Practical tanning; a handbook of modern processes, receipts, and suggestions for the treatment of hides, skins, and pelts of every description

Front matter

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Preface

Practical Tanning, here presented for the consideration and guidance of the Leather Industrials of the United States and foreign countries is distinctively an American up-to-date treatise; no English, French or German book having been consulted in its preparation. Furthermore, in it will be found nothing whatever copied from any previously printed American book. It is what its title imports, "A Hand-Book of Modern Processes, Receipts and Suggestions for the Treatment of Hides, Skins and Pelts of Every Description." It is the result of the experience and study of the author and of those of many other practical men with whom it has been his good fortune to come into association and consultation.

One special feature of the volume to which he would call attention is that of the chapters on the Patented Processes of Tanning, Tawing, Depilating and Bating. These patents, which are given with sufficient detail to be clearly understood, serve to indicate the aims and ends of the most progressive and most intelligent investigators among tanners and chemists in the direction of placing this great industry upon a scientific basis, and what has been accomplished in that direction. The patents, the author has in most cases given with proper reserve, and without actual endorsement; but they are all suggestive, and therefore worthy of examination and investigation.

In writing this book the author has aimed to put before his readers information relating to the manufacture of many kinds of leather at once valuable and interesting. He makes no claim to infallibility nor to be above criticism. The book does not cover the entire field of leather manufacture; it does, however, contain a large amount of practical information so presented that the leather worker can readily understand it, and having made it a part of his mental capital can utilize it with benefit to himself and to the product of his skill.

Vi * V PREFACE.

J

Leather making as a trade cannot be wholly learned from a book; but a good book is an important aid to that end. Its value comes out only when the information in its pages is thoroughly assimilated and applied in practice. The author hopes that this one will be appreciated for its good qualities rather than be criticised for its short-comings.

In conclusion he would only add, that as is the uniform practice of the publishers, they have provided the work with a copious table of contents as well as a very full index, which will render reference to any subject in it at once prompt, easy and satisfactory. Louis A. Flemming

Hillsdale, Michigan, April 5, 1903.

Chapter I. Sh"eepskins

PAGE

Wool-pulling — Pickled skins ; The first operation to which sheepskins are subjected; Close relations between the soaking process and the subsequent processes ; Time required for soaking ; Effects of too much soaking ............ 1

How the best results are attained; Treatment of the pelts after soaking; Effect of heating; Wool-pulling with sulphide of sodium; Common method of using sulphide of sodium ....... 2

Strength of the sulphide of sodium liquor; Applying the sulphide of sodium and lime ........... 3

Length of time required for the action of the depilatory solution; Treatment of the skins after pulling ........ 4

The liming process; Action of lime; Swelling property of a lime; Renewal of the first lime; Mode of making a new lime; Length of time the skins should be left in the lime ....... 5

Time required to lime sheepskins of average thickness; Addition of fresh lime; Sensitiveness of the skins whilst being passed through the processes preparatory to the actual process of tanning .... 6

Effects of low liming and of over-liming; Use of sulphide of sodium in connection with lime; Cause of many of the imperfections met with in finished leather 7

Removal of grease found in sheepskins; Object of the drenching process; The bran drench ........... 8

Use of sour tan liquor; What the action of the bran drench is due to; Souring the drench ......... 9

Another method of preparing and using the bran drench; Amount of drenching required by sheepskins ....... 10

Drenching sheepskins by the use of animal and bird dung; Drenching with lactic acid ; Mode of using lactic acid ...... 11

The pickling process; Composition of the liquor in which the skins are pickled, and length of time they should remain in it . . . .12

Wool-pulling with the new XXX depilatory, patented . . . .13

Advantages gained by the use of this patented depilatory; The sweating process ............ 14

(vii)

yiii CONTENTS.

