GIFT OF 
 
 PROF. W.B. RISING 
 

INTRODUCTION 
 
 TO 
 
 CHEMICAL-TECHNICAL 
 ANALYSIS 
 
 BY 
 
 PROF. F. ULZER AND DR. A. FRAENKEL 
 
 DIRECTORS OF THE TESTING LABORATORY OF THE ROYAL TECHNOLOGICAL MUSEUM, 
 
 IN VIENNA 
 
 (AUTHORIZED TRANSLATION) 
 
 WITH APPENDIX BY THE TRANSLATOR 
 
 HERMANN FLECK, NAT. Sc. D. 
 
 INSTRUCTOR IN CHEMISTRY, UNIVERSITY OF PENNSYLVANIA 
 
 PHILADELPHIA 
 
 P. BLAKISTON'S SON & CO. 
 
 1012 WALNUT STREET 
 
 1898 
 
II lo 2. 
 
 COPYRIGHT, 1898, BY 
 P. BLAKISTON'S SON & CO. 
 
 PRESS OF 
 
 an & Co., 
 
Preface. 
 
 IT is generally conceded that it is advisable to give students of 
 chemistry as broad an experience as possible in the use of analytical 
 methods, in order to have them acquire skill in manipulation and to 
 acquaint them with the important bearing of chemical analysis. 
 
 This experience can, in a great measure, be obtained by supple- 
 menting the usual preparatory courses in gravimetric and volu- 
 metric analysis with instruction in the execution of methods which 
 are being constantly applied in the analysis of industrial products. 
 The authors of this book have had much experience in teaching 
 chemical-technical analysis, and in the following pages have pre- 
 sented many methods of this description in a series of examples, 
 selected from a variety of products. They have been very fortunate in 
 their choice, and have undoubtedly done much to assist the earnest 
 student. 
 
 The conviction that a course of this character would be wel- 
 comed by English-speaking students, and helpful not only to them 
 but also to many who are already engaged in industrial pursuits, has 
 led the translator to publish the little volume in its present form. He 
 has not edited the text, but has taken the liberty to add an appendix, 
 in which are incorporated additional examples which actual labor- 
 atory testing has shown to be highly instructive, as well as exceed- 
 ingly valuable, in the direction of imparting skill in manipulation. 
 
 In this connection, too, the translator would take occasion to 
 acknowledge his great indebtedness to Mr. Walter T. Taggart, 
 B. S., for valuable assistance rendered in the reading of the proof 
 and the preparation of the index. H. F. 
 
 (iii ) 
 
 237357 
 
Table of Contents. 
 
 PAGE 
 
 I. Products of Technical Chemistry, i 
 
 1. Iron Pyrites, I 
 
 2. Pyrite Residuum, . 3 
 
 3. Sulphuric Acid, .... ...... 4 
 
 4. Fuming Sulphuric Acid and Anhydride, 5 
 
 5. Nitroso Acid (Nitrated Acid), . 7 
 
 6. Brine, 1 1 
 
 7. Crude Hydrochloric Acid, . . . . . . . .12 
 
 8. Soda, ; . . . . . . . . 13 
 
 9. Sodium Aluminate, . . . . . .''. . .17 
 
 10. Weldon Mud, 18 
 
 11. Boiler- Water, 20 
 
 12. Fuel, 27 
 
 13. Furnace Gases, .......... 32 
 
 II. Cement and Clay, ... ,35 
 
 1. Lime, . . . 35 
 
 2. Marl, 37 
 
 3- Clay, 39 
 
 A. Empirical-Technical Analysis, ...... 40 
 
 B. Rational Analysis, ........ 42 
 
 C. Analysis by Mechanical Means (Suspension), . . -43 
 
 D. Pyrometric Tests, . . . . . . . -45 
 
 III. Metallurgical Industry, 51 
 
 1. Iron, . . . . . . . . . . . 5 1 
 
 2. Zinc Blende, 57 
 
 3. Zinc Dust, ........... 59 
 
 4. Crude and Refined Copper, 60 
 
 IV. Alloys, 68 
 
 1. Phosphor- Bronze, ......... 68 
 
 2. White Metal, 69 
 
 3. Iron Alloys, .......... 70 
 
 V. Fertilizers, 72 
 
 1. Phosphate Fertilizers, 75 
 
 2. Potassium Fertilizers, ......... 77 
 
 3. Nitrogenous Fertilizers, ........ 78 
 
 4. Mixed Fertilizers, . . . . . . . . .78 
 
 (v) 
 
VI TABLE OF CONTENTS. 
 
