Harkin Weigh and Select I I Your Hides! | j In addition to giving you absolutely true and faithful j I weight, we file also a statement as to the contents which j j will prove of real value to you. j ! i I Such information on Dry and Green Salted Hides as j "average run of weight," "quality," "condition," I "plumpness," "appraising of damaged shipments," etc. | Do not be satisfied with simple weighing — know what is Wm. Harkin & Sons Members of the Custom House Entries 61 Beekman St., New York I the condition of your shipment. ! Oldest established selectors, arbitrators, and attested city | I w^eighers of hides in New^ York. | i I I — — — I ! \ I Association of American Weighmasters, Inc. and Forwarding | j fflli7aiiTfliinili^lrrffirr^iniirBlT7TTlrrffl?nili7^li?^lg^lff^lff^li7^ NATURE AND CONTROL OF TANNERY PROCESSES 23 Method of Ascertaining Weight of Dry Leather-Forming Substance in Wet Hides ' At the conclusion of one or another of tlie various beamhouse processes, it is often desirable to know the actual weight of dry leather-forming substance In the raw material, and consequently, the maximum weight of leather whieh the material may be expected to yield. Calculation of the dry weight from the weights of the soaked or limed hides leads to variable figures by reason of the variability of the swelling of the hides in practise, while actual drying and weighing of portions of the hide-material itself is im- practicable on account of the impossibility of getting really average samples. The method to be described is an old one, but is given here for the benefit of those who may not know of its ex- istence. The method consdsts in weighing the wet hide while it is totally immersed in water. The hide is sus- pended from the arm of a delicate balance (of ten to fif- teen pounds capacity) by means of a thin copper wire into the water contained in a pit deep enough to allow the hide to hang free from contact with the sides or bottom, and its weight in this position is then noted. The weight in water of the hide multiplied by 3.38 will be found to equal the average weight of the hide when perfectly dry. By subtracting the dry weight thus obtained from the original wet weight, a true measure is obtained of the amount of swelling which the hide has undergone. PlgttT* A. 7«rttoal 301 ■^^g#~" Srcat DDota Hftlr 3h«athe Braotoroa pill oraln Uembrace •■••' ^^l^r- Pi-oct 'Leather Laborat Book" The Pickling Process Next in order after bating comes the pickling of the hides. Pickling serves a two-fold purpose: viz., (1) it removes from the hide any lime remaining in the form of calcium carbonate. t2) it imparts to the hide just out of the alkaline bate-liquor an acid charge, making the hide re- ceptive to the subsequent entrance of the acid chrome-tanning liquor by thus preventing the precipitation of basic chrome on the surface of the hide. Pickling is, in a stprfi sense, a part of the chrome- tanning process, or, at least, a prerequisite of it. Pickling consists in paddling or drumming the bated goods for an average period of twelve hours in a one-half to one per cent, solution of some moderately strong acid, the solu- tion containing, besides the acid, a large proportion (e. g., ten per cent.) of common salt. Almost any acid will do, but sulfuric acid is preferred on account of its low cost. Using sulfuric acid, then, in the presence of an excess of com- mon salt, the composition of the finished pickle-liquor will include the following substances: viz.. (a) Common salt, as NaCl; (b) Glauber's Salt, as Na^SO.; and (c) hydrochloric acid as HCl, the sulfuric acid originally used disappearing from the liquor after combining with the common salt present to form Glauber's Salt, and releasing its equivalent of hydro- chloric acid, according to the following equation: H.SO,+2NaCl=iNa2SO.-f2HCl. The action of tlie pickle-liquor in removing from the hides any lime remaining in the form of calcium carbonate depends on that of the hydrochloric acid present, hy which the insoluble calcium carbonate is converted into soluble calcium chloride. Apropos of the second and principal function of the pickling process, namely, that of imparting to the hide an acid charge, it should be stated, first of all, that hide-sub- stance is amphoteric by nature; i. e., hide-substance is capable of acting either as a weak base, or as a weak acid. Hide-substance, therefore, will combine with either acids or alkalies to the accompaniment of- swelling. Now, just as the swelling produced by alkalies is known to be due to the "active" hydroxyl, or OH-groups released by them, so is the swelling produced by acids due to the "active" hydrogen, or H-groups, common to all acids. The swelling of hide produced by alkalies, on the one hand, and by acids, on the other, is similar in all respects save one; namely, that while alkaline-swelling is accompanied by more or less plumping (or, increase in elasticity) of the hide, acid-swelling is attended by little or no plumping. In the pickling process, however, the object is not to swell tlie hide, but merely to impart to it an acid charge. Now, it is known that the degree of swelling is proportional NATURE AND CONTROL OF TANNERY PROCESSES The New SHERIDAN PRESS Revolutionizes the Finishing of Leather 9 EF PRESS Built With or Without Automatic Conveyor The double impression leather cam. which first heats and then presses the leather, materially improves the appearance of the finished leather, and produces much higher selections than possible on any other press. I ^PFFD I ^^ "^ speed of lo to 14 im- I C4C'C'T"vl Equipped with the best and most I 01 hhU I pressions per minute, our 1"-^''^ ^ ^ I up-to-date friction clutch under ab- solute control at all times. With this type of con- struction, it is impractical for the operator to get his hands under the head of the press. automatic conveyor, with quick return motion, gives an enormous output, with only one operator. THE PRESSURE INDICATOR shows at all times the pressure obtained, and acts as an ad- ditional insurance against the danger of breaking press. The AUTOMATIC TEMPERATURE CONTROL and RECORDING THERMOMETER guarantees at all times the uniform heating of the head, also records and insures the exact heat obtained on the ironing or graining plate. T. W. & C. B. SHERIDAN CO. KSTABLISHED 18,S5 OFFICES AND SALESROOMS 009 SO. CLARK STRKKT ath" tannage finds application In the production of inner-sole splits and linings, glove- leathers, etc.— in general, whenever a soft leather is required. In the "one-bath" process of chrome-tanning, the chrome is not reduced within the hide, but is present in already-reduced form in the liquor in which tlie hide is tanned. A "one-bath" chrome-liquor is, therefore, green or violet in color. The principle of "one-bath" tanning de- pends upon the impregnation of the pickled hides by a solution of chromic sulfate (or. rarely, chromic chloride), which is acid at first, but later in the process is made "basic" (i. e., reduced in acidity) in order to "fix," or render insoluble, the chrome compound absorbed by the hides. "One-bath" chrome-liquors are prepared, either (1) by dissolving in water some proprietai-y preparation in dry form of tlie type of "Tanolin," (the latter consisting of basic chromic sulfate in admixture with sodium sulfate and other substances), or (2) by "reducing" a dichromate- Eulfuric-acid solution prepared in the tannery with (a) sodium thiosulphate; or with (b) sodium bisulfite (NaHSOj) ; or with (c) gaseous sulfur dioxide (SOj); or w^th (d) cane sugar, or glucose; or with (e) glycerine; or with (f) a mixture of two or more of the aforenamed sub- stances. When the reduction of the dichromate-acid solution Is effected by means of the first substance, namely sodium thiosulfate, free sulfur is formed, and will remain sus- pended in the finished liquor; sodium bisulfite and gaseous sulfur dioxide, on the other hand, yield chrome-liquors that are free from sulfur, such liquors being used whenever an especially firm, and "tight" leaUier (e. g., "patent" leather) is desired. Cane sugar, glucose, and glycerin, being or- ganic materials, behave in a different manner in contact with the chromic-acid mixture than do the inorganic ma- terials referred to above (as a. b. and c); the chrome, it 28 NATURE AND CONTROL OF TANNERY PROCESSES f IRC ^ LotNo.9875 I SUPREMO i Quebracho Extract ' i RepuWica del Paraguay " Exportacion i Despite the decrease in leather production there is a consistently growing increased demand for — Supremo Brand Quebracho Extract The proof is our production record 1919 6030 tons 1920 ...8527 " 1921 16966 " 1922 25000 '* A record any firm can be proud of What is the answer? SUPREMO BRAND solid ordinary High in Purity — Uniform in Quality — Consistent in Tanning Strength Manufactured and Sold only by International Products Company 120 BROADWAY NEW YORK NATURE AND CONTROL OF TANNERY PROCESSES 29 Is true, becomes reduced as before, but much less heat is evolved la the reaction'", while less than half the quantity of the sugar or glycerin employed is "used-up" (i. e., be- comes oxidized) by the chromic acid, the finished chrome- liquor being usually violet in color. On account of the presence of the excess reducing agent and the aldeliydic- oxidation-products formed by the action of the chromic- acid upon the sugar or glycerin, and also because the chrome in such a liquor is present in modified form, a sugar or glycerin chrome-liquor is "milder" (i. e., less asitringent) in action (also less uniform in composition) than a "hypo" or bisulfite-reduced liquor, and is used prin- cipally in the production of the finer leathers, namely, calf and kip. The color of the reduced chrome-liquor has been described as being either green or violet. Violet chrome- liquor, for instance, may be formed by dissolving any re- duced chrome-salt (e. g., chromic sulfate) in cold water. Green chrome-liquor, on the other hand, may be made, either by dissolving the chrome-salt in hot water, or by heating to boiling the violet solution. Now, in chemical composition, botli the green and violet chrome solutions are identical. The green chrome-liquor, however, is found to produce greater swelling of hide, and to tan more rapidly than the violet liquor. The explanation of this dissim- ilarity in action between the two chrome substances is found in the difference between the dissociation-coeffi- cients of (i. e., in the number of chrome and acid-groups released in solution by) the two substances; thus, the dissociation-coeflicient of the green solution hais been found to be more than ten times that of the violet solu- tion; i. e., more than ten times the number of chrome and acid-groups are released within the green chrome- liquor, than are split from the violet salt in solution. This, therefore, explains the greater activity or "astringency" of "hypo" or bisulfite chrome-liquors which, being formed at boiling temperature, are green in color, than that of sugar or glycerin liquors which having been produced at lower temperatures, are therefore, violet in color. The tanning constituent of "one-bath" chromerliquors, namely chromic sulfate, has been refeiTed to as being present in the liquor in dissociated form; i. e., it exists in the form of its two separated chemical groups. The com- position of these groups, however, is not constant for every