LIBRARY OF THE * UNIVERSITY OF CALIFORNIA. Cla&s ANIMAL FATS AND OILS ABERDEEN UNIVERSITY PRESS ANIMAL FATS AND OILS THEIR PRACTICAL PRODUCTION, PURIFICATION AND USES FOR A GREAT VARIETY OF PURPOSES THEIR PROPERTIES, FALSIFICATION AND EXAMINATION A HANDBOOK FOR MANUFACTURERS OF OIL- AND FAT-PRODUCTS, SOAP AND CANDLE MAKERS, AGRICULTURISTS, TANNERS, ETC., ETC. LOUIS EDGAR ANDES WITH 62 ILLUSTRATIONS TRANSLATED BY CHARLES SALTEE LONDON SCOTT, GKEENWOOD & CO. PUBLISHERS OF THE 19, 21, AND 23 LUDGATE HILL, E.C. 1898 GENERM- PREFACE. As in the case of Vegetable Fats and Oils, consider- able improvements have been introduced into the preparation of the animal products belonging to the same category ; and, whilst for the most part relating to mechanical methods, have given this industry a marked impetus. Now-a-days the preparation of tallow and hog fat is conducted in a rational manner, and the manu- facture of that valuable food-stuff butter is carried on according to methods calculated to thoroughly utilise the raw material milk and to yield a pro- duct endowed with a better flavour than under the primitive conditions formerly prevailing. Improve- ments have also been made in the preparation of bone fat, waste fat, fish oils, etc., all of which I have thought it advisable to include in the present work in order to render it more acceptable to those interested in the fat industry. LOUIS EDGAR ANDES. 121034 TABLE OF CONTENTS. Introduction ] Occurrence, Origin, Properties and Chemical Constitution of Animal Fats 6 Preparation of Animal Fats and Oils 20 Machinery for Breaking down Fat 23 Pans and Apparatus for Fat Melting 26 Toncou's Tallow-Melting Plant 28 Tallow-Melting Plant for Sulphuric Acid Method ... 30 Wilson's Tallow-Melting Apparatus 32 Gellhorn, Flottmann & Co.'s Tallow-Melting Apparatus . . 33 Lockwood & Everitt's Tallow-Melting Apparatus ... 38 Steam Apparatus for Tallow Melting 40 Rivoir's Steam Apparatus for Tallow Melting . . < . 42 O. Heintschel's Tallow Melting, etc 44 Fat-Extracting Apparatus with Corrugated Bottom ... 49 Extraction Plant 51 Dr. Ahrens' Apparatus for Extracting Bone Fat ... 52 Kaleczok's Bone-Fat Extracting Apparatus .... 57 Holdhaus' Apparatus for Extracting Fat 58 Meikle's Apparatus for Extracting Bones, etc 59 Machalski's Apparatus for Extracting Fat and Glue . . 61 Schweitzer's Extraction Plant 62 W. O. Robbin's Extractor 63 Perfected Extraction Apparatus 64 Presses 66 Hydraulic Presses 66 Hydraulic Tub Presses 68 Brinck & Hiibner's Hydraulic Presses 69 Simple Presses 72 Fish Oil Screw Press 73 Filtering Apparatus .74 Animal Fats and Oils: Raw Materials, Preparation, Properties and Uses 75 Alligator and Crocodile Oil 75 Butter : Raw Material and Preparation . . ; . . 76 Properties 89 Vlll TABLE OF CONTENTS. PAGE Adulterations .92 Beef Lard or Re-Melted Butter 93 Testing 95 Candle-Fish Oil .......... 105 Mutton Tallow 106 Hare Fat 108 Goose Fat . 108 NeatsfootOil 108 Bone Fat .... . Ill Bone Boiling 114 Steaming Bones 116 Extraction 120 Refining v . 122 Bone Oil 124 Artificial Butter: Oleomargarine 125 Margarine Manufacture in France .125 Grasso's Process 128 " Kaiser Butter " 130 Jahr and Miinzberg's Method . 131 Filbert's Process . . . . - . . . . . .132 Winter's Method 132 Human Fat 132 Horse Fat . .135 Beef Marrow . . 136 Turtle Oil 136 Hog's Lard : Raw Material ...... . 137 Preparation 138 Properties 139 Adulterations 141 Examination 141 Lard Oil . .149 Tallow : Beef Tallow : Raw Material 150 Preparation 151 Melting in Open Pans (Rendering) 152 Melting with Caustic Soda 157 Melting with Sulphuric Acid 157 Stein's Tallow-Melting Process . 158 Rovard's Tallow-Melting Process 159 Melting by Steam . 160 Properties . . 160 Adulterations 163 Examination 164 Determination of Value 166 TABLE OF CONTENTS. Detecting Adulterations . . . ..... 16 ^ Kefining, Hardening and Bleaching ...... 171 Animal Oil : Dippel's Oil ......... 176 Fish Oils ............ 177 Whale Oil ........... 181 Porpoise Oil : Brown Fish Oil ...... Dolphin Oil ........... 182 Sperm Oil ........... 18S Arctic Sperm Oil .......... 183 Finback Whale Oil ......... 184 Greenland Whale Oil ......... 184 Seal Oils ............ 185 Walrus Oil : Seal Oil ......... 187 Archangel Seal Oil ......... 187 Greenland Seal Oil ......... 187 Greenland "Three Crown "Oil ....... 187 Swedish " Three Crown "Oil ....... 188 Newfoundland Seal Oil ........ 188 South Sea Seal Oil ......... 188 Caspian Seal Oil .... ..... 188 Fish (Waste Train) Oil ...... . . 189 Liver Oils .... ........ 190 Properties .......... .193 Coal-Fish Oil ...... .... 194 Shark's-Liver Oil ....... . 194 Kay-Liver Oil .......... 194 Testing Fish Oils .......... 198 Artificial Train Oil .......... 202 D6gras : Tanner's Grease ......... 204 Examination of Degras ........ 207 Preparation from Fish Oil ........ 211 Degras according to Herrburger ...... 213 Preparation of Commercial Degras ...... 213 Wiener on Degras ......... 215 Olein Degras ........... 216 Degras from Waste Fat ........ 217 Black Degras ........... 218 Wool Fat ............ 218 Properties ........... 220 Purified Wool Fat . ..... 221 Spermaceti .......... . 223 Examination of Fats and Oils in General . . . . 226 Index ............ 233 b ILLUSTRATIONS. PIG. FAGB 1. Edge Runners 22 2. Fat-Grinding Mill 23 3 and 4. Fat-Cutting Machine 24, 25 5. Portable Melting Stove .26 6. Fixed Pan for Direct Fire Heat 27 7. Tallow-Melting Plant 28 8. Tallow-Melting Plant 29 9. Melting Pan. (Vertical Section) 30 10. Tallow-Melting Plant with Direct Fire 31 11. Wilson's Tallow-Melting Apparatus 33 12. Gellhorn, Flottmann & Co.'s Tallow-Melting Plant. (Ground Plan) .34 13. Gellhorn, Flottmann & Co.'s Plant. (Section through Boiling House) 35 14. Steam Plant for Tallow Melting 39 15. Steamer for Melting Tallow 41 16. Steam Apparatus for Tallow Melting (Rivoir) . . .'42 17. HeintschePs Tallow-Melting Apparatus. (Front Vertical Section) 45 18. Heintschel's Apparatus. Details of Melting Pan ... 46 19. Heintschel's Apparatus. (Lateral Section) . . . .47 20. Heintschel's Apparatus. (Filtering Cylinder) ... 48 21. 22. Fat-Extracting Apparatus with Corrugated Bottom . 49 23. Fat-Extracting Apparatus with Corrugated Bottom. (Front View) 50 24. Fat-Extracting Apparatus. Arrangement of Funnel . . 50 25. Ahrens' Bone-Fat Extractor. (Cross Section) . . .53 26. Ahrens' Bone-Fat Extractor. (Cooler) 54 27. Kaleczok's Bone-Fat Extracting Apparatus .... 57 28. Holdhaus' Fat-Extracting Apparatus 58 29. Meikle's Bone-Fat Extractor 60 30. Machalski's Fat and Glue Extractor 61 31. Schweitzer's Extractor . . 62 32. Robbin's Extractor . .63 33. Apparatus for Recovering Fat and Glue 64 Xll ILLUSTRATIONS. FIG- PAGE 34, 35. Hydraulic Tub Press 68 36. Brinck & Hiibner's Hydraulic King Press .... 70 37. Brinck & Hiibner's Hydraulic Box Press .... 71 38. Hydraulic Margarine Press 72 39. Fish Oil Screw Press .73 40. Filter Press 74 41. De Laval Separator. (Elevation) 79 42. De Laval Separator. (Section) 80 43. Fesca's Centrifuge .81 44. Rennes' Butter Machine 83 45. Brochardt's Butter Machine 84 46. Bergedorfer Cremometer ' 87 47. Zeiss' Butyro-Refractometer 98 48. Killing's Viscosimeter 102 49a. Bone Crusher. (Section) 112 496. Bone Crusher. (Viewed from above) 113 50. Bone-Boiling Pan 114 51. Perforated Vessel for Bones 115 52. Bone Steamer . 117 53. Friedberg's Bone Steamer .120 54. Butter and Churning Machine 127 55. Margarine Worker 128 56. Butter Mill with Fluted Rollers . . . . . .129 57. Moulding Machine for Margarine 130 58. Greaves Press 153 59. Greaves Press 154 60. Greaves Press 155 61. Degras Pan 215 62. Westphal Balance 227 ANIMAL FATS AND OILS. INTRODUCTION. THE products known under the name of " animal fats " are closely related, in respect of both chemical and physical properties, to the vegetable fats. Like these latter, they are, almost exclusively, compounds of one, or frequently several, fatty acids with glycerine ethers ; are, at ordinary tempera- tures, either solid, semi-fluid or perfectly liquid ; leave be- hind permanent fatty marks on paper ; dissolve in boiling alcohol and other liquids ; can be mixed together when in a melted condition, i.e., in the warm, and are all lighter than water, so that they float in that liquid. When rubbed in thin layers on other substances, such, for example, as the skin, wood, etc., they repel watery liquids, and thereb}^ afford a certain amount of protection against the penetration of same. Finally, they exhibit what is generally denoted a " greasy feel " w r hen handled. The fats are encountered throughout the animal kingdom, in all its classes and subdivisions. They are met with both in mammals, birds, amphibia, fishe,s, and even in in- sects, and occur particularly in separate layers under the skin, interspersed in the flesh, between the intestines, or stored in the brain ; and a great part of the nutriment ab- sorbed into the animal economy is converted into fat. Under certain circumstances the fat accumulated in the animal body will serve to support the individual, for a short 1 % ANIMAL FATS AND OILS. time, as a means for the continuance of life during periods when the supply of nutriment is either reduced or entirely suspended. This is observed in the case of animals (e.g. y bats, bears, hedgehogs, etc.) that lie dormant through the winter (hibernate) and awake in spring (or in a favourable season) reduced in flesh. The amount of fat stored up in the animal body is a particularly variable quantity and depends on the supply of food, mode of life and other circumstances. As a rule, the accumulation of fat is favoured by a secure and undisturbed existence, but may also be considerably increased by arti- ficial means, as we shall see later on. The different ani- mals turned to account for their fat are comparatively few in number, and comprise in fact only those that are bred on a large scale to be utilised partly for food and partly for technical purposes. Moreover, the fat of many animals is uneatable, being of unpleasant odour and flavour ; and in the case of many others it is not present in sufficient quantity to serve our purpose. There can be no doubt that the fat of animals, equally with their flesh, was employed by man, even in the earliest times, for manifold purposes, originally, however, for food alone. The use of fat for curative purposes value in which respect is still attributed to bear's grease, badger fat and dog's fat by country folk came later. Burning fats for the purpose of illumination, their use for application to the body to enable it to better withstand inclement weather, as also for impregnating clothing and other articles in order to make them soft, supple and waterproof probably formed the next stage of extension ; and, finally, in recent times only, their techni- cal utilisation was developed. As regards curative powers, the only fat at present play- ing an important part in this respect is cod-liver oil scarcely any one now-a-days believes that bear's grease and other fats INTRODUCTION. <> have any healing powers, and the substance sold under this name is merely lard and tallow. As progress developed in chemico-technical matters, and as the population increased, attention was naturally directed towards the recovery and utilisation of fats, and we can see by the enormous consumption of soap, candles, etc., the great importance attaching to the production of animal fats in the present age. Moreover, the bye-products obtained in the working up of fat play an important role, and this is particularly the case with glycerine, which is now produced in enormous quantities. Whereas half a century ago the glycerine formed during saponification and left behind in the sub-lye was simply allowed to run to waste along with the lye, it is to-day a highly important article of commerce, the amount annually produced throughout the globe being some 40,000 tons not altogether, it is true, from animal fat, but, from vegetable fats as well. Of this quantity about 26,000^ tons are produced in the manufacture of stearine and 14,000 tons in soap-making. The preparation of fish oils the best qualities of which are used as cod-liver oil for medicinal purposes, whilst the inferior grades are only used for technical purposes, serving as emollients in leather dressing has also greatly increased ' in extent, although the industry has not, of course, assumed 1 the same importance as that of the other animal fats. So far as the method of preparing animal fats is con- cerned, this was until comparatively recently of a very primi- tive description : the crude fat was melted or " rendered '* in open pans heated by direct fire either with or without water, perhaps then melted again for purification, and after- wards put on the market. The unpleasant exhalations attendant on some fat-rendering operations, especially when old fats (partly intermixed with putrescent flesh), bones, etc., were being treated, and which contaminated the atmosphere 4 ANIMAL FATS AND OILS. of all the neighbourhood round such tallow-boiling estab- lishments, finally led the authorities to insist on a modifica- tion of the arrangements, so that at the present time fat- melting works with their perfected appliances carry on their occupation without producing any smell and without incon- venience to the vicinity. In recovering fat from bones, glue as well as fat is produced, the raw material being thereby fully utilised in a rational manner. The importance attained by animal fats in the world's commerce can be gathered from the subjoined statistics, though the figures will certainly have already been exceeded since the dates mentioned. Fish oil annually produced. Spermaceti and Sperm Oil, 1,485,000 hectolitres (of 22 gallons) ; other kinds, 1,170,000 hi. Oil from sea fowl, 58,500 hi. The amounts of train and fish oils imported into England were : 1888. 1889. 1890. Tons 16,861 21,051 20,302 Value - - - 323,579 442,699 419,926 Exports from the United States : 1889. 1890. Gallons 483,208 1,844,041 Value 127,412 $440,773 German imports and exports : 1890. 1891. Imports - 142,668 124,008 Exports 1,948 1,871 Liver Oil. Newfoundland produces annually 1,250,000 galls., valued at 200,000 ; Norway exported (in 1877) 130,600 barrels, of a value of '336,600 ; Norway and Sweden in 1879, 143,165 hi. (about 3,150,000 galls.). Spermaceti and Sperm Oil. America produced in 1878 1,300,959 galls. ; 1879, 1,285,454 galls. The exports of sperm oil from New York amounted to 912,603 galls, in 1878 and 1,089,137 galls, in 1879. This trade has somewhat fallen off INTRODUCTION. 5 in recent years ; in 1889 the exports amounted to 98,823 galls., worth 869,628, and in 1890 162,565 galls., value $124,601. Solid Spermaceti exported from the U.S.A. : 1888. 1890. Lbs. 425,479 447,384 Value - - .... 11,386 $116,757 (?) Lard and Lard Oil. The United States produced : 1884-85. 1885-86. 1886-87. Lbs. - - - 480,405,000 514,230,000 527,032,000 1887-88. 1888-89. 1889-90. Lbs. - - - 487,179,000 483,902,000 624,227,004 One-third to one-half the above is "compound lard" (lard mixed with cotton-seed oil and beef stearine). The pro- duction of this " compound lard " rose to 300,000,000 Ibs., but receded in 1890 to 225,000,000 Ibs. Lard exported from the U.S.A. : 1886. 1887. 1888. 1889. 1890. Lbs. - 231,509,570 321,523,746(?) 270,245,146 318,242,990 471,083,598 Value - 22,523,197 22,703,921 23,516,097 27,329,173 33,455,520 One-third of the exports come to Great Britain and Ire- land. German imports and exports of Lard : 1890. 1891. Imports 910,277 875,343 Exports 1,364 . 1,484 Tallow. Total production in Europe (1882), 355,700 tons ; U.S.A., 330,000 tons ; other countries, 60,000 tons ; total 745,700 tons. The exports of Kussian tallow have considerably diminished of late years ; in 1860 they totalled 40,300 tons ; 1870, 21,100 tons ; 1880, 10,400 tons. On the other hand, the exports from the U.S.A., Australia and, in a smaller degree, from South America have increased. In 1883 the exports were: U.S.A., 45,000; Australia, 28,000; Argentina, 10,500 ; Uruguay, 12,000 tons. 6 ANIMAL FATS AND OILS. Exports from the U.S.A. : 1886. 1887. 1888. 1889. 1890. Lbs. - 52,699,115 84,099,951 75,470,826 77,844,555 112,745,370 Value - $2,435,349 $3,772,837 $3,736,488 $3,942,024 $5,242,158 German imports and exports in metercentners (of 2 cwt.) : 1888. 1889. 1890. . 1891. Imports - - - 62,263 118,126 132,232 108,133 Exports - - - 12,047 5,154 5,925 6,812 OCCUEEENCE, OEIGIN, PEOPEETIES AND CHEMICAL CONSTITUTION OF ANIMAL FATS. Fat is found in all the organs constituting the animal organism and in individual places accumulated in large quantity as well as in all animal fluids, with the exception of urine. Certain animals exhibit a greater tendency to secrete fat than others, the domestic animals having this faculty particularly well developed. In the animal organism fat is generally found enclosed in special cells, in larger amount in connective tissue, in the panniculus adiposus under the skin, in the plexus of the abdominal cavity, in the vicinity of the kidneys, in the marrow of the bones and spine, in the brain, in the liver and in the milk ; occurring pathologically in so-called fatty tumours and in fatty degeneration of the various tissues. Concerning the origin of the fat in the animal body the following may be asserted : The fat stored up in the bodies of animals fed on a generous diet does not consist solely of ready-formed fat absorbed from the food, but is to a consider- able extent elaborated in the body from other chemical compounds. From an exhaustive study of the composition of the nutriment of the herbivorous animals, coupled with a knowledge of the remarkable changes undergone by organic bodies outside the organism and reflection on the importance OCCUEEENCE, OEIGIN, ETC., OF ANIMAL FATS. 7 of the individual constituents of nutrition, Liebig was led to believe that the carbohydrates (starch, dextrin, sugar) played an important part in the formation of fat within the body ; and on the basis of his assumptions the opinion prevailed during several decades that the formation of fat from carbo- hydrates was an unassailable fact. In proof hereof were specially advanced the facts that in the carnivora which, apart from fat, consume no non-nitrogenous food, the elabo- ration of fat is generally deficient but increases considerably when they are placed on a mixed diet with an excess of carbohydrates ; that the bulk of the food of herbivorous animals consists of carbohydrates ; and finally, that bees when fed for a long time solely on wax-free honey or sugar are still able to produce wax i.e., a fatty body without loss of health or weight. Recent researches made by Voigt and Pettenkofer, how- ever, have made it seem very probable that the albuminoid substances in the food are, apart from the ready-formed fats therein, the chief source of fat, and that quite a different interpretation must be put on the indubitable functions discharged by the carbohydrates in this connection ; the latter do not represent the special material from which the fat stored in the body is produced direct, but are none the less essential, in the dietary of the herbivorous animals at least, in order that fat may be elaborated. Pettenkofer and Voigt have demonstrated that in both carnivorous and herbivorous animals the decomposition of albuminoid substances invariably results in the separation of fat which in the course of further substantive alterations is either completely consumed, or else, when protected from further oxidation by the presence of other easily oxidisable substances like the carbohydrates, remains as a residue in the body and is laid up therein as a valuable store of reserve force to be drawn upon in time of need. The importance 8 ANIMAL FATS AND OILS. of the carbohydrates in the formation of fat is therefore restricted to preventing the combustion of the fat separated in the decomposition of the albuminoids, so that the fat has the opportunity of accumulating within the tissues. Actually, the fat and albuminoid matters of the dietary are always sufficient, even in the case of the enormous fat production exhibited by milch kine, to yield the fat formed, and fatten- ing with carbohydrates is only efficient provided albuminoids be simultaneously supplied. By means of a methodic system of dieting (" fattening" or " feeding") an increase of the fat and flesh of animals destined for the slaughter-house can be produced. As the body fills up in the course of fattening the animal assumes a condition of imperfect health, for which reason highly justifi- able objections have been raised against over fattening (a course of feeding first practised in England) not only from a medical standpoint but also in view of the utilisation of the meat. The most nutritious and best flavoured meat is only obtainable from animals in a condition ranging from incipient fattening up to the half-fat stage, whilst very fat beasts, on the other hand, yield chiefly tallow and fat, but their flesh and blood are deficient in the constituents acting most effectually on the transfer of matter in the animal economy. The following animals are those whose fat is most prized and utilised : Oxen, sheep, pigs and horses ; among birds the goose almost exclusively; and also the large marine mammals, such as the whale and seal, the dolphin, merlangus, shark, and a number of smaller fishes, such as the cod, ray, herring, sprat, sardine, anchovy, etc. The storage places of fat in the animal body are various. It is often encountered in considerable masses directly under the skin (as in the pig) or between the intestines (belly fat), in the brain (in the sperm whale), in the liver (of numerous OCCURRENCE, ORIGIN, ETC., OF ANIMAL FATS. 9 fishes) ; or, finally, distributed throughout the whole body, so that in order to recover it the entire carcase must be boiled or pressed (small fish, such as the anchovy, etc.). At ordinary temperatures the animal fats when in a pure state are solid or liquid ; the colour ranges from white to yellowish- white, pale yellow or brown (fish oils). The solid fats melt at between 20 and 45 C., and the liquid fats become semi-fluid or quite firm at temperatures from 5 C. downwards. The boiling-points are various, and when heated still further all the fats are decomposed, their glyce- rine being converted into acrolein, a substance with a most unpleasant smell. The specific gravity of the animal fats is lower than that of water and can, as in the case of the vegetable fats, be regarded as a characteristic indication of their purity. When fresh, the animal fats, for the most part, have an agreeable odour, the only exceptions being sundry fish oils ; on the other hand, when old, they have generally a rancid and unpleasant, sometimes putrescent and even repulsive, smell (old bone fat, blubber, etc.). The flavour of some, i.e., those generally employed for alimental purposes (butter, goose fat, lard), is agreeable ; in others (tallow, especially mutton tallow), unpleasant ; and in the case of fish oils, occasionally nauseous. Nearly all fats will produce, even at the ordinary temperature, grease spots which do not disap- pear on warming, and even those of highest melting-point give rise to grease spots when heated. When absorbed by a wick, all fats will burn with a more or less illuminating, smoky and strong-smelling flame. The solid fats when viewed under the microscope at the ordinary temperature appear throughout as a mixture of solid and liquid substances. The solid portion consists mainly of crystals in the shape of plates, needles or tufts, which are composed of free fatty acids. If the fat be warmed 10 ANIMAL FATS AND OILS. on a glass slip up to the melting-point, sundry solid amor- phous granules will still generally be left behind in the mass. On cooling, the fatty acids crystallise out again, mostly in the form of needles. In fats poor in olein the liquid portion appears in the form of drops, but forms the fluid matrix in those rich in olein. This fluid mass when viewed under the microscope frequently appears not to be homo- geneous, but to contain drops with a different power of refraction from the rest. The fats are insoluble (or, according to recent statements, soluble, though with extreme difficulty) in water, and but little soluble in cold alcohol, though generally soluble in hot alcohol, ether, benzene, petroleum ether, etc. (at least in the warm). Like their vegetable congeners, the animal fats consist principally of neutral glycerides of the fatty acids, and there- fore have the general formula C 3 H 5 (0 OC K 1 ), wherein K 1 represents a monovalent hydrocarbon radicle. In addition to this the fats may also contain free fatty acids. Sperm oil and the spermaceti obtained therefrom contain, however, no glycerides, but ethers of the higher alcohols of the fatty series, and should (along with shark oil and probably all the oils de- rived from marine animals and having a sp. gr. of less than 0*888 at 15 C.) properly be relegated to the category of the waxes. All fats may be saponified, i.e., decomposed into fatty acids and glycerine, by alkalis, dilute acids and by means of superheated steam. By this process the follow- ing acids and alcohols have been separated from the fats and waxes : A. ACIDS. 1. Saturated Acids of the General Formula C n H 2n 2 . C 4 H 8 O 2 Butyric acid. C 5 H 10 O 2 Isovaleric acid. C 6 H 12 2 Caproic acid. OCCURRENCE, ORIGIN, ETC., OF ANIMAL FATS. 11 C 8 C 9 C 10 OH C C 16 C J7 C M < H 16 H 10 H.O H* H 30 ^ H^ 2 2 2 o, 2 2 2 8 2 2 2 Caprylic acid. Pelargic acid. Capric acid. Laurie acid. Myristic acid. Isocetic acid. Palmitic acid. Daturic (margaric) acid. Stearic acid. Arachic acid. Medullic acid. H^ 2 Lignoceric (carnaubic) acid. Hgo 2 Hyenic acid. Hja 2 Cerotic acid. Hgg 2 Melissic acid. H 2. Unsaturated Acids (with Double Bond) of the General Formula C n H 2n . 2 2 : C 5 H 8 2 Tiglic acid. C 16 H 30 2 Hypogeic acid. C 18 H 34 O 2 Physetoleic acid. Cj 9 Hge 2 Oleic acid. C 22 H 42 O 2 Doeglic acid. 3. Acids (with Triple Bond) of the General Formula *Cn H 2n _ 4 2 : C 16 Hgg 2 Linolic acid. C I7 H 30 2 Elseomargaric acid. 4. Acids of the General Formula C n H 2lH j 2 : C 18 ELjo 2 Linolenic acid. C 18 H^ O 2 Isolinolenic acid. 5. Ketone Acids of the General Formula C n H 2n . 2 3 : C 18 H^ 3 Ricinoleic acid. C 18 HM 3 Rapic acid. B. ALCOHOLS. 1. Trivalent Alcohol of the Formula C n H 2n+2 3 : C 3 H 3 O 3 Glycerol (glycerine). 12 ANIMAL FATS AND OILS. 2. Monovalent Alcohols of the Fatty Series, ivith the Formula C n H 2n+2 : C 16 H 34 Cetyl alcohol (ethal). C 18 H 38 Octodecyl alcohol. 37 Hgg O Ceryl (iso-ceryl) alcohol. C 30 H 62 Myricyl (melissyl) alcohol. 3. Monovalent Aromatic Alcohols. C 24 H 44 Cholesterin. ^26 H 44 O Isocholesterin. C 26 H^ Phytosterin. The fats consist most frequently of the glyceride of pal- mitic acid (palmitin, tri-palmitin) C 3 H 5 (C 15 H 31 C0 2 ) 3 ; the gly- ceride of stearic acid (stearine, tri-stearine) C 3 H 6 (C 17 H 3i5 C0 2 ) 3 ; the glyceride of oleic acid (olein, tri-olein) C 3 H 5 (C 17 H 33 C0 2 ) 3 . Other acids occur in small quantities in various fats, a high proportion of such an acid being generally characteristic of a certain fat. Such are : Butyric acid, as a glyceride (butyrin) in the proportion of 2 per cent, in cow's butter. Isovaleric acid, occurring in combination with glycerine in dolphin and porpoise oils. Of the caproic acids, isobutylacetic acid occurs as caproin in butter, in which caprylic and capric acids also are present in the form of caprylin and caprin ; so that cow's batter con- tains about 8 per cent, of the glycerides of these acids. Medullic acid, as a glyceride in ox marrow. Hyenic acid, in the anal gland of Hycena striata. Physetoleic acid, in sperm oil ; and Doeglic acid, in Arctic sperm oil. The solid and liquid animal fats differ from one another in consistency, this being dependent on the varying propor- tions of the individual glycerides present in each ; stearine and palmitin being solid at the ordinary temperature, where- as olein is then liquid. The foregoing constitute the basis of the fats and may be considered as a tri-glyceride. All OCCURRENCE, ORIGIN, ETC., OF ANIMAL FATS. 13 rancid fats contain free fatty acids, the formation of which rests on a decomposition effected by the air, whereby glycerine and free fatty acids are produced. The saturated fatty acids up to capric acid, and the oleic, doeglic and various vegetable fatty acids are liquid at the ordinary temperature, the remainder being solid. Butyric, caproic, caprylic and capric acids, being capable of distillation without decomposition, under ordinary pressure, are therefore styled volatile fatty acids. 1. Butyric Acid. This acid is liquid at the ordinary temperature and exhibits, when freshly distilled, an odour resembling that of acetic acid, but in a dilute condition has a very strong smell like rancid butter. It boils at 162'3 C., sets in a flaky condi- tion at - 19 C., and has a sp. gr. of 0*958 at 14 C. It is readily soluble in water and can be separated therefrom as oily drops by calcium chloride or by common salt ; with alcohol and ether it is miscible in all proportions. Solutions of butyric acid have a corrosive acid taste, redden litmus and decolorise a slightly alkaline phenol- phthalein solution. Methyl orange also is reddened by solutions of butyric acid containing no butyric salts. If a dilute aqueous solution of this acid be distilled the acid passes over completely in the distillate ; in the case of very dilute solutions the attainment of this object is facilitated by previously neutralising the acid with soda, concentrating the liquid by evaporation, and distilling after adding dilute sulphuric acid. Concentrated butyric acid when warmed with alcohol and concentrated sulphuric acid forms butyric-ethyl-ester (ethyl butyrate), which is recognisable in small quantities by its very agreeable odour of pine-apple. To detect the presence of butyric acid in very dilute solutions by this reaction the 14 ANIMAL FATS AND OILS. liquid is neutralised with soda, evaporated to dryness, and the residue warmed with alcohol and sulphuric acid. A portion of the butyric acid is also etherised during the saponification of fats, containing this acid, by strong alcohol and caustic potash. 2. Caproic Acid. Of the isomeric caproic acids isobutylic acid occurs in fats. It is a liquid, soluble in but not miscible with water, and possesses a smell resembling that of perspiration. The sp. gr. is 0-925 at 20 C. ; boiling-point, 199'7 C. ; setting- point, below - 18 C., at which temperature it is still liquid. 3. Caprylic Acid is also liquid, but sets, on cooling down to 12 C., to a crystal- line mass, melting at 16'5 C. Boiling-point, 236 to 237 C. ; sp. gr. at 20 C., 0'914. It has an intense smell of perspiration and is soluble in 400 parts of water. 4. Capric Acid forms at the ordinary temperature fine flakes which melt at 31'3-31'4 C. and emit a goaty odour. The sp. gr. of the melted acid is 0'93 at 37 C. ; it boils at 268-270 C., and 1 part of the acid is soluble in 1000 parts of boiling water. 5. Palmitic Acid. Pure palmitic acid consists of fine tufted groups of needles, or, after melting and re-solidification, of a crystalline scaly mass with a nacreous lustre ; it is tasteless and inodor- ous, melts at 62 C., and at this temperature has in the liquid state a sp.'gr. of 0*8527. At about 350 C. it is for the most part volatile without decomposition and will boil at 268'5 C. when the pressure is reduced to 100 mm. of mercury. When melted palmitic acid is placed on paper, or an alcoholic or ethereal solution of the acid is left to evaporate OCCURBENCE, OEIGIN, ETC., OF ANIMAL FATS. 15 thereon, a grease spot is produced. This acid is soluble with difficulty in cold alcohol, 100 parts of the solvent taking up only 9*32 parts of acid, but it is very readily dissolved by boiling alcohol, and may therefore be very easily re-crystallised from this solvent. The alcoholic solution has an acid reaction. Dilute acids have no action on palmitic acid, but it dissolves in concentrated sulphuric acid, re-crystallising, however, unchanged on dilution. Boiling concentrated nitric acid attacks it very slowly. The salts of palmitic acid are very similar to those of stearic acid, but are somewhat more readily soluble. 6. Stearic Acid. Pure stearic acid crystallised from alcoholic solution forms white lustrous laminae which melt at 69'2 C. to a perfectly colourless fluid and set to a translucent crystalline mass on cooling. When heated to 360 C. it begins to boil and partly decomposes, but may be distilled without altera- tion under reduced pressure at 291 C. under a pressure of 100 mm. When distilled by superheated steam it also passes over without apparent decomposition, but according to observations made in the distillation of fatty acids on a working scale a small portion is really decomposed, being converted into solid hydrocarbons of the C n H 2tl+2 series. The sp. gr. of this acid at 11 C. is almost identical with that of water, but at higher temperatures it floats in the latter liquid owing to its greater coefficient of expansion. The sp. gr. of the acid melted at 69'2 C. is 0'8454. Stearic acid is devoid of flavour or smell, handles greasy, and will leave a greasy mark on paper whether applied in the melted state or in solution. It is insoluble in water, but readily soluble in hot alcohol, though in cold alcohol it is even more difficult to dissolve than palmitic acid. One part of 16 ANIMAL FATS AND OILS. stearic acid dissolves in 40 parts of absolute alcohol ; ether absorbs it readily, and at 23 C. 1 part of benzene will dissolve 0*22 part, and 1 part of carbon bisulphide 0'3 part of stearic acid. 7. Hypogeic Acid. White needles, melting at 33 C., gradually turning brown and decomposing in the air, forming liquid fatty acids of rancid flavour. 