PAGE

CHAPTER II. The Manufacture of Chrome-tanned Sheep Leather

Preparation of sheepskins for chrome tanning; Removal of grease from sheepskins; Removing the acid from pickled skins; A very satisfactory method of tanning pickled sheepskins with one bath chrome liquors . 15

Common method of drenching pickled sheepskins; Temperature of the drench; Effect of the whiting and salt 16

Drenching in a solution of coal tar bate and sal-soda; A common method of chrome tanning sheepskins 17

Principal use of sulphate of alumina; Preparation of a solution of tanning material; Test for ascertaining whether the skins are tanned through. 18

Washing the skins; Tanning pickled skins without drenching; Mode of tanning pickled sheepskins without having the acid removed from them 19

Another method of tanning pickled sheepskins . . . • . 20

A new one-bath process of acid tanning and mode of carrying out this process.

Preparation of S. Z. solution and of S. K. solution; Tanning of sheepskins with one-bath chrome liquors in paddle vats . . . .23

Mode of handling the liquors; Necessity of using soft water; Quantity of tanning material required 24

Test for ascertaining whether the skins are tanned; Tanning sheepskins in two-bath processes; Removal of the acids in the skins; Manner of carrying out the most commonly used process of two-bath tanning . 25

Quantity of chromic acid required; Essential point in the first bath; Treatment of the skins after removal from the drum . . . .26

Composition of the second bath; A process of two-bath tanning . . 27

Finishing chrome-tanned sheepskins into glove leather; Coloring; Mordants used ............ 28

Ox-blood is a very popular shade and how a good color can be obtained; A good shade of ox-blood ........* 29

The various shades of brown and tan; Yellow glove leather; Mahogany shade 30

A good fat-liquor; Another very good fat-liquor; A very practical method of preparing chrome-tanned sheepskins with sumac . . . .31

Aniline dves on this leather ......... 32

Economy to use only the best dyes; Difficulties encountered in coloring chrome-tanned leather; Method of dissolving aniline dyes; Preferred method of dyeing; Brand of aniline colors referred to . . . .33

Ox-blood shade; Very desirable tan shades ...... 34

Sulfamine-dyed sheepskins; Yellow chrome-tanned glove leather; Rich dark ox-blood; Glazing chrome-tanned sheepskins — colored; Clearing the grain of grease .......... 35

Liquor for a clear, bright finish; Finishing the skins into black shoe leather 36

CONTENTS. IX

PAGE

Increasing the solidity and firmness of the leather; Coloring the flesh blue or purple; Blacking the grain; Preparation of a good striker to develop the color 37

Application of glycerin; Clearing the grain of greasy matter; A good glazing liquor for sheepskins 38

Trouble with chrome-tanned sheep leather, and prevention; Cause of defect in leather; Good method of preventing the trouble; Bath of sumac or palmetto extract; Decoction of sumac leaves . . . .39

Mordanting chrome-tanned sheepskins .40

Chapter III. Sheepskins

ALTJM, OIL AND NAPA PROCESSES.

Processes of alum tawing; Removal of the animal grease; Removing the acid used as a pickle; Mode of obtaining an ordinary quality of leather . 41

Preparation of an extra fine quality of alum leather . . . . .42

A process of white tawing, recently patented in Germany; Preparation of very soft and tough white leather ....... 43

Method of tawing for making sheepskins and lambskins into very soft, strong glove leather 44

Use of Turkey -red oil in the tanning of sheep and lambskins into glove leather; Combination process of alum and chrome . . . .45

Preparation of a very good fat-liquor for this class of stock; Sheep and lambskins oil-tanned; Good method of washing out the lime . . 46

Process of oil-tanning; Process of heating the leather; Removal of surplus oil 47

Preparation of very soft, tough glove leather; Mode of oil-tanning sheep and lambskins ... . . . . . . . . .48

Tanning the skins by a combination of the oil with the salts of alumina; The making of Napa leather; Origin of the Napa tannage; Classes of leather made ........... 49

Original process of making Napa leather, and modifications of it . . 50

Coloring black Napa; Manner of using direct blue paste; Preparation of a good blacking for this class of leather; Dampening the skins down for staking; Buffing the skins; Finishing black Napa leather . . .51