kind of chrome-liquor, but varies with the "basicity"" of the liquor. Thus, if the "basicity," as determined by chem- ical analysis, reads, for instance, 0.63, the liquor contains pure chromic sulfate (Cri(S0,)3) only; if the "basicity" is 0.95, the dissolved chrome compound has the compo- sition Cr2(SO,)2(OH)j — known as the "firstrbasic-chromic- sulfate" — this being formed by the addition to the liquor of just the right amount of some alliafine substance (such as caustic soda), of which the effect is to replace one of the SO,, or "acid"-groups in the chromic sulfate with two hydroxyl, or OH-groups derived from the alkali; finally, if the "basicity" of the chrome compound is found to be 1.89, its chemical formula would read Crj(SO,) (OH), — this being known as the "second-basic-chromic-sulfate" — and in this it will be seen that two of the three 90,-groups originally present have been replaced by tour O.H groups from the alkali. Chrome-liquors having intermediate basicity-values consist of a mixture of two, or, possibly, of oven three of the compounds described. Now, as the "basicity" of the chrome substance increases, its solubility in water dimin- ishes; i. e., ^.he more OH or hydroxyl-groups there are added to the chromic sulfate, the less soluble does the lat- ter become. On this extremely valuable property of the chromic compounds does the principle of "onenbath" tan- ning depend. The final chrome-product which would be obtained were all three of the SO,-groups in chromic sul- fate replaced by OH-groups — in other words, were the chromic sulfate completely "neutralized" — is chromic hy- droxide, Cr,(OH)„ — a quite insoluble substance, but one also devoid of tanning properties. Whichever method of preparing a "one-bath" stock- liquor is employed, the tanning liquor made therefrom should contain an amount of chrome equivalent to approxi- mately two per cent of chromic-oxide (CrjOj), or four per cent of sodium bichromate on the drained weight of the pickled hides. Approximately one-third of this amount of chrome is dissolved in the liquor into which the hides are entered, the remaining two-thirds being added in two or four doses at intervals of every hour or half-hour. (AH of the chrome is not added to the liquor at one time, for that would produce too rapid surface-tanning, and so hinder the penetration of the chrome into the interior of the hide.) The "acidity" of the tanning-liquor at the start should be so adjusted that the proportion of chromic-oxide to acid (CrjOj : SO3) is approximately 1:1; in other words, the "basicity" should average 1.00. The concentration (i. e., the "strength") of the liquor, in terms of chromic-oxide, may vary, — in the case of paddle-tanning, from one-half to three-fourths per cent; in that of drum-tanning, from one to one and one-half per cent. In addition to the chrome, the tanning-liquor should contain about one-third pound of common salt, or Glauber's salt, or a mixture of both, to one gallon of the liquor. The specific gravity reading of chrome paddle-liquors may vary from 5° to 9° Baume. From the foregoing it will be noted that the percen- tage of "neutral" salts (viz., common salt and Glauber's salt) dissolved in the tanning-liquor is only about one-half of that required by the pickle-liquor previously described. The immediate effect upon the pickled hides of this re- duced salt-concentration of the chrome-liquor is to cause the hides to swell still further; thus, in practise, where the pickled hides have absorbed sixty-five per cent of pickle-liquor, they will absorb, in addition, during the tanning process ten or twelve per cent of the chrome- liquor. It is of no advantage to have more salt present in the chrome-liquor with the object of retarding this further swelling, for the effect of more salt would be to decrease the rate of tanning, after the manner about to be described. The presence of the chrome, moreover, will prevent too great swelling, for the hides receive a surface- tanning almost as soon as they are placed into the liquor. During the first hour or two in which the hides are in contact with the chrome-liquor, a greater number of acid-groups are removed from solution than chrome-groups. The basicity-value of the liquor is thus caused to rise at first. After this, however, and during the remainder of the tanning period, the relative absorption of the acid and chrome groups becomes reversed, i. e., more chrome than acid-groups are taken out of the liquor, the excess acid- groups then causing the "basicity" of the liquor to fall in value. Now, inasmuch as the rate of tanning is greater the more "basic" the chrome liquor, and vice versa, the effect of the increased acidity of the liquor as the tanning pro- ceeds is to slow up the tannage, and, finally, to stop It altogether. In order to allow tanning to proceed once more, then, the excess acid groups must be removed from solution by neutralizing them with alkali. In the first stage 30 NATURE AND CONTROL OF TANNERY PROCESSES of tanning, i. e., until tlie hides are "struck tlirough" by the chrome liquor, no alkali must be added to the liquor, else the insoluble chrome tanning compound thereby formed is deposited in the surface-layer of the hide, and this would prevent the entrance of the chrome-liquor into the interior of the hide. The addition of alkali to chrome tanning-liquors is, therefore, made about midway in the process, i. e., after the lapse of, say, the first twenty hours of paddle-tanning, or that of the first four hours of drum- tanning. In practise, the amount of alkali (which may be in the form of caustic soda, sodium carbonate, or sodium bicar- bonate,— preferably the latter) that is added to chrome tanning-liquors averages one per cent of the drained weight of the pickled goods. This quantity of alkali is dis- solved in water, and one of four or six equal portions of the solution is added to the tanning-liquor (which must be kept agitated) at an interval of every two hours, or of every hour. For rendering chrome tanning-liquors "basic," the ideal quantity of alkali is one which, when dissolved in the chrome-liquor exactly neutralizes the excess acid- groups released in tanning, and then brings the liquor al- most, but not quite, to the "precipitating-point," i. e., to the point at which the chromic sulfate in solution has com- bined with so many OH-groups as to have become nearly insoluble; for, tanning will proceed at the greatest rate (i. e., the fixation of chrome will be a maximum) when the liquor is almost, but not quite at the "precipitating-point." Now, the "precipitating-point" of a chrome-liquor Is quite independent of the basicity-value of the liquor; in fact, it bears but little relation to the "basicity" in the ordinary sense of this term. The "precipitating-point" — and, hence, the amount of alkali that must be used in order to approach this point— is controlled by at least five variables; these may be summed up as follows: (1) The concentration of the tanning-liquor. (2) The "basicity" of the liquor at the start of opera- tions. (3) The "basicity" of the liquor at the point the alkali is to be added. (4) The percentage of dissolved "neutral" salts in the liquor. (5) The temperature of the tanning-liquor. The concentration of the chrome-liquor affects the "pre- cipitating-point" by causing the chrome to precipitate out sooner the further the liquor is diluted. This is especially true of very "basic" liquors. The nature of this phenome- non is not perfectly understood, but may find explanation of a kind similar to that which accounts for the effect of "neutral" salts upon the action of chrome-liquors (see be- low). The difference between the initial and final basicity- values of the tanning-liquor — showing the extent to which the tannage has progressed — is a measure of the number of excess acid-groups released in solution; the greater this difference (i. e., the more excess acid-groups in solution), therefore, the more alkali will the liquor require. The presence of "neutral" salts in the chrome-liquor affects the "precipitating-point" in a very marked manner. With- out increasing the total acidity — in other words, without lowering the measurable basicity-value — of the liquor, yet in the presence of "neutral" salts, and in proportion thereto, more alkali will be required to bring the liquor to its "precipitating-point" than if no such salts were pres- ent. Wilson and Kern-" account for the effect of dissolved •The Ac :if Ne Upon Chroi Liqr •-Jour "neutral" salts upon chrome tanning, by stating that such salts become "hydrated" in solution (i. e., the salts attach to themselves, or combine with, a certain amount of water) ; by thus lessening the volume of water in which the acid-groups are dissolved, the effect of the salts is to In- crease the acid-concentration of the solution; the effect of more acid, then, is to make the use of a greater quan- tity of alkali necessary. The different "neutral" salts are, however, not all "hydrated" to the same extent; sodium sulfate, for example, has been found to combine with nearly twice the quantity of water that unites itself to sodium chloride, or common salt. To sum up, then, the effect of dissolved salts is to retard the tanning action of the chrome-liquors, and to make the use of comparatively "basic" chrome-liquors possible. Lastly, the influence of temperature upon the alkali-requirement of a chrome-liquor is simply a sequel to the "neutrar'-salts-effect; i. e., the higher the temperature of the tanning-liquor, the less the "hydration" of the salts, and the lower, therefore, the concentration of the acid-groups in the liquor. A warm chrome-liquor, being, in effect, more "basic" than a cold liquor, will, therefore, require less alkali to bring it to the "precipitating-point" than would the cold liquor. To the five variables referred to, another should be added, namely, that of the weight of the pickled goods entering the tanning-liquor. According to the weight of the pack, a greater or less amount of alkali will be required by the chrome-liquor, as more or less acid is introduced by the pickled hides. From what has been written, the fact will be apparent that chrome-tanning liquors can be completely exhausted, or deprived of their chrome-content, — in other words, all the dissolved chrome can be deposited in the hides, — if a sufficient quantity of alkali, added in small doses, and at the proper intervals during tanning be employed. Leather produced in this manner will, however, be of a soft and flexible (i. e., "stretchy") nature, resembling "two-bath"- tanned leather. Such a leather is not well-adapted for use in making shoe-uppers, for which a firm and "tight" leather is more to be preferred. Very "basic" liquors are also known to tan irregularly. Moreover, inasmuch as the swelling of hide, which — other things being equal — is known to take place, not only through the transverse di- mensions, but also throughout the length and breadth of the hide, the more "basic" the chrome-liquor is kept during tanning, the lower will be the yield of leather as measured by the surface area obtained. The foregoing considerations must, hence, be allowed to govern the amount of alkali that is to be used in tanning, and this, in practise, is kept very carefully regulated. Analytical Control. The procedure to be followed in the analytical