8. Physetoleic Acid has the same composition as the preceding acid, but differs considerably therefrom in being unaltered by the action of nitrous acid. It melts at 30 C. 9. Oleic Acid. It is difficult to obtain oleic acid in a perfectly pure state. In this condition it appears as a colourless and inodorous oil which sets at 4 C. but does not melt again below 14 C. ; the sp. gr. at this temperature is O898. Under ordinary pressure the acid is undistillable, but when heated by steam at a temperature of 250 C. passes over unchanged. When perfectly pure it does not redden litmus paper, but, on the other hand, exerts an acid reaction on phenol- phthalein, since the fresh fatty acid mixture (very rich in oleic acid) prepared from fats by saponification and subse- quent acidification of the soap solution can be accurately titrated by means of this indicator. When exposed to the air oleic acid becomes yellowish or yellow, smells very rancid, and reddens litmus. This acid is insoluble in water, but readily soluble even in dilute cold alcohol. It may, however, be thrown down from its solutions by the addition of a large volume of water. An attempt has been made by David to found a method OCCUEEENCE, OEIGIN, ETC., OF ANIMAL FATS. 17 of separation for this acid on account of its greater solubility than the solid fatty acids in a mixture of alcohol, water and acetic acid. If into 7 parts (1 molecule) of oleic acid there be dropped gradually 4 parts of bromine (1 mol.), with continual shaking, the whole of the bromine will be taken up and dibromostearic acid will be formed. From its method of preparation this body is known as the bibromide of oleic acid. The reaction occurs according to the equation : C 17 H 33 COOH + Br 2 - C 17 H 33 Br 2 COOH. (Oleic acid.) (Dibromostearic acid.) When suitably purified the product forms a clear oil. A similar reaction is obtained with an alcoholic solution of oleic acid in presence of an alcoholic solution of iodine containing mercuric chloride. If nitrous acid be allowed to react on oleic acid the latter sets hard in a short time and becomes converted into the isomeric elaidic acid, which can then, by re-crystallisation from alcohol, be obtained in the form of plates melting at 45 C. 10. Doeglic Acid, C 19 H 36 2 , has received but little attention hitherto ; it is a yellow oil similar to oleic acid an-d setting at 4 U C. When fats or fatty acids are treated with caustic alkalis or lead oxide they are saponified. Concentrated alkaline lyes effect saponification with great difficulty, and therefore none but dilute lyes should be used. In the process of saponifica- tion stearine and palmitin are more quickly decomposed than olein. On being melted with caustic potash, oleic acid = autopal- mitic acid ; erucic acid = auto-arachic acid ; hypogeic acid = automyristic acid, and their isomers are decomposed into palmitic, arachic myristic and acetic acid. Concentrated 18 ANIMAL FATS AND OILS. sulphuric acid, in proportions of from 8 to 10 per cent., forms with fats at high temperatures sulpho acids, which, when treated with water, split up again into free fatty acids, glycerine and sulphuric acid. If fats or oils be treated with alkali carbonates, albumin, or an aqueous solution of gum arabic, they are thereby emulsified, and the same result is obtained by the action of ammonia. Alcoholic ammonia solution when allowed to act for a long time at ordinary temperature converts the fats into acid amides. Chlorine and bromine form substitution products with the fats or fatty acids of the methane series. Iodine does not, but forms, however, like the above re-agents, addition products with the glycerides or the fatty acids of the un- saturated hydrocarbons. Nitric acid exerts a strong oxidising reaction on the fats, etc., and forms oxalic acid, succinic acid and adipinic acid. On exposure, especially in thin layers, to the air, the animal fats turn rancid ; they, however, never dry, as do certain of the vegetable oils, to a solid skin, but remain always in their original, more or less greasy, condition. In becoming rancid a part of the non-volatile fatty acids, especially oleic acid, is liberated, and occasionally a com- plete separation into fatty acids and glycerine occurs. Kan- cidity spreads in solid animal fats to a much smaller extent than in the vegetable oils, and they keep longer and better in proportion as their olein content is lower and that of the glycerides of the solid fatty acids higher. This condition (rancidity) is, however, in a high degree prejudicial to the animal fats on account of its effect on the flavour. Under defective storage conditions and under the influence of ordi- nary sunshine temperature, rancidity sets in so quickly that butter, for example, may become uneatable in a few days if not sufficiently protected from the air. The opinions preva- lent on the causes of rancidity are somewhat divergent, but OCCURRENCE, OEIGIN, ETC., OF ANIMAL FATS. 19 there can be no doubt that when air is sufficiently excluded rancidity, if not altogether prevented, can be retarded for a considerable time. Liebig put forward the view that rancidity is induced by the influence of the extraneous substances present in the fat ; Lohwig assumed a fermentative action in presence of water and air ; whereas Kosch considered it due to oxida- tion by atmospheric oxygen, an opinion also shared by Duclaux ; and Berthelot ascribes it more particularly to moisture, the action of which is facilitated by the presence of extraneous substances, oxidation being merely a concomitant reaction. Von Kechenberg, Fliigge, Paschulin, H. Schulz and Neneki believe rancidity to be caused by the action of unorganised fat-destroying ferments, or by microbes. Groger assumes that in turning rancid the fat is decomposed by water into fatty acids and glycerine, followed by oxidation through the action of atmospheric oxygen, both on the fatty acids and on the glycerine, since the latter is no longer de- tectable in a free state. The fatty acids are split up into< bodies (acids), poor in carbon but rich in oxygen, belonging partly to the fatty acid series and partly to the oxalic acid series. Among the latter class azelaic acid (C 9 H 16 4 ) has . been identified. Ritsert, who occupied himself very intently with the^ establishment of the causes of rancidity, demonstrated thafc; the rancidity of pure fat is not caused by either aerobic or anaerobic bacteria. The fat when protected from air and light remained perfectly sweet, and germs inoculated therein died, although able to live in rancid fat. Neither can fer- mentative action be assumed, since sterile fat heated in a closed vessel for several hours at 140 C. becomes rancid! under the influence of light and air. Moisture is non- essential to rancidity, dry fat becoming more rancid under the influence of air than when moist ; but the process is one. 20 ANIMAL FATS AND OILS. of oxidation solely, induced by atmospheric oxygen, without the collaboration of any organisms. The operation proceeds more rapidly in proportion as light is admitted, oxygen not being absorbed when light is excluded, neither does air cause Tancidity in the absence of oxygen. Pure lard kept in the *dark remains sweet even after a lapse of two months. The carbon dioxide of the air has the same influence on fat in the absence of light as pure carbonic acid, only less intense, and is absorbed by fat both in the light and in the dark in comparatively small amount, the fat becoming thereby , tallowy, but not rancid. Both nitrogen and hydrogen are inactive towards fat, whether in the light or in the dark, and ]puxe butter behaves exactly like pure lard. Aerobic and anaerobic bacteria can live on rancid fat, but mot if an excess of free fatty acids be present. The practical results of these researches is that the prime -essential condition for the prevention of rancidity in fats is complete exclusion of air, which being secured, exposure to the light or storage in the dark is immaterial. PBEPABATION OF ANIMAL FATS AND OILS. The method employed for preparing animal fats and oils, that is to say, the treatment of the crude fats, differs somewhat from that pursued for the vegetable fats and oils, but finally conduces to the same end, viz., separation from the accompanying extraneous substances non-fats. In all materials yielding vegetable fats and oils we have to do with fruits, seeds, etc., forming a dry, solid, and occasionally even hard mass, from which the fats can be obtained solely by the application of considerable force, or, when in a pulverised or pulpy condition, by extraction with special solvents. The animal fats, on the other hand, are devoid of the characteris- tic shell encasing the vegetable materials, the fat lying dis- tributed throughout various parts of the animal body and PKEPAEATION OF ANIMAL FATS AND OILS. 21 enclosed in, or completely occupying, cellular tissues ; this mode of occurrence of the animal fats influences the method of treatment to be employed. Whilst the oil- and fat-producing seeds and fruits will bear any length of transport, and come to us from distant parts of the world to be worked up, the crude animal fats must be treated within a short time and generally at the place of their production if they are to be prevented from becoming putres- cent, whereby their quality as well as the amount of yield would be seriously depreciated. True, there are certain methods of transport that can be employed and, as in the case of meat brought from America and Australia, will 1 preserve the raw material intact ; only, these are much too - expensive, and there is, moreover, no reason why the material' should not be treated on the spot. Most of the animal fats are prepared by a simple process of melting (rendering) in suitable pans, and when separated from the residual tissue by straining are ready for further use. Other fats, e.g., blubber (fish fat), are partly expressed by the pressure of the material itself when piled up into large heaps, the remainder being recovered as in some other instances by boiling in water or by the action of the press. Butter is obtained by a process peculiar to itself, the finely divided fat globules in the milk uniting, under the influence of concussion arid agitation, to finally form a lump of fat. The extraction process which plays a great part now-a- days in the recovery of vegetable fats and oils, on account of the greater yield it ensures, is employed for animal fats in individual cases only, e.g., the recovery of bone fat and of the residual tallow in greases. In consequence of this peculiar composition of the raw material the mechanical appliances used in the preparation of the fats are different from those for vegetable fats and oils. They consist of : 22 ANIMAL FATS AND OILS. 1. Machines for comminuting the fat ; 2. Pans of various construction for melting down the crude fat ; 3. Extraction plant for bone fat whereby glue can be recovered at the same time ; 4. Presses for pressing blubber, as well as for separating the liquid and solid fats ; 5. Filtering apparatus. FIG. 1. Edge Kunners for Crushing Fat. Latterly also the operation of separating the fat of fishes and marine mammals into its solid and liquid components by centrifugal force has come into practice. The centrifugal machines used for this purpose deliver the liquid fat either over the edge or through lateral apertures in the inner drum ; and machines of any known type are suitable. Those varieties of tallow (raw tallow, core or kidney suet) that are used for making artificial butter are separated into MACHINERY FOR BREAKING DOWN FAT. 23 their solid and liquid constituents by heavy pressure, and the so-called press tallow is prepared in the same manner by pressing tallow previously refined by melting. The purification of the animal fats is effected by repeated meltings over water, or bleaching by chemicals an opera- tion but seldom resorted to. For the removal of small solid particles the fat is liquefied and poured through sieves or filter cloths. Blubber is also treated the same way or FIG. 2. Fat-Grinding Mill (W. Kivoir). clarified by filtration by means of various mechanical appli- ances, such as filter presses or filtering apparatus of the kinds described in the author's work on Vegetable Fats and Oils (q.v.). MACHINEKY FOR BREAKING DOWN FAT. Animal fats are delivered to the melter in lumps of all sizes, sometimes (as in the case of whale blubber) even in large blocks of considerable circumference and thickness ; 24 ANIMAL FATS AND OILS. but they cannot be worked up while in this condition since it would, on the one hand, necessitate the use of excessively large vessels, and on the other, the melting down in an unbroken state would take up too much time. However, it is not merely a question of dividing the fat into small portions, but also, and principally, of breaking down and loosening the cellular tissues in which the fat is enclosed, without which rupture of tissue an insufficient yield of pure fat would be obtained and the greater part of the material FIG. 3. Fat-Cutting Machine with Revolving Knives. would have to be exposed to an excessively high temperature in order to make all the fat run out. The fat is therefore comminuted before melting, an operation that can be effected in divers ways. The simplest but most cumbrous and tedious method is by chopping on a block with a sharp knife or hatchet. A better plan is to employ a knife, movable vertically about a fixed point a kind of chopping machine- but this also is insufficient for working on a large scale. In England edge runners, i.e., heavy millstones made to revolve over a horizontal surface by means of a driving pulley (placed MACHINERY FOE BREAKING DOWN FAT. 25 above or below), are used, and crush the fat by their weight, the membrane of the cellular tissue being thereby ruptured and the fat converted into a pulpy mass of a considerable degree of fineness. Eoller mills may also serve for crushing fat, but the fat- grinding machine shown in Fig. 2 is more efficient. This machine consists of an iron frame on which are mounted grooved (sharp-edged) rollers driven by toothed FIG. 4. Fat-Cutting Machine with Revolving Knives. gearing and belting pulleys, and at the top a wooden box or hopper feeding the fat to the rollers. When the rollers are set in motion and the fat placed in the box, the rollers (which move in opposite directions) draw the fat in, cut it and crush it, and then allow it to drop into a receiver situated underneath. In this case the material is riot only torn apart but comminuted as well. 26 ANIMAL FATS AND OILS. The most efficient of all are the cutting machines such as are shown in Figs. 3 and 4. In the hollow of the cast-iron stand a number of sharp- edged knives are placed, which re- volve, and thereby rapidly cut in pieces the material placed in the upper dish, and deliver it by its own weight into a receiver below. PANS AND APPAEATUS FOE FAT MELTING. The pans for melting the fat may be selected in accord- ance with the requirements of the business, so long as it is FIG. 5. Portable Melting Stove with Pan. merely a question of small quantities or of such kinds of fat, e.g., hog fat, as evolve no malodorous vapours, or, finally, when the works are situated in a place where the neighbour- hood suffers no inconvenience by the production of a strong smell, e.g., blubber- melting works in the vicinity of the fishery. The pans may be mounted either on portable stoves, as is particularly the case in blubber refining, or else surrounded by brickwork, and, therefore, fixtures. In either case, however, the heating gases should come in contact PANS AND APPARATUS FOR FAT MELTING. 27 with the bottom of the pan only, in order to prevent the melted fat becoming overheated, a condition that would re- sult not only in the discoloration (browning) of the fat, but also cause danger from fire. Iron or wooden vats heated by a steam coil, or jacketed pans, may also be advantageously employed. / A portable melting pan is depicted in Fig. 5, consistmg of FIG. G. Fixed Pan Heated by Direct Fire. a sheet-iron stove with furnace door and flue and a wrought- iron or copper pan. The dome-shaped bottom of the pan is protected (around the spring of the dome) from the action of the fire by means of a partition wall. A fixed pan heated by direct fire is shown in Fig. 6. The pan stands above the level of the bottom of the furnace, and is accessible by means of steps. The melted fat can be run off through a tap near the bottom of the pan. In large establishments, especially in inhabited districts, tallow melting in open pans is prohibited by the authorities, and the use of closed vessels is enjoined. A number of these 28 ANIMAL FATS AND OILS. appliances are described and illustrated in the following pages. TALLOW-MELTING PLANT DESIGNED BY TONCOU. The inodorous tallow-melting plant devised by Toncou is depicted in Figs. 7 to 9. The installation comprises sixteen pans A, each of which is fitted with a hood B (Fig. 9), to- gether with a tubular superstructure and a manhole C for FIG. 7. Tallow-Melting Plant Heated by Direct Fire and Fitted with Deodorising Furnace.- A, melting pan ; B, hood ; C, manhole ; D, furnace for each pan ; E, vapour catcher ; F, flue common to all the furnaces ; G, supplementary furnace ; H, draught flue leading to G ; J, draught hole ; K, grating ; L, fireproof arch ; M, register. filling and emptying the pan. The vapour catchers (hood, etc.) B are connected with a draught flue H, about 30 in. high and 26 in. wide, which conveys the vapours under the white-hot dome of a small furnace (situated directly beneath a shaft E, which is about 110 ft. high), where they are com- pletely consumed. The whole of the furnace fires are con- nected with the aforesaid shaft by a common flue F. In PANS AND APPARATUS FOE FAT MELTING. 29 very large works a draught hole J is provided, through which air enters and dilutes the vapours, which then pass through a grating K into the furnace C, the products of the com- bustion going on in the latter streaming through a grating into the fireproof arch L, and thence into the shaft. The hearth of the furnace G is 36 in. wide and 47 in. long. Coke fuel is employed here in order to reduce to a minimum the water vapour in the products of combustion. M is a FIG. 8. Tallow- Melting Plant with Direct Fire and Deodorising Furnace. vertical register or damper for shutting off the connection between the furnace G and the shaft E. In the same way the horizontal damper N serves to open up communication, when desired, between the flues H and F in order to divert the vapours from the pans whilst the fire is being kindled in G. By means of a second vertical damper the furnace gases can be diverted through the fire G, the horizontal damper N being assumed as open for that purpose. This 30 ANIMAL FATS AND OILS. arrangement presents the great advantage that the vapours and gases to be burned need not pass through the fuel, the place where the coal is consumed being distinct from the chamber wherein the actual destruction combustion of the gases is effected, so that, since pure air alone is admitted to the fuel, the fire can be made stronger or reduced at wilL It goes without saying that the gratings K and L must be FIG. 9. Vertical Section of a Melting Pan. made of fireproof material (firebrick). This notwithstanding, the brickwork easily becomes damaged on account of the large quantity of moisture contained in the vapours. TALLOW-MELTING PLANT FOE SULPHURIC ACID METHOD. In order to obviate the numerous inconveniences attend- ant on the melting of tallow in open pans, and the great PANS AND APPARATUS FOR FAT MELTING. 31 expense of large installations for working without smell, a practice has latterly arisen of melting tallow with the assist- ance of dilute sulphuric acid. An apparatus designed by Vohl for this purpose is shown in Fig. 10. This consists of a lead-lined, cast-iron pan A, with cylin- drical cover B and lid C, fitted with a mica plate D. A similar plate is fitted in the door E, and by this means inspection of the course of the operation proceeding inside the pan is facilitated. At night an artificial light is placed FIG. 10. Tallow-Melting Plant with Direct Fire (for Acid Treatment). A, lead-lined cast-iron pan ; B, cylindrical cover ; G, domed lid ; D, mica plate ; E, door ; F, outlet tap for tallow ; G, tap for drawing off the acid liquor ; H, hearth ; J, pipe leading from pan to con- denser ; K, condenser box ; L, lid ; M, packing round the rim ; N, outflow pipe ; 0, effluent for the easily condensable gases ; P, condenser ; Q, outflow pipe ; R, outflow ; S, outflow pipe for the permanent gases ; T, flue ; U, ash-pit. over the mica plate in the lid C. Mica is selected for these windows on account of its greater durability and security as compared with glass. The door E serves for the admission of the tallow and hermetically closes B, besides serving for withdrawing the greaves left on the grating at the bottom of the pan when the operation is terminated, after the tallow has been run off through the tap F and the acid liquor through G. The gases and vapours generated in A during 32 ANIMAL FATS AND OILS. the melting process pass through the pipe I to the condenser K, which is closed by a lid L packed around the edge M. Inside, the box K contains a number of inclined platforms covered with slaked lime. The box itself is made of wood impregnated with tar and asphalt. The condensed water runs away through the pipe N and forms in the swan-neck E a water-seal preventing the escape of vapour. The nncondensed gases and vapours issue from K via the pipe into the lead-lined condenser P, which is filled with coke or pumice, impregnated with sulphuric acid, and the accumu- lated liquid runs off at the bottom through the pipe Q to the discharge pipe R, the permanent gases, etc., being finally led through the pipe S into the conduit T which debouches in the ash-pit U below the hearth of the furnace H where they are consumed. These gases can be delivered underneath the fire without any fear of reducing the draught, since they have been mostly freed from water in the condenser. The ash-pit U is fitted with an iron door by means of which a powerful draught can be induced for exhausting all the gases from the apparatus and carrying them to be consumed in the furnace. V is a funnel leading to the shaft and effecting the removal of the furnace gases. In working this apparatus 20 parts of water previously mixed with J to 1 J parts of concentrated sulphuric acid are employed for each 100 parts of tallow to be melted. The sulphuric acid serves to effect the chemical decomposition and unlocking of the cells. WILSON'S TALLOW-MELTING APPAEATUS. In the Wilson apparatus (Fig. 11) the steam enters through the perforated pipe G beneath the false bottom. The plate F fits tightly over the aperture E and the vessel is charged with tallow to two-thirds of its capacity. The steam pressure may be as high as 3| atmospheres, a pressure PANS AND APPAKATUS FOR FAT MELTING. 33 which is maintained during ten hours. The condensed water collects beneath the false bottom and can be drawn off when required. The melted tallow runs away through the taps P P, and the greaves are finally removed through the aperture E. FIG. 11. Wilson's Tallow-Melting Apparatus. GELLHORX, FLOTTMANN & Co.'s STEAM APPARATUS FOR TALLOW MELTING. The fat to be melted is introduced into the melting pan A, through the neck, and rests on a grid B covered with fine filter cloth. The pan is situated in the basement, and the neck projects through the ground floor, an arrangement economising both time and labour in charging the pan. The latter is constructed of strong sheet-iron, jacketed with a tin case and slag wool lagging to prevent loss of heat by 34 ANIMAL FATS AND OILS. radiation. When the melting pan A is filled with crude fat water is poured in until the charge is covered, and the neck is then closed by a steam-tight lid. Steam is conducted from the boilers C through the pipe D into the melting house as far as the pan A, where it passes FIG. 12. Gellhorn, Flottmann & Co.'s Steam Apparatus for Tallow Melting. (Ground Plan.) down the two vertical branches E and F (fitted with valves G, H), the former of which extends almost to the bottom of the pan. To start the process the valve G is opened and admits steam (at a pressure of 3 atmospheres) into A below the grid B, whereby the water is first raised to the boil and PANS AND APPAEATUS FOR FAT MELTING. 35 the fat to melting-point. The operation lasts five hours, during which time the boilers have of course to be refilled several times, so that the steam pressure continually recedes and it may happen that the pressure of steam in the boiler becomes less than that in the pan. To prevent the steam escaping from the latter back into the boiler by way of the feed-pipes E, D, a back-pressure valve J is affixed in D. A FIG. 13. Gellhorn, Flottmann & Co.'s Plant. (Section through Melting House. ) A, melting pan ; B, grid with filter ; C, boilers ; D, steam pipe ; E, . F, branch therefrom to A ; G, H, valves in pipes E, F ; J, back-pressure valve ; K, pipe to condenser ; L, valve in K ; M, condenser ; N, receiver ; . 0, water pipe ; P, pipe conveying the gases to the furnace ; Q, K, dis- charge pipes; S, general outflow pipe; T, manhole; U, pipe from.A^ to W; V, valve in pipe U; W, clarifying vat ; X, conduit from W to/ Y ; Y, clarifying pan ; Z, steam pipe leading to Y. and D are also provided with pressure gauges to enable the 1 pressure to be observed. When the differences of pressure; are considerable the valve G is closed. Also at the end of one hour the valve G is shut and the valve L in the pipe- K opened, whereupon steam and the malodorous gases, evolved by the crude fat pass, in company with contained 36 ANIMAL FATS AND OILS. globules of fat, from A into the condenser M, which, together with the attached receiver N, is half filled with cold water. The pipe K is continued w r ithin the condenser M and de- bouches below the level of the water therein. Sufficient water is supplied by the pipe to condense the vapour and fix the malodorous gases in the water, whilst the uncon- densed gases pass with the fat globules and warmed water into the receiver N, and the gases that do not remain in the latter then pass through the pipe P to the back of the fire- bridge in the boiler fire where they are consumed. The inclined tube Y in the receiver N serves to keep the water level in M and N constant by drawing off a quantity of warm water equal to that of the cold supplied and delivering it into the pipe R, which discharges it through the common outfall S into the open air, where it can be mixed with soil for manure. The fat accumulating in time in the receiver N is re- moved through the manhole T. Taps leading to the outfall pipe S are fitted to the receiver and condenser in order to draw off their contents when they have to be emptied and cleaned. Condenser, receiver and melting pan are built of strong sheet iron. When the gas is all removed the supply of water to the condenser is arrested, and the pan A discon- nected from the condenser by closing the valve L. G being reopened, fresh steam is admitted into A, and the crude fat is again melted, this time for four hours, whereafter G is once more closed and the vapour and gas again passed through the condenser as already described. When the gauge on the pan shows that all the pressure is removed, A is closed and left for an hour, during which period of repose the pre- liminary clarification of the melted fat from the admixed solid residue and dirt is effected. The valve H in the pipe F being then opened, steam enters the upper part PANS AND APPARATUS FOR FAT MELTING. 37 of the pan and presses on the surface of the fat there float- ing on the water ; and when the valve V is opened the fat and water are forced through the pipe U into the clarifying vat W, the water entering first and being followed by the tallow, which is freed from the solid residue and coarser particles of dirt by the filter B, these latter being removed from A through the lower opening, which at other times is tightly closed. The clarifying vat W is of sheet-iron and has the largest possible surface ; here are separated the particles, of dirt, part of them sinking to the bottom and part form- ing a thin scum on the surface of the fat. After remaining; at rest in this vat for six to eight hours the fat is then gradually floated upwards by means of water, admitted 1 through the pipe 0, until it runs off through the tapped pipe X into the clarifying pan Y, the water and deposited dirt in W being drawn off from the bottom. The vessel W is covered in, the vapour which enters when the mass is forced over from the pan A escaping through a pipe extending into the open air above the roof. The clarifying pan Y is a wrought-iron jacketed pan, open at the top, constructed to stand the working pressure (3 atmos.) of the steam in A, and lagged with lead and slag wool to prevent radiation. Before the fat is admitted the pan is partly filled with clean cold water, and then, when the fat is in, the mass is gently boiled by means of steam admitted into the jacket space from the pipe D via Z. After treating in this way for an hour, during which time the scum is taken off, the valve in the pipe Z is closed, and the steam and water of condensation are run off through S. When the mass is so far cooled that it begins to set, the tap in the pipe leading from the bottom of the clarifying pan is opened and the contents drawn off, the water and dirt first, and then the purified fat, which is delivered into the transport casks. In the hot season cold water from is 38 ANIMAL FATS AND OILS. passed into the jacket space around the pan and assists the setting of the fat. By means of this apparatus perfectly pure tallow is pro- duced. LOCKWOOD AND EVERITT's STEAM PLANT FOE TALLOW MELTING. The advantages of this plant consist chiefly in the complete destruction of the evil-smelling vapours injurious to health, and in the security of the apparatus against explosion, the fat being gradually melted in a digester. The apparatus con- sists of two parts, viz., a melting pan and a furnace for con- suming the evolved gases and vapours, these two parts being connected by a pipe J. The pan, or digester, which contains the fat to be melted, consists of a steam-tight cylindrical vessel A surrounded by a jacket B. In order to make the apparatus extremely firm since it has to bear a tempor- ary pressure of 7 atmospheres the top and bottom of the cylinder are connected by iron stays and the jacket with the inner cylinder by stay bolts, in addition to which the steam pipe C, which serves to regularise the temperature of the charge of fat, also assists in strengthening the pan. Under the vessel, which is mounted on feet, is a furnace, the hot gases from which pass through flues G cut in the brickwork in such a manner that the gases come in contact with as large a surface as possible of the pan and finally escape into the chimney. The melting pan is filled by way of a manhole E, and the residual skin, greaves, etc., are removed through an opening F. The removal of the liquid fat is effected by an exhaust pipe M turning on a swivel joint D, and fitted at the end with a strainer to keep back extraneous matters, the other end leading to an outlet pipe U, through which the fat, forced upwards by the pressure in the pan, is delivered to any convenient spot. The gases and vapours generated PANS AND APPARATUS FOR FAT MELTING. 39 during the melting of the crude fat are led through the junction pipe J to the Argand furnace (as the inventor designates this portion of the apparatus). Here the gases at first traverse a system of heated tubes and then issue through four burners P arranged symmetrically around the furnace, and are there mixed with atmospheric air and burned. FIG. 14. Steam Plant for Tallow Melting. A, sheet-iron pan ; B, jacket ; C, steam pipe ; D, stay rods ; E, manhole ; F, outlet ; G, flue ; H, hearth ; J, pipe leading to furnace ; K, pressure gauge of steam jacket ; L, pressure gauge of digester ; M, exhaust pipe with strainer ; N, swivel joint ; 0, system of tubes ; P, burner ; Q, opening and air chamber ; R, hearth ; S, tube ; T, flue ; U, outlet pipe. The products of combustion in ascending surround the spiral and escape into the chimney T. The air requisite for com- bustion enters at the upper part of the furnace, at G, into an air chamber enclosed in the brickwork, where it is heated, and thence passes to the burners below. In order to increase the draught a small tube S conducts heated gas under pres- 40 ANIMAL FATS AND OILS. sure into the space below the hearth E. With this descrip- tion the working of the apparatus can be explained in a very few words. After the jacket B has been filled with water up to a level with the top of the flue, the charge of fat is placed in the digester, care being taken that the exhaust pipe M is first raised to its highest position and fixed there. Simul- taneously with the closing of the feed-opening the Argand furnace is kindled, and as soon as a moderate amount of pressure is indicated by the gauge K the tap in the pipe J is opened and the gases allowed to escape to the combustion furnace, which must in the meantime have become hot enough to ensure the destruction of the malodorous gases. The heating of the melting pan is so regulated that the pres- sure inside the pan does not exceed 2J atmospheres and that in the jacket space not more than 4 atmospheres. In order to ascertain when the melting is complete, samples may be taken from time to time through the pipe M. The capacity of this digester is generally 7J tons. When the residual tissues are intended for fodder they are dried at night in the pan itself, a low fire being kept up in the combustion furnace. STEAM APPARATUS FOR TALLOW MELTING. A simple form of tallow melter heated by steam is given in Fig. 15. The apparatus consists of a pan covered with a hood which is fitted with an effluent pipe. The tube through which steam at a pressure of several atmospheres is admitted is wound in spiral form in such a manner that the upper tier of the coil is situated at a level about one-third the height of the pan, the others being directed progressively downwards until the lowest one makes its exit at the foot of the vessel. Since the steam enters at the top of the coil and condenses to water therein, it is necessary to give PANS AND APPAKATUS FOB FAT MELTING. 41 the coil such a pitch that the water can run away freely. At the commencement of working the steam is regulated so that water alone issues from the lower extremity of the coil, and the steam current is allowed to act until the crackling sound caused by the evaporation of water from the greaves is heard inside the pan. To facilitate the removal of the melted fat the bottom of the pan is rounded and is fitted with a pipe, above which is a sieve supporting the greaves, these latter being after- wards removed through a lateral opening (covered by a FIG. 15. Steamer for Melting Tallow. screwed lid) on a level with the false bottom. A water gauge, fitted at the side of the pan, enables the height of the melted tallow in the vessel to be observed. The pan is also lagged with wood to prevent the radiation of heat. A slow current of steam may be passed through the coil even while the pan is being charged, the current being turned on more fully, as already described, when the pan is closed. Directly the fat is melted the steam is shut off, the fat being then run away through the pipe at the bottom of 42 ANIMAL FATS AND OILS. the vessel, which is refilled with tallow after the greaves have been cleared out. BIVOIR'S STEAM APPARATUS FOR TALLOW MELTING. This apparatus, displayed in Fig. 16, works without smell, and the liquefaction of the fat is effected by steam under a pressure of from 3 to 5 atmospheres. The pan is made of wrought iron, with a riveted, rounded bottom, FIG. 16. Steam Apparatus for Tallow Melting (W. Kivoir, Offenbach- on-Main). and stands upright on a wrought-iron frame. In the lower fourth of the cylinder two perforated false bottoms are fixed at a little distance apart, the fat to be melted being laid on the upper one, which is readily accessible from outside through a lateral aperture closed by means of a bow and screw and situated on the same level with the false bottom. This opening serves for clearing out the greaves. PANS AND APPARATUS FOR FAT MELTING. 43 Between the false bottoms there is a lateral tap for drawing off the melted fat. Beneath the lower false bottom is situated the steam coil, and below that again, in the deepest part of the pan, ;are the tap and pipe for emptying the vessel completely. At the top of the apparatus is a manhole, fastened by a bow -and screw, through which the pan is filled, and entered for cleaning ; and an escape pipe for the vapours is also situated in the top of the vessel. When the apparatus is connected with a steam supply working at a pressure exceeding 5 atmospheres it must be provided with a safety valve, pressure ; gauge, reducing valve and back-pressure valve between the pan and the feed-pipe. Where steam is not available the -apparatus can be modified so as to be set in brickwork and generate the steam required for the melting process. For working with indirect steam, i.e., without the steam and fat coming into direct contact, the maker supplies jacketed pans well tinned inside, the heat being then applied by a steam coil situated in the space between the two walls of the pan. A cold water coil is also provided, so that the temperature can be regulated as desired. The interior fittings comprise a vertical pipe and a draw-off tap as in the case of the single pan, a tap for completely emptying the vessel being placed, with its attached pipe, centrally, at the lowest point in the bottom. The pan itself is supported on a wrought-iron stand. In order to accelerate the melting process stirrers are provided which squeeze the lumps of melting fat between arms. These stirrers are made of well-tinned wrought iron and are easily taken out for cleaning. Motion is imparted from a driving pulley above and a pair of cone wheels, and they can be arranged for driving either by hand or power. By reason of their simplicity and great capacity Eivoir's .melting pans have proved exceedingly useful and are pre- 44 ANIMAL FATS AND OILS. ferred by experienced melters to more complex and less practical systems. For melting good quality tallow (premier jus, edible fat) Kivoir makes simple, round, wooden vats heated by direct steam, which is admitted through a coil at the bottom. A draw-off tap for the melted fat is placed at a moderate height above the foot, the fat being delivered to this tap by a jointed pipe, an arrangement which allows the clear fat to be drawn from any level within the vat. A cleaning-out valve is fitted in the bottom, the aperture being large to enable the residue to be removed from the vat with ease and the latter swilled out with water. All the ironwork coming in contact with the fat is well tinned. 0. HEINTSCHEL'S TALLOW-MELTING, CLARIFYING AND FILTERING APPARATUS FOR CONTINUOUS WORK. The apparatus shown in various points of detail in Figs. 17 to 20 consists of three parts : the melting pan A, the clarifier B and the filtering vessels C 1 C 2 C 3 . The melting pan is a cylindrical vessel with a funnel- shaped bottom, which, as shown in Figs. 17 and 18, is jacketed, the intermediate space between the walls contain- ing a heating apparatus H 1 , composed of coiled or transverse pipes or pouches. In the axis of this pan is situated a verti- cal filtering cylinder F 1 (Fig. 19), projecting through both lid and bottom of the pan and fitted with stirrers and overhead driving gear. Being open below and projecting through the bottom W, this cylinder communicates with the second chamber B, unless closed by means of a slide or trap, etc.. V, whereby the two chambers can be isolated. Close to the filter tube, in the deepest point of the bottom of A, is a second opening (Fig. 19), so that a valve adjustable from out- side enables A and B to be connected with or shut off from one another. The filtering cylinder has a perforated jacket,. PANS AND APPARATUS FOR FAT MELTING. 45 whereby the fat introduced into A through the feed-opening E is, after being melted by the warm air in the double walls or heating apparatus, enabled to filter through the openings in the said cylinder. When V (Fig. 18) is open the fat drains away and collects in B. In order to increase the filtering capacity the tube F may be replaced by perforated filter tubes, the perforations being made only on the side of FIG. 17. Heintschel's Tallow-Melting, Clarifying and Filtering Apparatus. (Front Vertical Section.) the tube opposed to the direction of movement of F, in order to prevent the clogging of the filtering surface. For the same purpose a slide, perforated with apertures correspond- ing to those on the cylinder, can be mounted thereon and by being moved up and down be made to clear away any fibres, etc., attaching themselves to the apertures ; or a scraper 46 ANIMAL FATS AND OILS. may be affixed to part of the apparatus so that its cutting edge rests on the filter cylinder and scrapes off any adherent matter during the rotation of the cylinder. The clarifying chamber B is situated underneath or by the side of A, and, like the latter, has a deepened bottom and a heating apparatus. At the deepest point in the bottom it is fitted with a closable aperture, and near this a telescopic or hinged tube (adjustable from the outside) or else a num- ber of taps at different heights. When a sufficient quantity FIG. 18. Heintschel's Apparatus. (Details of Melting Pan.) of melted fat has been run off from- A into B then the cham- bers are isolated by closing the aperture of communication. In consequence of their different specific gravity, the various grades of tallow, as well as the admixed particles of fibre and water, quickly separate in layers, the better, lighter grades being at the top, the others successively lower, and the water and fibrous particles weighted therewith, lowest of all in the deepened bottom B ; so that by suitably adjusting the draw- off tube, or by way of the taps, definite grades of melted fat can always be run off from above downwards and conducted by the flexible tube D into the clarifying vessels. PANS AND APPARATUS FOK FAT MELTING. 