 PAGE 
 
 VI. Sugar Industry, 79 
 
 1. Beets, 82 
 
 2. Beet Juice, Thin Juice, . 84 
 
 3. Crude Sugar, Filling Material, Green Syrup, Molasses, . . 84 
 
 4. Press Cake, 91 
 
 5. Lime Saccharate, ......... 91 
 
 6. Bone Black, .91 
 
 VII. Fermentation Industries, 95 
 
 1. Raw Products Containing Starch, 95 
 
 2. Starch, 99 
 
 3. Malt, 100 
 
 4. Yeast, . 103 
 
 5. Spirits, 105 
 
 6. Methyl Alcohol (Wood Spirit), 107 
 
 VIII. Fats, Waxes, Mineral Oils, . 109 
 
 A. F'ats, 109 
 
 1. General Methods, 109 
 
 2. Classification of Fats, 114 
 
 3. Investigation of a Few Common Fats, . . . .117 
 
 B. Waxes, . . . .121 
 
 1. Vegetable and Animal Waxes, . . . . .121 
 
 2. Mineral Waxes, . .125 
 
 C. Mineral Oils, 125 
 
 1. Mineral Lubricants, . . . . . . .126 
 
 2. Petroleum (Illuminating Oil), 129 
 
 3. Gas Oil, . . . 131 
 
 D. Products of the Fat Industry, 131 
 
 1. Materials Used in Oiling Wool, . . . . . 131 
 
 2. Soaps, 133 
 
 3. Turkey-Red Oil, .138 
 
 4. Glycerin, 140 
 
 IX. Mordants and Tanning Materials, ....... 143 
 
 A. Mordants, 143 
 
 1. Alumina Mordants, 143 
 
 2. Chromium Mordants, 145 
 
 3. Iron Mordants, ........ 146 
 
 4. Tin Mordants, 146 
 
 5. Antimony Mordants, 147 
 
 6. Copper Mordants, . . . . . . . . 147 
 
 B. Tanning Materials, . 147 
 
 1. Tanning Extracts, . . . . . . . .148 
 
 2. Raw Products, 149 
 
 X. Textile and Dyeing Industries, 151 
 
 1. Textile Fibers, 151 
 
 2. Bleaching Materials, 153 
 
TABLE OF CONTENTS. Vli 
 
 PAGE 
 
 3. Sizing Materials, 154 
 
 4. Finishing Materials, . . . . . . . . .156 
 
 5. Dye-Stuffs, .158 
 
 XI. Products of the Coal-Tar Industry, ...... 165 
 
 1. Crude Benzene, .......... 165 
 
 2. Crude Xylol, 165 
 
 3. Crude Anthracene, . . . . . . . . .166 
 
 4. Crude Carbolic Acid 167 
 
 5. Dimethyl Aniline, ......... 168 
 
 Appendix, 
 
 A. White Paint (White Lead), 169 
 
 13. Manganese Dioxide, Bleaching Lime, Etc., .... 169 
 
 1. Manganese Dioxide, ........ 169 
 
 2. Bleaching Lime, ......... 172 
 
 3. Hydrogen Peroxide and Permanganate, . . . .172 
 
 C. Asphalt and Asphaltic Substances, . . . .... 172 
 
 D. Food Stuffs, 174 
 
 1. Milk, 174 
 
 2. Butter, .'77 
 
 3- Tea, 178 
 
 4. Coffee, . . . 179 
 
 5. Cocoa and Chocolate, . . . . . . . .180 
 
 6. Flour and Other Cereals, 182 
 
 7. Pepper, 183 
 
 Abbreviations. 
 
 Be. =r Beaume. 
 
 c.c. = Cubic Centimeter. 
 