control of the chrome-tanning process will depend on whether the "two-bath" process, or the "one- bath" process is being used. In "two-bath" tanning, an important requirement is the complete reduction of the chromic-acid absorbed by the goods from the first liquor. To test whether or not the chrome has been completely reduced, the spent liquor, or washings from the wet leather may be treated with dilute acid, potassium iodide, and starch, when a blue color will develop in the presence of unreduced chrome. The quantities of chrome absorbed by the goods, or conversely, those remaining in the spent-liquor, may also be deter- mined by any of the well-known methods. In "one-bath" tanning, each batch of stock chrome- liquor is, first of all, tested for NATURE AND CONTROL OF TANNERY PROCESSES 31 (1) The percentage of chrome, as Cr,0:,; (2) The percentage of acid, as SO3; (3) The basicity-value (found by dividing the percent- age of CnOj by that of the SO3) ; (4) Unreduced chrome (if the liquor was prepared in the tannery by the reduction of a dichromate-acid solution) ; (5) Tbe percentage of "free" sulfur (if the liquor was reduced with sodium thlosulfate, or "hypo.") From the percentage of chrome found by analysis may be calculated the number of pounds of chromic-oxide, or of sodium dichromate, present in every gallon of the liquor; on the basis of this value, then, the number of gallons of the liquor required in the tanning of a given weight of the pickled goods is measured out. Chrome stock-liquors con- taining unreduced chrome should not be used until such liquors have been treated with a further quantity of re- ducing-agent. The routine control of a "one-bath" chrome tanning- liquor in process should include the following determina- tions: viz., (1) That of the quantity of alkali required near the end of the tanning period to bring the liquor to its "precipitating-point"; (2) That of the basicity-value of the spent-liquor, and of the percentages of chrome and acid remaining in the liquor at the end of the tanning period. The quantity of alkali that must be added to the liquor to bring the latter to its "precipitating-point" is most readily determined by titrating a measured volume of the filtered liquor with an alkali-solution, until the "pre- cipitating-point" is caused to appear". A sample of the liquor is withdrawn from the paddle-vat or drum, treated with kaolin, and filtered through paper until perfectly clear; of the filtered liquor, an aliquot is measured out into a flat-bottomed glass dish, the latter placed upon a water-bath and heated until the liquor is of the same tem- perature as that of the liquor in the paddle-vat or drum; the dish is now supported upon a ring-stand placed over a white surface in such a position as to allow the entrance of light from a window through the sides and bottom of the dish; the standard alkali-solution, contained in a burette, is now slowly run into the liquor — which must be kept stirred — until the first appearance of a turbidity that remains per- manent is noted. The number of cubic centimeters of alkali-solution used is read off. and the number of pounds of alkali required by the liquor-contents of the paddle-vat or drum is then calculated on the basis of the known strength of the standard solution, and upon that of the gross volume of the tanning-liquor. The titration of the liquor should preferably be carried out with a pure caustic- soda or borax-solution, and not with a sodium-carbonate or bicarbonate-solution, even where the carbonate or bi- carbonate will be subsequently used for rendering the tan- ning-liquor "basic"; the reason caustic-soda or borax should be used for this purpose is that neither of these substances liberates carbon dioxide (CO2) during the titra- tion, the effect of carbon dioxide — acting in solution as an acid — being to delay the "precipitating-point" of the chrome-liquor beyond the point at which it should occur. The use of sodium carbonate, or bicarbonate, in the tan- ning-liquor, on the other hand, is to be preferred to that of caustic soda, for in this case, the presence of the car- -Douglas Mc- bon dioxide will act as a factor of safety in preventing the possible precipitation of a portion of the chrome in the vat-liquor to which the alkali is being added. The determination of the basicity-value of the spent chrome-liquor, and that of the percentages of chrome and acid remaining in the liquor at the end of the tanning period, are made to show the extent to which the tannage has progressed, as well as to furnish an indication of the quantity of chrome that is run to waste as each paddle-vat or drum is drained of its liquor. In addition to the foregoing determination, the meas- urement of the swelling power of a chrome-liquor may be made — as in the case of pickle-liquors— by means of the electro-metric method, and this will also show the rate of tanning of which the liquor is capable. The percentage of chrome absorbed and fixed by the hides during the usual process of "one-bath" paddle — or drum-tanning is about two-thirds of that initially present in the tanning-liquor. The remaining one-third is, more often than not, run to waste in the "spent" liquor, and as chrome is not an inexpensive substance, the money-loss resulting from this practice will amount to a considerable figure in the course of, say a year's operation. A3 in tho case of a pickle-liquor, however, it is quite practicable to restore a used chrome tanning-liquor to its original strength — merely by the addition of more stock-liquor,— and to use the same liquor repeatedly for, perhaps, ten or more packs of goods. Practical experiments in chrome paddle-tanning" conducted some time ago by the author of this paper have shown that the only variable diflScult of control in the replenishment of chrome liquors is the "neutral" salts-content of the liquors. Thus, during tan- ning, the percentage of common salt, and of Glauber's Salt in the liquor gradually rises, a greater quantity of these salts being always found in the spent-liquor than had been initially used in preparing the fresh liquor. Of course, on entering the pack of pickled goods into the chrome-liquor, the original salt-content of the latter becomes at once in- creased by several hundred pounds; inasmuch, however, as the hides undergo further swelling during tanning, in other words, since the amount of liquor absorbed by the goods is greater after tanning than it was before, it actually hap- pens that a portion of the salts used in preparing the tan- ning-liquor is removed therefrom by the pack of goods. The increase in the salt-content of the liquor after tanning is, therefore, not due to the salts transferred to it by the hides from the pickle-liquor, but is produced, in fact, (1) by the Glauber's Salt present in the stock chrome-liquor from which the tanning-liquor was made, and (2) by the alkali that is subsequently added for the pui'pose of rendering the liquor "basic"; in the latter case, the action of the acid in the tanning-liquor is to neutralize the alkali added thereto, and so produce a further quantity of Glauber's Salt. The Glauber's Salt thus added to a paddle-vat liquor during tanning will amount to, in practise, 75 or 100 pounds. By means of the above-described alkali-titration, however, it is possible, to a great extent, to counteract the effect of the increased salt-concentration of the replenished chrome- liquor, and merely by employing the amount of alkali indi- cated in the titration, to cause the replenished liquor to tan just as rapidly, and quite as uniformly, as a freshly-pre- pared chrome-liquor. The replenishment of a "one-bath" chrome tanning-liquor may be practised with entire success if the following means of control are adopted as a routine measure; viz.. 32 NATURE AND CONTROL OF TANNERY PROCESSES SOLVAY SODA For the Tanning Industry The Solvay Process Company — leaders in the manufacture of AlkaH since 1881 — with plants at Syracuse, N. Y., Detroit, Mich., and Hutchinson, Kansas and with warehouses at all leading shipping points, is in a position to serve the tanning industry in ALKALIES with superior quality and service. A staff of technical men who have studied the tan- ning industry are available, without charge, to help in solving any problems you may have that are effected by alkaH. They have helped many. WING & EVANS, INC. Selling Agents for THE SOLVAY PROCESS CO. Address nearest office or distributor: MING & KVANS. IXC. THE DR.XCKETT CHKMIC.\L, CO. 23 WilUam Street. New York, N. Y. 30 N. Dearborn Street. Chicago, III. 89 State Street, Boston, Mass. 626 Book Building, Detroit, Mich. S31 Fonrth Avenue, Pittsburgh, Fa. Cincinnati, Ohio Cleveland, Ohi Syr N. Y. Cit.v Stocks carried at all principal shipping points. HEADQUARTERS FOR mllH«.M«Jl.J!IJ,».l»lJ!HJlJ,^« AN ILLUSTRATION OF MODERN TANNERY ENGINEERING We build Beamhouse and Tanyard Equip- ment of every descrip- tion — And carry a full line of rebuilt leather working machines. ALEXANDERTRAUD&SONS 126 POLK ST., NEWARK, N. J. 'rniii;Hi¥M'iiiumdAiu NATURE AND CONTROL OF TANNERY PROCESSES 33 Before replenishing the spent-liquor, determine, by analysis, its chrome-content and basicity-value. On the basis of the chrome-content, add enough stock-liquor to restore the strength of the tanning- liquor to its original value; then, to the resulting liquor, add enough alkali to bring the basicity- value of the liquor up to its former point also. Perform the alkali-titration of the tanning-liquor in the usual manner, and at the proper time, and add to the liquor the amount of alkali indicated in the titration. After the passage of three or four packs of goods through the liquor, determine the specific gravity of the latter by means of an hydrometer. If the specific gravity is found to exceed 9° Baume, add enough water to the spent-liquor to reduce the reading to below 9°, determine the chrome-con- tent and basicity-value of the diluted liquor, and proceed as in (2). Method for Finding the Capacity of Tannery Paddle- Vats Tanks and Pits without Resorting to Measurements In routine control-work Involving the analysis of tan- nery-liquors, results are usually expressed in percentage by volume (e. g., in grains per one-hundred cubic centi- meters), or, less frequently. In percentage by weight (e. g., in grams per one-hundred grams, or pounds per one-hun- dred pounds). When the object is to compare the one liquor with another, this manner of expressing analytical results is the only one that allows of comparisons to be made. When, however, it is desired to replenish a given liquor in order that it may be used over again, or where the inventory-value of such a liquor is to be determined, it then becomes necessary to calculate from the analysis the total number of pounds that the liquor contains of lime, or salt, or acid, or chrome, — as the case may be. In order to arrive at these values, then, the gross volume of liquor that is being dealt with must be known, — in other words, the capacity in gallons or in pounds of the vat or drum holding the liquor must first be determined. In the case of square pits, or cylindrical drums or tanks having plane ends, it is, of course, a simple matter to find the volume or capacity of these, merely by obtaining certain dimen- sions of the vessel, and then multiplying these together. On account