47 The solid constituents (greaves) collecting, in the course of the continuous melting process, in the bottom of the melt- ing chamber A, as well as water, blood residue, etc., are drawn off from time to time through into the empty clarifying chamber, where they are clarified, the hot liquid fats they still contain being removed through T ; and, finally, the less valuable, thick residues are withdrawn FIG. 19. Heintschel's Apparatus. (Lateral Section.) through into the vessels placed underneath, where they can be subjected to further treatment. In this process, by means of the continuous series of operations performed in succession (melting, clarifying and drawing off), the capacity of the apparatus is far in advance of the old-fashioned plant as regards both the quantitative and qualitative results ob- tained. Moreover, this system possesses the additional ad- 48 ANIMAL FATS AND OILS. vantage that by drawing off through the adjustable pipe B and collecting extremely uniform grades of melted fat in the corresponding clarifying vessels, a well-assorted class of goods is produced and the raw material utilised to the best advan- tage. In order to enable the separation of the fats to be effected according to specific gravity in the chamber A 1 , another construction is given to the filtering cylinder. This is perforated with a convenient number of holes or slits ar- i 00 FIG. 20. Heintschel's Apparatus. (Filtering Cylinder.) ranged in rings at different heights and is provided with a well-fitting inner tube perforated to correspond. Thus, for example, if the fat is to be separated into three portions at equal intervals of height, three equidistant rows of rings are provided. By raising or lowering the tube, e.g., through a distance equal to one-third of the interval between the rings, the sifting rings opposite the one layer are brought into juxtaposition,^the openings in the other two being covered and thereby closed. By this means a qualitative PANS AND APPARATUS FOR FAT MELTING. 49 separation of the melted fats can be effected even in the melting chamber A, uniformity of quality being thereby more effectually ensured. FAT-EXTRACTING APPARATUS WITH CORRUGATED BOTTOM. The apparatus shown in plan in Fig. 21, and in side and front view in Figs. 22 and 23 respectively, is designed for FIG. 21. Fat-Extracting Apparatus with Corrugated Bottom. V* FIG. 22. Apparatus with Corrugated Bottom. (Side View.) melting fat or extracting it from fatty substances. It is en- closed on all sides and heated internally by steam passing through several series of parallel pipes a arranged at different heights, the walls being covered with insulating material to prevent radiation. The arrangement is such that the steam 50 ANIMAL FATS AND OILS. from a common feed-pipe c enters each series at the same time, so that a uniform temperature is maintained through- out all parts of the tubes and apparatus. In order to increase the influence of the heat, radiated from the pipes, on the fat or fatty matter in the flat boxes c, and, with this object, to obtain the largest possible extent of surface, the bottom of the box is made of corrugated tinplate, an arrangement greatly in- creasing the area of surface exposed in comparison with a flat bottom. In the hollows formed by the corrugations are fixed semicircular or angular strips of iron, which are perfo- rated all along the edges, so that the melted fat can run FIG. 23. Melting Apparatus with Corrugated Bottom. (Front View.) FIG. 24. Arrangement of Funnel. through into the channel formed by the iron strips and hol- lows of the bottom and run down to the front of the box, which is laid at an angle for this purpose. Not only is the draining of the fat facilitated by this arrangement but the impurities are also retained. The fat arriving at the front of the boxes runs down through apertures there into open channels e, which convey it to a vertical collecting pipe. In this case the corrugations extend to the front end of each box. Instead, however, of having a channel e underneath, the front edge of the box may be inclined towards the centre of the apparatus, and when this is the case the corrugations PANS AND APPAEATUS FOE FAT MELTING. 51 do not extend quite to the edge, but a ledge sloping down towards the middle of the apparatus is attached thereto. The fat coming from the channels or boxes runs into this ledge and is conveyed therein to the centre of the apparatus. Under these ends are arranged stays (fastened near the collecting pipe) which catch the fat and lead it into the col- lecting pipes, from whence it passes to the collecting vessel. Another method of draining the fat from the front end of the boxes consists in allowing it to fall direct into a channel at the bottom of the apparatus, in which case the ends are arranged stepwise, the upper ones always projecting beyond those successively lower, so that the fat can drop direct from each to the channel e' 2 , which slopes down towards the middle and terminates there in a collecting pipe. To prevent the fat splashing as it falls into the channel the latter is made in the shape of a funnel, with an angle as acute as, possible, so that splashing is out of the question. This, channel may either be provided with a small lateral opening discharging into a concave channel e 2 , or may have an open- ing at the bottom, under which a partition wall e l t covered with a shed roof, is arranged. Instead of fitting the boxes with corrugated bottoms a& described, ordinary melting vessels may be employed, corru- gated plates being fitted either on the bottom or at a slight distance above. The fat is placed on these plates so that the melted fat flows down the channels and collects in the bottom of the vessel, to be then drained away in a suitable manner. EXTEACTION PLANT. As already mentioned, the extraction process, which in the vegetable fat and oil industry is of considerable impor- tance, is only employed in isolated cases for animal fats, the nature of the latter being different. Bone fat is the chief fat recovered by extraction, and rationally conducted establish- 52 ANIMAL FATS AND OILS. inents either extract the fat alone from the bones and treat the residual matter in other ways, or work up the bones com- pletely in one operation. The forms of apparatus described in that section of the author's work Vegetable Fats and Oils dealing with extraction processes (q.v.) are also applicable for the treatment of bones as well as of the residue (greaves) from fat-boiling works, whilst the plant now described is Intended specially for the extraction of bone fat only. DR. AHRENS' APPARATUS FOR EXTRACTING BONE FAT. Latterly it has been proposed to replace the benzene ralmost universally employed for depriving bones of their fat Iby carbon tetrachloride, which is a powerful solvent of fat, has a constant boiling temperature, is uninflammable and leaves behind no unpleasant smell in the fat after saponifi- cation. If, however, carbon tetrachloride be used in the ordinary fat-extracting apparatus a remarkable phenomenon is observed : the fat is either black or very dark brown in colour. This results from the decomposition products of the carbon bisulphide always present in commercial tetrachloride, the bisulphide forming, with the ammonia in the bones and iron in the blood, sulphocarbonates, which split up into carbonates and sulphur compounds, which are always dark coloured and remain behind in the extracted fat after the removal of the solvent by evaporation. On the other hand, chemically pure carbon tetrachloride cannot be employed, on account of its high price. Nevertheless, the present process and the apparatus there- for enable the ordinary tetrachloride, contaminated by car- bon bisulphide, to be used, the above-named objection being obviated. The process consists in depriving the bones of their fat in an open extractor fitted with two perforated false bottoms and a cooler, the cooling water of which covers the bones and the solvent. The ammoniacal vapours expelled PANS AND APPAEATUS FOR FAT MELTING. 53 from the bones during the heating of the solvent, form, with the accompanying air, bubbles, which ascend through the liquid and carry with them the carbon tetrachloride. In order to separate these bubbles of air, ammonia and tetra- chloride into their constituent compounds, a number of sieves arranged spirally and connected by fine sieves are fitted in the cooler, against which the bubbles impinge, whereby, in conjunction with the action of the water trick- FIG. 25. Ahren's Bone-Fat Extracting Apparatus. (Cross Section.) ling down the partition walls, the tetrachloride is deposited in the form of specifically heavier oily drops, which are re- conducted to the extractor, whilst the air escapes and the ammonia is retained by the cooling water. In the appended illustrations Fig. 25 shows the general plan of the appara- tus and Fig. 26 a modification in the construction of the cooler affixed to the top of same. The method of working the form depicted in Fig. 25 is as follows : After the extrac- tor A has been filled with bones through the upper manhole 54 ANIMAL FATS AND OILS. so that they reach nearly up as high as the upper false bottom m (which prevents their floating), the manholes and O 1 are closed and carbon tetrachloride is run in from the storage vessel R until the bones are covered and the solvent attains the level of m, which can be ascertained by means of the. windows. The tap a' 2 of the pipe supplying the solvent is then closed and water is poured into the cooler B through a neck s until the level of the upper manhole is attained. Meanwhile the valve a 1 of the overflow pipe u is closed, the manhole cover being off. The solvent in A is then heated to boiling-point by a steam coil B 1 under the lower grating FIG. 26. Ahrens' Bone-Fat Extracting Apparatus. (Cooler.) (false bottom) m and dissolves out the fat contained in the bones. The vapours of carbon tetrachloride evolved during the boiling ascend into the water in the cooler, are there con- densed and fall back into A, to then renew their course. At the commencement of boiling, air and ammonia are given off from the bones and carry some tetrachloride with them. The partition walls Y in the cooler B, which serve to sepa- rate the bubbles of gas, run in a spiral direction upwards, inclining towards the axis of the cooler and being connected together by fine sieves. The ascending bubbles impinge on. the spiral walls and are diverted laterally, passing from one compartment into another until they burst. By the impact PANS AND APPARATUS FOR FAT MELTING. 55 of the bubbles on the partition walls and their passage through the sieves, the tetrachloride is, under the concomi- tant action of the cooling water, deposited, and, with the assistance of the stream of water trickling from S, rolls down the steep plane until it reaches the lowest point, whence it is diverted back into the extractor. The ascending ammoniacal vapour is dissolved by the cooling water and is conveyed away through the overflow pipe u for further treatment. This overflow pipe is fitted with a cover in the vicinity of its em- bouchure in order that the descending tetrachloride may be diverted sideways. Any tetrachloride carried away, not- withstanding this arrangement, is removed by a separating funnel D fixed at the lower extremity of the overflow pipe, where it falls to the bottom and is conveyed through a short pipe dmto the conduit e and into a circulation vessel, whilst the cooling water runs away from the separating funnel. When, after several hours' exposure to the tetrachloride, the bulk of the fat is dissolved, the solution is run off through the tap a into the still c, and the extractor re-charged (after closing a and opening a 2 ) with solvent from the vessel B to the same height as before. The solvent is distilled off in C and is condensed in the cooler K, whence it flows through e and E back into the extractor. The circulation vessel E, which is connected to the cooler K on the one hand and with the extractor on the other, serves to control the pro- gress of the operation, in that the liquid distilled from the fat flows into it (E) from the cooler and thence into the ex- tractor. For the purposes of this control a water-gauge glass is attached to the circulation vessel, so that by observing the fluctuations of the level of the liquid in the gauge the course of the operation can be judged. The extraction of the fat is gradually effected in the fore- going manner, and the solvent becomes progressively poorer in fat. As soon as a sample taken from c 1 , between the ex- 56 ANIMAL FATS AND OILS. tractor and the still, is found to be free from fat the extraction is finished, and the expulsion of the solvent from A is proceeded with. This is accomplished by admitting direct steam into A through pipes a 4 by closing the taps a and c, turning the steam valve k l back to k, drawing off the cooling water through the pipe b 2 , closing the manhole lid b and then opening the tap b 3 of the pipe leading to the cooler. Here- upon the solvent passes over into the cooler K, where it is condensed and returned to the vessel E for use over again, whilst the fat is freed from the last traces of solvent in the still C and is finally drawn off. Several of these extractors can also be united to form a battery, and the solvent re- maining in the first extractor at the conclusion of the opera- tion may be transferred to the second extractor ready filled with bones, an arrangement saving both time and steam. Moreover, at the commencement of operations the (closed) extractor can be connected with an air pump in order to exhaust the bones of air and gas and thus reduce the amount of gas evolved ; this without deviating from the principle of the invention. In Fig. 26 the cooler B is modified in so far that it is flattened at the base and expanded laterally and connected w r ith the extractor A by a shut-off valve a 5 . The cooler may be also jacketed or fitted with a worm tube to reduce the temperature. By the method of extraction in open vessels with carbon tetrachloride boiling at 65 to 78 C. according to its degree of purity the employment of a uniform low temperature, and consequently the production of good fat, is rendered feasible, the decomposition of the solvent being, furthermore, prevented, since all the evolved gases and salts are removed by the supernatant cooling water. In addition to this the glue in the bones is greatly protected by reason of the low temperature employed and of the insolubility of the glue in tetrachloride. PANS AND APPARATUS FOR FAT MELTING. J. KALECZOK'S BONE-FAT EXTRACTING APPARATUS. 57 The vessel a, which is fitted with a perforated false bottom, is filled with bones, and the opening b closed. Here- upon, the hemispherical steam pan is placed under steam pres- sure, and the tap d in the feed-pipe supplying the solvent (ben- zine) opened. The benzine flows from the feed-pipe b on to the hemispherical surface, where it is vaporised, and ascends, FIG. 27. Kaleczok's Bone-Fat Extracting Apparatus. along with the vapours given off by the bones, through the pipe e into the condenser/. The condensed solvent and the water (the steam from the bones) arrive at the chamber h, whence the water runs off through the pipe i, and the benzine continues on its way through the chamber g and thence through the feed-pipe back to the vaporising pan. The fat extracted from the bones, accompanied by a small quantity of the solvent, runs away from a through the pipe k to the 58 ANIMAL FATS AND OILS. vessel I containing the steam coil in. The steam pipe in the bottom of a is arranged as a spiral coil. A screen fitted over the benzine supply pipe prevents the extracted fat from coming into contact with the hot steam pipe. A number of small apertures in the benzine pipe per- mit the outflow of the solvent on to the hemispherical surface of the vaporising pan. The effluent liquid is immediately vaporised, so that overflow is impossible. A flange, which serves to support the feed-pipe, forms the connection between several branch tubes. THE FIG. 28. The Holdhaus Fat-Extracting Apparatus. HOLDHAUS APPAEATUS FOR EXTRACTING FAT AND DRYING THE EESIDUE. The apparatus displayed in Fig. 28 serves for the extrac- tion of fat from tissue and also for drying the residue. It consists -of a drying cylinder A, provided with an arrange- ment for warming and manipulating the contents. A series of cylindrical vessels H is superimposed, and these communi- cate with the drying cylinder by apertures I in the bottom. These vessels are also provided with suitable openings for PANS AND APPARATUS FOR FAT MELTING. 59 the admission of the material into the recipients, and each is fitted with a workable piston M, which can be forced down- wards by the mechanism provided for that purpose and squeezes the liquid out of the boiled material. The liquid is then drawn off through the tap e 2 . The vapours from the vessels H are condensed and removed by means of one or several condensers and suitable pipes. The pressed material is then transferred from the vessels into the drying cylinder, where it is freed from moisture. MEIKLE'S APPARATUS FOR EXTRACTING BONES, SEEDS, FISH, ETC. The cylindrical vessel (Fig. 29) is divided into an upper and lower chamber by means of a perforated partition sup- porting a layer of filtering material, and is also fitted with a hollow lid, conical projections on the under side of which facilitate an evenly distributed dropping of the solvent. The hollow space within the lid can be heated or cooled by means of the contained steam and cold water pipes. The steaming chamber is steam jacketed and is also fitted with a small steam jacket or steam disc on the inside. The lower chamber is provided with a similar heating appliance, and both are fitted with revolving stirrers mounted on a hollow shaft, which extends through the partition, and is perforated with lateral apertures. When the apparatus is to be used the raw material is placed in the upper chamber and impregnated with the solvent, which is forced in, under pressure, through a supply pipe perforated to ensure uniform penetration. The re- sulting fatty solution then filters through the partition and heat is applied to the lower chamber, whereby the solvent is vaporised and ascends, not through the filter, but by the easier passage, viz., the hollow shaft, and escapes through the lateral apertures thereof. The vapours are condensed 60 ANIMAL FATS AND OILS. by the cold water pipe in the hollow lid, and the conical pro- jections present the advantage of preventing the condensed liquid from collecting at one place, in that it drops uniformly from all the points formed by these cones, and so impreg- nates the material evenly. The extraction, therefore, pro- FIG. 29. Meikle's Extractor for Bones, Seeds or Fish. ceeds continuously, and the stirrers can be set in action when convenient. When the operation is completed the hollow lid is no longer cooled, but heated like the rest of the appara- tus, and the vapours then pass to the condenser. As soon as the extracted oil or fat is removed, the apparatus can be filled with a fresh charge of material. PANS AND APPARATUS FOB FAT MELTING. 61 APPARATUS FOR EXTRACTING FAT AND GLUE. E. J. Machalski of Brooklyn has constructed an apparatus for this purpose, the details of which are as follow : At the bottom of the vessel destined for the reception of the materials to be treated is placed a steam disc for heating same. Three pipes debouch into the vessel, one of them conveying the (vaporised) solvent, the second removing the excess of this FIG. 30. Machalski's Extractor for Fat and Glue. vapour to the condenser and the third supplying water. Underneath the vessel are placed recipients for collecting the fat and glue, and there is also a battery of cisterns for con- centrating and purifying the liquid glue, so arranged, one above the other, that the liquid runs through the series by gravitation, to be finally forced up through a pipe into special clarifying vessels. 62 ANIMAL FATS AND OILS. SCHWEITZER'S EXTRACTION PLANT for animal (and vegetable) materials is composed of an ex- traction cylinder fitted with manholes at the top and side, a condenser, an evaporator and the vessels destined to receive the condensed solvent. The pipes and valves effect the following combinations : Extractor with condenser, evapo- rator and condenser, condenser and storage vessel. The ap- paratus produces a perfectly dry residue, because the solvent used has a much higher boiling-point than that of water. e FIG. 31. Schweitzer's Extractor for Animal Material. The method of working is as follows : The materials are placed on the grating in the extractor, and the solvent is ad- mitted. Then all the communications are shut off except that between the extractor and condenser, and the solvent is heated by steam pipes nearly to boiling, whereby chiefly water vapour is evolved. The fat is dissolved and falls through the grating, and when the extraction is terminated the fatty mixture is transferred to the evaporator and heated to boiling, whereupon the connection leading to the con- PANS AND APPARATUS FOR FAT MELTING. 63 denser is opened and the fat or oil afterwards drawn off. If the residue is to be freed from the small portion of adherent solvent it is then heated to boiling in the extractor, and the evolved vapour is led into the condenser. W. 0. BOBBIN'S EXTRACTOR. This apparatus (Fig. 32) is described by the inventor as consisting of a cylinder (for containing the material to be extracted) traversed by a perforated tube for the admission under pressure of the solvent or of air. In the interior of FIG. 32. W. 0. Bobbin's Extractor. the cylinder runs, on a guide way, an accurately fitting carriage, for the reception of the raw material, and provided with a slip extending from top to bottom. The operation is effected by filling the carriage with the material under treat- ment, the latter being then exposed to the action of the selected solvent, passed into the cylinder under pressure. When the extraction is completed the excess of vapour is driven over into the condenser by air, whereby the press residue is simultaneously dried, and the fat run off. 64 ANIMAL FATS AND OILS. PEEFECTED EXTRACTION APPAEATUS. In the various other extraction processes the separation of the fat and the concentration of the crude glue liquor have to be effected in separate, independent vessels, an arrangement entailing special attendance on each. In the present case, however, the entire process, viz., the steaming of the raw material, the recovery of the pure fat and the concentration of the glue liquor, is performed at one time and in the same apparatus. To this end the pipe d as can be seen in Fig. 33 through which the liquid flows from the vessel A to B, FIG. 33. Apparatus for Recovering Fat and Glue from Animal Residues. is provided with a fairly wide aperture i at the upper end, whilst the lower end reaches nearly down to the bottom of the vessel. On opening the valve e, the mixed liquid and vapour pass over from A into B, and the vapour is con- ducted away through i and the pipe li to the condenser C, whilst the liquid portion runs quietly down the pipe d and separates at the bottom of the vessel into fat and glue liquor, without, as hitherto, being mixed up together and heated by the current of steam. The separation of the steam can also be effected in another way. Thus, for example, the pipe d is diverted side- ways into a boiler, in the lid of which is placed a wide, open pipe, whilst from the lower part of the pan the pipe d ex- PANS AND APPARATUS FOE FAT MELTING. 65 tends nearly to the bottom of the vessel. The mixture of steam and liquid flowing in tangentially through the pipe d streams along the walls of the pan, whereby the steam is separated from the liquid, the latter flowing downwards through a pipe d, whilst the steam escapes through an up- cast pipe I and passes thence through the pipe h to the con- denser C. In the completed form a plate is provided, against which the mixture of steam and liquid, entering laterally through d, impinges, and is separated into these components, the liquid running down through a pipe, whilst the steam passes round the plate and escapes upwards through the aperture. The same separation can, of course, also be effected by other means. After the complete separation of the fat from the glue liquor has been accomplished in the lower part of the vessel B, the former is drawn off through the tap /, and the residual glue liquor concentrated in B itself. To this end a heating apparatus, e.g., a steam jacket, is placed at the lower extremity of the vessel B, and by this means the glue liquor is raised to boiling-point and thoroughly concen- trated. The vapours thereby expelled pass through the pipe h to the condenser C, where they are completely thrown down, the concentration being in this manner effected en- tirely without smell. The nitrogenous dry matter in 'the glue liquor is left as a residue and may be removed by a suitable opening provided in the vessel B. This new apparatus consequently offers the great advan- tage that the steaming process in A is in nowise influenced by the concentration in B, and both operations can be carried on at the same time ; only for that purpose the condenser must be of sufficient capacity to cope simultaneously with the vapours delivered by A and those evolved from the glue liquor in B. Whereas, in earlier forms of apparatus, the products con- sisted of dried bones (or meat), fat and glue liquor, in the 5 66 ANIMAL FATS AND OILS. present instance they comprise merely fat and the whole of the solid substances present in the carcase. By the abolition of the easily decomposable glue liquor, an important hygienic advantage is, however, gained without the other favourable points of the process especially as regards absence of smell being impaired. PKESSES. Presses play a merely subordinate part in the recovery of animal fats and oils, whilst in the case of vegetable substances of this nature they form the chief mechanical appliances used. For animal fats they are employed in the following instances : 1. For expressing the residue from the fat-rendering process (greaves : see Greave presses) ; 2. For pressing tallow to separate it into its solid and liquid components ; 3. For pressing the blubber from marine animals. Greave presses are simple spindle presses, but, for the other purposes mentioned, hydraulic presses are mostly used, and these will now be generally described : The hydraulic press is founded on the principle of the uniform transmission of pressure throughout liquids in closed vessels, and such presses consist of two separate parts the press proper and the pump. The first is composed of : a press plate terminating below in a piston (moving in the movable cylinder contained in the lower enclosed portion of the machine) ; a head plate ; and (as a rule) four pillars connect- ing the press head with the base of the apparatus. In this latter is also placed the connecting piece effecting a junction between the press cylinder and the pump cylinder. The pump is of the plunger type, with two cylinders of unequal diameter, the larger becoming automatically disconnected when the pressure attains about 20 in., the further pressure 6T required being effected by the smaller cylinder alone. The minimum of pressure varies for each press, and the overstep- ping of the maximum pressure is prevented by the automa- tic action of a safety valve. The pressure produced by the pump is transmitted through the liquid water, glycerine or a mixture of both and also through the connecting valve and the liquid in the press cylinder, and exerts on the piston of the latter a force per unit of space equivalent to the pressure per unit produced by the pump (small) piston. As soon as the desired pressure is attained the connecting valve is closed, so that the pressure in the press cylinder may not be influenced by any leakage in the pump. In order to re- duce the pressure a second valve in the connecting gland is opened and the liquid returned to the pump chest without passing through the cylinder. In this manner the valve of the pump is preserved on the one hand, and on the other the same liquid is used over and over again, no renewal,, beyond the small amount wasted by leakage, being required.. Hydraulic presses of both vertical and horizontal form are employed, the former being, however, the kind mostly used 7 in tallow-melting works. In those employed for pressing; fat, a number of press plates of trough or box form are- superimposed, so that the lower part of each engages in the upper part of the one next below and presses the material'' contained therein, the outflowing fat being conducted into a-, common channel. For warm pressing, the press plates are> fitted with appliances for steam heating, swivel pipes per- mitting the introduction of steam at one side of the cast- or wrought-iron plates and the removal of the condensed water on the other. Where several hydraulic presses are at work in the same room, they can be all fed from the same pump ;. but where they are in separate rooms, then working by ac- cumulators can be practised with great advantage. A hydraulic tub press is shown in front and side view and 68 ANIMAL FATS AND OILS. in section in Figs. 34 and 35. The press consists of the press cylinder A and the piston B, situated between two pillars on which the troughs E slide by nisans of rings. These troughs carry a solid iron plate and are surrounded below by a channel d d for collecting the expressed fat. The boxes G containing the fat to be treated have double walls and are provided with a circular row of apertures at the top of the FIG. 35. Hydraulic Tub Press. (Side View and Section.) inner wall. These boxes are filled with fat, which may have been previously cast in moulds of suitable size, and are then covered over with a horse-hair cloth. When the press is started the troughs E are pressed into the boxes G, the liquid fat runs out of the openings below the upper rim of the latter and collects in the channels d. As soon as the opera- tion is completed the pressure is removed, whereupon all the parts of the apparatus recede into the positions they PEESSES. 69 occupy in the drawing. The boxes G are taken out on to the table and replaced by others ready filled with fat, so that the time the press is standing idle is reduced to a minimum. Among the new forms of hydraulic presses prominence is due to those of Brinck & Hiibner of Mannheim, by reason of their important advantages, consisting of : 1. Quicker and simpler service with greater capacity ; 2. Abolition of expensive press cloths ; 3. Production of uniform cakes of fat ; 4. Great durability without attrition of expensive parts. The general construction is as follows : In the press are situated four, six, eight or ten wrought-iron or steel rings, one above another, and each fitted with a finely perforated steel bottom. Between each pair of rings is placed a cast- iron or cast-steel press plate, convex on the upper surface but flat on the under face. On these plates, which are guided by the pillars of the press, rails are affixed for carry- ing the press rings, and on these the latter slide when being placed in, or removed from, the press ; and, in addition, each press plate is provided with a large encircling channel to catch the expressed liquid fat. The presses are filled by simply laying over the perforated steel bottom of each ring a horse-hair, wool or felt cloth, covering this with the fat to be pressed, and the latter, again, with a second similar cloth. When all the rings are full the pressure is turned on and the fluted upper face of each plate forces its way up into the ring next above, the liquid fat running out through the horse- hair cloth, the perforated steel plate and the grooves in the press plate, into the channel. When the fat is caused to flow uniformly from the entire surface of the cake it has only a thin layer to traverse, and thus runs away rapidly and yields a thoroughly uniform press cake. In pressing particularly heavy cakes the rings become too heavy to be lifted out, so on this account the ANIMAL FATS AND OILS. presses are fitted with two lateral frameworks and a double .set of rings, and as soon as one set of rings containing the FIG. 36. Brinck & Hiibner's Hydraulic Ring Press. pressed fat is drawn out on to the side frame to be emptied and refilled, the other (filled) set is pushed into position from PRESSES. 71 the other side frame, so that the operation is simple and goes on without interruption. FIG. 37. Brinck & Hiibner's Hydraulic Box Press. By making suitable boxes in place of the rings the cakes can be made in square or trapezoid form of suitable size. All presses are provided with appliances for heating each 72 ANIMAL FATS AND OILS. part with steam or hot water, and, as each mould rests between two heated plates, the temperature is uniform and results are attained that no other system of pressing can yield. The presses are constructed for pressures of 300 atmospheres and over, and the cylinders, pillars and nuts are of cast steel. When it is a question of pressing fat without heat, FIG. 38. Hydraulic Margarine Press. simple presses without boxes, rings or tubs are used ; such a press being shown in Fig. 38. The fat is packed in sacks and trimmed on the plate of the press, and when the loading is completed pressure is applied, whereupon the fat runs out and is caught in a suitable manner. The pressing of blubber is generally effected in very primitive presses worked by levers. Of course a quantity of the product is lost, but Eose, Downs & Thompson of Hull have constructed a screw PKESSES. 73 press for fish oil highly suitable for this purpose (Fig. 39), only moderate pressure being required. The shaft carrying the screw spindle is fitted at either end with fast and loose driving pulleys, that on the one end being driven by a straight and the other by a crossed belt, so that the plates of the press can be raised or lowered by steam power, and also, when necessary, stopped at once. The actual press is placed FIG. 39. Fish Oil Screw Press (Rose, Downs & Thompson). within a steam-jacketed chamber, the outer walls being of wrought iron strong enough to stand the pressure, whilst a door of similar construction and also heated by steam forms a secure and hermetical seal during the time the press is at work. The charge is packed in sacks and laid between metal press plates. The press can also be constructed to work with hydraulic pressure, and for certain purposes the jacket- ing chamber is omitted. 74 ANIMAL FATS AND OILS. FILTEKING APPAEATUS. The animal fats do not require such a thorough-going purification as vegetable products of the same class. For one thing the animal fats are generally solid and there- fore have to be brought into the liquid condition before they can be purified or filtered ; and, on the other hand, they are mostly put to technical uses, whereby they sustain a certain amount of alteration, e.g., saponification or melting, which purifies them. The fats destined for alimental purposes are FIG. 40. Filter Press Worked by Power (Rose, Downs & Thompson). prepared by repeated pressings, and since unlike the vege- table fats none of the solid and extraneous matters in the animal fat escape through the press cloths, a further puri- fication appears superfluous. As a matter of fact, it is only the liquid fats of the ani- mal kingdom, the fish oils, that are purified by filtration when required for alimental or better-class technical pur- poses. The reader is therefore referred for information on the subject of filtering apparatus to the author's work on ANIMAL FATS AND OILS. 75 Vegetable Fats and Oils, and on the present occasion men- tion will be made of only a single appliance, viz., a FILTER PRESS FOR LIQUID ANIMAL FATS (Fisn OILS). Fig. 40 depicts a filter press particularly suitable for filtering fish oils, and capable (with thirty-six compartments) of treating twenty tons of oil with ease ; moreover, the press can be worked every day for a week at a time without re- quiring cleaning. As soon as the separate divisions have been fitted with the filter cloths and the screw tightened up the machine is ready for work. The material to be filtered can be fed direct and the filtrate removed by pumping. The press is self-contained, requires no setting and can be easily fitted up, all that is required to make it ready for work being connection with a source of power, direct or through intermediate shafting. ANIMAL FATS AND OILS: KAW MATERIALS, PREPARATION, PROPERTIES AND USES. ALLIGATOR OIL AND CROCODILE OIL (ALLIGATOROL, KROKODILOL). Haw Material. The amphibia known as alligators or crocodiles that is to say, the fat contained in their flesh. Preparation. No particulars are obtainable, but pro- bably by melting like tallow. Properties. Alligator oil is of the consistency of oint- ment, semi-fluid, reddish in colour, with a sp. gr. of 0'928, and contains 32 per cent, of margarine and stearine, 1*5 per cent, of free oleic acid, 60 per cent, of olein and 0*02 per cent, of iodine. Crocodile oil is of a reddish colour, but more liquid than alligator oil. A mixture of both is met with in commerce. Uses. Both kinds are technically employed in tanning. 