Process for the production of very soft, tough leather . . . .52

Another process of preparing sheepskins for linings, bindings and similar purposes; To produce quickly and cheaply a soft, tough leather from sheepskins suitable for gloves and mittens; Preparation of the mixture for this purpose ........... 53

Process especially adapted to sheepskin fleshers to be used in the manufacture of gloves, for bindings, etc. ; Preparation of the fluid for this purpose 54

Handling the skins in the early processes of the beamhouse . . .55

Tanning of sheepskin fleshers by any of the chrome processes . . .56

X CONTENTS.

CHAPTEK IV.

Wool Skins.

the tanning of shearlings, sheep pelts for mittens. rugs and similar purposes.

PAGE

A good method of tanning the skins ....... 57

To color the skins; Another method; Preparation of a tanning solution . 58

Method of tanning sheep pelts with the wool on 59

Cheap and simple method of preparing sheep pelts with the wool on .60 Effect of salt and alum used in tanning sheep pelts; Handling the pelts during tanning; Scouring the wool after tanning . . . . .61

Treatment of greasy skins; Tanning the skins in bark extract . . .62 Draining and oiling the skins; Mode of obtaining a desirable shade of brown; Production of a light golden color ...... 63

To bleach the wool on alum-tanned sheepskins; A very simple and effective method of removing the grease from sheep pelts; Manner of very cheaply tanning wool-skins ......... 64

Another method somewhat speedier; Wool -washing soap and its preparation ... . . . . . . . . . . .65

A very satisfactory method of tanning sheepskins with wool on, shearlings, etc. ............. 66

Most important requisite in dyeing the wool; Best way to scour the alumed pelts; Mode of obtaining a seal brown . . . . .67

Method for accomplishing the bleaching of sheep pelts, lambskins and goatskins tanned with the wool and hair on ..... 68

CHAPTER V. Sheepskins

bark, extract, and chamois tanning.

Use of various tannages; A good method of using palmetto extract; Tanning of pickled skins ......... 69

Mode of obtaining a dull finish; A combination tannage; Preparation of very excellent leather by combining a chrome and a vegetable tannage; Use of palmetto extract to supplement the chrome tannage . . .70

Removing the acid from pickled skins; Use of palmetto extract in combination with quebracho; The coloring and finishing of vegetable tanned skins; Preparation of sheepskins for coloring . . . .71

Effect of the use of hard water: Cleanliness a very important element . 72

Skins that have acquired a dark shade from the tannage should be given the dark shades of dye; Lactic acid a very good article to use in coloring sheepskins 73

Sorting the skins; Applying the dye and finishing the leather; Various methods employed .......... 74

CONTENTS. XI

PAGE

Drumming the leather in warm sumac liquor before coloring it with aniline dyes; Preparation of the coloring bath 75

Desirable shades; Ox-blood; Desirable chocolate shade; Desirable shade of green .......••••• 76

Use of logwood in dyeing bark tanned leather black; A good black on bark and extract tanned sheepskins 77

Skivers and mode of making this class of leather; Preparation of a good drench for this class of goods . . . •■ . • • .78

Various materials used in tanning skivers; Necessity of careful handling

of the stock during tanning 79

Tannage for a common grade of leather; Coloring of sumac-tanned skins. 80

Numerous ways of finishing skivers; Use of embossing machines; Special value of aniline colors for the maker of this class of leather; A good process of tanning ' 81

Chamois leather and its production; Kemoving the lime; Treatment of the skins; Eemoval of surplus water; Application of oil . • .82

Process of heating; Effect of insufficient and of overheating; Eemoval of the oil; Finishing processes • .83

Varying methods of treating the skins; Preparation of chamois leather by passing the prepared skins through a twenty-five per cent. Turkey-red oil solution . . . . . . . . . .84

CHAPTER VI. Goatskins, beamhotjse work. pbeparing the skins for tanning

Object of the soaking and softening process; Freeing dry-salted skins from salt; Softening dried skins; Use of solutions of chemicals to hasten the soaking and softening . . 86