of the irregular shape of paddle-vats, however, the finding of their capacity by geometric means is a com- plex problem, involving the use of calculus. The following simple method has been devised by the author, and used by him with considerable success for the calibration — by analytical means, instead of by measure- ment — the liquor-contents of tannery paddle-vats. The first requirement is that the position of the water-line within the vat that is to be calibrated be fixed with respect to the height at which the vat, when placed into use, will be filled with liquor. Wooden strips marking the water-line are therefore nailed around the inside walls of the vat, and in all subsequent operations the volume of the liquor is kept constant by always bringing the latter to a level with the upper end of the wooden marking-strips referred to. The calibration of the vat is then performed in the following manner: The vat is filled with water to the level of the water-line, and a quantity (in the proportion of approxi- mately ten pounds to 2,000 gallons) of sulfuric acid (or any soluble acid, salt, or alkali, of known percentage purity, and whose recovery from solution may be quantitatively effected) is added, allowed to dissolve, and the solution thoroughly mixed by plunging it (say, for five minutes, by hand), or by other effective means. A sample (1) of the acid-liquor thus prepared is withdrawn and set aside. To the contents of the vat is now added a second portion of two or three times the quantity of acid originally given, this portion being, however, accurately weighed to within two per cent, the acid allowed to dissolve, and the liquor again thoroughly mixed; of the acid-solution in the vat, a second sample (2) is withdrawn and set aside. The second addition of acid is followed by a third of the same, or a larger quantity, the same degree of accuracy being ob- served in weighing, and a third sample (3) is taken of the acid-liquor in the vat. Fifty-cubic-centimeter aliquots of the different samples are now titrated with a tenth-normal alkali-solution, and the acid values thus found are ex- pressed in grams — 100 cubic-centimeters of sulfuric acid (HjSO.) present in each sample. The volume of the liquor in the vat is calculated in the following manner: Letting A, B and O equal the g/lOOcc of HjSO, found in samples (1), (2) and (3), respectively; and L', and L" the weight in pounds of sulfuric acid added to the liquor the second and third times, respectively; and P the percentage strength (correct to the first decimal) of the acid used; and G the volume in U. S., gallons of liquor in the vat; then, inasmuch as 11.983 g/lOOcc are equivalent to one- pound/gallon, G will equal L,' x P x 11.983 I: B— A or (check), G will equal L" x P x 11.983 II. C— B If the capacity of the vat thus obtained is found to be in the vicinity of 2,000 gallons, the results of equations I and II should check to within fifteen gallons, the accuracy of the foregoing method having been found to be 99.2 per cent. NATURE AND CONTROL OF TANNERY PROCESSES 3^ -with apoloqies to jXndrew Jet^c^ens Co. GET IT THIS WAY Firsl tan-— chrome Second lan-QUERMOS Ask us to show you how to use QUERMOS to get rich, fast colors, and a velvety finish that your customer **loves to touch." C. A. SPENCER & SON CO. 183 ESSEX ST., BOSTON NATURE AND CONTROL OF TANNERY PROCESSES Rctanning of Chrome Leather 35 The object of retanning chrome-leather is to complete the tanning of the goods. In the production of combination- tanned leather (i. e., of leather tanned with both chrome and vegetable materials), the purpose of retanning is two- fold; viz., (1) To complete the tannage, and (2) To impart to the resulting leather the appearance and character of vegetable-tanned leather. By reason of the peculiar nature of "one-bath" chrome- tannage, it is practically impossible to produce fully-tanned leather by this process without leaving the goods in con- tact with the liquor for an excessive length of time, or without the use of an excessive amount of alkali, the effect of which is to render the leather soft. Because of this ten- dency of a "one-bath" chrome-liquor to produce soft leather when caused to yield all of its chrome to the hide, such a liquor is never allowed to become completely exhausted during tanning. Instead, at the conclusion of the allotted period in which the goods are in contact with the liquor. the goods are moved into a fresh chrome-liquor, and al- lowed to absorb a further amount of chrome, the latter be- ing subsequently "fixed" by the use of alkali in the manner already described under "The Chrome Tanning Process." Chrome-retanning is unusually carried out in a drum by the use of a "one-bath" liquor, of which the percentage- strength is about one-half of that employed for the initial tanning-liquor. The quantity of alkali used is proportion- ately less, and the period of retanning is usually about one hour. After retanning, the wet leather is piled for a period of several days on the floor, the piles being covered with burlap for the puri)ose of preventing the goods from becom- ing dry. During the time in which the leather is left thus, the greater portion of the dissolved chrome in the liquor held by the goods will unite with the leather (i.e., the chrome will become "fixed"), the additional tannage thus produced (amounting, in practise, to about 70 per cent of the available chrome present) causing the absorbed liquor to become quite acid in reaction. 'Neutralizing'' of Chrome Tanned Leather The final step of the "one-bath" chrome-tanning process consists in neutralising the excess acid released in tanning. The object of "neutralising" chrome-tanned leather, then, is ll) To render the chrome-substance deposited in the hide still more "basic", thus making the tannage quite stable and permanent; and (2) To prepare the leather for the subsequent fat- liquoring process by removing the excess acid referred to, together with the soluble chrome- salts remaining in the leather. The name "neutralisation," as applied to this final step of chrome-tanning, is a misnomer. The object in treating the chromed hides with alkaline solutions is not to neutralise the leather itself, but merely to reduce the "acidity" of the leather. "Neutralisation" is, therefore, a somewhat delicate operation; if carried too far, it would result in a portion of the chrome-substance in the hide being converted into chromic hydroxide, — a substance known to possess no tanning power. The foregoing cir- cumstance obviously excludes the use of any of the "stronger" alkalies, such as caustic soda, or even soda ash, in the neutralisation-treatment, for, even in very di- lute solution, any strong alkali would carry the neutralisa- tion of the surface of the leather too far before the interior was thoroughly penetrated. In practise, "neutralisation" of chrome-leather is ef- fected by the use of borax, or some equally mild alkali. The chromed hides are first washed in a drum with water, which serves to remove the greater portion of the acid and uncombined chrome-salts. The leather is then drummed in a one-half percent solution of the alkali (of which, in the case of borax, up to three per cent on the weight of the chromed stock may be given) until the desired degree of "neutralisation" is obtained. Probably the safest method of "neutralising" chrome- leather is that of Stiasny. of which method brief mention may here be made. In the method of Stiasny, the leather is paddled or drummed in a solution of ammonium sulfate (NHJ.SO.) and soda crystals (NaOH+Na,CO,). This is equivalent to, but cheaper than using a mixture of am- monium sulfate and ammonia, the soda in the former case reacting immediately with the ammonium salt and liberat- ing ammonia in accordance with the following equation: (NHj),SOj-!-2NaOH = 2NH,+Na.,SO,+2H..O. The ammonia thus set free combines with the excess acid in the leather, while the presence of the "neutral" salt Na^SO,, simultaneously formed, so reduces the already feeble dissociation of the ammonia, that by varying the concentration and proportion of these materials, the "neutralisation" may be exactly regulated to the required extent'". Analytical Control. The percentage of "free" acid remaining in the leather after "neutralising" may be deter- mined by digesting in water a weighed portion of the finely-divided leather, and titrating the resulting extract with a standard alkali-solution. Absolute results cannot, however, be obtained by any such method, for it must be remembered that the chrome-substance in the hide will continue to yield a portion of its combined acid so long as the leather is in contact with water. For control purposes, however, the results will be relative if the proportion of leather to water, the temperature of the latter, and the time of digestion be kept constant. A more accurate idea of the extent of the neutralisa- tion is obtained from the "basicity" of the chrome-sub- stance in the leather, found by determining the percent- ages of both chrome (as CnO;,) and total acid (as SO^) by the fusion method, and then dividing the one result by the other. In most cases it will be found sufficient to test for the -11. R. Profter.-Luc'. Cit. NATURE AND CONTROL OF TANNERY PROCESSES iiiiiiiiiiii;iiiiiiiiiiiiii{iiiiiiiiiiii!ii!iiiiiiiiiiiiiiiiii!niui!iiii ATISFACTORY fat-liquoring results are obtained only by using the best oils. We recommend any of the following materials as being particularly adapted to imparting to the leather those re- quirements most especially desired. Sulphonated Oils Moellon Degras Neatsfoot Oils Potash Soap Curriers' Greases SALEM OIL & GREASE CO. SALEM, MASS. ill nil iiiiiiiiiiiiiiir BASE -h FINISH = ? Let us help you with this problem First — Send us some pieces of your unfinished base, and, if possible. Second — Send us a finished piece of the color desired. We will send you the right finish to get the right results. TANNERS AND CURRIERS WHITTEMORE— WOODBURY'S COLORED PIGMENT FINISHES FOR GLAZING Pigment Finishes in the various Colors for CALF. SIDE. SHEEP and GOAT LEATHERS. Where a Glazed Finish is desired our Pigment Finishes are easily the best. We would be pleased to furnish samples. WHITTEMORE -WOODBURY CO. 412 MEDFORD STREET, CHARLESTOWN, MASS. IP wmm NATURE AND CONTROL OF TANNERY PROCESSES 37 "degree" of acidity in the "neutralised" leather by deter- mining the reaction of the wash-liquor in which the "neu- tralisation" was effected. The spent liquor should in all cases show a neutral, or an acid reaction to methyl-orange indicator, showing that the neutralisation-treatment has not been carried too far. After the leather has been "neutralised." cuttings from the neck and butt portions are immersed in boiling water for a period of five minutes. If fully tanned, the leather will show no loss of pliability at the conclusion of the boiling period; if, on the other hand, the leather has been insufficiently tanned, the action of the boiling water will cause the cuttings to .shrink and curl up, and to be- come "horny" when dry. Chrome-leather should not be undertanned. The best chrome leathers contain from four to five per cent of chromic-oxide (CrjOj). Well-filled leather is obtained by keeping the chrome tanning-liquor as nearly neutral (i. e., as "basic") as possible. The more a leather is tanned, the more fat-liquor will it require, and the better will be the penetration. The heavier the leather is tanned, the less "stretch" will it give, and the more resistant to friction will it be ■■'°. nefects."