76 ANIMAL FATS AND OILS. BUTTER, Raiv Material. Cow's milk, as being the richest in fat of the secretions of all mammals. Preparation. Milk contains a fat butter which is pre- cipitated when the milk is exposed to strong and continuous agitation. The phenomena have been explained by Soxhlet as follows : The fat forms along with the other constituents of the milk a perfect emulsion of small drops of very different sizes. In this condition the fat is endowed with the property of remaining liquid at temperatures whereat the butter ob- tained from same would be solid. This peculiarity results from the superficial tension proceeding from the extremely thin layer of serum (also known as the serum envelope) lying within the sphere of attraction of the globules. In the same way as molten masses in general can be made to congeal by vibration, so in the manufacture of butter a few drops are- first made to solidify by mechanical concussion and increase in size by contact with liquid fat. The larger congealed fat drops thus produced attach themselves by impact to others, and so, finally, the greater part of the fat becomes collected into small mulberry-like adherent masses separable from the other constituents of the milk by skimming. Therefore, in the process of butter-making, the fat drops, on the one hand, are congealed, and, on the other, the solidified particles are united to a coherent mass. In point of chemical composition milk is a highly com- plex substance. The following constituents occur (though in quantities varying between certain limits) in all sound milk : casein, albumin, fat (butter), lactose (milk sugar) y salts, extractive matter and water. The proportions vary, even in one and the same animal, according to the mode of feeding, age of the individual, etc., within certain limits, so that a universally applicable analysis of milk cannot be given. ANIMAL FATS AND OILS. 77 The subjoined figures are, however, the mean of a large number of analyses : Average Cow's Milk. Percentage. Limits of Variation. Water ... - 87'5 83'0-90'0 per cent. Solid (dry) matter 12-5 IO'O-17'O Containing : Fat (butter) 3-4 0-8-8-0 Casein 3-2 2-0-4-5 Albumin 0'6 0-2-0-8 Lacto-protein .... O'l 0-08-0-35 Milk sugar ...... 4'5 0-3-6-0 Ash 0-7 0-7-0-9 The greatest care and cleanliness are essential in the preparation of butter, by reason of its extreme liability to absorb extraneous flavours and odours, and the best fresh milk immediately undergoes an unfavourable alteration under the influence of even very small quantities of fermentative spoiled milk. For this reason storage chambers for milk have to be selected with great care, and attention devoted to keeping them scrupulously clean. Very widely divergent methods are employed for pre- paring butter from milk. In one the milk is divided into two portions : 1. A cream very rich in fat, this being taken for churn- ing ; whilst 2 The second portion (poor in fat), the skimmed, blue thin milk, is put to another use, or the entire milk is churned. In separating the cream from the milk three different methods are practised : 1. The milk is left to itself as a layer, some 4 in. deep, in shallow pans (shallow setting) until the cream collects as a consistent mass on the surface. 2. The milk is set in high vessels, 16 to 20 in. in height (deep setting, or Schwartz process), and kept at a tempera- ture of 2 to 4 C. 78 ANIMAL FATS AND OILS. 3. The milk is separated almost instantaneously in special centrifugal machines (milk separators) into skim milk and cream. The first method is the oldest, and is still practised in- many dairies. The vessels employed are either of wood, well- fired stoneware, enamelled cast iron or pressed tinplate. When the cream has finished rising it is skimmed off with a flat spoon or separated from the skim milk by means of special appliances. In small dairies basins are often used from which the skim milk can be poured away direct, the cream being retained by a cream catcher. When kept for some time, or when the cream is a long while in rising, the products skim milk and cream arrive at the initial stages of acid fermentation. With regard to No. 2, this method presents the advan- tages of keeping the products sweet, requiring fewer vessels, occupying less room, and being independent of the state of the weather. On the other hand, the cream is thinner and more bulky; consequently the yield of butter milk is increased. No. 3. In " separating " milk the liquid, enclosed in a rapidly revolving drum, is, by the action of centrifugal force, divided in such a manner that the specifically heavier milk is impelled against the outer walls, whilst the specifically lighter cream is forced towards the centre. This process enables the work to be carried on uninterruptedly and pro- duces none but sweet cream. Among the various types of cream separators that of Laval has proved the best in prac- tice. In this apparatus the fresh milk runs continuously in, whilst the cream and the skim milk leave the machine by two separate outlets, these products being obtained in such a condition that the cream may be either sold as a luxury of diet or worked up into butter, whilst the residual milk makes an excellent cheap food. The separator consists of an oval hollow vessel A, of best Bessemer cast steel, and ANIMAL FATS AND OILS. 79 holding about 1J galls., which is encased in a cast-iron housing and rests on the spindle K. This latter stands loosely in a wood bearing in a depression in the pivot h, which is driven by the small band pulley and intermediate gear at such a rate that it makes 6000 turns a minute, whereby the spindle and the receiver are carried round by adhesion. The central supply pipe a, with two lateral delivery tubes, is screwed in the bottom of A, and over this is slipped the tube / (leaving an annular space of about ^ T in.), FIG. 41. The De Laval Separator. (Elevation.) the low r er end of which is fastened to a ring which forms the bottom of the small chamber c ; and over / again is placed the tube d, which expands below into a cup-shaped cover forming the upper part of the chamber c, the whole being joined to A by four screws. From the bottom of c projects the bent open tube b, reaching to the inner periphery of A. If now the milk be admitted through a into the receiver, which is running at full speed, it is forced with great power against the walls, the time required to fill A sufficing for the separation of the milk into its constituents, of which the 80 ANIMAL FATS AND OILS. specifically lighter cream collects around the central supply pipe and is driven upwards as the supply proceeds into the narrow annular space between a and / and to the chamber c, whence it runs away through a pipe. The thin milk rises up through b into the small chamber c and thence through the opening between d and /into the chamber B, whence it escapes through a discharge pipe. The Bechtolsheim " Alpha " separator, driven by power, will treat up to 460 galls, of milk per hour, leaving only about 0'2 to 0*3 per cent, of fat in the skim ; smaller machines FIG. 42. The De Laval Separator. (Section.) are also made for hand driving, to separate 15 to 60 galls. per hour. In Fesca's centrifugal machine the operation is not con- tinuous. The milk enters through the funnel a into a roomy cylinder A running at high speed, whereby the cream is forced, in the direction indicated by the arrows, towards the centre, where it is retained by the cylinder b, whilst the thin milk runs away from the periphery of A through openings in the bottom, and. entering the jacket space B, is run off through the pipe C. At the end of about an hour the liquid ANIMAL FATS AND OILS. 81 escaping from C is not merely thin milk, but milk that is only slightly separated, owing to the chamber b being full of cream. When this is observed the driving belt c is slipped on to the loose pulley and the drum is allowed to empty itself. As the centrifugal force decreases the cream runs out into the jacket space and is caught in a separate vessel at C. When it is all out the operation can be re-cornmenced. The separation of the cream is effected more readily at somewhat higher temperatures than it is in the cold, so that it FIG. 43. Fesca's Centrifuge. is advisable to either put the milk through directly it comes from the cow or else to warm it up to blood heat. On the other hand, the keeping qualities of the butter improve in proportion as the milk after milking, or the cream after sepa- rating, is brought down to the desired low temperature, for which purpose special coolers are. used, consisting of a cool- ing chamber for the liquid, surrounded by one or two series of tubes through which cold water is continuously flowing. The product is drawn off after a certain time into a vessel underneath. 6 82 ANIMAL FATS AND OILS. As we have already seen, sweet or sour cream is obtained as the raw material for butter-making, according to the system pursued. There is no difference in the yield of butter whether the cream be sweet or sour, but there is in point of flavour, sweet cream yielding a sweet, nutty- flavoured butter, whilst that from sour cream has a sour and (when the cream has been kept long) even a rancid taste. The cream temperature for butter-making should be about 15 C. in summer and 20 C. in winter. The principle of the process has already been discussed. It is necessary to subject the cream to powerful and uniform agitation, the regulation of which constitutes the aim of a large number of appliances, and as every year sees the introduction of new ones, it is impossible to refer to them all. The types of construction may be divided into classes, according as the butter is produced by 1. Beating (dashing), 2. Stirring, 3. Shaking. As to which is the best the opinions of butter-makers widely diverge. So far as the constitution of the butter itself is con- cerned, it is immaterial which method is pursued, the only question being that of forming the butter in the shortest possible time and in the highest degree of purity. Among the appliances may be mentioned : The percussion churn (farmer's churn) is the oldest but least recommendable, by reason of the great expenditure of force required ; Le- feldt's rotary barrel churn ; Davis' rocking churn ; the roller churn; the Holstein barrel churn, etc. 1 Among those suit- able for work on a large scale Eennes' butter machine should be mentioned ; this belongs to the type of percussion and dasher churns. 1 Translator's Note. There are many makers of these different styles of churns, those above being evidently intended by the author as typical examples. ANIMAL FATS AND OILS. 83 The milk is placed in a box J so arranged that there is no difficulty in running in the cream and removing the butter, both being effected through the flap K. The buttermilk is drawn off through an opening at the bottom of the vessel, generally kept closed by means of a ball valve. The beating of the milk is accomplished by a pair of dashers P P alternately raised and lowered by eccentric gearing. A disc A with grooved rim rotates on a fixed axis and carries the two ropes c c, which are also connected with the rods T T FIG. 44. Rennes' Butter Machine. attached to the dashers PP. A also carries an iron arm. connected with the fly wheel G at F by a rod E, the pin F^ forming at the same time the crank of the fly wheel. The- distance from the centre of the guide disc to the point of attachment of the connecting rod with the iron arm being greater than the radius of F, A can therefore merely rotate through an arc the radius of which is double that of F, while F makes a complete turn. The arm is rigidly attached to the disc and therefore the latter can only make an alter- nating semicircular movement, during which the points at 84 ANIMAL FATS AND OILS. which the ropes c c are attached have a similar motion, i.e., a semicircle, whereby the attached rods T T are caused to rise and fall alternately. These rods move vertically through suitable apertures in the cover of the box J, and since the ropes c c are placed exactly opposite one another the one rod T begins to rise at the same instant that the other rod com- mences its descent. A perforated partition N is placed between the dashers P P, and, finally, the cream chamber J is surrounded by a vat which can be filled with hot or cold water as desired. FIG. 45. Brochardt's Butter Machine. Brochardt's butter machine (Fig. 45) belongs to the class wherein the separation of the butter is effected by the stir- ring produced by the vertical rotation of an axis. This machine consists of driving gear K, which, by means of wheels I and J, sets a shaft B in rapid motion. B carries a series of vertical dashers and also a pipe d connected with a toothed wheel H, which in turn is in connection with the wheel I. At the lower end of the tube d are fixed a num- ber of horizontal rods F forming the spokes of a wheel, and ANIMAL FATS AND OILS. 85 a similar wheel is situated below and is connected with the upper one by the vertical dashers G. The shaft c, which is attached to the box of the lower wheel, is supported in a bearing in the bottom of the churn. There are thus in the machine two systems of dashers (G, C), both of them movable, though in opposite directions. This opposite motion, produced by the force acting on the two cone wheels H and I from the wheel J, causes, as can readily be under- stood, a very brisk movement of the cream in the churn, and quickly effects the separation of the butter. The proposals that have been made for admitting air r or for adding acids or alkalis to the cream in the butter- making, in order to facilitate the- rapid separation of the fat,, have proved unsuitable. The butter produced by one or other of these mechanical processes contains a large proportion (16 to 22 per cent.) of enclosed buttermilk, which causes the butter to quickly become rancid, unless thoroughly worked out. This butter- milk contains, when sweet cream has been used, both milk- sugar and casein in solution ; or, when the cream was sour, solid casein, in addition to dissolved lactic acid. All these substances are readily decomposable, the milk-sugar being converted into lactic acid by the lactic ferments present, and then causing the casein to curdle. On this account the cavities in butter prepared from sweet cream and not further purified very soon exhibit small lumps of curd together with a liquid tasting strongly of lactic acid. After a short time, particularly in summer, the lactic acid is converted into the evil-smelling butyric acid, whereby the butter assumes a repellent taste and smell. When the butter has been made from sour cream, then lactic acid will be present ready-formed in the fresh butter, and the decom- position of this acid into butyric acid will occur much sooner than in the case of sweet-cream butter. The decom- 86 ANIMAL FATS AND OILS. position, once set up, extends also to the fat, and the butter will very soon assume a disagreeable, irritating taste and cheesy smell, which render it unfit either for eating or cook- ing purposes. Butter that has undergone such alteration can only again be rendered suitable for cooking by a care- fully performed re-melting. It is therefore essential to remove the buttermilk in order that the butter may keep and taste well, and the more com- pletely this is effected the more successfully will that object be attained. As has been shown by experiments (particu- larly on a small scale) wherein the butter was carefully freed from the adherent buttermilk, such really pure butter is surprisingly stable, in so far as it is kept at a temperature not exceeding 15-16 C., the pure fat being much less liable to decompose than that in contact \vith the butter- milk. In order to get rid of the latter the butter must be carefully washed with cold water, care being taken at the same time that the butter is in a condition as finely divided as possible, and that all the particles thereof come into con- tact with the continually renewed water employed. Working the butter by hand is insufficient for large dairies, and therefore special machines have been made in which the butter is worked, either between grooved rollers or on a table, by a kneading roller, driven by hand or power. As a rule, eight or ten kneadings are sufficient to work out all the buttermilk, and all that then remains is to make the butter up into the form in which it is to be sold. In winter time, and when the cows are fed largely on straw and sloppy fodder, the butter is very pale in colour, and attempts are made to remedy this by using butter colouring. At present general use is made for this purpose of arnatto (dissolved in hemp-seed oil or linseed oil), butter yellow or, in small dairies, even carrot juice, the butter being either mixed and kneaded up with the colouring or else the ANIMAL FATS AND OILS. 87 latter is added to the cream before churning, this last named plan resulting in a more uniform distribution of the colour. The Bergedorfer cremometer (De Hardt's patent) is based on the separation of cream by centrifugal force. This ap- paratus is adapted for separator work, especially the Laval a FIG. 46. Bergedorfer Cremometer. machine, and consists of : (1) a steel disc a (Fig. 46) to fit the separator, and containing (in a hollowed-out receptacle) a number of lateral borings for holding the test tubes ; (2) forty-eight test tubes b with metal fittings together with a case for holding same ; (3) a tin measure c for filling the tubes ; (4) a needle d for regulating the amount of milk in the 88 ANIMAL FATS AND OILS. tubes ; (5) a scale e for reading off the percentage of cream ; (6) a cover/ with steam pipe for warming the disc a; (7) a handle g for lifting the disc out of the stand. The apparatus is worked in the following manner : The milk to be tested is thoroughly mixed by agitation and pour- ing from one vessel to another, to ensure uniformity of sample, and is then, by means of the tin measure, poured into the metal receptacles forming the lower portion of the test tubes b. The tubes are then pressed into the receptacles, whereby the milk rises in the glass portion and the excess escapes through a small aperture at the top, through which aperture the needle d is inserted to adjust the quantity of milk in such a manner that none of the contents will afterwards escape as a result of expansion on heating. The tubes are next placed in the borings in the disc a, which rests in the separator stand and has in the mean- time been warmed up to 40 C. (maximum, 50 C.) by steam introduced by means of a rubber tube inserted through a corresponding hole in the lid, the cavity in the disc being also half filled with warm water for the same purpose. In fitting up the disc with the samples care must be taken to arrange the tubes symmetrically, in order that equilibrium may be maintained during the succeeding operation. Forty-eight samples may be treated at a time, the disc being kept in motion for twenty minutes at the ordinary speed of the separator, viz., 6500 turns per minute. As soon as the disc comes to a standstill the test tubes are taken out and the height of the sharply defined column of cream ascertained by applying the graduated scale, the markings on which correspond to 3 per cent, of cream and are further subdivided to record i and T V of 1 per cent., T V of 1 per cent, being easily read off after a little prac- tice. It is not absolutely essential to read off the percentage of ANIMAL FATS AND OILS. 89 cream at once, as this can be done with equal accuracy even some twenty-four hours later. The glass tubes are cleaned in a simple manner by filling the metal portion with warm water and pressing home the upper part, whereby the water is driven through the tube. The metal part and the bore holes are cleaned out by means of suitable brushes. Properties. The colour of butter varies considerably and ranges from a very pale to a fine deep yellow, winter butter being gener- ally the palest, whilst summer butter is more highly coloured, this characteristic greatly depending on the composition of the fodder. The consistency is to an uncommon degree in- fluenced by the prevalent atmospheric temperature, so that one and the same butter is fluid in summer and hard and solid in winter. Taste and odour should be agreeable and purely butter-like. Specific Gravity at 16 C. : 0'936 to 0'943 (Hagen), 0'9275 (Winter-Ely th), 0'926 (Casamajor) ; at 37'8 C. : 0'911 to 0-913 (Bell) ; at 100 C. (water at 15 C. = 1): 0'865 to 0*868 (Konig) ; at 100 C. (water at 100 C. = 1) : 0'901 to 904 (Wolkenhaar). Mel.ting-Point.3r to 31'5 C. Setting-Point. 19 to 20 C. (Wimmel). Melting-Point of the Fatty Acids. 38 C. Setting-Point of the Fatty Acids. 35'8 C C. (Hiibl), 37'5 to 38 C. (Paris Laboratory). Hehner Number. 87 '5. Saponification Value. 227. Reichert Number. 14'00. Iodine Number. 26'0 to 35'1 (Hiibl), 32-0 to 38'0 ; very old butter : 19*5 (Moore). Unmelted unsalted butter contains under normal con- ditions, according to Konig : 90 ANIMAL FATS AND OILS. Fat 87-0 per cent. Casein 0-6 ,, Milk-sugar 0-5 Salts 0-3 Water 11-7 The composition, however, varies considerably, in that on the one hand the fat may amount to 95 per cent., whilst on the other the water may form as much as 35 per cent. In consequence of its content of water and casein, butter quickly turns rancid. Attempts are often made to combat this rancidity by kneading the butter with 3 or 4 per cent, of common salt after thorough washing. According to Benedikt the same end may be better attained by keeping the butter in a melted condition until it has thoroughly clarified and then separating it from the precipitated water and casein. Milk fat treated in this way is, however, no longer saleable as butter, and also lacks the characteristic flavour of this article. Apart from traces of colouring matter, lecithin, choles- terin, etc., pure butter fat consists solely of the tri-glycerides of the fatty acids. Up to the present, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid and oleic acid have been isolated therefrom. An unusually high percentage of glycerides of the volatile fatty acids is specially character- istic of butter, but the bulk is composed of stearine, palmitin (classed both together as margarine) and olein. The composition of butter is : (According to Schaedler) Margarine 66 per cent. Olein ------ 28 Butyrin 6 , , (According to Winter-Blyth) Stearine and plamitin - 5OO per cent. Olein 42-2 Butyrin - 7'7 Caprin, caproylin (H ,, ANIMAL FATS AND OILS. 91 It may be calculated approximately as follows : When the Hehner number of a butter is found to be 87 '5 and the average molecular weight of the insoluble fatty acids 270, then the sample contains 91*65 per cent, of glyce- rides of the non-volatile fatty acids olein, palmitin and stearine. If the iodine number be 30*1, it follows that the olein -content is 85*96 per cent. ; therefore such a butter the glycerides of the volatile fatty acids being calculated by difference contains : Margarine 55*69 per cent. Olein 35-96 Butyrin, caproin, etc. - 8-35 ,, 100-00 per cent. An indication of the nature of the volatile fatty acids is afforded by the Eeichert number. According to Meissl, the fatty acids distilled from 8 grms. of butter require, on an average, 28*48 c.c. of J^-normal alkali for their saturation ; consequently, the fatty acids from 100 grms. of butter re- quire 57*56 c.c. of {-normal alkali. This corresponds to 0*729 parts of glycerine radicle (C 3 H 2 ), which, deducted from -8*35, leaves 7*62 parts as the volatile fatty acids obtainable from 100 parts of butter. Therefore, 7*62 parts of volatile fatty acids require 57*56 c.c. of normal alkali for their satu- ration, and consequently their average molecular weight is about 139. The molecular weight of butyric acid is, how- ever, 88, that of caproic acid is 116, of caprylic acid 144, and of capric acid 172. Consequently, Winter-Blyth's statement that butter fat contains 7*7 per cent, of butyrin and only 0*1 per cent, of glycerides of other volatile fatty acids requires correction, in that the percentage of caproin, caprylin and caprin is much higher. As revealed by the microscope, fresh cow's butter con- sists of perfectly spherical transparent fat globules. Hassall 92 ANIMAL FATS AND OILS. found crystals in older butter, these being, according to Mylius, best detected when the fat is examined under the polariser with crossed Nicol prisms, the crystals alone being then illuminated, whilst the rest of the field is in darkness. On prolonged exposure to the air, butter assumes the smell of tallow and becomes white. The setting of butter after melting does not progress uniformly, but a kind of crystallisation occurs. The portions nearest to the walls of the vessel are the first to crystallise, and they differ in com- position from those remaining longer liquid in the interior of the mass. Sometimes this separation proceeds so far that an oil (" butter oil ") is obtained, which can also be isolated by allowing the melted butter to set at 20 C. and then sub- jecting it to pressure. ADULTERATIONS OF BUTTER. The additions made to butter are of a very divergent nature. The coarser forms of adulteration consist of clay, chalk, gypsum, starch, meal, potato starch, ground white cheese, etc. Borax, water-glass and alum are sometimes added to preserve the butter and increase the weight by attracting the largest possible amount of water. To impart a yellow coloration, small quantities of arnatto, saffron, curcuma, azo dyes, etc., are frequently added. The most important adulteration, however, is that of added extraneous fats, such as hog fat, tallow, goose fat, cotton stearine, cocoa-nut fat and palm fat worked up with oil, and particularly oleomargarine. Though the addition of matters not belonging to the fat series can be easily deter- mined both qualitatively and quantitatively, the detection of extraneous fatty matters in butter was long attended with great difficulty, until, finally, suitable methods therefor were elaborated by Kottstorfer, Hehner and Eeichert. Of these r ANIMAL FATS AND OILS. 93 however, Keichert's alone still gives reliable results, since, according to Moore, mixtures can be prepared from oleo- margarine and cocoa-nut oil to give exactly the same Hehner and Kottstorfer numbers as true butter. By means of the specific gravity determination and the Eeichert number the purity of a butter fat can be decided satisfactorily in almost every case. Since, however, it is not impossible that the manufacturers of artificial butter may also succeed in pre- paring products with the correct Reichert number, it may be that other tests will have to be again resorted to in ad- dition to Reichert's method. For this reason these, along with a few older methods of testing butter, are subjoined. BEEF LARD OR RE-MELTED BUTTER. Butter, as is well known, easily turns rancid if not care- fully kept, and such butter is, therefore, frequently converted by a careful re-melting into " beef lard " for culinary pur- poses. When butter is carefully melted by itself over a fire, a froth, mainly consisting of unremoved casein, collects on the surface of the liquid ; but the solution of milk-sugar in water, present in the butter as a result of insufficient wash- ing, is, however, not so easily removable, and remains in the butter. In practice it is generally considered sufficient to skim off the froth from the liquefied butter, so long as any forms, and to then fill the butter direct into wooden tubs, where it is left to set. When the melting is carelessly performed and the tem- perature allowed to rise a little, this results directly in the development in the liquefied butter of an irritating, un- pleasant taste, due to the formation of certain decomposition products. Therefore, as butter is an expensive product, it is advisable to proceed carefully in melting, so as to pre- serve the quality, the increased expenditure of labour being amply compensated by the improved results. 94 ANIMAL FATS AND OILS. The best plan is to place the butter to be treated in a. shallow vessel of thin, well-tinned sheet iron, this being set in another which is filled with water, and to which heat can be applied. Butter being, like all fats, a bad conductor of heat, melting would take a long time unless facilitated by stirring. So long as any of the butter remains umnelted, the water in the outer vessel may be kept on the boil, but as soon as the whole is liquefied the temperature is lowered until the butter is just fluid, and in this state it is left in repose for several hours without stirring. Whilst in this condition of repose the particles of casein rise to the surface completely, and the aqueous liquid ad- mixed with the butter subsides to the bottom, leaving the butter clear and transparent. Skimming is now practised, the most suitable method being to remove the uppermost layer by a skimming spoon and pour it on to a cloth of close texture spread out in a hair sieve, whereupon the fat runs away through the cloth, leaving behind the particles of casein. Only when the surface of the butter has been cleared of every particle of froth is the removal of the fat proceeded with, and is then continued until only about an inch deep of fat is left in the vessel, the residual portion being allowed to solidify, in which condition it can readily be separated from the underlying layer of water. The product (" beef lard ") thus obtained is a perfectly pure butter fat, without the slightest trace of rancid or em- pyreumatic flavour, and it is much better to prepare butter for cooking purposes in this way than to run the risk of its turning rancid. A small sample of the " beef lard " taken from the setting vessel should be of a pure yellow colour and very translucent, a condition which can be attained by allowing the butter to cool only very slowly, i.e., at a suitable and gradually decreasing temperature, so that the fat can crystallise uni- ANIMAL FATS AND OILS. 95 formly. Usually the colour of the product is somewhat duller than that of the original butter. TESTING BUTTER. Benedikt prescribes the following methods for the test- ing of butter fat : Organoleptic Reaction. Hager steeps a cotton wick in the fat, previously clarified by warming, and lights it for two minutes. In the case of pure butter a smell of burnt butter is perceptible but with oleomargarine the smell is that of acrolein. Specific Gravity. Bell determines the sp. gr. of the sample at 37'8 C. (= 100 F.), at which temperature the sp. gr. of butter is 0*911 to 0*913, and that of oleomargarine and other fats 0'9028 to 0'9046. Konig performs the estimation at 100C. and finds for pure butter 0*866 to 0'868, or for adulterated samples 0*859 to 0*865. According to Adolf Mayer, who works with the ordinary areometer, at 100 C. (or, more correct!) 7 , at the temperature of boiling water), and thereby obtains figures of merely re- lative, not absolute, value, the state of the barometer must be taken into account, since a difference of 2 mm. in the barometer reading causes the sp. gr. to vary by 0*0001, so that the frequently occurring differences of 40 mm. of pressure will cause a discrepancy of 0'002, whilst the total difference in sp. gr. between natural and artificial butters amounts to only 0-007. Casamajor employs the Hager method. The fat is melted in a spoon and one drop is introduced into 56'5 per cent, alcohol, the sp. gr. of which is exactly midway between butter (0*926 corresponding to 53*7 per cent, alcohol) and oleomargarine (0*915 = 592 per cent, alcohol) at 15 C. Should an air bubble adhere to the drop of fat it is detached 96 ANIMAL FATS AND OILS. by the aid of blotting paper. If the drop does not sink a slight concussion will cause it to do so if heavier than the liquid. Butter sinks to the bottom, whilst oleomargarine floats. If a drop of the melted sample be poured on to the spirit, warmed to 30 C., it will set, if butter, whereas oleo- margarine remains liquid, although both float. On reducing the temperature to 15 C. the latter fat solidifies as well, and butter sinks. A " butter " that will not sink in 55 per cent, alcohol is oleomargarine with at most a third of cow's butter. According to Moore, adulteration of butter by a mixture of oleomargarine and cocoa-nut oil cannot be detected by this means, since the sp. gr. of the cocoa-nut oil (0*9167 at 37'7 C.) is high enough to raise the sp. gr. of the mixture to that of butter (0-911 at 37'7 C.). E mulsifi ability . According to Adolf Mayer, butter ex- hibits a greater capacity for forming emulsions than any of the fats employed to adulterate it, because the latter have been melted in the purifying process. He therefore sought to establish on this basis a simple method of testing, which, however, cannot be regarded as perfectly reliable. Solubility. The following tests for butter are based on the different solubilities of butter and its adulterant fats : Hoorn dissolves 1 grm. of the sample in 7 c.c. of petroleum spirit and leaves the solution to stand a few hours in tightly closed vessels at 10 to 15 C. Butter fat remains dissolved, whilst veal fat, tallow and hog's lard separate out. Miinzel dissolves 1 grm. of the fat in 12' 5 grms. of ab- solute alcohol (sp. gr., 0'797) on the water bath, closing the tube with a cork pierced to allow the passage of a thermo- meter, which reaches down to the bottom of the tube. The latter is then removed from the water bath, dried rapidly and the temperature at which the fat begins to set noted. Miinzel obtained the following results : ANIMAL FATS AND OILS. 97 Commencement of Solidification. Pure Butter + 10 per cent, of horse fat 20 30 10 tallow 20 30 10 hog lard - 20 30 Margarine butter Butter + 25 per cent, of oleomargarine - ,, ,,50 34 C 37 40 44 40 43 46 38 41 43 56 40 48 Horsley, Balland, Husson and Filsinger have made use of the varying solubility of pure and adulterated butter in ether or ethyl alcohol as a test of purity. Crook employed carbolic acid as solvent, and his results were confirmed by Lenz, with only a slight divergence in the values. Ten grains (O648 grm.) of the filtered fat are dissolved in a gauged testing cylinder at about 66 C., shaken up with 1*5 c.c. of liquid carbolic acid (containing 373 grms. of crystallised car- bolic acid and 56* 7 grms. of water) and warmed on the water bath until transparent. After standing a while at ordinary temperature, one has either a clear solution (butter) or two strata separated by a clear line of demarcation (beef, mutton, hog fat). The volume of the lower stratum amounts to : Beef fat Mutton fat - Hog fat Crook. 49-7 per cent. 44-0 49-6 Lenz. per cent. 39-1 37-0 After sufficient cooling, more or less deposit is apparent in the upper layer. With 5 per cent, of hog fat Lenz could no longer detect any separation into two layers, but at the end of twenty-four hours a crystalline turbidity, differing from that observed in true butter, made its appearance. More recently Zeiss' butyro-refractometer has been largely used for butter testing, adulterations being rapidly detectable 98 ANIMAL FATS AND OILS. therewith. This instrument, supplied by C. Zeiss of Jena, is shown in Fig. 47. A and B are the hot-water jackets surrounding the two prisms and facilitating the testing of the fats at temperatures above their melting-points. C is a hinge on which B turns, D the water feed pipe and E the FIG. 47. Zeiss' Butyro-Refractometer. outflow pipe. The bayonet catch for the hot-water jacket is at F, and G is a pin serving to adjust the object ; H serves as a support for A and B, and J is the reflector. This instrument is based on the principle that the re- fractive powers of the fatty acids afford a means of deter- mining their purity. It consists chiefly of a pair of prisms ANIMAL FATS AND OILS. 99 enclosed in a jacketed metal case, which, by the aid of a current of water, enables the substance enclosed between the two prisms to be kept at a constant higher or lower- temperature. Above the prisms is mounted a telescope with a scale, on which the position of the critical line of the sub- stance between the prism can be read off direct. According to the position and colour of the critical line red in pure butter, otherwise blue it can at once be determined, by the aid of the reduction tables supplied with the instrument, whether the butter is natural or artificial. With a little practice, twenty to thirty examinations can be made in the hour. Woollny obtained the following values for natural butter, margarine and mixed butter, expressed in degrees of the scale at 25' J C. : Natural butter 49-5-54-0 degrees. Margarine - - ... 58-5-66-0 ,, Mixed butter - - - . - - 54 '0-64-8 ,, Butter with a refractometer index of 54'0 is always an object of suspicion, and should be subjected to further examination. The complete analysis of butter is performed as follows : 1. Estimation of Water. Five to ten grms. of butter are weighed out into a covered beaker and melted in the air oven. When the fat is clear it is filtered (still in the oven)* through a tared filter into a tared flask, care being taken to> pour through the filter as much of the fat and as little of the; underlying water as possible. The aqueous residue is then evaporated in the beaker at 100 C., and the whole of the re- maining substance is placed in the desiccator and weighed, dried, cooled and re-weighed until the weight is constant or varies by not more than 1 m.grm. The loss in weight sus- tained by the fat the weight of the beaker being known at the outset gives the amount of water therein. 100 ANIMAL FATS AND OILS. 2. Estimation of Fat. The residue in the beaker is loosened as well as possible from the bottom by means of a glass rod and washed with water-free ether 011 to the filter, which has been placed in a funnel in the mouth of the iiask holding the bulk of the fat, the beaker and rod being jrinsed and the filter and contents washed with ether until :a test drop on a watch glass shows that all the fat is re- moved. The ether is then distilled off and the fat dried in the air oven at 100 C., cooled in a desiccator and weighed when cold, the operations being continued until the weight is constant. 