Serious danger in connection with the soaking process; Good rule to be observed in soaking; Damage resulting from heating; Importance of guarding against heating ......... 87

The liming process; Office of any material used upon raw skins in preparing them for tanning into leather; Use of red arsenic in connection with lime; Preparation of a new lime with red arsenic. . . .88

Preparation of a good lime; Use of red arsenic and sulphide of sodium in conjunction with lime . . . . • • , ■ .89

Very good results obtained from the use of sulphide of sodium and lime; Various methods of using sulphide of sodium; Practice when it is desirable to save the hair .......•• 90

Mixing lime with the sulphide of sodium; Slacking the lime . . .91

Application of the mixture of lime and sulphide of sodium; Further plumping of the skins ......•■•• 92

Gathering limes; Placing the skins in the first lime; Treatment of the skins in the lime; Process with the use of paddle vats. . .93

Xll CONTENTS.

PAGE

Bating or puring of goatskins ......... 94

Essential qualities of goat leather at the present time; Production of these qualities; Distinct actions of lime upon raw skins; Effect of the use of lime alone upon goatskins ........ 95

Effect of red arsenic upon the grain; Bates and bating; Materials used for this purpose; Pigeon and dog dung; On what the efficacy of manure bate depends ........... 96

Preparation of manure bate; Avoidance of stains and burns; Some disturbing influences in bating ........ 97

Necessity of thoroughly cleansing goatskins; Further treatment after the skins have been pured in the manure bate ...... 98

The bran drench as applied to goatskins; On what the efficacy of this process depends; Preparation of the drench 99

CHAPTER VII. The Chrome-Tanning of Goatskins

The original and most commonly used two-bath process, and practical method of carrying out this process ; Preliminary pickle . . . 101

Composition of the first bath of this process; Another method of giving the skins the chrome liquor .... .... . 102

Composition of the second bath of the process; A new process of two-bath chrome-tanning ........... 103

A common process of tanning goatskins with the one-bath chrome liquors 104

Tanning of goatskins directly after the drenching and washing with the one-bath chrome liquors, without the use of the sulphate of alumina and salt 105

Preparation of good leather by tawing the skins in the solution of sulphate of alumina and salt; Another good method of tanning the skins . . 106

A method of tanning goatskins with the one-bath process . . . 107

Another satisfactory method of tanning the pickled goatskins; A new process of acid tanning .......... 109

S. Z. solution and the S. K. solution, and their composition . . . 110'

Chrome-tanning alum-tanned goatskins; Preparation of very fine kid leather; The chrome part of this process Ill

Suggestions and precautions in the making of light leather by any chrome process of tanning; Advantage gained by sorting the skins; Advisability of the use of a liberal quantity of salt in the tanning liquor . . . 112

Great nicety of proportions required for two-bath processes; Manipulation of one-bath liquors when used in paddle vats; Strength of liquor used . 113

Use of tanning material that is left in the bath; Length of time required for tanning skins in drums; Fat-liquoring ...... 114

Sorting the tanned skins before being fat-liquored; Certain defects and their correction; Cause and prevention of an open porous grain; Prevention of a gray bottom on black leather . . . . . .115

CONTENTS. xnl

PAGE

Flanky goatskins; Cause of a faulty condition of the flanks; Injury to the skins by prolonged drumming • '

Coarse, rough grain along the necks and shoulders of goatskins and how this defect may be overcome; Necessity of very carefully handling the cheaper grades of goatskins

Treatment of goatskins in a hot bath of sumac; Effect of the use of excessive quantities of salt in chrome-tanning

Chapter VIII

The Finishing of Chrome-Tanned Goatskins into Colored and Black, Geazed and Dull Leather.