— A. Seymour- Jones— Lentlief Trades Kev April 11)15. The Fat Liquoring Process The purpose of fat-liquoring chrome-tanned leather is three-fold; namely, (1) To restore to the leather the oils or fats removed from the hide in the beamhouse processes, and thus to prevent the leather from becoming hard and "cracky" when dry; (2) To increase the tensile strength of the leather; (3) To render the leather wholly, or partially water- resistant. In the case of chrome-leather, the fact is well-known that before it has received a small quantity of oil, chrome- leather cannot be "wetted-back" again (i. e., the leather becomes water repellent) once it has been allowed to dry out. Fat-liquoring is merely a special form of applying oil to leather, the oil being given in the form of a water-emul- sion to the wet leather. The advantage of employing a water-emulsion of the oil, instead of applying the oil in its natural form to the dry leather, is that, in the former case, a small quantity of oil suffices to render the leather soft and flexible, while to produce the same effect with dry leather, a much greater quantity of oil would have to be applied. The reason that this is the case will be stated below. Pat-liquoring renders leather soft, and increases its tensile strength by lubricating and separating the fibres of the leather. The principal effect of the oil is, in fact, the separation of the fibres composing the leather, for it has been shown that the tensile strength of degreased leather, — while less than that of the leather with its fat-liquor left in. — is always greater than that of the leather before it has received any fat-liquor". Fat-liquoring, therefore, alters the fibrous structure of leather. The more oil in the form of fat-liquor that is incorporated with the leather, the more water-resistant, and the greater will be the ten- sile strength of the leather. All natural oils may be caused to emulsify (i. e., may be caused to mix with water) by several means. The first requirement is that the oil be broken up into small par- ticles (or, globules), which, in practise, is effected me- chanically by vigorous shaking or agitating. The "break- ingup" of the oil must be effected in the presence of an "emulsifying-agent," which may consist of any water-solu- ble colloid, such as " Thus, in the production of "patent" leather, the common practise is to degrease the le.nther after fat-liquoring, and before applying the varnish. (1) Gum acacia, gum tragacanth, "Tragasol," "Irish Moss," etc.; (2) Albumin, casein, or gelatin; (3) Sulfonated oil; (4) Soft, or hard soap; (5) Wool fat, or degras, of which the effect is to form a film around the oil-globules, and so prevent these from "running together" (or, coalesc- ing). Milk may be cited as a typical emulsion. In milk, butter-fat is held in water-suspension by the action of the dissolved casein, the casein preventing the fat-globules from rising to the surface. The readiness with which an oil may be "broken-up," or emulsified, depends principally upon its surface tension (i.e., upon the natui-al force which keeps the molecules composing liquids from repelling each other) ; the lower the surface tension of the oil, the more readily is it emulsi- fied, and the more permanent is the emulsion. Neatsfoot, linseed and olive oils are more easily emulsified, and form more stable emulsions than either castor oil or mineral oil, because, of the oils in the first-named group, the sur- face tension is only about one-half of that of castor oil or mineral oil. True emulsions are characterised as being more viscous (i. e., less "fluid") than the oils from which they are made. Emulsified oils penetrate wet leather more uniformly, and are absorbed more rapidly than natural oils are absorbed by dry leather, because the surface tension between oil and water is less than that between oil and air. Just as the oil having the lower surface tension emul- sifies the more readily (i. e., produces the finer particles), so will such an oil penetrate wet leather most rapidly. The effect of increased temperature is that of lowering the surface tension of oils; hence, the higher the temperature employed in the fat-liquoring process, the more uniform and rapid will be the absorption of the oil by the leather. In general, the oils most suitable for treating leather are those of the "semi-drying," or "non-drying" variety (i. e., oils which do not tend to harden or solidify on exposure to air). Oils of the "semi-drying" variety are castor, neats- foot, and olive; of the "non-drying" oils, ordinary mineral, or paraffin oil is an example. Fish (e. g., cod or menhaden) oils belong to the class of "drying" oils; the latter, — being subject to atmospheric oxidation and hardening, — are, for this reason, not so well adapted as the oils in the first- named groups for the purpose of softening and nourish- ing leather. The disadvantage of neatsfoot oil is that — 38 NATURE AND CONTROL OF TANNERY PROCESSES THE LIQUOR IN YOUR CELLAR In the fat liquor Drum hangs the fate of your leathers. Good mellow leather, soft, evenly penetrated, bright colors, and perfect gloss, absolutely free from grease, gum and spue come from using our specially treated oils and fat liquors instead of the ordinary kind. For 25 years tanners have depended on them, and competitors have vainly tried to make something as good as our TREATED COD OILS and TREATED NEATS- FOOT OILS, which run ABSOLUTELY UNIFORM. Write us that you are interested in getting better results, and in saving time and money. Ask us to send literature, samples or salesman — Which? SECCOMB-KEHEW- BRADLEY COMPANY Office 10 Post Office Sq. Boston Established 1854 Factory Maiden, Mass. SULPHONATED OILS CASTOR AND COD FAT LIQUORS BLENDED TO MEET EVERY REQUIREMENT JOHN SHAW & CO. Manufacturing Chemists 15 ELKINS STREET - - - - SO. BOSTON, MASS. ESTABLISHED ISfiO NATURE AND CONTROL OF TANNERY PROCESSES unless very carefully "col(l-presseci"~it tends to form "spue" on the surface of the finished leather with which it is incorporated. Mineral, or paraffin oils are quite inert substances; while lacking the nourishing and filling prop- erties of castor, neatsfoot, and olive oils, mineral oils may, however, be freely and safely employed in the f:il-li(ninriiis of leather, provided, always, they can first be brought into the form of a stable emulsion. For use in fat-liquor, preference should be given to the heavier grades of min- eral oil (e. g., those having specific gravities at 60° Fahren- heit of .88 to .92); on account of the fact that the lighter mineral oils are more or less volatile (i. e., tending to evaporate) at ordinary temperatures, the use of these is best confined to the "oiling-off" of the grain-surface pre- paratory to the glazing of the finished leather. Degras is the oxidation-product of cod-liver oil, formed in the "chamoising" of sheep-skins, while wool-fat, or cnide lanolin, is a natural wax extracted from raw wool. From crude wool-fat is obtained, by distillation, a liquid wax known as "oleine." The emulsifying property of these substances is shown by their capacity to mix with large volumes of water. In addition, however, to being excel- lent oil-emulsifiers, degras, wool-fat, and oleine possess in themselves filling and nourishing qualities in a high de- gree when used upon leather in the form of fat-liquor, either alone, or in combination with one or more of the natural oils. Within very narrow limits only does the color of the oil, or oils used in the fat-liquoring process determine the color of the leather. The color which the fat-liquored leather will assume depends on the amount of oil that is left in the surface-layer of the leather; in other words, the better the penetration of the fat-liquor into the interior, the lighter will be the color of the leather, and vice versa. Of the different emulsifying-agents cited above, the effect of water-soluble gums and protein-substances (see 1, and 2 in the list) is not only to form a protective coat- ing around the oil-globules, but also to counteract the up- ward movement of the oil-globules due to the force of gravity. Gums and proteins, however, have the disadvan- tage of decomposing In solution rather easily, and for this reason, are seldom employed as oil-emulsifiers. Modern fat-liquors, on the other hand, are of two kinds: namely, "acid fat-liquors," and "alkaline fat-liquors." "Acid" fat- liquors are those prepared with sulfonated oils, while "alka- line" fat-liquors are made from ^oap, wool-fat, or degras. The emulsifient used in preparing "acid" fat-liquors, name- ly, sulfonated oil, is made by treating any fatty oil, such as castor, corn, neatsfoot, or fish oil, with concentrated sul- furic acid, the effect of the acid being to convert a portion of the oil into its sulfo-fatty acid; the sulfo-fatty acid thus produced forms the emulsifying principle of the sulfonated oil, enabling the latter to mix with water, and to carry along with it into solution other natural oils with which it may be incorporated. Properly^made "acid" fat-liquors are sel- dom, if ever, more than faintly acid in reaction; more often than not they are quite "neutral," and may even show an alkaline reaction. On account of the fact, however, that by nature they are inclined to be "acid", sulfonated oils are particularly well-adapted to the fat-liquoring of chrome-leather, which, when wet, is always slightly "acid" by nature. On the other hand, the nearer the reaction of the "acid" fat-liquor approaches neutrality, the lower will be the surface tension of the oil, and the better, therefore, will the fat-liquor be enabled to penetrate the leather with which it is in contact. "Alkaline" fat-liquors, having soft or hard soap as their base, and often containing wool- fat, degras, or moellon, are, as a rule, much heavier (i. e., more viscous) in body than "acid" fat-liquors. The sim- plest way to make an "alkaline" fat-liquor is to heat any fatty oil, and then to stir into it a very small quantity of caustic potash (sufficient to saponify only a small portion of the oil) dissolved in water, and after this to add warm water until the emulsion is of the desired consistency. This method of preparing an "alkaline" fat-liquor is, of course, equivalent to that in which the oil is added in a fine stream to a hot soap solution, the product obtained in either case being quite the same. The quantity of soap used in making "alkaline" fat-liquors should be just suffi- cient to produce a stable emulsion with the oil. A correct proportion of soap will impart to the leather a feeling of "fulness" not obtained without the use of soap, while an excess of soap will produce a leather that is difficult to finish. In the preparation of "alkaline" fat-liquors, pot- ash, or soft soap, finds preference over soda, or hard soap, for two reasons: viz.,, first, potash soap is a more power- ful oil-emulsifient than soda soap; secondly, the use of pot- ash soap permits the leather to be afterwards glazed, while hard soap— on account of its action in cementing together the fibres of the leather — renders glazing difficult, and is quite apt to produce "flat" and dull-appearing leather. By