3. Determination of Ash. The residue collected on the ffilter and the filter itself are carbonised in a platinum cur- ,cible at a moderate heat and, after extracting several times with distilled water and filtering, calcined thoroughly. The filtrate is then poured by degrees into the ash in the cooled -crucible and the whole dried in the water bath, incinerated with the used filter in the (covered) crucible, cooled and weighed, the weight of the two filters being deducted from the result. In the case of salted butter, only the total amount of the mineral salts can be given, the exact esti- mation of the sodium chloride being impossible in the presence of the other ash constituents also containing chlorides. As, however, butter generally contains no more than O'lO per cent, of ash, the percentage of chlorine can only be very small, and the amount of salt used can therefore be very approximately determined from the chlorine in the ash. 4. Estimation of Protein. Eighty to 100 grms. of butter are weighed out and the fat separated completely after evaporating the water from the other constituents in the manner already described in the estimation of moisture and fat, the residue, carefully collected on the filter, being used for the determination of nitrogen ; the result multiplied by 7'042 gives the percentage of protein. Bearing in mind, ANIMAL FATS AND OILS. 101 however, that it is doubtful, especially in the case of old butter and that from sour cream, whether all the nitrogenous bodies belong to the albuminoid group, a little uncertainty probably attaches to the figures given for protein. 5. Estimation of the Soluble Non-Nitrogenous Matter (milk-sugar, lactic acid, etc.). The percentage content of water, fat, ash constituents and protein having been pre- cisely determined by two satisfactory and concordant analy- ses, then the figures thus obtained are added together and the total deducted from 100, the remainder being regarded as expressing the percentage of non-nitrogenous organic matter. According to observations made in the Kaaden- Laboratory, attempts to estimate this group direct do not generally attain the desired object, since in the washing of" the fat-free residue more or less of the nitrogenous matter passes into solution. The figures ascertained for non-nitro- genous organic matter by difference are also affected by the uncertainty attendant on those for protein. As it is desirable, for the purpose of judging the purity of a butter, to know the chemical composition of the butter ash, the complete ash analysis of unsalted, unwashed, well- worked butter is now given ; the ash amounted to 0*1485, per cent. : Crude Ash. Moisture C0 2 Carbon Silica and sand KoO CaO - - - - MgO- PA Cl Iron, H 2 S0 4 and loss From which must be deducted oxygen 0-600 per cent.. 0-233 0-333 0-533 19-000 7-583 22-700 3-232 43-520 2-560 0-283 100-577 per cent. 0-577 100-000 per cent. 102 ANIMAL FATS AND OILS. Purified Ash. Na 2 CaO - MgO- - - - PA- - - - 01 - Iron, H 2 S0 4 and loss Deduct oxygen - 19-329 per cent. 7-214 23-092 3-287 44-273 2-604 0-288 100-087 per cent. 0-087 100-00 per cent. FIG. 48. Killing's Viscosimeter. For distinguishing between butter and margarine, and also for estimating the content of extraneous fats existing in butters, Dr. Killing employs the viscosity test. Since the ordinary types of viscosimeter are unsuitable for this pur- pose, by. reason of their insufficient accuracy and by re- quiring excessive quantities of fat, he constructed a special viscosimeter wherein these defects were obviated. In this apparatus (Fig. 48) eleven samples of margarine of various origin and price gave viscosities (the duration of outflow of water at 20 C. = 100) ranging between 313'3 and 317*4, ANIMAL FATS AND OILS. 103 whereas in eight natural butters the viscosity varied from 276*2 to 281'3. The author considers these investigations by no means final, the principles underlying the method having still to be determined by experience. In any case, the method appears advantageous, in that no chemical know- ledge is required for its performance. The apparatus used by Killing is constructed as follows : The lower opening of the glass cylinder C is closed by a perforated caoutchouc stopper traversed by a tube R which supports a pipette-like vessel G (holding about 50 c.c.) closed above by a tap H and tapering off below to an aperture about 1 mm. in diameter. The body of G contains a ther- mometer T, ground to fit the tubulus. Marks are inscribed on the pipette close below and above the bulb, and a third about 10 cm. above the upper one. G and R are fitted by grinding. The cylinder is closed at the top by two semi- circular corks K, one of which carries a thermometer T 1 , and the entire apparatus is supported over a beaker B by the clamps of the stand S. To standardise the apparatus the two thermometers T and T 1 are immersed in a beaker of water and compared w T ith a normal thermometer at 20 and 40 C., at which latter temperature the examination of the butter is per- formed. Therefore, if the thermometer T registers 39*5 C. when the normal instrument records 40 C., the test must be carried out at the former temperature as indicated by T. The same applies to T 1 , and is essential in order that the results, which depend greatly on the temperature, may be concordant when obtained by different observers. To set the apparatus in working order the two semi- circular corks K with the thermometer T 1 are removed, the vessel G taken out and the thermometer T withdrawn. The butter is melted at 50-60 C. in a drying oven and sepa- rated from the non-fat by filtration, some 60 c.c. (sufficient 104 ANIMAL FATS AND OILS. for the test) of the clarified fat being kept in readiness in the oven. On the other hand, about 1J litres of water are warmed up to 43 C. in an enamelled iron saucepan fitted with a lip for pouring, the thermometer T 1 being used for stirring the liquid. As soon as the prescribed temperature is attained the flame is extinguished, and the butter then cooled (by dipping the beaker in cold water and continually stirring with the thermometer T) from its temperature of 50-60 C, down to 40'5 C. When this moment has arrived T is placed in position without any further cleaning and the butter drawn up in G by suction to the upper mark, the greased tap shut and G placed upon E, whilst the beaker containing the rest of the butter is placed under the appara- tus. The water, cooled in the interim down to 42 C., is next poured as quickly as possible into the cylinder C, leaving just enough room for the insertion of the semi-cylindrical corks, one of which always remains attached to the ther- mometer T 1 , even whilst the latter is being used to stir the water in the saucepan. When these operations have been carefully performed both thermometers will in a very short time register 40 C., whereupon, by gradually opening the tap, the oil is allowed to run out until the upper level corre- sponds with the mark over the bulb, and the tap is then fully opened by a quick movement of the one hand, whilst the other sets the chronoscope in motion, the latter being stopped when the oil has run off to the level of the lower mark. With a little practice, the times observed with one and the same material will agree to within a second, the varia- tions mostly amounting to a J to J a second. By stating the time of outflow of water at 20 G. as equal to 100 and re- ferring to this the time taken by the butter or margarine fat, the viscosity number is derived. According to Dr. C.- Aschmann, 5 grrns. of the fat should, ANIMAL FATS AND OILS. 105 for the differentiation of natural and artificial butters, be treated by the usual Keichert-Meissl method for the liberation of the fatty acids and the latter dissolved in 60 c.c, of ether, 20 c.c. of the solution being then placed in a 100 c.c. glass tube (about 40 cm. long) along with 8 c.c. of normal potash and 30 c.c. of a solution of common salt (sp. gr., 1*075), and the whole well shaken up. At the end of one or two hours the ether will have collected above the brine, but will not be clear, being rendered turbid by precipitated matter, the height of which will, in the case of natural butter, measure only 20 to 30 mm., but for margarine will amount to at least 60-70 mm., and will, with a little practice, afford an accurate differentiation. Uses of Butter. For alimental purposes. CANDLE-FISH OIL (GULACHONOL). Raw MaterialThe candle fish (" Gulachon " or " Onta- chon "), found in enormous shoals in the bays on the coast of British North America and Alaska. This fish, which is also highly prized as a food, is so rich in oil that it is used in the dried state for torches : hence its name. Preparation. No information is available on this point, but probably by pressing like all other fish oils. Properties. Schaedler reports on this new and interesting product as follows : The oil as it is put on the market contains a deal of palmitin and probably stearine, so that it is only semi-fluid at the ordinary temperature. The olein, for so this product must, for medicinal purposes, be regarded, forms a clear, pale, straw-yellow liquid of fishy smell, differing from, and to many tastes probably less repugnant than, liver oil. The sp. gr. is 0'9071 at 15 C. and 0'9012 at 25 C., whilst that of liver oil varies between 0'92 and 0'93, but is generally 0'9227 at 15 C. When mixed with sulphuric acid 106 ANIMAL FATS AND OILS. (1 vol. of acid to 5 parts of oil) the temperature rises 55 C., whereas liver oil under the same conditions undergoes a rise of 112 C. The colour reactions also differ from those of liver oil, nitric acid (sp. gr., 1*27), mixed with one-third of its volume of the oil, producing at once a rose coloration gradu- ally changing to amber yellow. At the end of fifteen hours the mixture will have thickened considerably and assumed a deep amber coloration. Liver oil treated in the same manner turned rose-red at first, then rapidly into amber, and exhibited the same coloration in fifteen hours' time, but was more fluid than the first-named mixture and interspersed with thicker layers. Sulphuric acid gives with candle-fish oil not the same beautiful purple colour that it does with liver oil, but a deep brown, subsequently inclining to both yellow and red. When this oil is saponi- fied the precipitated fatty acids amount to 95*85 per cent, of the oil. Candle-fish oil contains about 20 per cent, of palmitic and stearic acids, 60 per cent, of olein and 13 per cent, of an unsaponifiable substance, which, being a peculiar and in- teresting body, deserves careful examination. At summer temperature this substance forms a mass of oily consistency, has a sp. gr. 0'865 to 0*872 at 15 C. inferior to that of any other constituent of ordinary fats, and appears to be similar to the unsaponifiable matter in sperm oil. MUTTON TALLOW (HAMMELTALG). Raw Material. The accumulations of fat in the flesh and tissues of the sheep. Preparation. Like beef tallow, by melting and by pressing the residual tissues from the melting process. Properties. Mutton tallow is similar to that of the ox, but less highly coloured, being white and rather hard and brittle. Initially inodorous, it assumes, after a brief exposure ANIMAL FATS AND OILS. 107 to the air, the well-known characteristic smell and taste of mutton, very quickly becomes rancid and agrees in this property with goat's fat, which it then resembles in smell. 'These odours are due, according to Chevreuil, to a volatile fatty acid (hircinic acid), which is, however, merely a mixture -of butyric acid with other volatile fatty acids. Specific Gravity at 15 C. 0'937 to 0'940 (Hagen), 0'961 {Dieterich) ; at 100 C., 0'860 (Konig). Meltiwj-Paint..4&-b to 47 '4 C., 46 C. (Schaedler). Setting-Point. 32 to 36 C., rising thereupon to 40-41 C. Old mutton tallow melts at 49-50 C., sets at 39-40 C. .and rises thereupon to 44-45 C. After setting, the fat, exhibits a flat surface and, internally, traces of crystalline structure. Setting-Point of the Fatty Acids. 45-46 C. ; also 43'2 C. (Dalican), 46-1 C. (Schepper and Seitel). Mutton tallow is soluble only in over 60 volumes of cold ether or 45 volumes of boiling alcohol of sp. gr. 0'821. It contains per 100 parts : Carbon .... . 76-61 per cent. Hydrogen 12-03. Oxygen - ' - - - 11-36 100-00 per cent. and consists of about 70 per cent, of stearine and palmitin (margarine) and 30 per cent, of olein. The olein obtained by pressure is colourless, with a faint odour of mutton and a sp. gr. of 0*913 at 15 C. ; 80 parts are dissolved by 100 parts of boiling absolute alcohol. On account of the crystalline appearance of the stearine yielded by this fat, mutton tallow is preferred by candle makers to that of the ox ; very frequently the two are met with melted together. Uses. Similar to those of beef tallow. 108 ANIMAL FATS AND OILS. HAKE FAT (HASENFETT). Hare fat is white, or occasionally somewhat yellowish, with characteristic smell and a mild, agreeable taste ; the consistency is rather softer than that of lard. Specific Gravity at 100 C. 0'861 (Konig). Melting-Point. 44-46 C. Setting- Point. 28-30 C. Co-efficient of Refraction (Zeiss) at 40 C. 49. Percentage of Solid Insoluble Fatty Acids. 95'47 per cent. Volatile Soluble Fatty Acids (Keichert-Meissl number) = 2*64 c.c. of ~ NaHO per 5 grins. Insoluble fatty acids : Melting-Point. 4S-50 C. ; setting -point, 39-41 C. ; co- efficient of refraction, 36. GOOSE FAT (GANSEFETT). Eaw Material. The accumulations of fat interspersed among the tissues and under the skin of the goose. Preparation. By carefully melting the cut-up fat and straining to separate the product from the cellular tissue. Properties. It is white to pale yellow in colour, trans- lucent, granular, frequently almost liquid at 10 to 12 C., of agreeable flavour and does not easily turn rancid. Melting-Point. 25 -W C. Setting -Point. 18 C., the temperature then rising to 22 C. (Schaedler). Saponification Value. 192'6 (Schaedler). Iodine Number. 71' 5 (Erban and Spitzer). Uses. For alimental purposes. NEATSFOOT OIL (KLAUENOL). Eaw Material. The hoofs of cloven-footed animals, oxen, sheep and goats. Preparation. The feet of the ox and the sheep contain a ANIMAL FATS AND OILS. 109 very liquid and stable fat. In order to obtain this substance the fresh feet are laid in cold water to wash away the ad- herent blood and, after the sinews have been removed, are then placed in sufficient boiling water to cover them. After immersion for a quarter of an hour therein they are taken out, the claws cut away and the feet split to separate the toes from the larger bones, the latter being then boiled in water by the aid of steam, whilst the former, which yield up their fat less readily, are placed in a pan and boiled over direct fire in the water that has already served for boiling the large bones. After a prolonged boiling the liquid is allowed to clarify, whereupon the fat rises to the surface and is poured off. The oil obtained in this manner deposits after some time a dirty semi-fluid fat, from which the liquid por- tion is separated by decantation. This oil is pale yellow in colour and thin at ordinary temperatures, setting only at a few degrees below zero C. It contains much oleic acid and only a little stearine, does not easily turn rancid nor does it readily thicken. After the fat still remaining in solution has been as far as possible separated by crystallisation and filtration, the liquid product forms a very good lubricating oil for clocks and delicate machinery. According to Th. Chateau, the preparation of neatsfoot oil is carried out in the following manner : The feet (" trot- ters ") of about 100 sheep are treated for twenty minutes in a pan of water warmed by the aid of steam up to 75 or 80 C. When the woolly hair comes away easily the pan is emptied, the feet scraped and the claws removed. The feet thus cleaned are tied up with string into bundles of eighteen and then subjected to extraction by boiling in water until the greater part of the contained oil is recovered, whilst the feet themselves are sold in the half-cooked state. From 100 to 125 bundles of eighteen are treated at a time. The yield of fat is somewhat variable, ranging from 1 Ib. to 21 Ibs. per 100 110 ANIMAL FATS AND OILS. sheep. The feet of animals that have had to traverse long distances before being slaughtered, such as is the case with American sheep, yield merely traces of neatsfoot oil. The boiled feet are immediately laid in a stream of cold water,, and when cooled are offered for sale. The oil obtained in this manner has a sp. gr. of O915, is translucent and grey in appearance, but clarifies on standing or by several nitra- tions, and is then very pale yellow in colour. Chateau, in his communication, reports that the majority of commercial neatsfoot oils examined by him were composed of other fats. E. Geissler points out that neatsfoot oil is, on account of the method of preparation, very often rancid, and that he has examined oils of this class containing 10 to 15 per cent, of free fatty acids. According to Schaedler, true neatsfoot oil from the hoofs of oxen is mostly mixed with that from the feet of the sheep. Benedikt distinguishes between ox neatsfoot oil, sheep's- foot oil and horse-foot oil, and states that commercial neats- foot oil is generally a mixture of oils from the hoofs of oxen, sheep, horses and swine. Data for the accurate differentia- tion of these oils are still entirely lacking. Properties. Neatsfoot oils are straw yellow, inodorous, of agreeable flavour and generally set only below C. Specific Gravity at 15 C. Neatsfoot oil, 0-914-0-916 (Allen); sheep's-foot oil, 0'9175 ; horse-foot oil, 0*913 (Schaedler) ; at 18 C., neatsfoot oil, 0'9142 (Stilurell). Adulterations. Purified neatsfoot oil is in good demand as a lubricant, and is falsified with refined cotton-seed oil, rape oil and mineral oils, the detection of which is not diffi- cult. Any admixture of pale fish oils can be recognised by the smell evolved when rubbed on the hands ; otherwise by phosphoric acid. Uses. Technical, as a lubricant for delicate machinery, clocks and so forth. ANIMAL FATS AND OILS. Ill BONE FAT (KNOCHENFETT). Raw Material. Large hollow bones and short flat bones, or rather the spongy substance of the latter. Bones are filled with a soft yellow or reddish fat (bone marrow) which serves to protect and support the blood vessels in the bone and also as formative substance for the white corpuscles of the blood. The bones worked up for their fat are those of the domesticated animals slaughtered for food and of the horse. As a rule, three products are obtained in the process : glue, fat and mineral matter, i.e., phosphate of lime, the latter in the form of purified bone or as a manurial sub- stance, or boneblack. Preparation. Originally the treatment of bones was con- fined to the extraction of the fat, the material being simply boiled in water and the fat skimmed off ; probably also the glue, so far as the latter was dissolved by the boiling water, was recovered, the residual bones being worked up by the turner or bone worker, or ground down into bone meal. The methods of manipulating bones employed at the present time may be directed to the attainment of four different objects : 1. The recovery of fat and boneblack as the primary ob- ject, with bone meal as a secondary consideration ; 2. Fat and boneblack as the main products ; glue and bone meal, bye-products ; 3. Fat, glue and bone manure or phosphate as the princi- pal products ; 4. The recovery of ammonia salts in addition to the pro- ducts named under 1 and 2. In any case, whatever products are to be obtained, the separation of the fat is necessarily the first task to be per- formed. Even in the event that bone meal is the sole manufacturing product in view, the recovery of the fat is 112 ANIMAL FATS AND OILS. unconditionally desirable on account of its relatively high value, and the bones are of no greater value for manure with the fat left in than without it. 1 The form in which the bones should be used for recover- ing the fat, the sole object at present in view, is always that of small lumps, such as are obtained by passing the bones through crushing rollers set closely together. In working with bones crushed by stamping, the meal and granules with which the unsorted lumps remain mixed unfavourably affect the progress of the operation, whether boiling or extraction, by clogging together and rendering the recovery of the fat more difficult. FIG. 49a. Bone Crusher. (Section.) Properly crushed bones contain no meal and but few granules, and are in this form best adapted for yielding up their content of fat. The recovery of fab may be effected in three ways : 1. By boiling, 2. By steaming, 3. By extraction. By simple boiling the bone cartilage is left almost entirely unaltered, the fat, however, being so imperfectly extracted 1 Translator's' Note. In fact they are the better for its removal, the fatty matter impregnating the bones retarding indefinitely their decomposition in the soil. ANIMAL FATS AND OILS. 113 by this operation that frequently only one half the quantity actually in the bones is recovered. By steaming the bones a much greater yield of fat is ob- tained, it is true over 90 per cent, being recovered by suffi- ciently prolonging the operation but, at the same time, a large portion of the cartilage is dissolved and converted into glue, which, if the manufacture of this article does not fall within the scope of the factory, is completely wasted, and even forms a burdensome waste product, in that the glue liquor, unless quickly discharged into a large volume of running water (river), very rapidly undergoes decomposition and infects the neighbourhood. The easiest method of FIG. 496. Bone Crusher. (Viewed from above.) getting rid of this glue liquor is by employing it for the irrigation of the land. Bone meal obtained from steamed bones is more easily dissociated than that prepared from unsteamed bones, on which account it has a more rapid fertilising action than the latter and is therefore, for this reason, usually considered by practical men as superior, though this is in reality not the case ; and, moreover, such bones when converted into boneblack are of lower value, owing to the extraction of the gelatine, and yield a black of inferior decolorising power. By the extraction process the fat is almost entirely ob- tained in solution, only a few parts per mil. at most being 114 ANIMAL FATS AND OILS. left behind in the bone. The cartilage, as well as the mineral matter, remains completely unaffected, and bones deprived of their fat in this manner may be used either for the preparation of a good bone meal which will have an abiding manurial effect or for the manufacture of boneblack. The extraction method is already undoubtedly recognised as producing the best results of any. FIG. 50. Bone-Boiling Pan with Lifting Gear and Perforated Vessel. 1. Bone Boiling. The oldest form of apparatus employed for bone boiling consisted of a large sheet-iron boiler set in brickwork and heated by direct fire. The pan was first filled with bones up to about 12 to 15 in. from the brim and water run in until the level of the liquid was about 8 in. below the edge, heat being then applied and continued until a fatty layer collected at the surface, this being skimmed off by flat ladles as fast as formed and collected in a wooden vat, where it was left ANIMAL FATS AND OILS. 115 to set. Under the fatty stratum there was always found a certain quantity of dark-coloured glue liquor, which was poured off. As soon as only a scanty amount of fat was found to be coming up to the surface of the water the opetfa- tion was considered at an end, the glue liquor was run off and the bones taken out of the pan, to be then dried and subsequently worked up. A slight improvement on this original practice of ob- taining fat from bones consisted in placing the latter in a tin cylinder (Fig. 51) perforated like a sieve in the lateral walls and suspended by a strong bow from a chain running over a FIG. 51. Perforated Vessel for Holding the Bones, pulley attached to a revolving crane, by the aid of which it could be lowered into the boiling pan. In this latter vessel the cylinder was allowed to remain until no further notable quantity of fat could be skimmed off the surface of the water, whereupon the cylinder was lifted out and replaced at once by another full of fresh bones, which were boiled in the same water, whereby a glue liquor was obtained of sufficient strength to pay for working up into glue. With regard, however, to the suitability of the same water for continuous use with fresh charges of bones, a 116 ANIMAL FATS AND OILS. difficulty soon arises, in that the density of the liquor be- comes so great that the ascent of the fat globules is hindered and they remain imprisoned in the liquor, water having to loe added as a diluent to enable the fat to separate. Where steam is available, the boiling is effected by direct steam, which presents the advantage that large wooden vats may be used and the consumption of heat is relatively low. Direct steam may also be employed in the following manner : the aforesaid perforated vessel is immersed in a wooden vat full of water, at the bottom of which is placed a coiled steam pipe, the steam from which heats the water to boiling. 2. Steaming Bones. The temperature of steam increases according to the pressure to which it is subjected, and it also forces its way more readily into the substance of bodies than when in the liquid state (water). These tw r o factors, conjoined with the circumstance that strongly heated fat is very fluid, cause bones that are subjected to the influence of fairly high- pressure steam to yield a far larger quantity of fat than can be obtained therefrom by simple boiling. Heated steam has, moreover, much greater solvent powers than hot water, and exerts this influence in the case of bones by converting a comparatively large amount of the cartilage into glue, so that in addition to obtaining a greater yield of fat from the bones by steaming, a more highly concentrated glue liquor is also produced than by mere boiling ; the steamed bones themselves, being rendered more friable by the solu- tion of an appreciable proportion of their cartilaginous sub- stance, are softened and can be more easily comminuted. The apparatus generally used with slight modifications for steaming bones takes the form displayed in Fig. 52. It consists of a cylinder 10 or 12 ft. in height and composed, ANIMAL FATS AND OILS. 117 like an ordinary boiler, of strong iron plates. In each of these cylinders, which are set up vertically and arranged in groups or "batteries," are two large apertures, E and A, which can be shut steam-tight by iron covers and bow-screws. In the upper convexity of the cylinder is fitted a pipe D com- municating with the boiler, and on the opposite side of the FIG. 52. Bone Steamer. top is a short pipe H, both this and D being provided with taps. At the bottom of the cylinder is a pipe L, also fitted with a tap and bent forwards, and the cylinder is fitted in- ternally with a perforated false bottom S immediately over the domed bottom. Generally four to six, or in large works eight and more, steamers are united to form a battery, the discharge pipes L being led into a common outlet, whilst the 118 ANIMAL FATS AND OILS. steam pipes D are supplied from a main feed pipe. The batteries may be surrounded by brickwork, but it is pre- ferable to mount them unenclosed and merely lagged with wood on a frame, the intermediate space between the boards and the steamer being packed with sawdust. For filling the steamers quickly and with the smallest ex- penditure of power, it is advisable to set the crushing mill at such a height that the crushed bones fall direct into trucks which run on rails above the upper manholes of the steamers and are unloaded there by tipping. Another set of rails runs along in front of the second manholes A, so that the spent bones can be discharged direct into trucks and transported therein to the breakers. As soon as a steamer is charged with bones it is hermetic- ally closed, the tap H is opened and steam admitted to the bones by opening D. The steam first entering is condensed to water, being cooled by the bones, but after a short time the temperature in the steamer will have so far risen that the steam no longer liquefies, but after driving the air in the apparatus out through the pipe H issues therefrom itself in a strong current. As soon as this is observed H is closed and the steam allowed to act on the bones, whereby the fat therein is melted and trickles down. At the bottom of the vessel there collects a liquid containing glue, and rendered turbid by imprisoned fat globules, a thick layer of fat surmounting the whole. From time to time, at intervals of about an hour, the tap L is opened a little way, the pressure of the steam expels the glue liquor and fat with great force, and the tap is only closed again when the characteristic sound indicates that steam alone is escaping. Steaming, with periodical removal of the fat, is continued until a sample of the effluent liquid shows that no more fat is coming away. The liquid in the steamer is then expelled by the steam, the steam pipe D closed and the outlet A ANIMAL FATS AND OILS. 119 opened, whereupon the steam is turned on again and forces the greater part of the charge of bones out through A, an operation greatly facilitated when the perforated false bottom S is arranged to slope well forward. The liquids obtained from the steamer consist of melted fat and a fairly concen- trated solution of glue retaining a large proportion of fat. To separate these constituents the liquor is run into a steam jacketed metal cylinder, the current of steam being regulated to produce sufficient warmth to keep the glue liquor rather fluid, so that, on standing, all the contained globules of fat are enabled to rise to the surface. When the separation is complete the fat is run off through a tap at the side of the cylinder and the glue liquor immediately drawn off through a valve in the conical bottom of the vessel to the concen- trating pans. The glue liquor being always fairly rich, it is advisable to work it up into glue in the factory, since, even if the resulting product be merely of low quality, the loss of valuable material sustained by the bone meal or bone- black is to some extent compensated thereby. It is some- what difficult, in the type of steamer described, to warm the mass quite uniformly ; consequently the melting of the fat takes a rather long time, so that a large amount of cartila- ginous substance is converted into glue. This may be remedied by an improved method of con- struction, wherein the steam pipe does not debouch into the top of the steamer but is modified in order to secure the better distribution of the steam through the charge of bones. The steam pipe (Fig. 53) is extended to the centre of the steamer and then passes downward in the direction of the axis almost to the bottom. A number of lateral apertures o are provided at various heights in the pipe, each of them being so pro- tected by a small bent metal plate d that no solid bodies can pass into the tube, whilst, at the same time, the free discharge of steam is ensured. These protectors were found 120 ANIMAL FATS AND OILS. necessary to prevent the obstruction of the pipe, otherwise, liable to occur, from small pieces of bone. The modus operandi of this arrangement is easy of ex- planation : The steam passes through the numerous aper- tures in the pipe and uniformly heats the bones in many places at once, the temperature consequently rising quickly to a point at which the fat melts out. The entire aim of the process recovery of the total amount of extractive fat in a short time and the consequent restric- FIG. 53. Friedberg's Improved Bone Steamer. tion to a minimum of the conversion of cartilage into glue- is attained by this very simple arrangement. Finally, by adhering to this construction the diameter of the steaming cylinders . can be increased and the bones still heated uni- formly. 3. Extraction. The extraction process is, as already stated, the only one by which it is feasible to obtain from bones the contained ANIMAL FATS AND OILS. 121 fat in its entirety and at the same time preserve the cartila- ginous substance perfectly intact, so that the best quality of boneblack may be prepared from the residue. Hence there is no need to undertake the manufacture of glue in order to make good the loss of matter a consideration of great value in simplifying the work of the establishment. The recovery of fat from bones by this process is based on the property of certain liquids, such as ether, carbon bi- sulphide, petroleum, benzol, etc., of extracting fat in the warm, bringing it into solution and then yielding it up again on simple distillation. In most cases use is made of the cheap petroleum spirit (benzine) available in large quantities, a special apparatus being employed on account of the great care necessary in view of the explosive and inflammable nature of the benzine. Among the apparatus for extracting fats, those of Deiss, Vohl, Seiffert, Lindner & Merz and Wegelin Hiibner are best known, all of which are described in the author's Vegetable Fats and Oils. The extraction of the comminuted bones is effected in precisely the same manner as there indicated for oil seeds and oil fruits. Properties. The bone fat obtained by merely boiling the bones is, unless perfectly fresh bones are used (and this is very rarely the case), of very inferior quality, dark yellow to light brown in colour and of repellent smell. The colour is due to the dark decomposition products of the putrefying bone cartilage, and the evil smell arises from similar pro- ducts, fats in general being characterised by the affinity they exhibit for absorbing and retaining odoriferous sub- stances. Bone fat prepared by the steaming process differs little from the last-named class in point of colour, but considerably as regards smell. The same partly decomposed bones that, in the ordinary method of simple boiling, would yield a fat with a repellent smell, will, if steamed, give a much less 122 ANIMAL FATS AND OILS. unpleasant-smelling product, the difference being attributable to the high temperature employed , whereby the greater part of the malodorous substances is immediately vaporised. The external appearance of the fat derived from bones varies considerably, that from perfectly fresh bones being pale yellow in colour and free from smell, whilst that from old bones is dark yellow to brown ; the consistency is either quite fluid, semi-fluid or like lard. Benedikt gives the subjoined data for fat from perfectly fresh bones : Specific Gravity. 0'914-0'916 (Allen). Melting-Point. 21 -22 C. Setting -Point. 15 C., the temperature rising to 17 C. (Schaedler). Saponification Value. 19O9 .