A number of processes involved in the finishing of goatskins into colored or black leather; Dyeing the grain side of the leather black . . .119

Manner of grain blacking; Dyes used _

Method of getting a blue flesh with nigrosine; Preparation of a good liquor or striker; Accomplishment of fat-liquoring and grain-blacking in one

.. , 121

Dyeing in dye boxes; The use of permanganate of potash m coloring leather; Methods of applying the permanganate of potash . . .122

Advantages resulting from this process

Methods of coloring skins after they have been treated with permanganate of potash; Process patented by W. N. Norris. Princeton, N. J.; Coloring chrome-tanned goatskins with aniline dyes . . • . . 124

Washing the skins; Use of sumac as a tanning material in coloring chrome-tanned goatskins; Another method of preparing the skins for

, . . 125

coloring .

Necessity of coloring chrome-tanned skins before they become dry; Use of fustic as a mordant or base for aniline dyes upon chrome-tanned

Palmetto extract as a mordant; Clearing the grain of grease . . • 1^'

Practical working directions for dyeing chrome-tanned goatskins; Mordanting the skins; Necessity of knowing the quantity of dye required. 128

Experiments on a small scale; Ox-blood shade; A dark rich ox-blood shade; A correct shade of ox-blood

Production of a good ox-blood shade; Browns; Desirable chocolate

brown

Various shades of brown; Tan shades; Increase of the solidity and firmness of the skins . . • '

Results obtained in the coloring process to a great extent influenced and determined by the methods employed in the processes through which the skins have been worked previous to coloring; Necessity of thoroughly soaking and softening goatskins before they are depilated or limed

XIV CONTENTS.

PAGE

Necessity of exercising care in handling the skins during the processes of

the beam house; Cleansing of lime ....... 133

Sorting the skins according to texture and quality; Results obtained in

the coloring process largely dependent on the quality of the water used;

Effect of very hard water; Softening of hard water . . . . 1 34 Dissolving aniline dyes;Coloring chrome-tanned goatskins with sulfamine

dyes; Practical working directions for getting several very desirable

shades with sulfamine dyes; Browns and dark tans .... 135 Dark chocolate; Chocolate shade; Formulas useful in getting light shades

of tan; Ox-blood shade . . . . . . . ... 136

Various shades of green; Fat-liquoring; The process of fat-liquoring . 137 Treatment of the skins after the coloring operations are completed;

Preparation of a very good fat-liquor . . . . . . . 1 38

Striking out; Working the skins soft . . . . . . .139

Glazing and finishing; Seasonings used; Clearing the grain of greasy

matter and solution for this purpose; Seasoning on black leather . 140

Seasoning for glazing colored leather; Application of a light coat of oil;

A process for kid-glove leather . . . . . . .141

Preparation of kid-glove leather by tawing; Preparation for tanning of

skins from which the grain has been removed after liming . . . 142 Essential qualities of glove leather . . . . . . . .143

Chapter IX

DONGOLA AND TnDIA-TaNNED GoAT AND SHEEPSKINS. DONGOLA TANNED GOAT AND SHEEPSKINS.

Purposes to which dongola tannage is especially applicable; Composition of dongola tannage; Soaking; Sheep pelts and their treatment . . 144

Soaking goatskins; Preparing the skins for tanning; Process of liming . 145

Drenching the skins; Preparation of the bran drench .... 146

Use of lactic acid in the preparation of both classes of skins; Pickling the skins; Preparation of a good pickle; The tanning process; Composition of the tanning liquor ......... 147

Another dongola liquor for both goat and sheepskins; Peculiar and distinctive qualities of palmetto extract ....... 148

Production of a leather possessing some of the qualities of both chrome and vegetable-tanned stock; Fat-liquoring and currying goatskins . 149

Preparation of a very good fat -liquor for combination-tanned skins; Fatliquoring sheepskins; Moistening back the leather before dyeing . 150

Clearing the grain of grease; Coloring the flesh ..... 151

Blacking the grain; Composition of the grain blacking; Application of the blacking; Application of the striker, and its composition . . 152

Coloring the flesh blue; Clearing the grain for colors; Finishing the leather 153

The coloring and finishing of India-tanned skins; Betanning with sumac. 154

CONTENTS. XV

PAGE

Alum, salt and gambier liquor; Treatment of the skins for black leather. 155

Use of logwood and borax; Treatment for very light and fancy shades; Clearing the grain of the leather when greasy; Use of Turkey-red or alazarine oils *

Another process for finishing India goat and sheepskins; Application of a solution of formic aldehyde . . • • ■

Method for the improvement of imperfectly tanned skins . . .158

CHAPTEE X.