reason of the fact that "alkaline" fat-liquors produce a greater degree of "fulness" than "acid" fat-liquors, the former are extensively used in the fat-liquoring: of chrome and combination-tanned split leathers, while "acid" fat- liquors find their principal application in the production of the more closely-grained shoe-upper leathers. Inasmuch as salts, in general, interfere with the fat- liquoring treatment (causing the oil-emulsion to break up), chrome leather should invariably be washed after being "neutralised," and immediately before it is fat-liquored. The washing of the leather is carried out in a drum with warm water (at 120° to 140° Fahrenheit), and lasts for a period of fifteen to thirty minutes, or until the goods are free from salts. After the washing of the goods the wash-water is run off, sufficient fresh water at 130° Fahrenheit to sub- merge the leather is run into the drum, the latter set into motion, and the warm fat-liquor then fed through the hol- low axle to the contents of the drum. By thus conducting the washing and the fat-liquoring in a single drum, the goods will be of the proper temperature to receive the fat- liquor when this is added, and the necessity of heating the drum prior to fat-liquoring is hence avoided. In order to insure success, the following points must be observed in the "acid"-fat-liquoring of chrome-tanned leather: viz., (1) that neither the wet leather nor the fatliquor is more than faintly acid in reaction; (2) that the temperature during the fat-liquoring treatment is 130° Fahrenheit or higher; (3) that a sufficient quantity of water be used to allow a portion of it to remain in the drum at the conclusion of the treatment. AVhen insufficiently neutralised, chrome leather is fat- liquored, the oil-emulsion will not penetrate, but, instead, the excess acid in the leather will cause a "splitting-up" of (i. e., liberation of the fatty acids in) the oil; thus, in place of the oil being deijosited within the interior, the 40 NATURE AND CONTROL OF TANNERY PROCESSES DYESTUFFS FOR LEATHER Present day fashions demand from the Tanner a wide range of shades, which are constantly fluctuating in popular favor. In view of this fact, — a Tanner must necessarily have a wide range of Dyestuffs and Formulae at his command. Furthermore, he must have the assurance that the Dyestuff is the RIGHT DYE- STUFF— both in QUALITY and PRICE. He should be confident that every lot he puts through will be identical with the preceding one. Standardization means SALES— CONFIDENCE. Bearing this in mind we offer the Tanning industry a complete line of ACID, BASIC and DIRECT COLORS. In addition we offer our long experience in Leather coloring; our laboratories and technical assistance; and a degree of serv- ice that is unsurpassed. Your problems are oi 93 Broad Street Factories Ashland, Mass. '>:^: Garfield, N. J. )licit your inquiries. D. J. LARKIN CO. Boston 3, Msiss. Selling Agents Henry Woods Sons Co. Wellesley, Mass. H. S. P. UNIFORM FINISH A Superior Pigment Finish IN ALL COLORS FOR KID, CALF SIDE, SHEEP For years we have been supplying the tanners at home and abroad with high grade products and unequalled service. OUR VULCAN FAT LIQUORS ARE SUPERIOR TO ANY ON THE MARKET CHEMICAL RESEARCH CO. Office and Factory Branches 652 SUMMER ST. LYNN, MASS. ST. LOUIS CHICAGO SULPHONATED OILS COD MOELLON NEATSFOOT BLOWN OILS CASTOR OIL SOAPS CORN The Oil & Chemical Corporation Refiners and Manufacturers of animal, vegetable and petroleum oils. 4600-4650 Iowa Street, Ch-cago VICTOR J. POLL « CO. Estabiisiioa :nii SULTAN SULPHONATED OILS Moe Ion Degras Extracts 163 W. AUSTIN AVE. CHICAGO Shoe and Leather Reporter Directory of Shoe Manufacturers for 1922 READY FOR YOU! NATURE AND CONTROL OF TANNERY PROCESSES 41 fatty acids will remain on the surface of the leather in the form of "spue." In order to counteract the acid-reaction of a sulfonated-oil fat-liquor, a small quantity of aqua am- monia is commonly added to the liquor before it is fed to the drum. The effect of temperature upon oil-emulsions has already been described; the fact may be stated here that a large percentage of failures are due to the use of too low temperatures in the fat-liquoring treatment. With chrome leather, temperatures up to 160° Fahrenheit may safely be employed. The volume of fat-liquor in contact with the leather must be large enough to enable the fat- liquor to reach all parts of the leather, and to allow the oil-emulsion to penetrate completely. Dark sjjots appear- ing in the finished goods are due to excess oil on the sur- face, the fat-liquor not having been absorbed by reason of employing an insufficient volume of water, or because the temperature during the lat-liquoring process was kept at too low a point. On account of the difficulty in obtaining even coloring of fat-liquored leather, leather which is to be finished with- out the use of pigments is usually dyed before it is fat- liquored. When dyed leather is to be fat-liquored, the vol- ume of the liquor is kept as small as possible in order to prevent excessive "bleeding," or stripping of the color from the goods. "Bleeding" of the color may, however, be checked by the addition to the fat-liquor of a suitable quan- tity of dye™. When employed upon dyed leather, the fat- liquor should be made as nearly neutral in reaction as possible. The proper quantity of oil for use upon chrome leather depends on the purpose to which the leather will be put in service, and, in practise, will vary between rather wide limits. Shoe-upper leather, for instance, may contain any- where from three to 15 per cent of oil, the lower limit be- ing for leathers that are to receive a high polish, such as kip and side, the higher values for the softer kid, and so- called "elk" leathers. In all cases where the leather is to be glazed or polished, an excessive amount of oil is to be avoided. Where it happens that — due to too much oil in the surface-layer — the leather will not glaze, the leather may first be brushed over with a dilute solution of formic, acetic, or lactic acid, after which the goods will usually be found to glaze quite readily. Lack of enough oil in the finished leather is not always responsible for the "crack- ing" of the grain so often observed in the case of shoe- leathers that have been in warehouse storage for a period of some months. "Cracking" of the grain is quite fre- quently the result of loss of moisture which leather stored in a dry or heated atmosphere suffers; in order, therefore, to prevent the grain thereon from cracking, leather must be preserved in a cool place where the atmosphere is not too dry. Analytical Control. Inasmuch as, in the fat-liquoring process, practically the entire quantity of oil fed to the leather becomes absorbed by it, the process itself will re- quire but little control of an analytical nature. The an- alytical work in connection with fat-liquoring is, therefore, confined to the testing of the raw materials (viz., the nat- ural oils employed, sulfonated oil, degras, sod-oil, wool-fat. soap, etc.) which enter into the preparation of the fat- liquors, and to that of the condition of the leather that is to be fat-liquored. The examination of the natural oils should include such determinations as specific gravity, degree of cold- test, acid-number, iodine-number, and quantity of unsaponi- ■■' Acporrting to the suggestion of M. C. Lamb. fiable oil present. The specific gravity and iodine-number usually serve to identify the oil under examination, while the presence of over five per cent of unsaponifiable oil will indicate admixture with mineral oil, wool-oil, or sperm-oil. The iodine-number (i. e., the percentage of iodine that the oil is capable of absorbing), moreover, measures the "dry- ing-power" of the oil; thus, the iodine-number of "non- drying" oils will range from zero to 65; that of "semi- drying" oils, from 65 to 120; while the iodine-number of "drying" oils will vaiy from 120 or 130, in the case of the fish oils, to 180, which is that of linseed oil. The degree of cold-test (i. e., the temperature at which the oil becomes solid) is indicative of the solid fatty-acid (e. g., stearin) content of the oil; thus, for example, the more stearin an oil contains, the higher will be the temperature at which the oil will freeze or become solid, and the more apt such an oil would be to form "spue" upon leather. The acid- number of natural oils is equivalent to the percentage of "free" fatty-acids present. A freshly-expressed oil will show a very low acid-number (e. g., not over 5), but as the oil is exposed to the action of moisture, air, and light, the acid-number will increase, and may reach the figure 50 in the case of such products as degras and moellon. A high acid-number does not necessarily indicate "rancidity" of the oil; since "rancidity" is produced, however, by at- mospheric oxidation, any increase in the acid-number of the oil usually means a corresponding increase in the "rancidity." In the fat-liquoring of leather, "free" fatty acids must be considered an advantage, insofar as they help to emulsify the oil; the excellent emulsifient proper- ties of degras and moellon, for example, are in part thus due to the high content of free fatty-acids possessed by these materials. Finally, it should be explained that a high percentage of unsaponifiable oil occurring in the oil under examination may not always represent so much mineral oil; thus, unsaponifiable oil may consist of liquid waxes (of the type of wool-oil, or "oleine") which, in com- bination with sulfonated oil, as a rule, yield fat-liquors of a very high grade. The analysis of sulfonated oils is made to determine the percentages present of water, ash, admixed unsaponifi- able oil, if any, and combined sulfuric acid as (SO3). Sul- fonated oils, as a rule, contain from 20 to 25 per cent of water. The percentage of ash will vary from 1.5 or less in the case of sulfonated oils neutralized with ammonia, to 5 or 6 in the case of oils finished with soda. The per- centage of combined SO;, — found by determining the per- centage of total SO;., and subtracting from this that of the SO3 present as Glauber's Salt — will indicate the degree of sulfonation to which the oil was subjected in the process of its manufacture; it varies from one per cent in the case of lightly-sulfonated oils, to five per cent in that of the highly sulfonated oils. In order to compare the sulfona- tion-values of two sulfonated oils, it will be necessary to first calculate their percentages of combined SO,, on the basis of the quantity of total fatty oil present in either oil. The degras, or moellon, that is to be used upon leather is first tested for melting-point, and for the percentages present of water, ash, unsaponifiable oil, "free" fatty-acids (i. e., acid-number), and oxidized fatty-acids. Degras will contain up to 15 per cent of oxidized fatty-actds; the latter substances possess a great affinity for leather, combining with it to produce a sort of additional tannage, and are hence considered a very valuable adjunct to the fat-liquor- ing treatment. Sod-oil is an inferior grade of degras, showing, as a rule, tree mineral acid, and a high percentage of ash; these arise from the sulfuric-aeid and lye-treat- NATURE AND CONTROL OF TANNERY PROCESSES OUR NEW TRADE MARK Nomad Products Nomad Degras. Nomad