(Valenta). Iodine Number of the Fatty Acids. Crude fat, 37'4 ; refined fat, 55-7-57-3 (Morawski & Demski). Uses of Bone Fat. Solely technical ; in the soap and lubricating oil industries. EEFINING BONE FAT. For the purpose of utilising bone fat it is essentially neces- sary to subject it to a process of purification to destroy the odours and colouring matters in the fat ; this process is carried out with either nitric acid or potassium bichromate, both of which exert a powerful oxidising action. In refining with nitric acid ^ to 2 parts by weight of acid are taken per 1000 parts of fat, the exact amount depending directly on the degree of impurity. Wooden vats, containing wooden appliances for stirring, and fitted with a steam pipe at the bottom, are used. The fat to be purified is placed in a vat, where it is melted by steam and heated to 70-80 C., the nitric acid being then run (from a glass vessel fitted with a glass tap) in a thin ANIMAL FATS AND OILS. 123 :stream into the fat, during which time the stirrers are kept iu continual motion. At intervals samples are drawn from the vat, cooled rapidly to cause them to set, and examined to obtain an idea of the condition of the fat. If the purification seems to be sufficient the stirrers are stopped and the fat washed, to which end it is allowed to run out in a thin stream into a second vat placed at a lower level and more than half full of water, besides being fitted with a steam pipe and set of stirrers. By admitting steam and simultaneously working the stirrers an intimate admixture of the fat and water is effected, and then after a short time the whole is left at rest, the water, after separation, being finally drawn off and re- placed by a fresh supply, whilst the fat is washed again in the same manner and is then considered sufficiently purified. By replacing the nitric acid by a mixture of equal parts of nitric acid and sulphuric acids, the purifying process is greatly accelerated, but the loss induced is greater than in the former case. The second purifying process is that in which sulphuric .acid and potassium bichromate are used. One part by weight of bichromate is dissolved in a very little water, and the solution placed in a stoneware vessel, 2 parts by weight of sulphuric acid being then poured and stirred in with a glass rod and the vessel left, covered up, for a couple of days. When sulphuric acid and potassium bichromate come in contact, chromic acid is liberated and dissolves in water to a red solution, whilst the potassium bisulphate formed at the same time crystallises out on the bottom of the vessel. From | to 2 per cent, of this chromic acid solution is added to the fat, according to the degree of impurity of the latter, and the stirrers are set in motion. When the reaction is concluded the fat is washed, at first ^vith only a small quantity of water, which becomes tinged with green or violet by the resulting chromic acid compounds, 124 ANIMAL FATS AND OILS. and these washings from various operations are collected and sold to colour manufacturers. By using a sufficiency of bichromate, even a very im- pure bone fat can be rendered perfectly white and free from smell, and this class of product sells at such a good price as- to well repay the high cost of refining. Kratzer employs for bleaching bone fat a mixture of 500' parts by weight of the fat, warmed to 70-75 C., and 5 parts, of 30 soda lye containing 2'5 parts of common salt, and leaves the whole to stand for six to eight hours or over night. The clear settled fat is then cooled to 40 C. and to it are added successively a solution of 2*5 parts by weight of potas- sium bichromate and 7'5 to 10 parts of 22 fuming hydro- chloric acid, mixed in by means of the stirrers, which are kept vigorously at work until the oil finally exhibits merely a green tinge with white froth, a sign that it is properly bleached. When finished, some 20 gallons or so of water at 75 C. are sprinkled over the surface from a watering-can and the whole covered up and left to stand, steam, if available, being blown in for ten to fifteen minutes. By this method of washing with hot water or steam the acid remaining in the bone fat is washed out and carried down. A bone fat bleached in this manner is, at the ordinary temperature, soft and lard-like in appearance, pure white or faint yellow in colour, and is specially characterised by the slowness with which it turns rancid when exposed to the air. BONE OIL (KNOCHENOL). In order to obtain the bone oil from bone fat, which is done by precipitating the more readily congealable stearine group of fats, the fat is exposed to a low temperature (about 2 to 9 C.), whereby the solid fat separates out and the oil can be then poured off. According to the Polytechnic Society of ANIMAL FATS AND OILS. 125 Berlin, much better results can be obtained by dissolving the fat in benzine and exposing the solution to cold. The clear liquid is poured away from the solid fat, and when freed from the solvent by distillation leaves pure bone oil. ARTIFICIAL BUTTER, OLEOMARGARINE, ETC. (KUNSTBUTTER, MARGARINBUTTER, OLEOMARG-ARIN, SPARBUTTER). By the above and similar designations is understood an artificial product obtained from constituents of beef tallow, prepared by special processes and worked up with milk and vegetable oils to a substance greatly resembling, or even identical with, natural butter in appearance, consistency and flavour. The manufacture of artificial butter is a fairly simple pro- cess, but nevertheless entails the exercise of intelligence and care in order to fulfil all the requirements imposed. A few of the methods in use are given hereunder, and the reader is referred for fuller information to Lang's work on Kunst- butter (3rd edition, 1895). MARGARINE MANUFACTURE IN FRANCE. Villon describes the process as follows : The first operation consists in the separation of the so- called, premier jus from the solid stearine and olein, melting at 38 C., and a liquid fat. The solid tallow is formed into pats, about 8 in. long by 7 in. wide and J in. thick, wrapped in linen cloths, and weighing some 2J Ibs. (1 kilo) each. Two hundred of these pats are placed in a hydraulic press by placing on the lower plate (covered with a canvas cloth warmed to about 50 C.) a layer of 5 pats, these being covered with another cloth also warmed to 50 C. and surmounted in turn by a second set of 5 pats, and so on until the whole 200 are in position. The operations must be performed quickly, so that the cloths have not time to become cold. The sepa- 126 ANIMAL FATS AND OILS. ration of the oleomargarine begins without pressing, owing to the pressure of the cloths and to the warmth to which ^hey are exposed, but as soon as the flow is observed to flag, the press is set to work, very slowly at first, the pressure being afterwards raised to 150 kilos (330 Ibs.) and even to 175 kilos (385 Ibs.). The pressed tallow (suif presse) remains behind in the cloths and is used for making stearine and tallow candles. The oleomargarine thus obtained is a yellow crystalline mass recalling ordinary butter, and is mixed with milk and cotton- seed oil or ground-nut (arachis) oil for churning. The pro- portions taken vary according to the quality in view, but the following have been ascertained : i. ii. Oleomargarine ... 800 kilos 500 kilos (of 2-2 Ibs. ). Milk 500 litres 500 litres (of 0-22 gall.). Cotton-seed Oil - 100 kilos 50 kilos. The quantity of oil is adjusted according to the time of the year, 30 to 40 per cent, being used in winter, whilst in summer the oil is occasionally omitted altogether. Sesame oil is sometimes used, the object of the oil, of whatever kind, being to impart to the oleomargarine the suppleness of butter. The oleomargarine is melted at 45 C., and the milk and oil are added at the same temperature, all being run into the churns through pipes from storage tanks several yards high, situated above the (wooden) churns. The materials are then thoroughly incorporated by means of dashers, the operation lasting about two hours, and the dashers being stopped towards the end in order that the quality of the product may be deter- mined. The mixture is then allowed to run out of the churn through an inclined wooden trough into a large vat, a jet of cold water impinging on the mixture, as it falls from the trough, in order to granulate the margarine. In the vat the product floats in cold water, and is removed by gauze strain- ANIMAL FATS AND OILS. 127 ers or sieves and left to drain for about two hours in per- forated vessels, whence it is transferred to revolving tables like those used for butter working, only larger. On these it is kneaded to express the milk, and the margarine thereby acquires the homogeneity of butter. The appearance of the product is improved by passing it in small portions through horizontal rotating fluted-roller working machines, after which it is made up into 1 Ib. (or i kilo) pats. This method FIG. 54. Butter and Churning Machine (W. Rivoir, Offenbach -am-Main). is the one most frequently employed, but the churned mix- ture can also be cooled by ice water from the ice-making machine, though this plan is not advantageous, since during the slight fermentation allowed to ensue before the mass is drained the flavour, sui generis, of a good margarine is, in this case, not attained. To obtain really good margarine the product must be allowed to set in small lumps enclosing small quantities of 128 ANIMAL FATS AND OILS. milk, and on this account the water used must not be too cold. A good butter flavour is developed by inoculating the margarine in the draining stage with a small quantity of a ferment obtained from artificial fermentation-cultures of good butter. Henri Grasso of Herzogenbusch (Holland) designs and supplies margarine factories for a diurnal production of 1 to 3 tons of artificial butter. The entire plant consists of : 1. One churn of 165 galls. (750 litres) capacity; FIG. 55. Margarine Worker (W. Rivoir). 2. One ordinary roller worker with patent " Salaman- der " rollers, filling sack, flap and truck ; 3. One margarine oil attemperator holding 165 galls. ; 4. Four margarine melters holding 165 galls. ; 5. One butter drier or mixing machine ; 6. Three milk acidifiers, each holding 77 galls. ; 7. One milk separator ; 8. One pasteurising apparatus, several coolers for cream, skim milk and pasteurised milk ; ANIMAL FATS AND OILS. 129 9. One milk warmer ; 10. One churn for natural butter ; 11. One margarine oil pump, worked by hand ; 12. One granulating spray, with tap. According to Grasso, the product is prepared as follows : The fresh milk is pasteurised, cooled, re-warmed, passed through the separator, cooled again and acidified with a pure culture (of ferment). It is then churned, and the resulting butter sold as "centrifuge" butter, the skim milk and re- sidual buttermilk being used in making the margarine butter. FIG. 56. Butter Mill with Fluted Rollers. By a suitable selection of the raw materials, oleomargarine and oil, various qualities of margarine butter can be pro- duced. The oleomargarine is melted in the margarine melter by means of hot water, the temperature employed depending on the composition of the oleomargarine used, being, when the latter is of lower quality and contains stearine, of course higher than when a purer material is used. The oil is not heated, but only warmed a little. In the actual preparation of margarine butter a certain quantity of milk is put into the churn and churned for about ten minutes, the necessary amount of oleomargarine and oil 9 130 ANIMAL FATS AND OILS. being then added at a certain temperature and the mass mixed with alternate increases and diminutions of tempera- ture, in order that it may be delivered at the end of the necessary time into the granulating pan, where it is granu- lated by the a-id of ice water. When thoroughly cooled, the now solid product is shovelled into small trucks and conveyed to the roller machine, where it is worked (kneaded), this last operation being repeated a dozen times, after which the margarine is salted, passed twice through the butter drier and then packed. FIG. 57. Moulding Machine for Margarine (W. Rivoir). " KAISEE BUTTER." According to a communication issued by H. & M. Pataky, patent agents of Berlin, it has been established on the basis of scientific experiments that levulose and substances con- taining same, when incorporated with edible fats by a special process yield a preparation that, unlike other fats, needs no admixture with bile to form an emulsion in the alimentary canal. -All edible fats liquefy, it is true, at the temperature of the body, but their emulsifying capacity is dependent on their intermixture with the biliary fluid in the intestines, and since the amount of this fluid is in most persons com- paratively small, the ordinary edible fats are only to a small extent actually digested, i.e,-, absorbed by the intestines. Of ANIMAL FATS AND OILS. 131 all the alimental fats hitherto known, good fresh butter is the easiest of digestion, owing to its superior capacity in com- parison with the others of emulsifying with relatively low proportions of bile. If, now, edible fats be incorporated with levulose, they liquefy in the human stomach and form emulsions with water at temperatures even below 37 C., so that their digestion is thus ensured. The process is carried out in such a manner that the fats, warmed to about 70 C., are mixed with an addition of a solution of levulose at the same temperature, the mixture being rendered thoroughly intimate by continual stirring until cold, so that it emulsifies when shaken or otherwise agitated with water at tempera- tures from about 14 C. upwards. Butter mixed with levulose (or substances containing same) by this process is allowed to be sold as butter in Germany, and a patent has been granted for the " Kaiser butter " prepared in this man- ner. In addition to the properties already enumerated, " Kaiser butter " exhibits the advantages of superior flavour and keeping qualities. Consequently, the consumption of butter would be increased, and that of the butter substitutes at present vended decreased, by the introduction of this pre- paration, the price of which is even lower than that of ordi- nary butter. PREPARATION OF ALIMENTAL FATS, ACCORDING TO JAHR AND MtJNZBERG. According to the above-named inventors, easily digestible alimental fats may be prepared by intimately mixing fat, warmed to 70 C., with a solution of levulose at the same temperature, the liquids being stirred without interruption until cold. The mass thus obtained can be emulsified by shaking or otherwise agitating it with water at temperatures ranging from about 14 C. upwards. 132 ANIMAL FATS AND OILS. FILBERT'S PROCESS. J. H. Filbert's process for preparing alimental fats con- sists in the admixture of tallow and cotton-seed oil, the former being gradually liquefied at the lowest possible temperature and the oil added, whereupon 'the mixture is vigorously stirred and beaten in order to reduce the size of the oil globules still further and bring about their intimate incorpo- ration. Simultaneously, air is blown through the mixture, so that the finished product is light in colour and the par- ticles of cotton-seed oil and minute air bubbles are held in suspension in the solid tallow. WINTER'S METHOD. A. M. Winter took out an American patent for the fol- lowing mixtures as alimental fats (! ! !) : 1. Fatty substances and refined mineral oil mixed in such proportions as will produce a stiff mass ; 2. Refined mineral oil and animal or vegetable fats in proportions calculated to form a stiff mass ; 3. Eefined mineral oil, oleostearine, tallow and vegetable oil (cotton-seed oil) ; 4. Sixty per cent, of refined mineral oil and 40 per cent, of fatty substances ; 5. Sixty per cent, of refined mineral oil, 30 per cent, of animal and 10 per cent, of vegetable fat ; 6. Sixty per cent, of refined mineral oil, 15 per cent. of oleostearine, 15 per cent, of tallow and 10 per cent, of cotton-seed oil. HUMAN FAT. The investigation of human fat is of merely scientific interest, and it can readily be understood that little is known on the subject. Chevreuil found this fat to consist of an ANIMAL FATS AND OILS. 133 olein and stearine, the latter differing from mutton stearine in yielding margaric acid instead of stearic acid. Heinz found, however, that the constitution was of a more complex character, and that in addition to palmitic and stearic acids other acids, one of them liquid, are present. The fat examined by Mitchell was freed from tissue at the lowest feasible temperature, was pale yellow in colour and some- what softer in consistency than butter. When re-crystal- lised from ether, only a small precipitate was produced, and this, after washing (with ether) and drying, melted at 51'5 C. Under the microscope the crystals exhibited some resemblance to those frequently obtained in the form of fascicular bundles from lustrous lard, in that the indi- vidual crystals exhibited the characteristic chisel-shaped ends. The analysis gave : Fat. Specific Gravity. At 25 C. (water at 25= 1), 0'9033. Melting-Point. 17'05 C, Setting-Point 15 C. Saponijication Value. 145. Saponijication Eq u iva len t . 287 . Reichert Number. (2' 5 grms.) O31 ^-alkali. Acid Number. (1 grm.) 63 mgrms. KOH = O3 per cent, of oleic acid. Bromine Number. Heat, 11*3 C. Iodine Number. 11'3 X 5*5 = 62'15. Fatty Acids. Melting-Point. 35'5 C. Setting- Point. 30'5 C. Iodine Number. 64. Iodine Number of the Volatile Fatty Acids. 92'1. Twitchell's modification of the Jean method of fractional precipitation was employed for determining the nature of the fatty acids, T9478 grms. of fatty acids (iodine number, 134 ANIMAL FATS AND OILS. 64) being dissolved in 25 c.c. of 95 per cent, alcohol and treated with T5 grms. of lead acetate dissolved in ,-10 c.c. of the same alcohol, and the flask well corked and left to stand all night. Next morning a little of the liquid was filtered off, the acids being recovered by agitation with ether and hydrochloric acid, and their iodine number ascertained. The precipitate was well washed with alcohol, the fatty acids recovered, dried, weighed and their iodine number deter- mined, oxidation being in each case carefully guarded against. The results were : Grams. Iodine No. Per Cent. Solid acids - - - 0-9779 37 50-2 Liquid acids (by difference) - 0-9699 92 49-8 The acids from the filtrate were still liquid at 15 C. ; those from the precipitate had a melting-point of 35*5 C. and a molecular weight of 278. From this may be calculated : Liquid acids in nitrate - - - - - - 99-8 per cent. ,, ,, reckoned as oleic acid - - - 20-06 ,, 37 x 50-2 _ 18-57 loo : ~6-9 Total liquid acids - 70-4 ,, Iodine number, 64 x 1QO 90 "9 70-4 Therefore, the liquid acids probably consist of oleic acid, with a small amount of unsaturated fatty acid, probably linolic acid. So far as the solid acids are concerned, the high mole- cular weight of the lead precipitate (of which only 20 per cent, should be considered as liquid acids) leads to the con- clusion that stearic acid or another high molecular acid is present. . The crystals obtained, after washing and drying, from the crystallisation of the fatty acids from 70 per cent, alcohol melt at 50'5 C., which is a lower melting-point than is exhibited by any other mixture of stearic and palmitic acids, ANIMAL FATS AND OILS. 135 according to Heintz' table, and indicates the presence of myristic acid, since the precipitate was entirely free from liquid acids. The filtrate on standing yielded a second pre- cipitate, also melting at 50*5 C. Human fat, according to these data, therefore consists of some 70 per cent, of liquid fatty acids, chiefly oleic acid, and 30 per cent, of solid acids, probably palmitic acid, together with small quantities of stearic and myristic acids and traces of lower volatile acids. HOUSE FAT, HORSE GREASE (PFERDEKAMMFETT, PFERDEFETT). Raw Material. Chiefly the fat found in the neck (under the mane) of the horse, and in addition all the fatty portions of the carcase. Preparation. The fat after separation from its integu- ment is collected and melted by steam if on a large scale, or simply by hot or boiling water in small works then strained and placed to set in suitable vessels. Properties. The actual mane fat of the horse is pure white and inodorous, softer in consistency than lard, melts at 30 C. and consists of 70 parts of olein and 30 parts of a mixture of stearine and palmitin. The other fat from this animal is thick, almost like pomade, and separates on standing into a solid portion and a supernatant liquid. At 10 C. it resembles lard, and at 8 C. tallow r ; it is of a dirty yellow-brown colour and pos- sesses a characteristic fatty odour. The marrow fat obtained from the large hollow bones of the horse is a waxy-yellow, greasy fat, becoming hard in the air ; it begins to run at 65 C. and is at 86 C. thick like syrup. By the aid of soda a very solid white soap can be prepared therefrom. Uses. Medicinal : for ointments in veterinary medicine. 136 ANIMAL FATS AND OILS. Cosmetic : for pomades intended to promote the growth of hair. Technical : for softening leather, lubricating machinery, wool softening, and the manufacture of soft soaps, for which it is specially adapted. BEEF MAEROW (KINDEEMARK). Raw Material. The large hollow bones of the ox contain a fat (marrow) which is identical with tallow, and is indebted for its characteristic taste to the cellular tissues which accompanies. Preparation. The bones are opened, i.e., split or sawn, whilst still fresh, and the marrow, which corresponds to the bone in shape, carefully collected. In old bones, no longer fresh, the marrow has no special value, and is then only classed as bone fat. It is carefully melted, separated from the cell tissue by straining and stored in a suitable manner. Properties. Melting -Point. 45 C . Setting -Point. 35 C., the temperature rising thereon to 40 C. In the natural state it is of a reddish colour (owing to the numerous blood-vessels by which it is traversed), hard, tallowy and exhibits a granular structure when set after melting. It consists of about 70 per cent, of palmitin and stearine and 30 per cent, of olein, is imperfectly soluble in boiling alcohol and also harder to dissolve in ether than is the case with tallow ; moreover, it becomes rancid more readily than the latter. Uses. For alimental purposes, as an addition to soups, which it strengthens ; in cosmetics, for pomades, ointments, etc. TURTLE OIL (SCHILDKEOTENOL). Raw Material. The eggs of the green and giant turtles of Jamaica and the Seychelles, and also those of the edible turtle. According to Brooks, it is obtained from the fat of these animals as well. ANIMAL FATS AND OILS. 137 Preparation. Turtle oil, or more correctly, turtle-egg oil, is prepared by crushing the eggs with a forked wooden instru- ment in an empty bucket and pouring water on the mass, whereupon, after a few hours' exposure to the heat of the sun, the oil collects on the surface of the water. Six thousand turtle eggs yield only 5 galls, of oil ; and as 50,000 galls, of oil are annually despatched to Para from the Orinoco, the Amazon and the Kio Negro, and 60,000 galls, are consumed by the native population preparing the oil, it will be evident that the turtles, which frequent the same sandbanks from year to year and lay 120 eggs apiece three times during the season, have extraordinary reproductive capacities. When turtle oil is obtained from the flesh by boiling, the yield is uncommonly large, a single turtle often producing 10 galls, of oil, so the output of 60,000 galls, at the Seychelle Islands is not very difficult of accomplishment. In Jamaica, also, the oil is prepared from the flesh of the turtle, presumably from Chclonia Cahonana. Seychelle oil is superior in flavour, and might, if its alleged properties are substantiated, form a substitute for cod-liver oil. HOG'S LAKD (SCHWEINEFETT, SCHMALZ). Raw Material. The fatty portions of the hog, and especially those lying beneath the skin and between the in- testines. The quality of the fat varies with the part of the body from whence it is derived ; that from the exterior fatty integument of the hog, surrounding the entire carcase of the animal immediately below the skin (especially on the back and sides), is more solid and curdy, though, at the same time, more easily melted out than that from the interior of the body along the ribs, the intestines and kidneys, which is generally known under the names of leaf, loin, kidney fat (Schmeer, Liesen, Lendenfett, Nierenfett, Filz). The proper preparation and assortment of hog's lard and the raw 138 ANIMAL FATS AND OILS. material therefor is very important. January and February are the best months, the fat being then more consistent than during the warmer seasons of the year. Apparently the colder season, as a result of increased respiration of the denser air, has an influence in rendering the deposited fat poorer in hydrogen and richer in carbon, the hydrogen, by reason of its greater affinity for oxygen, being the first to enter into combination with the latter during respiration at low temperatures. Winter fat is accordingly richer in stearine, whilst summer fat contains more olein. The method of feeding and the health of the animal also exert a not un- important influence on the constitution of hog fat, so that soft and greasy fat is also met with in winter. Pigs fed ex- clusively on acorns always yield a somewhat yellowish fat. Lard in the greatest quantity and of the best quality, both as regards consistency and appearance, is supplied by the intes- tinal fat of young pigs, this fat consisting mainly of cell capsules enclosing the pure fat and requiring to be broken before the melting process. Preparation. Hog fat is prepared in the same manner as tallow, by carefully melting the raw material and separating it from the cellular tissue and other residual fleshy matter. The fatty substance intended for melting is freed as well as possible from all adherent pieces of skin, sinews and flesh, and then cut into small cubes with knives or in the cutting machine, the material so prepared being repeatedly washed with water until the w r ashings run away clear and colourless, after which it is transferred to the melting pan. This is generally of w r ell-tinned copper, and is heated by direct fire, though steam-jacketed enamelled iron or large stone- ware pans may be employed. The melting fat is constantly stirred with large wooden paddles, the work being con- tinued until the liquid has become perfectly clear and all the water is evaporated. The clear fat is then poured ANIMAL FATS AND OILS. 139 through straining cloths, stretched on frames, into the storage or transport vessels, and after being slightly cooled is stirred until it has become white and opaque, although still thickly fluid. If the fat were allowed to simply set by itself, the contraction occurring in congelation would give rise to fissures in the mass, which would admit air to the interior and thus unfavourably influence the keeping quality. When, on the other hand, it is stirred until completely set, then so much air is stirred in that all cannot escape, and rancidity is still further facilitated. The stirring must therefore be dis- continued at the proper time, whilst the fat is still soft enough to run together without leaving any interstitial spaces. When this particular method of cooling is not adopted a quantity of oily fat congregates on the surface and, being readily liable to alteration by rancidity, exerts an un- favourable influence on the consistency of the subjacent mass. The residual matters (fragments of tissue, greaves) left behind in the straining cloths and in the pan are heated again in the pan to a somewhat higher temperature and then pressed in a so-called greaves-press, leaving the solid portions behind as greaves. The resulting fat is generally somewhat coloured and possessed of a peculiar roast smell. In the large hog-slaughtering establishments in America the fat is generally melted in apparatus similar to that described on p. 116 et seq., and heated by steam under pressure, the pre- cautions necessary in the case of tallow melting being, however, dispensed with, owing to the absence of any unpleasant smell. The greaves are used as an inferior food stuff and fed to cattle, or, when obtained in large quantities, employed for the manufacture of potassium ferrocyanide. Properties. Sp. gr. at 15 C., 0'931-0'932 (Hager), 9380 ; at 50 C., 0-8818; at 69 C., 0*8814; at 94 C., 0'8628 other methods mentioned is, even when carefully 172 ANIMAL FATS AND OILS. strained, however, not free from admixed undissolved sub- stances, i.e., solid matters, and therefore cannot be used for all technical purposes. Though well adapted for the prepa- ration of ordinary soaps, candles, etc., it is unsuitable for fine toilet soaps, and for this purpose requires to be refined. The refining of tallow consists in melting the same, in presence of water, over a fire or by means of steam, with or without the addition of certain chemicals reputed to exert a purifying influence. The simplest and oldest method is by one or more re-meltings in an open pan over direct fire and with an addition of 5 per cent, of water ; the steam melting process, wherein a current of steam is passed into the melted fat, is new. It is an essential condition of the old clarifying process that the water should boil without- ceasing and be thoroughly mixed with the fat by means of stirrer& worked by hand or mechanical means, so that the latter substance is kept in a state of emulsion. When this mixing has continued for an hour the fire is drawn and the contents of the pan left at rest. During the slow cooling of the mass the lighter impurities rise to the surface and are skimmed off with a very fine strainer ; the heavier and bulky impurities, on the other hand, sink to the bottom, as does also the water, so that a mucilaginous layer of dirt and fat is formed between the strata of fat and water. The precipitation can, of course, only be complete pro- vided the cooling of the tallow proceeds with extraordinary slowness. For this reason a very slow fire is kept up under the pan, or else the latter is, by being covered up with a lid, cloths, etc., kept from cooling down too quickly. Generally speaking, the fat in a pan of medium size will require about twelve hours to clarify thoroughly. The purified tallow is then skimmed off, or drawn off, through a tap at the side, and is placed in the transport packages, or if a second clarification' is desired, transferred to another pan. Very often common ANIMAL FATS AND OILS. 173 salt, alum, salamrnoniac, etc., are added to the water used for re-melting, an aqueous liquid of unusually high density being thus obtained, from which the fat separates more easily than from ordinary w r ater. When steam is employed for clarifying it permeates the tallow, liquefies it and forces it through a strainer of very fine mesh, which keeps back the impurities. In addition to these tw r o principal methods, others have been proposed with the object, partly of purifying, partly of hardening and bleaching, and partly of sweetening the tallow by freeing it from unpleasant adherent smells. To effect the latter object (the cause of the smell being usually due to rancid fatty acids) the tallow is meloed along with a solution of soda or borax, the modus operandi being otherwise exactly the same as when water alone is used. Hardening the tallow is effected by various means. Apart from the old urine process (employed in slow-going soap- boiling establishments), the hardening process is based on a partial conversion of the olein in the tallow into solid elaidin by the action of acids, particularly nitrous acid. Alum, dilute sulphuric acid, potassium bichromate and manganese dioxide are also employed for hardening tallow, the pro- ducts in any case being oxy-fatty acids formed by the action of oxygen, whereby the final product is rendered harder and more brittle, and at the same time whiter in colour and almost inodorous. According to one prescription, a mixture of 500 grams of concentrated sulphuric acid and 500 grams of concentrated nitric acid is stirred into 100 kilos of melted tallow, and after allowing the acid mixture to react for a certain time is washed out again with pure water until the reaction is perfectly neutral, the tallow being finally heated over a gentle fire till all the water is evaporated. When oxidising agents are employed, vapours are alw r ays 174 ANIMAL FATS AND OILS. evolved which contain whole groups of the volatile fatty acids r butyric, valeric, caproic and caprylic acids. Under the in- fluence of nitrous acid, on the other hand, the reduction products of this acid appear in great quantity, and hydro- cyanic acid is never wanting. For this reason, hardening with this reagent can only he effected in closed vessels and the gases must be suitably led away and rendered innocuous. If the tallow obtained from crude tallow by melting at 60-65 C. be allowed to crystallise at 35 C. and is then pressed, " prime press tallow " is obtained, whilst crude cuttings yield under similar treatment " press tallow seconds/' the expressed liquid portion being in the former case classed as " prime margarine " and in the latter " margarine seconds ", The liquid portions of tallow can also be separated from the solids without pressure, since the solid crystalline bodies have higher melting- and setting-points than the liquid sub- stances. To effect this separation the tallow is melted in large quantities (two to three tons at a time) by the aid of steam coils in large wooden vats, the vessels being then closed and left at rest for eight or ten days at a room tem- perature about 1 or 2 C. under the melting-point of the tallow. The fat has time to cool down very gradually, and the solid fatty acids crystallise in hard granules out of the liquid mass, settling on the walls and bottom of the vats in large conglomerate cauliflower-like aggregations. The liquid portion, the tallow oil, remains clear in the centre of the vessels and is then poured off, the crystalline lumps being left a while to drain and afterwards melted in water, poured out and allowed to set. In this way a product resembling press tallow is obtained. Nevertheless, neither this nor press tallow rightly deserves the name of " hardened tallow," since they are no longer tallow in its pristine state, viz., stearine, palmitin and olein, but consist merely of stearine ANIMAL FATS AND OILS. 175 and palmitin, and therefore have an altogether different constitution. In order to increase the whiteness of the product tallow is frequently bleached, the operation being oftentimes com- bined with the hardening process. Bleaching is effected exclusively with chemicals, viz., chromic acid, manganese dioxide and hypochlorites. The various methods will be merely briefly mentioned in this place, having been already fully described in the author's Vegetable Fats and Oils. 1. Bleaching ivith Chromic Acid or Potassium Bichromate. 100 kilos of the tallow to be bleached are melted along with 1 kilo (2'2 Ibs.) of sulphuric acid previously diluted with 6 litres (T32 galls.) of water ; thereupon 500 grams (1*1 Ibs.) of powdered red chromate of potash are added and the whole gradually raised to boiling. When cold, the deposited acid liquor is drawn off, and the tallow re-melted with water and washed in the warm until no further re- action is discernible. 2. Manganese Dioxide and Sulphuric Acid. To 100 kilos of tallow is added 1 litre of concentrated sulphuric acid diluted with 30 litres of water, the fat being then melted and mixed with 1 kilo of the strongest manganese dioxide. The boiling mass is at first turned black by the manganese compound, then bluish, and finally (when the latter is com- pletely decomposed) white. It is then left to cool, the bleach liquor drawn off, and the tallow freed from the chemicals by repeated meltings with water. 3. With Hypochlorites. 