Patented Processes of Tanning and Tawing. Patented "method of tawing" (by Messrs. Dolly and Crank) for the final finishing of East India kips, goatskins, basils, and white leather,

and the improvement of imperfectly tanned skins 159

A particular case which serves to illustrate the steps involved. . . 160 Variation in the amount of solution employed; Time required. . . 161 Temperature of the bath; Improvement of tanned or imperfectly tanned

skins and hides

Effects produced on these skins; Hastening of the action of the natural tannins as introduced into the skin; Effect of the peculiar action of

formic aldehyde upon the fibres of the skin 163

Special advantage afforded by this process; Property of formic aldehyde of fixing the collogen and other gelatinous constituents of the skin; Sulpho-compounds or their mixture with fats and oils; Investigations

of Armand Miiller, of New York i64

Benefit derived from the use of these oils; Production of the oils or sulpholeates; Examples of the methods of using the sulpholeates for tanning leather

Alum tawing with Turkey-red oils 1D °

Oil-tanning or chamoising; Object of this process of alum tawing . . 167 Preparation of the solution; First step in the process; Preparation of the second bath . . . • • • • • • * ' '

The use of formic aldehyde as a tanning agent; Preparation of the skins for the process; Treatment of the skins with the formic aldehyde in the

form of a solution

Use of the formic aldehyde in a gaseous state 17 °

A French process by the use of which, it is claimed, that the cohesion of

the fibres is destroyed and putrefaction is prevented . . . .171 Process, patented by Chas. Knees, Oshawa, Canada, for which it is claimed that it makes leather that is waterproof, elastic, pliable, heat

and frost -proof ' '

New method for belt, shoe and leather laces, patented by James C. Mc-

Connell '174

Preparation of the stuffing mixture ■

Process with bark liquor, saltpetre, alum and glauber salt, patented by J. W Hitt, Lisle, N. Y 17b

XVI CONTENTS.

PAGE

Process of tanning which consists of the use of an antiseptic tanning composition, patented by Julius Engelke, Cincinnati, O. . . . . 176 Process of rapid tanning, patented by John Hoelck, Chicago, Ills. . . 179 Another process of tanning hides somewhat similar to the foregoing . 181 A composition of matter with processes of tanning ..... 182 A process of tanning which has for its object the treating of hides and

skins in such a manner as to prevent them from becoming hard . . 183 A process which has for its object the providing of a method of tanning leather whereby the hides are rendered soft and pliable, patented by

Process of manufacturing and finishing leather which is adapted for the use of vamps and tops of shoes, patented by C. E. and H. A. Lappe,

Pittsburg, Pa 185

Rapid process of drum tanning, patented by Jacques Durio, Turin, Italy. 187 Another rapid process of drum tanning, invented by S. and G. Durio,

Turin, Italy 191

Practical application of the original Schultz two-bath process . . . 193 Description of another process discovered and patented by Schultz . . 196 Tanning of skins according to the Zahn process ..... 197 Treatment if the leather is to be colored fancy shades .... 198 Description of an improved process [of chrome-tanning, patented by W.