Paddle Oil. Nomad Pure Moellon Degras, Nomad Olive Fig Soap. No. 1. Guaranteed Pure Potash. Nomad Fig Soap No. 50. Nomad W. Sulphonated Ceistor Oil especially prepared for white leathers. Nomad A. Sulphonated Newfoundland Cod Oil especially prepared for Chrome upper leather. Nomad S. Sulphonated Newfoundland Cod Oil for upper and sole leather, bark and chrome splits. Nomad Guaranteed Pure Newfoundland Cod Oil. FRED W. DAMON 214 PURCHASE ST. BOSTON, U. S. A. NATURE AND CONTROL OF TANNERY PROCESSES 43 ments which sod-oils receive in the course of their manu- facture. Commercial degras and sod-oils are usually ad- mixed with natural oils and tallow, which must hardly be regarded as adulterants. Degras and sod-oil, however, often contain mineral oil and wool-grease, which, if present, will be found in the unsaponifiable portion extracted from the former substances. Soaps used in the preparation of "allialine" fat-liquors should contain no "neutral" salts, inasmuch as the latter tend to break up oil-emulsions in general. The nature of the fat or oil (i. e., whether a solid or a liquid fat), and that of the alkali (i. e., whether soda or potash) of which the soap was made may be determined by chemical an- alysis. The analysis of soap may also include the deter- mination of the water-content, and that of the presence or absence of rosin, filler, and free caustic alkali. NATURE AND CONTROL OF TANNERY PROCESSES In this color card are exhibited 54 dyeings, showing Acid and Basic Dyes on samples of Sumac-Tanned Sheepskin, and a .omplete range of Mode Shades on Chrome-Tanned Calf- skin. Dyes for Leather M OST tanners know the advantages of using "National" dyes, either in brush or paddle dyeings on vegetable tannages for drum dyeings on chrome-tanned leather. A full range of colors is obtainable. These extend from the bright shades produced by "National" acid and basic dyes on vegeta- ble-tanned skins to the popular browns, cordovans, grays and blacks on chrome-tanned skins. "National" leather dyes possess the valuable properties of easy application, brightness, fastness and evenness of shade. The illustration above shows the latest color card issued for the use of tanners and leather manufacturers. A copy will be gladly sent upon application. National Aniline and COeo, Inc. New York Boston Chicago Hartford Charlotte Montreal Toronto Providence Philadelphia San Francisco NATIONAL DYES NATURE AND CONTROL OF TANNERY PROCESSES Appendix to Nature and Control of Tannery Processes Tile C'olorinc of Leather. The Coloring of Leather LEATHER is colored with dye woods, coal tar dye- stuffs or pigments. The most important dye woods used are logwood, fustic and hypernic. Besides pos- sessing a high degree of coloring properties, these dye woods have tanning qualities and also mordanting proper- ties for basic dyes. Many vegetable tanning agents which are used to give the grain of the leather some particular quality, or to fill the fibres of the leatlier, also have some slight dyeing properties, but are more generally used as mordants for the basic dyes. The most important method of dyeing leather, however, is by the use of coal tar dyes, and these are usually considered under the following divisions; Basic dyestuffs Alizarine or mordant dyestuffs Acid dyestuffs Sulfur dyestuffs Direct dyestuffs Dyestuffs diazotised and de- Dyestuffs oxidized on fibre veloped on fibre Dyestuffs commonly known as vat colors, such, for ex- ample, as indigo, are not suitable for leather. BASIC DYESTUFFS are most commonly used be- cause leather was formerly made almost entirely with vegetable tanning materials. These colors are also suita- ble for chrome leather, after it has been properly mor- danted with a vegetable tanning material. Basic dyes are best dissolved by mixing them thor- oughly with cold water and then raising the solution to nearly a boil with a steam jet. Cold water is most advan- tageously used because basic dyes frequently contain ma- terial which is likely to cake if the dyes are put into hot ■water. Auramine, for instance, should not be dissolved in water over 175° P. If the water is hard the basic dyes should be wet with one-half their weight of acetic acid Ijefore the water is added. Phosphines which are not af- fected by the hardness of the water may be dissolved with- out the addition of acetic acid, even in very hard water. Dyes were formerly made by the purification of a by- product of magenta, but the new phosphines, such as phos- phine G N, are made synthetically and are much purer compounds. Basic dyes as a class are not very fast to light, and in this respect many acid, direct and alizarine dyes are su- perior to basic dyes. It should be remembered that it is practically impossible for the dyer of leather to secure such excellent results as are possible for the textile dyer, because the tanner cannot boil the leather. National Phos- phine G N, Bismarck Brown 53, Safranine A, Methyl Blue BD and New Blue D A cone, are faster to light. National Auramine O, Chrysoidine Y Ex. and 3T, Fuchsine N B Cry. Methyline Violet 2B and Victoria Green W. B. Cry. pos- sess the greatest penetrating qualities of the basic dyes. Basic dyes are much improved in their fastness to fat liquor and finishing if they are after-treated with tartar emetic, potassium titanium oxalate or bichromate of pot- ash. These salts also give more level results with basic dyes if the bottom is fixed with them before dyeing. ACID DYES are used on all kinds of tannages. They readily dissolve in hot water and do not require a mor- dant. The depth of color obtained by their use is much improved by the addition of sulfuric or formic acid to the dye bath. Best results are obtained by adding the acid towards the end of the dyeing operation. The use of an acid is, however, undesirable, especially on chrome leather, if after dyeing the leather has to be fat liquored with an alkaline emulsion of oils, because the acid is liable to cause grease spots by curdling of the fat liquor. Whenever acid is used the leather should be thor- oughly washed afterwards. Some of the best levelling acid dyes are National Wool Yellow EX Con. Wool Orange A Cone; Wool Orange GG Cry., Fast Crimson G R, Fast Crimson 8 B L, Alphazurine 2 G, Alizarin© Sapphire F S, and Acid Fast Violet B G. These colors are reasonably fast to light and are also easily dissolved, which causes them to penetrate the leather and to produce very level shades. They are excellent for making light pearl and ecru shades, but are not suitable for dark shades. Acid colors which are in the most common use are National Metanil Yellow 1955, Azo Yellow A5W, Resorcine Brown R and R W, Wool Scarlet B R, Croceine Scarlet MOO, Fast Red S Cone. Acid Bordeaux, Wool Violet 4 BN, Pure Soluble Blue, Induline N T, Durol Blue H R, Buffalo Black N B R, Buffalo Black A R, Acid Green L Cone, and Nigrosines. The most important of these colors for leather dyeing is the line of Nigrosines which is used to produce blue- blacks on vegetable and chrome tanned leather and for making black seasons for finishing leather and for black- ings and shoe polishes. The Nigrosines most commonly used for dyeing leather are: National Nigrosine 128 (bluish) National Nigrosine 27722 (greenish jet) Those used for seasonings and blackings: National Nigrosine 2011 cone, (bluish) National Nigrosine 4523 cone, (jet) National Nigrosine 3099 cone, (greenish jet) Those Nigrosines which are ammonia proof are: NationaKNigrosine 51457 (bluish) National Nigrosine 19903 (bluish black) There is also to be considered Spirit Nigrosine SG, which is soluble in alcohol, but not soluble in water, and which is related to the above nigrosines. Acid dyes are used extensively on vegetable and chrome tanned leather as a bottom for basic dyes which are precipitated by the acid dyes and produce full level colors. Their greatest usefulness in fancy shades has been to produce brown glazed kid where they are used on chrome tanned goat skins, bottomed with fustic and logwood. Acid dyes are not firmly fixed on leather by any proc- ess; they have a tendency to bleed off in the fat liquor, wherein lies one of the greatest objections to their use. DIRECT DYES have created an important place for themselves in the dyeing of chrome leather. They attach themselves directly on to this material without any mor- dant, but they have only a slight affinity for vegetable leather. For this reason they give better results on chrome leather after it has not been retanned with any vegetable tanning agent. There are, however, some direct dyes which are suit- able for producing very light and level shades on vegetable tanned leather. Direct dyes are readily soluble in water and, unlike 46 NATURE AND CONTROL OF TANNERY PROCESSES American Dyewood Dyes for Leather For hides properly tanned, it is only necessary to use dye-stuffs of proven value to secure maximum service in any leather. WE RECOMMEND Logwood Extracts, Hematine Pastes and Crystals, Hy- pernic Limawood and Redwood Extracts, Fustic Extracts, Persian Berry Extracts, Ground Turmeric, Gambler Paste and Sumac Extract. The qualifications of the above dyestuffs on chrome tanned leather are as follows: 1. They penetrate thoroughly; 2. They dye absolutely level; 3. They produce a mild tanning action; 4. They improve the feel and strength of the grain; 5. In consequence of the above, they are applied to give the necessary grounding for aniline colors so that uniform shades may be produced with regularity. FOR DYEING AND FINISHING, WE RECOMMEND Russett Phosphine for tan base, Russett Brown for dark and brown base; Russett Mahogany; Russett Red for Russia red base; Ebonite for blacks; etc., etc. For Other Shades Write for Leather Shade Cards Liquid Extracts sold in barrels of 500-550 lbs. Crystals Extracts sold in boxes of various sizes. 