100 kilos of tallow are heated along with a solution of 1 kilo of soda in 10 litres of water, until the tallow is melted, a clear solution of 1 kilo of bleaching powder in 7 litres of water being stirred in and the mixture raised to boiling, whereupon sufficient dilute sulphuric acid to produce a faintly acid reaction is gradually and carefully incorporated therewith. After standing, the 176 ANIMAL FATS AND OILS. aqueous liquor is drawn off and the (melted) fat washed with water until no more acid can be detected. Since, in the two last-named bleaching processes, noxious vapours producing coughing may under certain circum- stances be given off, the operation must always be carried on with the bleaching vat placed under a metal cover dis- charging into the open air. Uses of Tallow. Medicinal : for ointments ; cosmetic : for pomades ; as a food-stuff : for cooking and frying, and in a special form as a substitute for butter ; technical : for candles, soaps and lubricants of various kinds. ANIMAL OIL (THIEROL). RECTIFIED DIPPEL'S OIL OR OLEUM ANIMALE FCETIDUM DIPPELI. Raiv Material. The tar resulting from the dry distilla- tion of bones. Preparation. The crude bone tar is placed in a still con- nected with a worm condenser. Liquid distils over rather quickly at first, and when it begins to cdme over less rapidly the fire is made up stronger, so that finally nothing remains in the still but an inflated black residue consisting of carbon, which is utilised for fuel. The distillate is pale to dark yellow in colour, of oily appearance, and characterised by the property of fluorescence it exhibits, the surface of the oil, when viewed at a certain angle, displaying a coloration in- clining to blue or red. It should be mentioned that when a parcel of bone tar is once in work after the first distillation, it must be worked up completely without cessation, since otherwise the oil will turn brown by oxidation during storage The distillate is shaken up with strong hydrochloric acid, then separated therefrom, washed with water and rectified in glass retorts. By this means a series of bodies, which ANIMAL FATS AND OILS. 177 readily decompose and give rise to dark colorations, are destroyed, and it then becomes easier to prepare an oil that will remain light-coloured. Since the action of oxygen is increased by high tempera- tures, an arrangement has been devised for re-distilling the first distillate after the acid treatment in a current of car- bonic acid (carbon dioxide), in which case a copper vessel may be used for rectifying. The current of carbonic acid gas must, however, be strong enough to fill the receiver in which the distillate is collected, in order to keep the animal oil out of contact with the air. By adhering to these precautions the distillate from the crude oil may be made to yield, after two rectifications, a product which is almost colourless, and will remain fairly so if air be excluded. On exposure to the air it becomes dark-coloured, even though several times recti- fied ; to prevent which discoloration, as far as possible, the oil should be stored, after rectifying, in air-tight bottles. Properties. Thin flowing and pale yellow when fresh, but brownish-black, from oxidation, when aged, with repel- lent smell. On treatment with sulphuric acid it is rapidly converted into brown masses. Uses. Medicinal : as a popular curative agent ; techni- cal : in the (sheep's) wool-dyeing industry. FISH OILS (THEANE). The fish oils are those liquid animal fats that are ob- tained from the fatty accumulations in the bodies of the large marine mammals ; from the liver of various smaller or larger fishes ; and finally by pressing a certain class of fishes, all inhabiting salt water. All fish oils are, at the ordinary temperature, more or less fluid, pale yellow to dark blackish-brown in colour, and mostly endowed with a suffocating, more or less disagreeable 12 178 ANIMAL FATS AND OILS. smell and taste. Of the fish oils whose chemical con- stitution is still insufficiently known one portion is classed with the liquid waxes (sperm oil and the spermaceti pre- pared therefrom), and they are all very easily distinguished, by their behaviour on saponification, from the remaining oils and fats. Both these products are devoid of glycerides, and contain instead, ethers of the higher fatty alcohols ; and shark oil and all the marine animal oils with a specific gravity below 0*080 at 15 C. may be classified in the same group, since the great majority of the glycerides have a higher specific gravity than 0'914. Little is known respecting the fatty acids occurring in the form of tri-glycerides in fish oils. The place of the oleic acid found in other oils seems to be occupied here by physetoleic acid, but it follows from the very high iodine number of fish oils, that large quantities of a glyceride of an acid poorer in hydrogen are present ; this cannot, however, be linolic acid, because fish oils are not endowed with drying properties. Most of the fish oils are blackened by gaseous chlorine,, whereas all other fats and oils are bleached by this reagent. The true and, partly, the wax-like fish oils as well give highly characteristic colour reactions : caustic soda of specific gravity T34 and syrupy phosphoric acid produce a red coloration ; nitric acid, sulphuric acid and nitrosulphuric acid give black or violet-black colorations. A large number of fish oils are met with in commerce and are classified according as they are derived from the carcase fat (blubber), the fatty liver or the whole fish, and also according to the genus of the animal yielding them. They are all employed either for medicinal (liver oil) or technical purposes. By the term fish or train tallow (Thrantalg) are indicated the solid fats (stearines) separating out from fish ANIMAL FATS AND OILS. 179 oils at temperatures near freezing-point, or obtained by pressure at such temperatures. They also occur under the name of " whale fat," whilst the liquid portions are known as "expressed whale oil" (chiefly consisting of physetolein), also erroneously termed spermaceti oil. The fish oils met with in commerce may be classified as follows : 1. Whale oils (train or blubber oils) : whale, sperm whale, fin-back whale, Arctic sperm, dolphin, porpoise, walrus, round- headed dolphin oil. 2. Seal oils : Archangel, Greenland, Newfoundland, South Sea, Caspian seal oil, walrus and Swedish " Three crown" oil. 3. Fish oils: herring, sprat, pilchard, sardine, sardella, menhaden oil, Swedish, Eussian, Italian, Spanish fish oil. 4. Liver oils : cod-liver oil, coal-fish oil, merlangus oil, pollack oil, sea-pike oil, sharkVliver oil, ray oil, ray-liver oil, Japan fish oil. The fish oils obtained from the blubber of the entire fish, or portions thereof, by boiling, contain in their natural state more or less animal gelatine (glue) derived from cartilaginous, matter. The various kinds of fish oil have different odours and flavours, which are indescribable, but when experienced a few times, fix themselves in the memory and form (the taste ; especially) a sure, if not agreeable, means of recognition. The various fish oils pure seal oil, whale oil, liver oil, train oil can be distinguished by the aid of fuming nitric acid and sulphuric acid, the colour reactions obtained being nevertheless unreliable. The violet colorations given by liver oils with sulphuric acid do not result from the presence of the biliary colouring matters, but, according to Salkowsky, cholesterin, the colour- ing matter (lipochrome) discovered by Kiihne and the fatty acids themselves take part therein. Further assistance in differentiation, and perhaps the detection of adulteration, 180 ANIMAL FATS AND OILS. should be afforded by the difference of solubility in hot alcohol, in that the latter will take up 4 per cent, of fish oil, 7 per cent, of liver oil, 15 per cent, of seal oil and its own volume of whale (blubber) oil. The fish oils are, for the most, only adulterated with lower grade train oils, and resin oil ; the medicinal oils rarely with vegetable oils (such as sesame and cotton-seed oil), which latter, by the way, can be detected by the elaidin re- action, fish oils remaining clear and transparent whilst the last-named oils deposit elaidin after some time, the fatty layer being thereby rendered thick and opaque. Further particulars are given under the different headings .relating to fish oils. COLOUR REACTIONS OF THE FISH OILS WITH ACIDS. Fuming nitric acid (specific gravity 1-45). Sulphuric acid (specific gravity 1-6-170). Nitric and sulphuric acids 1 : 1. Seal oil. Red-brown. Reddish-yellow, then reddish- brown, finally brown-red (blood colour). Reddish, then brown. Whale oil. Brownish, then brown, finally blackish-brown. Brown, then blackish-brown. Yellow, then reddish, later a dirty brown. Liver oil. Blood red, then brownish-red to brown. Violet to blackish-violet. Yellow-red, then brick-red, finally red-brown with violet tinge. Fish oil. Brown. At first greenish, then brown, finally quite black. Yellow, then greenish, subse- quently brown. ANIMAL FATS AND OILS. 181 1. Whale Oils (Tram or Blubber Oils) (Walthrane). Raw Material. The fat of marine mammalia sea cow, walrus, manatee, dolphin, porpoise, sperm whale, Arctic sperm whale, Greenland whale. Preparation. The dead carcases are hauled on deck or, if near the land, on shore, and the cutting out of the blubber is at once begun. The men stand on small platforms let down the side of the vessel, and cut strips, about a yard wide, in the blubber (which is 18 to 30 inches thick) right round the carcase, over the back and belly ; then attach a rope to the strip and haul at the windlass, whereby the rope is tightened and the blubber draws loose, the men cutting it away from the carcase with sharp spades, so that the whole envelope of blubber is removed spirally by turning the body over, and is hauled on deck. The blubber is first placed 'tween decks, and is there cut up by machinery into smaller pieces, which are packed in casks, to be subsequently stowed in the hold. In many instances, however, it is immediately melted down on deck, in an iron pan set in brickwork, the oil being strained and filled into casks, whilst the residue (greaves) serves as fuel. The blubber in the casks begins, after prolonged storage, to putrefy in consequence of the decomposition of the tissues and other animal matters, and a part of the oil runs out of its own accord and is collected in special recipients. When the vessel arrives at her destination the blubber still left in the barrels is melted down over a fire or by steam, and the self-run oil is also heated to about 100 C. to allow the im- purities to subside. In some places the blubber, after being cut up, is melted in large pans 14 to 20 feet high, by direct steam, for five to eight hours. The carcase itself, when stripped of blubber, is either thrown back into the sea. or worked up for manure. 182 ANIMAL FATS AND OILS. The dorsal fat yields darker oil than the belly fat, and is treated separately. The yield ranges from 6 to 20 tons of blubber per whale. When the work is performed in a rational manner, con- siderable quantities of oil, though of inferior quality, are obtained by treating the flesh and bone in the carcase with high-pressure steam, the residual portions being dried and sold as manure. Smaller marine mammals, such as the porpoise, are dis- embowelled, cut into pieces, and the flesh and fat, as well as the bony skeleton, extracted by boiling over direct fire or by steam. (a) Porpoise Oil. Brown Fish Oil is pale yellow, brown- yellow or brown, with a smell resembling that of sardella oil, but loses this on exposure to air, and assumes a deeper shade of colour. The fresh oil is neutral to litmus paper, but absorbs oxygen from the air, and then has an acid reaction. Its specific gravity at 15 C. = 0'9220 ; setting-point, - 15 C. Cold alcohol dissolves 1'2 per cent.; boiling alcohol, 20 per- cent. The constituents of this oil are : glycerides of physe- toleic, oleic, stearic, palmitic and valeric acids. (Z>) Dolphin Oil. Round-headed Dolphin Oil is pale yellow in colour and has a strong fishy smell ; specific gravity at 15 C. = 0-918 ; at 20 C. - 0'9175. One hundred parts of boiling alcohol of specific gravity 0'812 dissolve 40 parts of the oil, the solution becoming turbid at 50 C. ; 100 parts of boiling alcohol of specific gravity 0'795 dissolve 60 parts. When exposed to low temperatures, the oil at 5 C. to 3 C. deposits spermaceti, and when thus freed from the latter substance dissolves in equal proportions in boiling alcohol, the solution exhibiting a weak acid reaction, which dis- appears on the addition of water. (c) White Fish Oil. (d) Porpoise Oil (Tiiminlerthran). ANIMAL FATS AND OILS. 183 (e) Narwhal Oil. Very pale in colour ; almost white. (/) Sperm Oil Cachelot Oil, of which a large fish will yield from 70 to 90 tons and 50 cwt. of spermaceti, is pale yellow to slightly brownish-yellow, clear, with a decidedly fishy smell and fairly fluid, with a specific gravity of 0*920 at 15 C. At 6 C. it begins to deposit spermaceti, and stearine at 8 C. Two vols. of the oil are soluble in 10 vols. of alcohol at the ordinary temperature ; and 7 vols. in 10 of boiling alcohol. It is miscible with ether in all proportions, and sets slightly under the elaidin test, thus differing from all other fish oils. One constituent of sperm fat is spermaceti oil (liquid sperm or whale oil). The alimentary canal and the bladder of this whale contain the highly-prized perfume known as ambergris. (g) Arctic Sperm or Dwarf Whale Oil. This product is colourless to brown, of slightly repellent smell, thin, with a specific gravity of 0'905 at 15 C. ; absorbs oxygen from the air and thickens, its specific gravity at the same time in- creasing. It contains a relatively low proportion of solid fatty acids since it remains liquid below 5 C., with merely a slight turbidity, and only below 2 C. becomes gruelly in con- sistency. It dissolves in 25 parts of cold and 2J parts of boiling alcohol, but separates out again, for the most part, on re-cooling. When treated with nitrous acid the oil exhibits a ten- dency to set. It contains only about half as much oxygen as other fish oils, and consists of : 79-87 per cent, carbon 13-36 ,, hydrogen 6'77 ,, oxygen 100-00 and, in addition to physetoleic acid, etc., about 1 per cent, of spermaceti. Doeglic acid C 19 H 35 -o-rO is a mixture of phy- 184 ANIMAL FATS AND OILS. setoleic acid and an allied acid, as is apparent from the un- even number of carbon atoms in the formula. (h) Fin-back Whale Oil, Keporkak Oil, Rorqual Oil. The oil is colourless to brown, and has a specific gravity of 0'915 to 0*920 at 15 C., according to class. It deposits a little stearine at 8 C., and thickens completely at 3 C. The dark kinds have a peculiar, highly-repellent smell. With ether it is miscible in all proportions, and the darker grades manifest the remarkable faculty of mixing with equal volumes of alcohol to form a clear solution, quickly sepa- rating, however, into oil and an alcoholic solution, 10 parts of alcohol taking up 4 vols. of the oil. If now this liquid be mixed up again it remains turbid and separates into the original volumes of oil and alcohol, the latter containing a little oil and stearine. In boiling alcohol nearly 4 parts are dissolved, and 4 vols. of the oil dissolve 1 vol. of alcohol. Fin-back oil contains : 77'05 per cent, carbon 12-05 ,, hydrogen 10-90 ,, oxygen 100-00 (i) Greenland Whale Oil. The carefully prepared oil is honey-yellow in colour, and smells and tastes like fish and tar. Specific gravity at 15 C., 0'925 to 0'927 ; a few crystals are deposited at 10 C., which increase as the temperature falls, until, at 2 C., nearly all the stearine and a little sper- maceti are down. Five vols. of the oil dissolve 1 of alcohol, and 10 vpls. of alcohol 1 of the oil, but at boiling heat 2 vols. of alcohol dissolve 5 of the oil ; it is also miscible in all proportions with ether. When heated for some time at 200 C. it decomposes and blackens. Its elementary com- position is : ANIMAL FATS AND OILS. 185 76'85 per cent, carbon 11-80 ,, hydrogen 11-35 oxygen 100-00 The whale oils are neutral when fresh but become faintly acid after a while, and behave similarly to seal oils under the influence of various reagents. Fuming nitric acid produces at first a brownish colora- tion with a very slight tendency towards blue, turning there- after brown, and finally blackish-brown. Sulphuric acid (specific gravity 1*65 to T70) colours them brown, subse- quently blackish-brown (blood colour in the case of seal oils). Nitric and sulphuric acid in equal volumes give, when mixed with an equal bulk of the oil, a yellow coloration, turning reddish and subsequently a dirty brown. Caustic soda colours all fish oils red-brown, as does also syrupy phos- phoric acid. The various whale oils, all of which deposit stearine along with a little spermaceti, near the freezing-point, are further treated for the preparation of sundry commercial grades, which are principally obtained from Norway. The pure oils, i.e., pale, brownish-yellow to brown, are known as " un- pressed whale oil " from the method of production, and are classified according to colour. When pressed below the freezing-point, two different products are obtained " whale fat " or " train tallow " and " pressed whale oils " containing no stearine. 2. Seal Oils. Raw Material, The blubber of the finned mammals, the walrus, seal, or sea cow, in the northern and southern oceans. Preparation. The carcases are brought to land and the skins removed and treated in a special manner. The blubber. 186 ANIMAL FATS AND OILS. which occurs as a more or less thick layer between the outer epidermis and the actual flesh, is then cut away as cleanly and carefully as possible, the entire sides thus obtained being placed in large recipients 9-11 yards long and nearly 9 yards wide, the bottoms of which are made of strong balks of timber, and the sides of wooden posts set very close together, the oil flowing out through the interstitial spaces. Below these vessels is a somewhat larger staunch wooden reservoir, only some 40 inches in height, for catching the escaping oil. Water is placed in the bottom, so that any leakage is de- tected without loss of oil, the water serving also to cleanse the oil from any admixture of blood. When the first-named vessel is filled with blubber up to a certain height the pres- sure of the mass begins to force out the oil, which then runs down into the reservoir below. The oil takes two or three months to all run out, but the product is divided by drawing off the oil at certain intervals and storing each lot in separate tanks, etc. The earliest runnings are pale, devoid of smell, and form the best quality, " light train oil," the quantity being some 10 per cent, of the total 60 to 70 per cent, of oil obtained. In proportion as putrefaction progresses with the length of storage, and the cellular texture is destroyed, the oil runs away more reddish-yellow in colour, the shade deepening continually by reason of the spontaneous and pro- gressive heat evolved in the mass, until finally the oil is a dark-brown, and possesses a disagreeable and repellent smell and taste, arising from the decomposition products evolved. When, after a long while, the oil ceases to run of itself, the entire s-tinking mass is shovelled out and made up in smaller heaps, the oil thereafter escaping being collected as an inferior quality. The residue still remaining is boiled in water in large iron pans along with all the fleshy and other portions that do not contain enough oil to run out spontaneously. During the boiling the oil ascends to the surface and is ANIMAL FATS AND OILS. 187 skimmed off, and the residue, when dried, makes a good manure. (a) Walrus Oil. (b) Seal Oil, Sea-dog Oil. In commerce there are two grades, the pale and the dark oil ; it is thinner than the first seal oils, has a specific gravity of 0*9250, and does not deposit stearine until 2 C. is reached. One hundred vols. of cold alcohol dissolve 1 vol. of the oil ; hot alcohol from 10 to 12 vols. ; 10 vols. of oil dissolve K vols. of alcohol. The fresh oil does not give an acid reaction. (c) Archangel Seal Oil, Sea-calf Oil. Colour pale-yellow to brown ; specific gravity at 15 C. = 0'9155 to 0'9165, the various grades having the following densities : Pale Archangel seal oil - - at 15 C. = 0-9165 Brown 25 C. = 0-9170 Sea-calf oil 15 C. = 0-9155 The product has a weak acid reaction and deposits stearine ;at 3 C. ; 100 vols. of cold alcohol dissolve J vol., and hot alcohol 8 to 9 vols. of the oil, 10 vols. of the latter taking up 1J vols. of alcohol. (d) Greenland Seal Oil. The commercial varieties have .the following densities at 15 C. : Clear pale Greenland seal oil, specific gravity - = 0'919 Clear brown ,, ,, = 0'921 - =0-924 Boiled - = 0-926 The grade known as Greenland "Three crown" oil is a mixture of various fish oils, principally seal and shark oil, the less important constituents being very small quantities of whale and walrus oils. The seal oil used for this product is the so-called " foots," i.e., the sediment obtained in the boiling and clarifying of seal oil. This forms the chief com- ponent, the shark oil thinning down the " foots," and 188 ANIMAL FATS AND OILS. imparting special properties on account of its low specific gravity. Sivedish " Three crown" oil is also a mixture of various seal oils with ordinary fish oils. Both kinds are met with adulterated with fatty vegetable oils. The specific gravity of the "Three crown" oil is 0'923. The Greenland "Three crown" oil deposits stearine below 5 C. The ratios of solu- bility in alcohol are as follows : 100 vols. of cold alcohol 1 vol. of oil, 100 vols. of hot alcohol 9 vols. of oil ; 10 vols. of oil dissolve 1 vol. of alcohol ; 10 vols. of oil require 7i- vols. of ether for their solution. (e) Newfoundland Seal Oil. The yellow, inodorous, darker and strong-smelling commercial varieties have densities of 0-927, 0-927 and 0'927, respectively, at 15 C. The setting- point is below 4 C., and the solubility ratios the same as the preceding class. (/) South Sea Seal Oil, from the long-nosed seal, sea elephant, sea lion, eared seal, or New Holland seal, is pale- yellow to brown in colour and has a specific gravity of 0'921 to 0-930 at 15 C. (g) Caspian Seal Oil. All walrus and seal oils have a disagreeable smell, that of the brown kinds, which is due to putrefaction products, being the least supportable. They contain glue but no albuminoids ; the former may be pre- cipitated by treatment with pigments and metallic salts. The specific gravity at 15 C. ranges from 0'915 to 0'930 ;. they are but slightly soluble in alcohol, and require almost their own volume of ether to effect their solution. A few already , deposit stearine below 5 C C., others set only below zero C. (at - 2 to - 3 C.) to a sold mass. When quite fresh their reaction is but faintly acid, but the percentage of acid increases with age. They contain principally glycerides of physetoleic, stearic, palmitic and (a little) oleic acid along; with small quantities of butyric acid, valeric acid, etc.. ANIMAL FATS AND OILS. 189 Light-brown Greenland oil consists of : 77-10 per cent, carbon 13-50 hydrogen 9 - 40 ,, oxygen 100-00 Fuming nitric acid gives a red-brown coloration with all seal oils. Sulphuric acid (specific gravity, 1'65-1'70) gives at first a reddish-yellow, then reddish-brown, and finally brown- red (blood-like) colour. Nitric acid and sulphuric acid equal volumes stain a reddish tinge at first, turning to brown and finally dark-brown. The tests for adulteration with other oils are directed towards other fish oils and resin oils, which can be recog- nised on the one hand by their greater solubility in alcohol, and on the other by their incomplete saponification. 3. Fish (Waste Train) Oils (Fischthrane). Eaw Material. Small fish, such as the herring, sprat, sardine, sardella, pilchard, menhaden, or the waste materials therefrom, and from smelt, salmon, silurus, sturgeon, etc. Preparation. The heads, gullets and entrails of the herring, sardine, sardella, etc., as well as the whole fish of these genera, when caught in excessive quantities and not otherwise utilisable perhaps already in a state of putre- faction are boiled with water in large iron pans, the fat collecting at the surface being skimmed off, clarified in large vats, and packed for sale ; the residue finds employment in the manufacture of fish guano. The use of sulphuric or hydrochloric acid has been found advantageous in boiling. In another process the fish are sprinkled with 5 per cent, (by weight) of a 45 Be. solution of ferric chloride or ferric sul- phate, which preserves them unaltered for four or five days ; they are then beaten to a pulp, and pressed, by which means a large quantity of water and oil is forced out. The press- 190 ANIMAL FATS AND OILS. ' cakes are easily dried, becoming friable and pulverulent, and can be pressed a second time between hot plates, or ex- tracted with volatile solvents, whereby a further quantity of oil can be recovered. Oil can also be obtained from such fish and fish waste by means of the centrifugal separator (Ger- man Patent, No. 23,974). (a) Herring oil, Swedish fish oil, Russian fish oil, Astra- chan herring oil ; (b) Sprat oil; (c) Sardine oil, Italian fish oil, Mediterranean fish oil ; (d) Pilchard oil, Spanish fish oil ; (e) Sardella oil ; (f) Menhaden oil ; (g) Salmon oil. These fish oils have a specific fishy taste and smell, and are pale yellow to brown in colour, with a specific gravity of 0-925 to 0-930 at 15 C. Near freezing-point they deposit stearine. Alcohol takes up only 2 per cent, of the oil in the cold and 3'5 per cent, in the warm, and 5 vols. of oil require 2 vols. of ether for their solution. All (waste) fish oils are browned by fuming nitric acid. Sulphuric acid of specific gravity 1*65 to 1'70 imparts a characteristic greenish colora- tion at first, turning to brown, and finally quite black. Sulphuric and nitric acid in equal volumes, mixed, produce at first a yellowish, then greenish, and subsequently brown coloration. 4. Liver Oils (Leberthrane). Baw Material. The livers of the following fish : Cod, ling, haddock, coal fish, merlangus, pollack, sea-pike, or small cod, shark (common shark, great shark, ice shark, hammer-headed shark), ray (prickly ray, smooth ray, spiny ray). Preparation. The process of preparation is not every- ANIMAL FATS AND OILS. 191 where alike, and is carried out with greater or less care, so that, naturally, the products differ both in point of colour, taste and smell. 1. After the catch the liver is cut out of the fish, collected, cleansed of blood and adherent entrails, and placed in high up- right casks fitted with three taps at th*e side and exposed to the sun. By this heat, and that developed spontaneously in the mass, a liquid is obtained resembling poppy oil, and known as " clear pale liver oil ". This product is drawn off through the two upper taps, and the contents of the cask are then weighted with stones. The oil obtained from longer stored liver is never so clear and well-flavoured as that from fresh. In the course of further spontaneous heating and the concurrent putrefaction a further quantity of oil, known as "clear brown liver oil" is obtained, and is drawn off through the bottom tap. The residue in the cask is boiled or roasted in iron pans and yields " brown liver oil ". 2. By steaming the liver a method calculated to advan- tageously replace the putrefaction process finer and more limpid oils of milder flavour and almost neutral reaction are obtained, whereas the self-run oils are always more or less decidedly acid. In the steaming process, the well-cleaned livers freed from blood and cut up small are treated with a little steam in closed vessels, whereby the tissues contract and the oil runs out. The product thus obtained is " medi- cinal (liver) oil " or " steam liver oil," and being mainly pre- pared at Bergen in Norway, is met with in commerce as " Bergen liver oil ". In the same way also " Newfoundland " and " Labrador liver oils " are prepared, these differing from the first-named only by a somewhat larger content of stearine, which begins to deposit at 7 to 5 C. The residues from the steaming process are pressed and yield a second, rather more highly-coloured oil. In the preparation of liver oil by steam the following points have to be observed : 192 ANIMAL FATS AND OILS. (1) Great care must be exercised in the selection of the liver, only perfectly sound livers but not green, reddish or blackish pieces being chosen, since the coloured kinds speci- fied are Only fit for tanners' oil. Liver that has lain for more than twelve hours in summer or twenty-four hours in winter is no longer suitable for medicinal oil. (2) Excessive cleanliness must prevail, and both the liver and the vessels must be cleansed with hot water every time. (3) The liver must not be heated above 70 C. nor exposed to that temperature for more than forty-five minutes ; the shorter the better. (4) Filtration must be very carefully performed in order to remove even the very finest solid particles from the oil. During the entire process the oil must not be exposed to the air any more than is absolutely necessary. (5) Pressing is a method employed chiefly in Scotland. The fresh liver, thoroughly cleaned and cut up small, is heated in iron pans to 80-90 C., and continually stirred until converted into a pulpy mass, which is then placed in large calico bags, filtered whilst hot, and the residue pressed in bags. At 15-16 C. the oil deposits a considerable quantity of stearine, which is removed by filtering. The well-cleaned and perfectly fresh livers are also heated along with water to 80 C. until all the oil has run out, the latter being skimmed off and filtered through flannel a second filtration following in order to remove the solid matters deposited during the interim. (a) Liver Oil. Cod-liver oil (Kabljauthran, Dorschleber- thran, Stockfischleberthran). The commercial varieties are : (a) Clear Pale Liver Oil. Colour, golden yellow ; smell characteristic, not disagreeable ; flavour fishy, not bitter ; reaction, faintly acid to litmus paper ; specific gravity, O923 ANIMAL FATS AND OILS. 193 at 15 C. ; solubility, 2'5-2'7 per cent, in cold, 3'5-4'2 per cent, in hot alcohol. (/3) Clear Brown Liver Oil. Colour, chestnut brown ; smell and taste, strong, bitter and irritating to the throat ; reaction, more strongly acid to litmus paper ; specific gravity, C'925 at 15 C. ; solubility, 2'5-3 per cent, in cold, 5-6 per cent, in hot alcohol. (7) Brown Liver Oil. Dark brown, occasionally Wackish brown in colour, greenish to bluish green by transmitted light* transparent in thin layers; peculiar, unpleasant, empyreumatic odour and bitter taste, highly irritating to the throat. The oil strongly reddens litmus paper, and has a specific gravity of 0*929 at 15 C. Alcohol dissolves 5'7-6'5 per cent, in the cold and 6*5-7 per cent, at boiling temperature ; ether dis- solves it in all proportions. Properties of Cod-liver Oil These, so far as regards colour, smell, taste and solubility, have been already detailed. The elementary composition is as follows : 75-91 per cent, carbon 12-22 hydrogen 11-87 ,, oxygen 100-00 Liver oils are mixtures of numerous glycerides : those of oleic, physetoleic, stearic and myristic acids ; and, more- over, contain free acids such as butyric, acetic, gallic acids, and gall constituents such as fellic acid, cholic acid, bilisalic acid, biliverdin, bilisulom. Among the bases present are small quantities of trimethylamine, propy- lamine, amylamine, hexylamine and a new base, hydro- toluidine, boiling at 198 to 200 C., as well as two non- volatile bases, aselline and morrhine (yellow oil 2' 5-3 per cent. ; white oil l'5-2 per cent. ; brown oil 4*5-6 per cent. of morrhine). 13 194 ANIMAL FATS AND OILS. There are likewise present, in organic combination, small quantities of chlorine, bromine, iodine, sulpho-phosphoric compounds, along with sulphatic and phosphatic salts of lime, magnesia and soda. (b) Coal-fish Oil (Saythran, Sayleberthran, Kohlfisch- thran). These oils correspond in flavour and smell with cod-liver oil. Cold alcohol dissolves 3*4 per cent., hot alcohol 6'5 per cent. The chemical composition agrees with the foregoing oil. Coal-fish oil exhibits the peculiarity of depositing solid fatty acids at 5 to 10 C., of which it contains, accord- ing to the researches of Kremel, twice as large a quantity as cod-liver oil ; although it should not be forgotten that their amount depends on the more or less careful removal of the stearin e during the preparation of the oil. The specific gravity is O925-O927 at 15 C. (c) Shark's-liver Oil (Haifischthran). The liver of the shark is very heavy, often weighing as much as 1 ton (giant shark) and yielding some 5 cwt. of oil. The colour of the oil is pale yellow and clear, and it still remains liquid when cooled to 6 C. ; its specific gravity is 0*870-0-875, or at most O880, at 15 C., a shark's-liver oil with a higher specific gravity than this being always re- garded with suspicion. The smell is peculiar, but not very repellent, like the taste, which produces an irritating after- effect. Ten vols. of cold alcohol dissolve 1 vol., hot alcohol 4 vols. ; 1 vol. of ether, 1 vol. of oil. The oil burns with a bright flame without carbonising the wick. The constituents are the same as in cod-liver oil, but in different proportion; the amount of iodine is somewhat larger. (d) Ray -liver Oil (Eochenleberthran). Colour pale or golden yellow ; taste and smell less unpleasant than in ordinary liver oil ; there is no acid reaction ; specific ANIMAL FATS AND OILS. 195 gravity at 15 C., 0'928; cold alcohol dissolves 1*5 per cent., hot alcohol 14'5 per cent., cold ether J vol., boiling ether 88 per cent. Near the freezing-point it deposits stearine ; and it contains a larger percentage of iodine than cod-liver oil. Chlorine gas produces scarcely any alteration. According to Benedikt, cod-liver oil is a highly complex mixture of small quantities of olein, physetolein, palmitin, stearine, etc., with the glyceride of a hitherto unknown fatty acid, probably belonging to the linolic acid series. It con- tains variable amounts of free fatty acids, for the saturation of which Kremel found 0'62 to 28'67 grams of calcium hydrate necessary per 1000 grams of oil. A little cholesterin (0*46 to 1'32 per cent, according to Allen and Thomson) is present and can be recovered by saponification and extrac- tion with ether, the characteristic tabular crystals of chole- sterin being obtained by recrystallising from alcohol the residue left after evaporating the ether. On the other hand, according to Jean, 6 per cent, of liver oil consists of; a pale yellow, oily, unsaponifiable mass, which is stained a beautiful red by the addition of one drop of sulphuric acid. Characteristic of this oil is its content of bile constituents,, by reason of which several colour reactions can be obtained.. The ash contains iodine, which can best be detected by saponi- fying the oil with caustic potash or soda, concentrating, calcin- ing the residue, and then testing for iodine in the ordinary manner. None of the iodine can be extracted by shak- ing up with water or alcohol, so that the intentional addition of potassium iodide to this oil can be detected by extracting with alcohol and testing the residue left on evaporating the solvent. Kremel made the examination of liver oils the subject of exhaustive study, principally with the object of finding characteristic indications for 196 ANIMAL FATS AND OILS. distinguishing cod-liver oil, Japanese oil, coal-fish oil and seal oil. As will be seen from the appended table, no reliable in- formation can be obtained from the specific gravity, iodine number or saponification value. On the other hand, coal- fish oil contains twice as large a quantity of solid fatty acids as do any of the other fish oils, which, however, may, as already mentioned, proceed from a careless separation of the stearine. Percentage of Melt- ing- Oil. Specific Liquid Solid point of the Acid Num- Saponi- fication Iodine Num- Gravity. Fatty ber. Value. ber. Acids. Fatty Acids. C. 1. Cod-liver oil, 1884 ^ _ _ _ 0-62 171 131 2 '1 3. 4. V 1883 92-12 88-88 6-72 7-55 50-5 1-41 2-06 2-23 171 189 127 126 127 5.1 2-32 v 128 6.J J 90-46 6-88 51 2-86 179 131 7. ,, 5 years old 0-922 1-47 178 140 8. 10 to 28-67 9. 10 0-927 _ 5-03 129 10.) 9-60 48-49 9-59 173 139 11. 'Clear pale me- 11-29 174 138 12. dicinal liver oil 11*57 173 141 13. 92-72 5-25 52 8-66 181 14. ! Cod-liver oilsfrom 87-00 12-75 51-52 6-78 181 135 15. ! 1883 and 1884 J 10-46 136 MX 0-925 75-32 19-04 55-56 1-26 177 137 17. 