M. Norris, Princeton, N. J 199

Advantage of this method of tanning ....... 201

Reducing with hydrogen dioxide when skins are saturated with a chromate, patented by Samuel P. Sadtler, Philadelphia, Pa. . . . 202

One of the various processes used to accomplish the changing of the chromic acid in skins into chromic oxide, patented by S. Chadwick,

Philadelphia, Pa 205

Method of tawing for the making of chrome leather, patented by H. Ende-

mann, Brooklyn, N. Y 206

One-bath process of chrome tanning ....... 208

Tanolin ( the Martin Dennis process) . . . . . . . 210

Process of chrome tanning which produces leather that possesses the good qualities of both alum and chrome leather, patented by Geo. W. Adler,

Philadelphia, Pa 213

Tanning of skin? with a liquor composed of whiting, salt, chrome, alum, saltpetre and muriatic acid; Another one-bath process for which waterproof qualities are claimed, patented by Joseph W. Smith, Girard, Ohio. 216 A simple one-bath liquor; Another interesting one-bath tanning liquor known as chromine, manufactured under patents by The Eureka Tannage Co., Philadelphia, Pa 218

A liquor useful in one-bath chrome-tanning called Progress Tan Liquor . 221 Vacrome, a single-bath mineral-tanning agent, made by the Vacuum Oil

Co., Rochester, N. Y 223

Preparation of liquors with the use of chrome-alum that have given good results when used upon light skins; Preparation of liquor for tanning skins ............. 225

CONTENTS. XV11

CHAPTER XI. Deerskins

PAGE

Removing the hair from deerskins; Mixture used for the purpose . .227 Object of liming the skins; Removing the grain of the skins; Various ways of tanning the skins; A process which produces good results upon

Another process that results in soft, tough leather . . . . . 229 Manner of tanning the skins; Composition of a liquor in which deerskins

may be satisfactorily tanned 230

Tawing with sulphate of alumina 231

An old-fashioned and very simple method of tanning deerskins . .232 Special adaptability of the chrome methods of tanning to deerskins; Pickling the skins; Tanning without pickling 233

A good method of chrome-tanning the skins " 234

Two-bath processes for tanning deerskins .235

A somewhat crude process of tanning deerskins in use among the Indians 236 Oil or chamois-tanning deerskins; Removing the lime from the skins;

Oiling and beating the skins 237

Process of heating; Effects of too high and of insufficient heating; Bleaching the skins; Various methods of handling the skins .... 238 Process for making very soft, tough leather of deerskins . . . .239

CHAPTER XII. Patented Methods of Depilating

Methods of using new XXX Depilatory, patented; Strength of the solution used ^ 41

Preparation of the second lime; Handling the slats while liming . .242

Treatment of light hair skins when the hair is not to be saved, and when it is to be saved 243

Use of new XXX Depilatory upon hides intended for sole leather; Methods of unhairing 244

Treatment of skins intended for various kinds of leather .... 245

Plumping or swelling of hides intended for splitting after unhairing with depilatory water ■ 246

Treatment of skins intended for tough upper leather if no value is placed upon the hair; Treatment of horse hides; An interesting process for preparing hides and skins for tanning invented and patented by John and Edward Pullman, London, England 247

Mixture of sulphide of sodium and chalk, or whiting, proposed for use in unhairing

Process known as the Pierson and Moor process, patented . . .250

XV111 CONTENTS.

CHAPTER XIII. Patented Processes of Bating

PAGE

German patented process of bating hides and skins and swelling them; Use of the sulfonic acids of the cresols as a bate; Employment of a mixture of the cresol sulfonic acid with varying quantities of free sulphuric acid 252

Mode of obtaining cresol sulfonic acids; Preparation of the bate; Antiseptic property of cresol sulfonic acid ....... 253

Process of bating by the use of a compound solution of sulphuric acid, borax and glauber salt, patented by N. Wilson, Becket, Mass. . . 254

Bating with potatoes and yeast, process patented by William Oetlinger, Philadelphia, Pa 255

The Norris new solid bate, patented by W. N. Norris, Princeton, N. J. 256

Bating with naphthaline sulphuric acids, patented by C. S. Hull and P. S. Burns, Boston, Mass 257

Advantages resulting from the use of the naphthaline sulphuric acids; The use of coal-tar bate . . ..... . 258

Preparation of the bating solution ........ 259