25-60 lbs. Alsi old in barrels of .350-400 lbs. Solid in special weights as ordered. AMERICAN Dyewood Company New York — Boston — Philadelphia — Hamilton, Ont. Works at Chester, Pa. NATURE AND CONTROL OF TANNERY PROCESSES 4T basic dyes, they are less soluble in acid solutions and become more soluble when an alkali is added to the dye bath. Because of this characteristic, chrome leather should be as nearly neutral as pos- sible before dyeing, in order to secure the most level results, and it is not necessary that the dye bath should be acidified, even at the end of the dyeing operation, as the colors exhaust completely unless there is an undue excess of the dyestuff. Direct colors most suitable for chrome tanned leather are: National Erie Fast Yellow WB " Yellow Y " Orange CG " Fast Orange A " Scarlet 8 BA '■ RedFD Niagara Sky Blue 6 B Diazine Black H. Ex. Erie Black GXOO Direct dyes are often improved in respect to their fastness to fat liquor by after treatment with bichromate of potash or copper sulphate. They seem, however, to be affected detrimentally by iron salts. Some direct dyes work better in the dye bath if 2-3% of salt is used. Na- tional Erie Black GXOO is the most important of the di- rect colors used by leather manufacturers. It has come into successful competition with logwood and Nigrosine on chrome leather. It does not yield a black as cheaply as logwood, but on the other hand it does not make the leather as tender or as harsh feeling as logwood. National Erie Black GXOO does not bleed in the tat liquor as much as Nigrosine. If it is used in connection with logwood, it should be dyed on the leather before the logwood, in order to give the deepest black result. A good black on chrome leather is obtained by dyeing the neutralized leather as follow.IRCL/IVST/-"40^42R4RKPL^ 4'2 BY THE MOST PERFECT METHODS fsi WE H/IVE UPW/^RDS OF 200 DIFFERENT P/ITTERNS /IND C-flN FURNISH /INY NEW DESIGN ORGR>llN YOU nAV REQUIRE FOR SPECI/^L PURPOSES IN FUIT PLATES OR ROLLS m E. & F. KING & COMPANY, Inc. Boston, Mass. Salem, Mass. DEALERS IN TANNERS' CHEMICALS PRICES AND SAMPLES ON REQUEST Manufacturers of THE FOLLOWING SPECIALTIES FOR WHITE LEATHER BOLTED KING WHITE For Use in the Mill No. 2 BOLTED KING WHITE For Top Dressing WATERPROOFING WHITE For Waterproof Top Dressing LEATHER WHITE For Pearl and White Splits also PIGMENT AND DUST COLORS For Split and Buck Leather and CASTOR AND LINSEED OIL COLORS NATURE AND CONTROL OF TANNERY PROCESSES 51 6 oz. National Safranine A 1 oz. National Metliylene Blue B B 1 pint Acetic Acid Then fix 15 minutes with 6 oz. Bichromate of soda When dyeing bark tanned side leather on a brushing machine or on a table, acid dyes give the most satisfac- tory results. BROAVN GLAZED KID is most successfully made with acid dyes on a vegetable bottom. The skins are first care- fully washed and neutralized. For 100 lbs. wet shaved weight Bottom 20 min. at 110 F. with IVa lbs. Fustic Ext. 2 oz. Logwood Cry. Fix 15 min. at 110 P. 1% oz. Chloride of Iron Drain off and dye 30 min. at 110 F. 4V^ oz. National Resorcine Brown R 41/2 oz. National Leather Mahogany C M Y 2 oz. National Fast Acid Red T K C 2 oz. National Induline N T Drain and wash. Fat liquor with 4% Acid Pat liquor Mahogany Glazed Kid For 100 lbs. wet shaved weight Bottom 20 minutes at 110 F. with 1% lbs. Sumac ext. % Ins, Hypernic paste Fix 15 minutes at 110 F. 2 oz. Bichromate of Potash Drain oft and dye 30 minutes at 110 F. 16 oz. National Mahogany Brown BL 2 oz. National Fast Red S. Cone. 2 oz. National Induline N T Drain off, wash, fat liquor with 4% Acid tat liquor. Vegetable Tanned Sheepskins and Goatskins are dyed with acid or basic dyes. The principal difference in treat- ing the different kinds of vegetable tanned leathers is made in the method o£ preparation for coloring. The dyeing operations should be carried out at about 110 F. India tanned sheep and goat skins contain consider- able grease as well as vegetable tanning material. The grease must be removed from the surface of the leather before it can be dyed a clear even color. This is done by washing the skins first in soda to free the grease, then retanning with sumac, then clearing with sulphuric acid, then finally the skins are rinsed with plenty of water. The skins to be colored black on the grain leaving the black white, are stained on the grain by brushing with 8 oz. National Basic Table Black, 2 oz. Acetic acid and 2 quarts gum Tragacanth solution to one pail of water. Pickled slieepskins tanned in sumac, are simply cleared with sulphuric acid and rinsed in water. Pickled sheep- skins tanned in quebracho, for fancy colors, are washed up in sumac, which is then fixed with tartar emetic. India sheep skins and pickled sheep skins are colored similarly and can be considered together. Whenever good fastness to washing is required, the skins should be dyed with basic dyes and the color set with bichromate of potash. On very light shades which must be slightly saddened, bichromate of potash must be used intead of blue or green, when possible. When full shades are made with acid dyes, such as bright reds, dyed with National Croceine Scarlet MOO, about 2 quarts of formic acid to 30 dozen skins should be added toward the end of the dyeing operation. Formic acid is generally chosen because it is quite as strong as sulphuric acid and will evaporate while sulphuric acid is stable. Dyes for ooze leather should be selected for their penetrating qualities. The best acid dyes for this purpose are National Wool Yellow Ex. con. Wool orange A Cone. Croceine Scarlet MOO add Induline N T, the best penetrating basic dyes are National Aura- mine O, Chrysoidine Y Ex. and 3 R, F^ichsine N. B. Cry. Methyl Violet 2 B cry. Coffee Brown 30 dozen Quebracho tanned sheepskins 85 ft. per dozen Dye 20 min. at 110 F. 6 oz. National Wool Orange A Cone. 12 oz. National Fast Brown BN Dye 20 min. at 110 F. 42 oz. National Phosphine W T 34 oz. National Bismarck Brown 53 7 oz. National Methylene Blue BB Fix 15 min. 110 F. 2 lbs. Bichromate of Potash 12 oz. Blue Stone. Tan 30 doz. Quebracho tanned sheepskins 85 ft. per dozen Dye 20 min. at 110 P 24 oz. National Wool Orange A Cone. 12 oz. National Resorcine Brown R Dye 20 minutes at 110 F 72 oz. National Phosphine W T 1% oz. National Methylene Blue BB Fix 15 min, 110 F. 2 11>6. Bichromate of Potash Chrome Tanned White Leather In addition to the usual process for making white leather, namely, by the use of alum and formaldehyde, chrome tanned white leather is commercially produced ac- cording to one of the following methods: namely, (1) For "soft" white leather (i. e., lining splits): Use of the ordinary two-bath process with an ex- cess of acid and sodium thiosulfate in order to effect the maximum deposition of sulfur within the goods. The sulfur so deposited renders the resulting leather very light in color. (2) For "firm" white leather: Use of a one-bath bisulfite chrome-liquor, followed by treatment with acid and sodium thiosulfate. In this process the deposited sulfur again acts as a "bleaching" agent. The leather is rendered perfectly white by the application of whiting (magnesium car- bonate). (3) By a combination of the onebath process and of the alum-formaldehyde process. The goods are first run in the chrome-liquor until "struck through," when they are neutralized with borax and entered into an alum-liquor containing alum, salt and flour. After being drummed In this liquor until tanned, the leather is treated with formaldehyde, and subsequently fat-liquored in an emulsion of starch, egg-yolk and sulfonated neatsfoot oil. The processes outlined above are typical of those em- ployed by well-known tanning concerns in this country. NATURE AND CONTROL OF TANNERY PROCESSES READY FOR YOU! As the edition is limited you will have to act quickly to receive your copy. PRICE $3.00 PER COPY Shoe and Leather Reporter Co. 166 ESSEX STREET BOSTON, MASS. Alphabetical Index to Advertisers American Dyewood Co 46 Arbib & Houlberg 16 Baker, G. W., Machine Co 16 Bill, E. H. & Co 16 Brisk, J. & Co 9 Brackett-Mason-Dodge, Inc 48 Cassidy, E. P. & Co 19 Chemical Research Co 40 Commonwealth Oil Co 42 Damon, Fred W 42 Dnrrnn Trading Co., Ltd 13 li.niii-, Martin Co 26 ]>,..vi\uv^,-v. 1 13 D.^liiir, Criram & Co., Inc 13 Du Pont, E. I. de Nemours & Co., Inc 18 Faraone, Frederick & Co 16 Fearon, Brown Co 13 Harkin, Wm. & Sons 22 Hauthaway, C. L. & Sons, Inc 20 Heymann, Albert & Co 21 Horwitz & Arbib. Inc 14 International Products Co 28 Johnstone, W. W 13 King, E. & F. & Co., Inc 50 Kossman, Anthony R 13 Lapham, Walter S 21 Larkin, D. J. Co 40 Louisville Cement Co 14 Lovejoy, D. & Son 20 Marden-Wild Corp 8 Montgomery, W. L. & Co 16 National Aniline & Chemical Co., Inc 44 National Oil Products Co 56 New York Color & Chemical Co 2 Oil & Chemical Corp 40 Persson & Co 16 Poll. Victor J. & Co 40 Quebracho Products Co., Inc 12 Ringler, F. A. Co 50 Rockland & Rockport Lime Corp 14 Salem Oil & Grease Co 36 Saxe, Sis 48 Schmoll, Armand, Inc 10 Schmoll, Fils & Co., Inc 1 Seccomb-Kehew-Bradley Co 38 Shaw, John & Co 38 Sheridan, T. W. & C. B. Co 24 Solvay Process Co 32 Spencer, C. A. cfe Son Co 34 Star, Jules & Co 4 Stehling, Charles H. Co 10 Sternteld, Weil & Co 13 Tannin, The Corp 6 Tauber, Frederick 13 Traud, Alexander & Sons 32 Tupman, Thurlow Co., Inc 10 Turner Tanning Machinery Co 55 United States Brokerage Co 19 Whitney Machine Co 54 Whittemore-Woodbury Co 36 Wing & Evans, Inc 32 Woburn Degreasing Co 48 Woburn Machine Co 53 NATURE AND CONTROL OF TANNERY PROCESSES THE NEW Superior Splitting Machine I. B. WILLIA-MS & SONS Dover, N. H. March 20, 1022. Woburn Machine Company Woburn. Mass. Gentlemen : The Superior Splitting Machine which you iustalled here is giving complete satisfaction and we are very glad to recommend it most highly. As far as we know. It is the best ma- chine of its Ivind in the marlvet. Its major superior points seem to be In more rigid and better construction, much more convenient and perfect ad- justments and a much more scientific Installation on tlie grinding equipment making it possible to obtain a very much better edge. We are using this machine on dry work and are getting excellent results, far more satisfactory than with our old machines. We have no doubt whatever but that it would be equally superior for wet work, if we happened to need it for this class of splitting. We find as stated above, we can get better edge and do not have the difficulty of its turning in the hard stock which we experienced with the other machines. We would particularly like to stress the point of its excellent construction, and fine workmanship put into its building. Very truly yours. P. C. B. I. B. WILLIAMS & SONS. This New Improved Splitting Machine has a heavier frame than any other built. Its con- struction tbruout is of the same sturdy proportions, made to work readily, steadily, con- serving time and labor charges. Every part is easily accessible to workmen. It is the one machine that docs the job efficiently at low pro- duction costs. March 24, 1922. Gentlemen : The Superior Splitting Machine which you installed here has given us perfect satisfaction. It has a good many advantages over the old Splitting Machine in the adjustments. One especially, is In changing tlie knife, great advantage over the old For Further Particulars write to the Manufacturers — Woburn Machine Company WOBURN, MASS., U. S. A. NATURE AND CONTROL OF TANNERY PROCESSES 7^his IS a perfect TaAe - ©fK oFa ^AtKEFL HIDE / Fleshiwgi^mmnes insure G> E FtFE^T^c^PfLESH I NG ^^«Iiiiiroiiiiniaiin<*"^«^ IMPROVED MODEL "M" FLESHING MACHINE XI %J AGENTS W. & C. PAN TIN Ijon(3on G. B. MARIO SPIGNO Genoa NATURE AND CONTROL OF TANNERY PROCESSES Turner No. 20 Beam House Machine The Turner Tanning Machine G>mpany offers a greater variety of Beam House Machines than all other Manufacturers combined, rang- ing in size from 24 inches to 1 26 inches, and handling anything from a rat skin to the largest hide. The illustration above is only one of this extensive line, this type being recommended for calf, sides, and horse. An Automatic Grinder supplied with all No. 20 Machines increases its value very materially, and is a distinct feature of this type. The Turner Tanning Machinery Company MAIN OFFICE AND WOBKS: PEABODY, MASS., U. S. A. NEWARK, NEW JEKSET MILWAUKEE, WISCONSIN LEEDS, ENGLAND PARIS, FRANCE NATURE AND CONTROL OF TANNERY PROCESSES Sulphonated Oils Spon|[ing Compound Products Moellon Degras Fig Soapt NATIONAL OE. PRODUCTS CO. HARRISON, N. J. pLAjrrs HARRISON, n. J. CHICAGO, ILL. ST. JOHNS, N. F. WAREHOUSES MBLWAUUE;! GLOVEBLSVflXI 70tONTO SAN FR.\RaSCO PEARODY QIMBEC tttf'^/ V^^'y \^^^'\'' \'^'.^'- %.'•--',/.. v^\^^ " ' ° •» O ^* . • ' " » ^ rO c ■> " . .„ -^^ 0^=^ ,• %^y ::^^-,%,.^J^ :-^k^-^'^^y' :]i!Mk.\./' :'J^^-- .^"..•. :•• /x ^1^- ,^^^''-^.: , ./% w .*^"^*, 'It- /% /^V;^^% ^'^ -^^ °- /'.V^^^X c^-^J^.>% /\c;-,^,\ o^'-