0-926 12-22 53 1-23 177 137 18. '.Coal-fish oils, 1883 1-29 179 129 19. f 0-925 74-20 20-60 1-49 181 126 20. J 0-927 70-00 21-34 52 1-68 181 123 21. Japanese liver oil 0-908 87-60 10-52 50-51 120 23' | Seal oils, 1883 0-925 0-925 85-20 88-29 10-23 9-80 57-5 57 1-95 2-01 178 179 127 128 The melting-point of the solid fatty acids is higher in seal oil than in the other kinds. ANIMAL FATS AND OILS. 197 According to Mayer, a liver oil is pure if, when shaken up with one-tenth of its bulk of nitro-sulphuric acid (1:1), it gives a coloration bright red at first but quickly turning to citron yellow, since in the other fish oils the transition is either not so clean or else a brownish-violet coloration is produced. Kossler agitates with aqua regia, with which pure cod- liver oil forms a greenish dark-yellow liniment, turning a permanent brown after half an hour, whereas white seal oil or a mixture thereof with cod-liver oil gives a faintly yellow liquid under this test. Kremel found the behaviour of the oil in presence of fuming nitric acid (specific gravity 1*50) a far more suit- able means of identification. If 10 or 12 drops of the sample be placed on a watch glass and 3 to 5 drops of nitric acid run in from one side, the following changes are. observed : Pure cod-liver oil becomes red at the plane of contact of the liquids, turning to bright red on stirring, but quickly changing into a pure yellow. Coal-fish oil becomes intensely blue at the point of influx, the colour changing to brown on stirring, and remaining so for two or three hours, to finally become black. Japanese fish oil behaves like the last named except that red streaks often accompany the blue. Seal oil is unaltered at first, and turns brown only after some time. The nitric acid reaction is so characteristic that the adulterations named can be detected easily in quantities from 25 per cent, downwards. The adulteration of -the oil with non-drying fatty oils can be detected by the iodine number, which is in these fish oils unusually high. Drying oils may be recognised by spreading a sample out 198 ANIMAL FATS AND OILS. thinly on the surface of a glass plate, in that the fish oils, although they oxidise very quickly, form no solid skin. If 1 part of fish oil be stirred up thoroughly with 2 parts of concentrated sulphuric acid in a tall glass, the mixture will be clear only in case no foreign fats are present. Testing Fish Oils. The better classes of fish oils are for the most part only adulterated with similar oils of low quality, falsification with other oils being practised on the medicinal oils only. In testing, regard must be paid to the specific gravity. Shark oil is the lightest, the specific gravity being 0'870 to O875 at 15 C.; next follow the whale (blubber) oils, 0-9100 to 0-925; the seal oils, 0'915 to 0'930 ; the liver oils, 0-920 to 0-950 ; and the fish (waste) oils, 0'925 to 0'930. These particulars refer only to the pale and clear brown oils, the darker sorts averaging about 0*005 more. A further guide to a decision is afforded by the varying solubility in alcohol. Seal and whale oils are very readily soluble (the former up to 15 per cent.) in hot alcohol, so that more than 1 vol. of oil dissolves in 1 vol. of alcohol, whereas liver oils dissolve only up to 6 or 7 per cent., and fish (waste) oils only to 4 per cent. By solution in alcohol the presence of resin and mineral oils can be detected at the same time (being charac- terised by their ready solubility in alcohol), but they require, however, to be confirmed by the saponification test, being themselves unsaponifiable. The addition of resin may also be proved by agitation in cold alcohol. For the identification of pure cod-liver oil, 10 parts of oil must, according to Mayer, be shaken up with one part of a mixture (1 : 1) of sulphuric and nitric acids, in a stoppered flask, whereupon pure cod-liver oil becomes a brilliant red, quickly changing to citron yellow, whilst other fish oils do not exhibit the transition into yellow so cleanly, but become more of a brownish violet. On agitating fish oil with con- ANIMAL FATS AND OILS. 199 centrated aqua regia, a greenish dark yellow liniment forms in the case of pure cod-liver oil, which changes in half an hour to a persistent brown, whereas white seal oil or a mix- ture of same with pure oil forms merely a pale yellow, faintly tinged mixture. The behaviour of the various grades in presence of fuming nitric acid of specific gravity 1'50 affords a better means for their identification. If 10 to 15 drops of the oil to be tested be placed on a watch glass, and 3 to 5 drops of the fuming acid be run in from the one side, the various fish oils behave as follows : Pure cod-liver oil turns red at the place of contact, the colour becoming a brilliant red on stirring up with a glass rod, but changing in a short time to pure citron yellow. Coal-fish oil becomes an intense blue at the point of con- tact (as in the reaction of biliary colouring matter with con- centrated sulphuric acid), changing to brown when stirred. This coloration persists for two or three hours, to finally pass over into a more or less pure yellow. Japanese fish oil behaves similarly, but oftentimes the blue coloration is accompanied by red streaks. Seal oil gives no colour reaction at the outset, and* is coloured brown only after some time. According to Salkowsky, the adulteration of liver oils w T ith vegetable oils can be recognised by the following methods : The Setting-Point and Melting -Point. The first of these is fairly low in fish oils, but the individual kinds vary con- siderably among themselves, owing to the removal of the solid portions in some by cooling. The time of the operation is also of importance, it being feasible in a few cases only, viz., palm oil, cocoanut oil, palm-kernel oil, when something like 20 per cent, is present, to detect them by the rapid setting of the liver oil. The Eeichert-Meissl number was found for liver oils after deduction of the correction 0*2 (O'l to 0'2 for the indicator 200 ANIMAL FATS AND OILS. per 5 grams). For the majority of the fatty oils few higher numbers were obtained ; only for cocoanut oil and palm- kernel oil were the numbers 7'38 and 3*48 found. Only these two oils would therefore be detectable with any degree of probability in fish oil, and then only when in large quantity. Estimation of the phytosterin content. The test is prefer- ably applied in two forms, in that on the one hand sulphuric acid is run direct into the oil in a watch glass, and, on the other, a few drops of the oil are dissolved in chloroform and then shaken up with the acid. A blue coloration ensues, the cause being attributable, not to the 0'3 per cent, of chole- sterin. nor to any biliary colouring matter present, but rather to a pigment known as lipochrome. The cholesterin of liver oil is not identical with that obtained from vegetable oils, the latter agreeing with phyto- sterin. Cholesterin sets to a pulp of laminated crystals, phytosterin to fascicular groups of solid needles. The melt- ing-point of the latter is about 132 to 134 C., that of cholesterin being 146 C. These differences are sufficiently characteristic to enable vegetable fats to be detected in liver oil. If 10 grams of liver oil be saponified with 10 grams of caustic potash and a little alcohol, then diluted with water to a 600-700 c.c. solution, shaken up with 500 c.c. of ether, and the ethereal extract filtered, evaporated and purified, if necessary, by a second saponification, the cholesterin will be obtained in a nearly pure state. That from pure liver oil will have a melting-point of 146 C., whilst that from oil containing 20 per cent, of vegetable oils will melt at 139 - 140 C. The microscopical examination of the cholesterin affords another means of detecting adulteration. The percentage of free fatty acids in good liver oils is very small, about 0*25 to 0*69 per cent., whilst most of the commercial vegetable oils contain larger quantities. ANIMAL FATS AND OILS. 201 The method proposed by Salkowsky for estimating the volatile fatty acids insoluble in water is rather cumbrous and uncertain in its results and is therefore not very suitable for use in practice. Whereas liver oil contains, according to Allen and Thom- son, 0'46 to 1-32 per cent, or, according to Salkowsky, only 0'3 per cent, of cholesterin, Jean found therein 6 per cent, of an oily, unsaponifiable substance, which gives a beautiful red coloration with a drop of sulphuric acid. In order to test the accuracy of these reports Fahrion determined the chole- sterin in thirty samples of fish oils, by Honig and Spitz's method. Of these, fourteen contained less than 1 per cent., eleven between 1 and 2 per cent., three between 2 and 3 per cent., and only two shark oils more than 3 per cent, of un- saponifiable matter. Shark oils are classed on the one hand with the liquid waxes, and on the other with the liver oils, the numbers obtained speaking more in favour of the latter assumption. In the case of cod-liver oils the darker sorts, as a rule, contain more cholesterin than the lighter grades. This may result from the method of preparation, the lighter qualities being obtained by cold, and the darker by the subsequent warm pressing. From the figures obtained it is permissible to conclude that the cholesterin content (6 per cent.) re- ported by Jean is quite possible. Duliere examined various liver oils and found the values given in the French Pharmacopoeia to be too low ; there the specific gravity is given as 0'920-0'922, whereas he found it to be 0-9271 at 15 C. Oil prepared from fresh livers should not redden blue litmus paper. Contrary to the views of various investigators, Duliere was unable to discover any alkaloids in perfectly fresh liver oils or in the white com- mercial oils. The iodine numbers of liver oils freshly pre- pared by the author, as well as those of good commercial 202 ANIMAL FATS AND OILS. grades, approximate very closely, and range from 144 to 151; the Indian and similar oils have iodine numbers varying between 116 and 138' 74, and that of Japanese oil is still lower, viz., 98*74. According to Duliere the saponification value of a good liver oil is between 19'48 and 21'61. ARTIFICIAL TRAIN OIL AND ITS PREPARATION. By artificial train oil is understood a dark-coloured pro- duct prepared from resin oil and extensively circulated in commerce under the name of " lion train oil " (Lowenthran). It plays an important part in chemical industries on the small scale. The pale train oils, commercially known as fish oils are as a rule pure, or at most adulterated, being rarely exclusively artificial products. The dark oil is, as already mentioned, chiefly a resin product. Although low quality materials alone are used for its production, the preparation is particularly difficult owing to the very particular requirements exacted b}^ consumers. The criteria of the quality of artificial train oil are colour, smell, viscosity, and feel, as well, of course, as deceptive appearance, it being necessary for the colour to be deep black, without fluorescence, by reflected light and reddish brown in thin layers by transmitted light. The oil must be perfectly clear and of at least the consistency of syrup. When rubbed between the fingers it should not exhibit any great degree of slipperiness, although not sticky, such as happens when, e.g., Vulcan oil is present. It is a decidedly difficult matter to produce from the materials at disposal (in Germany) an artificial train oil that can fulfil the above requirements and be sold at the low prices brought about by foreign competition. The chief material employed is the so-called resin stock oil, which in correspondence with the properties of the pro- ANIMAL FATS AND OILS. 208 duct, should be very thick and have the least possible smell and bloom. The paler and clearer the stock oil the better it is adapted for the purpose in view, a turbid and consequently darker resin oil being much less suitable. The next constituent in point of importance is " blue oil," the quality of which is an even more particular matter than that of the resin oil. The specially strong smell and fluorescence characteristic of Galician " blue oil " are gener- ally so difficult to remove or mask, that here already the fundamental causes of bad quality in the final product are to be sought. Unimportant as raw materials are the nitric acid and molasses, by means of which nearly all " lion train oils " are prepared. 2 parts of resin oil are mixed with 1 part of "blue oil " (the proportions are varied according to the degree of viscosity desired), a fairly concentrated nitric acid being then added which de-blooms the mixture probably by the forma- tion of nitro compounds from the hydrocarbons of the resin oil, and moreover deodorises and darkens the product, 1*5 to 2 per cent, of acid being sufficient to effect these objects so far as is possible with these raw materials. The smell of resin oil in particular does not entirely vanish, but this does not matter much, as in the finished product it will resemble train oil. The addition of 2-4 per cent, of molasses helps both the colour, and more particularly the masking of the smell. During the entire process the temperature in the pan inst Spontaneous Ignition of Coal. Precautions for Preventing Explosions of Fire-damp and Coal Dust. Employment of Electricity in Mining, particularly in Fiery Pits. Experiments on the Ignition of Fire-damp Mixtures and Clouds or Coal Dust by Electricity. III., Indica- tions of an Existing or Incipient Fire. IV., Appliances for Working in Irrespirable Gases : 1, Respiratory Apparatus; 2, Apparatus with Air Supply Pipes, (a) The Bremen Smoke Helmet, (b) The Miiller Smoke Helmet, (c) The Stolz Rescue Mask; 3, Reservoir Apparatus; 4, Oxygen Apparatus. The Schwann Respiratory Apparatus. The Fleuss Respiratory Ap- paratus. The Improved Walcher-Giirtner Pneumatophor, (a) The Single Bottle Apparatus, Instructions for Using the Pneumatophor, Taking to Pieces and Resetting the Apparatus ready for Use ; (b) Two Bottle Apparatus (Shamrock Type). The Neupert Rescue Apparatus (a) Cross-dams of Clay ; (b) Masonry Dams, Gallery Linings. Wagner's Portable Safety Dam. Analyses of Fire Gases. Isolating the Seat of a Fire with Dams: Working in Irrespirable Gases ("Gas-diving ") : 1, Air-Lock Work (Horizontal Advance) on the Mayer System as Pur- sued at Karwin in 1894 ; 2, Air-Lock Work (Horizontal Advance) by the Mauerhofer Modified System. Vertical Advance. Mayer System. Complete Isolation of the Pit. Flooding a 30 Burning Section isolated by means of Dams. Wooden Dams: (a) Upright Balk Dams; (b) Horizontal Balk Dams ; (c) Wedge Dams, Masonry Dams. Examples of Cylindrical and Dome- shaped Dams. Dam Doors: Flooding the Whole Pit. VI., Rescue Stations: (a) Stations above Ground; (b) Underground Rescue Stations. VII., Spontaneous Ignition of Coal in Bulk. Index. Illustrations. Sheet I., Respiratory and Rescue Appliances Precautions against Fire. Sheet II., Respiratory and Rescue Apparatus. Sheet III., Respiratory and Rescue Ap = paratus- Stretchers. Sheet IV., Dams. Sheet V., Signalling Appliances Dam Construction Cable Laying. Sheet VI., Working with Diving Gear in Irrespirable Gases Gallery Work. Sheet VII., Working with Diving Gear in Irrespirable Gases (Mayer System) Appliances in the Shaft. Press Opinions. "A work of this extremely valuable character deserves to be made widely known amongst colliery managers and mining engineers at home and abroad." Coal and Iron. "This book is, in a manner, unique. The literature of mining accidents is fairly extensive, but it consists largely of departmental Blue Books." Sheffield Daily Telegraph, "A concise and lucid description of the principal methods pursued, especially in fiery mines, and of the various appliances employed, such as respiratory and rescue apparatus, dams, etc." Staffs Advertiser. "The prevention of spontaneous combustion in collieries and the extinction of underground fires are duties that fall heavily on many colliery managers. They should, therefore, welcome this translation of Mr. Lamprecht's German treatise." Ironmonger. THE PREVENTION OF SMOKE. Combined with the Economical Combustion of Fuel. By W. C. POPPLEWELL, M.Sc., A.M.Inst., C.E., Consulting Engineer. Forty-six Illustrations. 190pp. 1901. Demy 8vo. Price 7s. 6d. ; India and Colonies, 8s. ; Other Countries, 8s. 6d. ; strictly net. Contents. Introductory. Chapters I., Fuel and Combustion. II., Hand Firing in Boiler Furnaces. III., Stoking by Mechanical Means. IV., Powdered Fuel. V., Gaseous Fuel. VI., Efficiency and Smoke Tests of Boilers. VII., Some Standard Smoke Trials. VIII., The Legal Aspect of the Smoke Question. IX., The Best Means to be adopted for the Prevention of Smoke. Index. Press Opinions. " Everybody interested in smoke prevention will derive the greatest benefit from Mr. Popplewell's treatise, and will learn much that is new to them." Public Health Engineer. "The Manchester expert who writes this book is thoroughly equipped for the task, and he has produced a work which ought to be in the hands of all Sanitary Inspectors and Health Committees, and it would be a useful present from manufacturers to stokers, instead of pos- sibly spending the value of the volume in payment of fines." Sheffield Independent. GAS AND COAL DUST FIRING. A Critical Review of the Various Appliances Patented in Germany for this purpose since 1885. By ALBERT PUTSCH. 130 pp. Demy 8vo. 1901. Translated from the German. With 103 Illustrations. Price 7s. 6d. ; India and Colonies, 8s. ; Other Countries, 8s. 6d. ; strictly net. Contents. Generators Generators Employing Steam Stirring and Feed Regulating Appliances Direct Generators Burners Regenerators and Recuperators Glass Smelting Furnaces Metallurgical Furnaces Pottery Furnace Coal Dust Firing. Index. Press Opinions. " The work is worthy of perusal by all consumers of fuel. It is exceedingly well printed and illustrated." Chemical Trade Journal. " The book will appeal with force to the manufacturer as well as to the technical student, whilst it is also of far more than average interest to the general reader." Halifax Guardian. "The importance that gas and coal dust firing have attained of recent years, and especially the great interest attaching of late to the question of coal dust firing, makes the appearance of the present volume most opportune." Iron and Coal Trades Review. Books on Plumbing, Decorating, Metal Work, etc., etc. EXTERNAL PLUMBING WORK. A Treatise on Lead Work for 'Roofs. By JOHN W. HART, R.P.C. 180 Illustrations. 270 pp. Demy 8vo. Second Edition Revised. 1902. Price 7s. 6d. ; India and Colonies, 8s. ; Other Countries, 8s. 6d. strictly net. 31 Contents. Chapters I., Cast Sheet Lead. II., Milled Sheet Lead. III., Root Cesspools. IV., Socket pjpes.V., Drips. VI., Gutters. VII., Gutters (continued). VIII., Breaks. IX., Circular Breaks. X., Flats. XL, Flats (continued). XI L, Rolls on Flats. XI1L, Roll Ends. XIV., Roll Intersections. XV., Seam Rolls. XVI., Seam Rolls (continued). XVII., Tack Fixings. XVIIL, Step Flashings. XIX., Step Flashings (continued). XX., Secret Gutters. XXI.,, Soakers. XXIL, Hip and Valley Soakers. XXI II., Dormer Windows. XXIV., Dormer Windows (continued). XXV., Dormer Tops. XXVI., Internal Dormers. XXVII., Skylights. XXVIII., Hips and Ridging. XXIX., Hips and Ridging (continued). XXX., Fixings for Hips and Ridging. XXXI., Ornamental Ridging. XXXIL, Ornamental Curb Rolls. XXXIII.,. Curb Rolls. XXXIV., Cornices. XXXV., Towers and Finials. XXXVI., Towers and Finials (continued). XXXVI L.Towers and Finials (continued). XXXVIII., Domes. XXXIX., Domes (continued). XL., Ornamental Lead Work. XLL, Rain Water Heads. XLIL, Rain Water Heads (continued). XLIIL, Rain Water Heads (continued). Press Opinions. "This is an eminently practical and well-illustrated volume on the management of external lead work." Birmingham Daily Post. " It is thoroughly practical, containing many valuable hints, and cannot fail to be of great benefit to those who have not had large experience." Sanitary Journal. "Works on sanitary plumbing are by no means rare, but treatises dealing with external plumbing work are sufficiently scarce to ensure for Mr. Hart's new publication a hearty recep- tion." I'he Ironmonger. HINTS TO PLUMBERS ON JOINT WIPING, PIPE BENDING AND LEAD BURNING. Third Edition, Revised and Corrected. By JOHN W. HART, R.P.C. 184 Illustrations. 313 pp. Demy 8vo. 1901. Price 7s. 6d. ; India and Colonies, 8s.; Other Countries, 8s. 6d. ; strictly net. Contents. Introduction. C apters I., Pipe Bending. II., Pipe Bending (continued). III., Pipe Pending (continued). IV., Square Pipe Bendings, V., Half-circular Elbows. VI., Curved Bends on Square Pipe. VII., Bossed Bends. VIII., Curved Plinth Bends. IX., Rain-water Shoes on Square Pipe. X., Curved and Angle Bends. XL, Square Pipe Fixings. XII., Joint- wiping. XIII., Substitutes for Wiped Joints. XIV., Preparing Wiped Joints. XV., Joint Fixings. XVI., Plumbing Irons. XVII., Joint Fixings. XVIIL, Use of "Touch" in Solder- ing. XIX., Underhand Joints. XX., Blown and Copper Bit Joints. XXL, Branch Joints. XXIL, Branch Joints (continued). XXIII. , Block Joints. XXIV., Block Joints (continued). XXV., Block Fixings. XXVI. , Astragal Joints Pipe Fixings. XXVI L, Large Branch Joints. XXVII I. , Large Underhand Joints. XXIX., Solders. XXX., Autogenous Soldering or Lead Burning. Index. Press Opinions. " Rich in useful diagrams as well as in hints." Liverpool Mercury. "The papers are eminently practical, and go much farther into the mysteries they describe than the title ' Hints' properly suggests." Scotsman. " The articles are apparently written by a thoroughly practical man. As a practical guide the book will doubtless be of much service." Glasgow Herald. " So far as the practical hints in this work are concerned, it will be useful to apprentices and students in technical schools, as it deals mainly with the most important or difficult branches- of the plumber's craft, viz., joint wiping, pipe bending and lead burning. . . . 'Hints' are the most useful things to an apprentice, and there are many in this work which are not to be found in some of the text-books." English Mechanic. "22 PRYHE STREET, HULL, 24th November, 1894. " Gentlemen, Your books to hand for which accept my best thanks, also for circulars. I myself got one of J. W. Hart's books on Plumbing from your traveller, and having looked through the same I can safely recommend it as being the best book I have seen. Mr. J. W. Hart treats exhaustively upon soldering and pipe bending, which are two of the most essential branches in the plumbing trade." THE PRINCIPLES AND PRACTICE OP DIPPING, BURNISHING, LACQUERING AND BRONZING BRASS WARE. By W. NORMAN BROWN. 35 pp. Crown 8vo. 1900. Price 2s. ; Abroad, 2s. 6d. ; strictly net. Contents. Chapters L, Cleansing and Dipping; Boiling up and Cleansing; Dipping. II., Scratch- brushing and Burnishing; Polishing; Burnishing. III., Lacquering; Tools; Lacquers. IV., Bronzing ; Black Bronzing ; Florentine Red Bronzing ; Green Bronzing. Index. Press Opinions. " Mr. Brown is clearly a master of his craft, and has also the immense advantage of being able to convey his instructions in a manner at once clear and concise." Leicester Post. "A thoroughly practical little treatise on the subject in all its branches, and one which should be in the hands of every tradesman or amateur who has lacquering to do." Irish Builder* 32 WORKSHOP WRINKLES for Decorators, Painters, Paper- hangers and Others. By W. N. BROWN. Crown 8vo. 128 pp. 1901. Price 2s. 6d. ; Abroad, 3s. ; strictly net. Contents. Parts I., Decorating. II., Painting. III., Paper-hanging. IV., Miscellaneous. Arranged in alphabetical order. Press Opinion. "Decorators, painters and amateurs -will find this a comprehensive work of reference on nearly every subject they are in need of.' Building News. HOUSE DECORATING AND PAINTING. By W. NORMAN BROWN. Eighty-eight Illustrations. 150 pp. Crown 8vo. 1900. Price 3s. 6d. ; India and Colonies, 4s. ; Other Countries, 4s. 6d. strictly net. Contents. Chapters 1., Tools and Appliances. II., Colours and Their Harmony. III., Pigments and Media. IV., Pigments and Media. V., Pigments and Media. VI., Pigments and Media. VII., Preparation of Work, etc. VIII., Application of Ordinary Colour. IX., Graining. X., Graining. XI., Graining. XII., Gilding. XIII., Writing and Lettering. XIV., Sign .Painting. XV., Internal Decoration. Index. Press Opinion. "The author is evidently very thoroughly at home in regard to the technical subjects he has set himself to elucidate, from the mechanical rather than the artistic point of view, although the matter of correctness of taste is by no means ignored. Mr. Brown's style is directness itself, and there is no tyro in the painting trade, however mentally ungifted, who could fail to carry away a clearer grasp of the details of the subject after going over the performance." .Building Industries. A HISTORY OF DECORATIVE ART. By W. NORMAN BROWN. Thirty-nine Illustrations. 96pp. Crown b\o. 1900. Price 2s. 6d. ; Abroad, 3s. ; strictly net. Contents. Chapters I., Primitive and Prenistoric Art. II., Egyptian Art. III., Assyrian Art. IV., The Art of Asia Minor. V., Etruscan Art. VI., Greek Art. VII., Roman Art. VIII., Byzantine Art. IX., Lombard or Romanesque Art. X., Gothic Art. XI., Renaissance Art. XII., The Victorian Period. Index. Press Opinion. "In the course of a hundred pages with some forty illustrations Mr. Brown gives a very interesting and comprehensive survey of the progress and development of decorative art. It cannot, of course, be pretended that in the limited space named the subject is treated ex- haustively and in full detail, but it is sufficiently complete to satisfy any ordinary reader ; indeed, for general purposes, it is, perhaps, more acceptable than a more elaborate treatise." Midland Counties Herald. A HANDBOOK ON JAPANNING AND ENAMELLING FOR CYCLES, BEDSTEADS, TINWARE, ETC. By WILLIAM NORMAN BROWN. 52 pp. and Illustrations. Crown 8vo. 1901. Price 2s. ; Abroad, 2s. 6d. ; net. Contents. A Few Words on Enamelling Appliances and Apparatus Japans or Enamels To Test Enamel for Lead Japanning or Enamelling Metals Japanning Tin, such as Tea Trays, and similar Goods Enamelling Old Work Enamel for Cast Iron Enamel for Copper Cooking Utensils The Enamelling Stove Enamelling Bedsteads, Frames and similar large pieces Paints and Varnishes for Metallic Surfaces Varnishes for Ironwork Blacking for Iron Processes for Tin Plating Galvanising Metal Polishes Colours for Polished Brass A Golden Varnish for Metal Painting on Zinc Carriage Varnish Japanese Varnish and its .Application. Index , THE PRINCIPLES OF HOT WATER SUPPLY. By JOHN W. HART, R.P.C. With 129 Illustrations. 1900. 177 pp., demy 8vo. Price 7s. 6d. ; India and Colonies, 8s. ; Other Countries, 8s. 6d. ; strictly net. Contents. Chapters I., Water Circulation. II., The Tank System. III., Pipes and Joints. IV., The Cylinder System. V., Boilers for the Cylinder System. VI., The Cylinder System. VII., The Combined Tank and Cylinder System. VIII., Combined Independent and Kitchen Boiler. IX., Combined Cylinder and Tank System with Duplicate Boilers. X., Indirect Heating and Boiler Explosions. XL, Pipe Boilers XII., Safety Valves. XIIL, Safety Valves. XIV., The American System. XV., Heating Water by Steam. XVI., Steam Kettles and Jets. XVII., Heating Power of Steam. XVIII., Covering for Hot Water Pipes. Index. 33 Brewing and Botanical. HOPS IN THEIR BOTANICAL, AGRICULTURAL AND TECHNICAL ASPECT, AND AS AN ARTICLE OF COMMERCE. By EMMANUEL GROSS, Professor at the Higher Agricultural College, Tetschen-Liebwerd. Translated from the German. Seventy-eight Illustrations. 1900. 340 pp. Demy 8vo. Price 12s. 6d. ; India and Colonies, 13s. 6d. ; Other Countries, 15s. ; strictly net. Contents. PART I., HISTORY OF THE HOP. i ' PART II., THE HOP PLANT. Introductory. The Roots. The Stem and Leaves. Inflorescence and Flower: Inflorescence and Flower of the Male Hop; Inflorescence and Flower of the Female Hop. The Fruit and its Glandular Structure : The Fruit and Seed. Propagation and Selection of the Hop. Varieties of the Hop: (a) Red Hops; (b) Green Hops ; ^c) Pale Green Hops. Classification according to the Period of Ripening: 1. Early August Hops; 2. Medium Early Hops; 3. Late Hops. Injuries to Growth: Malformations; Diseases Produced by Conditions of Soil and Climate: 1. Leaves Turning Yellow, 2. Summer or Sun- brand, 3. Cones Dropping Off, 4. Honey Dew, 5. Damage from Wind, Hail and Rain ; Vegetable Enemies of the Hop: Animal Enemies of the Hop. Beneficial Insects on Hops. PART III., CULTIVATION. The Requirements of the Hop in Respect of Climate, Soil and Situation : Climate ; Soil ; Situation. Selection of Variety and Cuttings. Planting a Hop Garden : Drainage ; Preparing the Ground ; Marking-out for Planting ; Planting ; Cultivation and Cropping of the Hop Garden in the First Year. Work to be Performed Annually in the Hop Garden: Working the Ground; Cutting; The Non-cutting System; The Proper Per- formance of the Operation of Cutting: I. Method of Cutting : Close Cutting, Ordinary Cutting, The Long Cut, The Topping Cut; II. Proper Season for Cutting: Autumn Cutting, Spring Cutting; Manuring; Training the Hop Plant: Poled Gardens, Frame Training; Principal Types of Frames ; Pruning, Cropping, Topping, and Leaf Stripping the Hop Plant ; Picking, Drying and Bagging. Principal and Subsidiary Utilisation of Hops and Hop Gardens. Life of a Hop Garden ; Subsequent Cropping. Cost of Production, Yield and Selling Prices. PART IV. Preservation and Storage. Physical and Chemical Structure of the Hop Cone. Judging the Value of Hops. PART V. Statistics of Production. The Hop Trade. Index. Press Opinions. " The subject is dealt with fully in every little detail ; consequently, even the veriest tyro can take away some useful information from its pages." Irish Farming World. " Like an oasis in the desert comes a volume upon the above subject." Hereford Times. "This is, in our opinion, the most scholarly and exhaustive treatise on the subject of hops that has been published." Brewers' Journal. Wood Waste Utilisation. THE UTILISATION OP WOOD WASTE. Translated from the German of ERNST HUBBARD. Crown 8vo. 1902. Fifty Illustra- tions. Price 5s. ; India and Colonies, 5s. 6d. ; Other Countries, 6s. net. Contents. Chapters I., General Remarks on the Utilisation of Sawdust. II., Employment of Saw- dust as Fuel, with and without Simultaneous Recovery of Charcoal and the Products of Distillation. III., Manufacture of Oxalic Acid from Sawdust (1) Process with Soda Lye; (2) Thorn's Process ; (3) Bohlig's Process. IV., Manufacture of Spirit (Ethyl Alcohol) from Wood Waste Patent Dyes (Organic Sulphides, Sulphur Dyes, or Mercapto Dyes). V., Artificial Wood and Plastic Compositions from Sawdust Production of Artificial Wood Compositions for Moulded Decorations. VI., Employment of Sawdust for Blasting Powders and Gunpowders. VII., Employment of Sawdust for Briquettes Employment of Sawdust in the Ceramic Industry and as an Addition to Mortar Manufasture of Paper Pulp from Wood Casks. VIII., Various Applications of Sawdust and Wood Refuse Calcium Carbide Manure Wood Mosaic Plaques Bottle Stoppers Parquetry Fire-lighters Carborun- dum. IX., The Production of Wood Wool Bark. Index 34 Foods and Sweetmeats. THE MANUFACTURE OF PRESERVED FOODS AND SWEETMEATS: A Handbook of all the Processes for the Preservation of Flesh, Fruit and Vegetables, and for the Prepara- tion of Dried Fruit, Dried Vegetables, Marmalades, Fruit-Syrups and Fermented Beverages, and of all kinds of Candies, Candied Fruit, Sweetmeats, Rocks, Drops, Dragees, Pralines, etc. By A. HAUSNER. With Twenty-eight Illustrations. Translated from the German of the third enlarged Edition. Crown 8vo. 225 pp. 1902. Price 7s. 6d. ; India and Colonies, 8s. ; Other Countries, 8s. 6d. net. Contents. Part I., The Manufacture of Conserves. Chapters I., Introduction. II., The Causes of the Putrefaction of Food. III., The Chemical Composition of Foods. IV., The Products of Decomposition. V., The Causes of Fermentation and Putrefaction. VI., Preservative Bodies. VII., The Various Methods of Preserving Food. VIII., The Preservation of Animal Food. IX., Preserving Meat by Means of Ice. X., The Preservation of Meat by Charcoal. XI., Preservation of Meat by Drying. XII., The Preservation of Meat by the Exclusion of Air. XIII., The Appert Method. XIV., Preserving Flesh by Smoking. XV., Quick Smoking. XVI., Preserving Meat with Salt. XVII., Quick Salting by Air Pressure. XVIII., Quick Salting by Liquid Pressure. XIX., Gamgee's Method of Preserving Meat. XX., The Preservation of Eggs. XXI., Preservation of White and Yolk of Egg. XXII., Milk Preservation. XXIII., Condensed Milk. XXIV., The Preservation of Fat. XXV., Manufacture of Soup Tablets. XXVI. Meat Biscuits. XXVII., Extract of Beef. XXVIII., The Preservation of Vegetable Foods in General. XXIX. Compressing Vegetables. XXX., Preservation of Vegetables by Appert's Method. XXXI., The Preservation of Fruit. XXXII., Preservation of Fruit by Storage. XXXIII , The Preservation of Fruit by Drying. XXXIV., Drying Fruit by Artificial Heat. XXXV., Roasting Fruit. XXXVI., The Preservation of Fruit with Sugar. XXXVII., Boiled Preserved Fruit. XXXVIII., The Preservation of Fruit in Spirit, Acetic Acid or Glycerine. XXXIX., Preservation of Fruit without Boiling. XL., Jam Manufacture. XLI., The Manufacture of Fruit Jellies. XLII., The Making of Gelatine Jellies. XLIII., The Manufacture of "Sulzen." XLIV., The Preservation of Fermented Beverages. Part II., The Manufacture of Candies. Chapters XLV., Introduction. XLVI., The Manufacture of Candied Fruit. XLVII., The Manufacture of Boiled Sugar and Caramel. XLVIIL, The Candying of Fruit. XLIX., Caramelised Fruit. L., The Manufacture of Sugar- Sticks, or Barley Sugar. LI., Bonbon Making. LIL, Fruit Drops. LIII., The Manufacture of Dragees. LIV., The Machinery and Appliances used in Candy Manufacture. LV., Dyeing Candies and Bonbons. LVI., Essential Oils used in Candy Making. LVII., Fruit Essences. LVIII., The Manufacture of Filled Bonbons, Liqueur Bonbons and Stamped Lozenges. LIX., Recipes for Jams and Jellies. LX., Recipes for Bonbon Making. LXI., Dragdes. Appendix. Index. Timber Trades. TIMBER : A Comprehensive Study of Wood in all its Aspects (Commercial and Botanical), showing the Different Applications and Uses of Timber in Various Trades, etc. Translated from the French of PAUL CHARPENTIER, Expert Chemical Engineer, Assayer of the French Mint, etc., by JOSEPH KENNELL. Royal 8vo. 437 pp. 178 Illustrations. 1902. Price 12s. 6d. ; India and Colonies, 13s. 6d. ; Other Countries, 15s. net. Contents. Preface. Part I., Physical and Chemical Properties of Timber. Chapters I., Com- position of the Vegetable Bodies Chief Elements M. Fremy's Researches. II., Elementary Organs of Plants and especially of Forests. III., Different Parts of Wood Anatomically and Chemically Considered. IV., General Properties of Wood. Part II., Description of the Different Kinds of Wood. Chapters V., Principal Essences with Caducous Leaves. VI., Coniferous Resinous Trees. Part III., Division of the Useful Varieties of Timber in the Different Countries of the Globe. Chapters VII., European Timber. VIII., African Timber. IX., Asiatic Timber X., American Timber. XL, Timber of Oceania. Part IV., Forests. Chapters XII., General Notes as to Forests ; their Influence. XIII. Opinions as to Sylviculture Improvement of Forests. XIV., Unwooding and Rewooding Preservation of Forests. XV., Exploitation of Forests. XVI., Damage caused to Forests Different Alterations. Part V., The Preservation of Timber. Chapters XVII., Generalities Causes and Progress of Deterioration History of Different Proposed Processes. XVIII., Dessication Superficial Carbonisation of Timber. XIX., Processes by Immersion Generalities as to 35 Antiseptics Employed. XX., Injection Processes in Closed Vessels. XXI., The Boucherie System, Based upon the Displacement of the Sap. XXII., Processes for Making Timber Uninflammable. Part VI., Applications of Timber. Chapters XXIII., Generalities Working Timber- Paving Timber for Mines Railway Traverses. XXIV., Accessory Products Gums Works of M. Fremy Resins Barks Tan Application of Cork. XXV., The Application of Wood to Art and Dyeing. XXVI., Different Applications of Wood Hard Wood Distillation of Wood Pyroligneous Acid Oil of Wood Distillation of Resins. Index. [See also " Wood Waste Utilisation" p. 33.] Fancy Goods Manufacture. THE ART OF DYEING AND STAINING MARBLE, ARTIFICIAL STONE, BONE, HORN, IVORY AND WOOD, AND OF IMITATING ALL SORTS OF WOOD. A Practical Handbook for the Use of Joiners, Turners, Manufacturers of Fancy Goods, Stick and Umbrella Makers, Comb Makers, etc. Translated from the German of D. H. SOXHLET, Technical Chemist. Crown 8vo. 168 pp. 1902. Price 5s. ; India and Colonies, 5s. 6d. ; Other Countries, 6s. net. Contents. Preface. Introduction. Chapters I., Mordants and Stains: Acids,* Alkalies, Iron Salts, Copper Salts, Aluminium Salts, Chromium Salts, Tin Salts, Lead Salts, Manganese Salts, Silver and Gold Salts. II., Natural Dyes: Redwood, Red Sandalwood, Madder, Orchil, Cudbear, Lac-Dye, Cochineal, Saffron, Annatto, Safflower, Fustic, Fustet, Quercitron, Flavin, Turmeric, Weld and its substitutes, Persian Berries, Barberry Root, Indigo, Logwood, Cutch, Galls, Sumach, Knoppern. III., Artificial Pigments: White Lead, Naples Yellow, Red Lead, Smalts, Ultra- Marine, Cinnabar, Prussian Blue, Orpiment, Realgar, Chrome Green, Chrome Yellow, Chrome Red, Chrome Orange, Mosaic Gold, Green Mineral Colours, Red Ochres, Rouge, Cadmium Yellow. IV., Coal Tar Dyes: Reds, Yellows and Oranges, Blues, Violets, Greens, Browns, Grey and Black Aniline Dyes Soluble in Fat : Resinate Colours, Aniline Lakes. V., Staining Marble and Artificial Stone: Red, Violet, Blue, Green, Yellow, Orange, Brown, Black, Execu- tion of Parti-Coloured Designs. VI., Dyeing, Bleaching and Imitation of Bone, Horn and Ivory Bone Bleaching Dyeing Bone: Black, Red, Yellow, Blue, Violet, Green, Grey and Brown Horn, Bleaching and Whitening Dyeing Black, Grey, Brown, Blue, Green, Violet and Red Imitation of Tortoiseshell for Combs: Yellows, Dyeing Nuts. Ivory: Dyeing Black, Red, Yellow, Blue, Violet, Green, Grey and Brown Further Remarks on Ivory Dyeing. VII., Wood Dyeing : Black, Grey, Brown, Violet, Blue, Red, Yellow, Green Imitation of Mahogany : Dark Walnut, Oak, Birch-Bark, Elder-Marquetry, Walnut, Walnut-Marquetry, Mahogany, Spanish Mahogany, Palisander and Rose Wood, Tortoiseshell, Oak, Ebony, Pear Tree Black Dyeing Processes with Penetrating Colours. VIII., Varnishes and Polishes: English Furniture Polish, Vienna Furniture Polish, Amber Varnish, Copal Varnish, Composition for Preserving Furniture. Index. Building and Architecture. THE PREVENTION OF DAMPNESS IN BUILDINGS ; with Remarks on the Causes, Nature and Effects of Saline, Efflores- cences and Dry-rot, for Architects, Builders, Overseers, Plasterers, Painters and House Owners. By ADOLF WILHELM KEIM. Translated from the German of the second revised Edition by M. J. SALTER, F.I.C., F.C.S., Member of the German Chemical Society of Berlin. Eight Coloured Plates and Thirteen Illustrations. Crown 8vo. 115pp. 1902. Price 5s. ; India and Colonies, 5s. 6d. ; Other Countries, 6s. net. Contents. Part I. Chapters I., The Various Causes of Dampness and Decay of the Masonry of Buildings, and the Structural and Hygienic Evils of the Same. II., Precautionary Measures during Building against Dampness and Efflorescence. III., Methods of Remedying Dampness and Efflorescences in the Walls of Old Buildings. IV., The Artificial Drying of New Houses, as well as Old Damp Dwellings, and the Theory of the Hardening of Mortar. V., New, Certain and Permanently Efficient Methods for Drying Old Damp Walls and Dwellings. Part II. Chapters I., The Cause and Origin of Dry-rot : its Injurious Effect on Health, its Destructive Action on Buildings, and its Successful Repression. II., Methods of Preventing Dry-rot to be Adopted During Construction. III., Old Methods of Preventing Dry-rot. IV., Recent and More Efficient Remedies for Dry-rot. Index. 36 Iron. SIDEROLOGY: THE SCIENCE OF IRON (The Con- stitution of Iron Alloys and Slags). Translated from German of HANNS FREIHERR v. ZUPTNER. 350 pp. Demy 8vo. Eleven Plates and Ten Illustrations. 1902. Price 10s. 6d. ; India and Colonies, 11s. ; Other Countries, 12s. net. Contents. Book I., The Theory of Solution. Chapters I., Solutions. II., Molten Alloys Varieties of Solutions. III., Osmotic Pressure. IV., Relation between Osmotic Pressure and other Properties of Solutions. V., Osmotic Pressure and Molecular Weight of the Dissolved Sub- stance. VI., Solutions of Gases. VII., Solid Solutions. VIII., Solubility. IX., Diffusion. X., Electrical Conductivity Constitution of Electrolytes and Metals. XI., Thermal Expansion. Book II., Micrography. Chapters I., General. II., Microstructure. III., The Micro- graphic Constituents of Iron. IV., Relation between Micrographical Composition, Carbon- Content, and Thermal Treatment of Iron Alloys. V., The Microstructure of Slags. Book III., Chemical Composition of the Alloys of Iron. Chapters I., Introduction. II., Constituents of Iron Alloys Carbon. III., Constituents of the Iron Alloys, Carbon- Opinions and Researches on Combined Carbon. IV., Opinions and Researches on Combined Carbon (Continuation). V., Opinions and Researches on Combined Carbon (Conclusion). VI., Applying the Curves of Solution deduced from the Curves of Recalescence to the Determination of the Chemical Composition of the Carbon present in Iron Alloys. VII., The Constituents of Iron Iron. VIII., The Constituents of Iron Alloys Manganese. IX., Remaining Constituents of Iron Alloys A Silicon. X., Gases. Book IV., The Chemical Composition of Slag. Chapters I., Introductory. II., Silicate Slags. III., Calculating the Composition of Silicate Slags. IV., Phosphate Slags. V., Oxide Slags. Appendix. I ndex. WORKS IN PREPARATION. TREATISE ON CLOTH FINISHING. By ROBERT BEAUMONT, of Yorkshire College, Leeds. WEAVING MACHINERY. Three Vols. By HARRY NISBET. COLOUR TERMS : THEIR PROPER USE AND MEANING. By DAVID PATERSON. USE OF WATER IN THE INDUSTRIAL ARTS. CHEMISTRY OF DYE STUFFS. Translated from German of Dr. GEORG VON GEORGIEVICS. [In the press. SUGAR REFINERS' HANDBOOK. ART OF BOOKBINDING. DENTAL METALLURGY. PRELIMINARY COTTON SPINNING AND WEAVING. By WALTER BAILEY. VENTILATION OF MINES. By ROBERT WABNER. Royal 8vo. Thirty Plates. About 250 pp. SIMPLE METHODS FOR TESTING PAINTERS' MA- TERIALS. By A. C. WRIGHT, M.A., B.Sc. Crown 8vo. Eight Illustrations. [In the press. SEALING WAXES AND OTHER ADHESIVES. By H. C. STANDAGE. HANDY GUIDES TO THE CHOICE OF BOOKS. Vol. I. PROSE FICTION. Vol. II. CLASSIFIED GUIDE TO TECHNICAL, TRADE AND COMMERCIAL LITERATURE. Others to follow . [In preparation. The Publishers will advise when any of the above books are ready to firms sending their addresses. * RETURN TO the circulation desk of any University of California Library or to the NORTHERN REGIONAL LIBRARY FACILITY Bldg. 400, Richmond Field Station University of California Richmond, CA 94804-4698 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS 2-month loans may be renewed by calling (415) 642-6753 1-year loans may be recharged by bringing books to NRLF Renewals and recharges may be made 4 days prior to due date DUE AS STAMPED BELOW 5 199i 1.21'