 C. Celsius. 
 Cone. Concentrated. 
 
 F. = Fahrenheit. 
 Gr. = Gram, 
 m.m. Millimeter. 
 Temperature (Celsius is understood unless otherwise indicated.) 
 
I. Products of Technical Chemistry. 
 
 IN this chapter a selection is made from the most important in- 
 dustrial chemical products as well as from the raw materials used 
 therein, and a description of the quantitative examination of the 
 same is given. The methods described are followed by those em- 
 ployed in the analysis of water, coal and furnace gas. 
 
 1. Iron Pyrites. 
 
 The most important determination is that of sulphur. The error 
 must not exceed . i per cent. In addition a water determination is 
 usually conducted, and less frequently estimations of copper and 
 arsenic. 
 
 (#) Sulphur. Following the method of Lunge, which is adopted 
 in the German Le Blanc soda factories, . 5 gram of finely-divided and 
 bolted pyrite is covered with 10 c.c. of a mixture of 3 vols. nitric 
 acid (sp. gr. 1.4) and i vol. fuming hydrochloric acid in an Erlen- 
 meyer flask. A funnel is inserted and the contents are warmed 
 until reaction begins. The flask is then removed from the water- 
 bath, and the reaction proceeds of its own accord until nearly 
 complete. The contents are warmed anew until the reaction is 
 finished. Solution takes place in about ten minutes. Only small 
 quantities of colorless substances, silica, barium sulphate, lead sul- 
 phate, etc., but neither dark particles nor sulphur, may remain un- 
 dissolved. The solution is evaporated to dryness in a porcelain 
 dish with an excess of hydrochloric acid ; the residue is moistened 
 with a few drops of hydrochloric acid, taken up with hot water, and 
 filtered. In the filtrate, at a temperature of 60-70 the iron is 
 precipitated with a slight excess of ammonia. The precipitate is 
 thrown on a sufficiently porous filter and washed with hot water 
 until i c.c. filtrate remains perfectly clear for several minutes on 
 addition of barium chloride solution. The filtrate is acidified with 
 hydrochloric acid, brought to boiling, and the sulphuric acid is 
 
 1 
 
2 CHEMICAL-TECHNICAL ANALYSIS. 
 
 precipitated with about 20 c.c. of a hot solution of barium chloride 
 (10 per cent.). The remainder of the analysis is conducted in the 
 usual manner. The sulphur in pyrite varies between 46 and 52 
 per cent. Spanish and Norwegian pyrites are characterized by 
 their high percentage of sulphur. 
 
 (^) Moisture. About 10 grs. sample are dried to constant 
 weight in an air-bath at 105. Usually four hours are required for 
 this operation. 
 
 (V) Copper. According to the procedure of Duisberger-Hiitte,* 
 five grams of the finely-ground and previously dried (100) min- 
 eral are gradually brought into an inclined Erlenmeyer flask con- 
 taining 60 c.c. nitric acid (sp. gr. 1.2). As soon as the ensuing 
 violent reaction ceases the flask is heated and the contents are evap- 
 orated until sulphuric acid vapors are evolved. The dry residue is 
 then dissolved in 50 c.c. HC1 (sp.gr., 1.19), 2 grams sodium 
 hypophosphite dissolved in 5 c.c. water are added, and the liquid is 
 boiled to remove the arsenic and reduce the iron. An excess of 
 concentrated HC1 is now added, followed by 300 c.c. hot water, and 
 hydrogen-sulphide gas to saturation. The precipitate is filtered off 
 and thoroughly washed. The filter is broken with a glass rod, and 
 the contents are washed back into the precipitates in flask. The 
 adhering particles on the filter, together with the main portion of 
 the precipitate, are dissolved in nitric acid and the solution is 
 evaporated to dryness on a water-bath. The residue is treated again 
 with nitric acid and water, neutralized with ammonia, and a slight 
 excess of dilute sulphuric acid is added. After cooling, the solu- 
 tion is filtered, the flask and filter are washed with w r ater containing 
 sulphuric acid, and the copper is determined electrolytically in the 
 filtrate after adding 3 to 8 c.c. nitric acid, or gravimetrically with- 
 out the addition of nitric acid as cuprous sulphide. From the per- 
 centage found, .01 is deducted for bismuth and antimony. Any 
 appreciable amount of copper in pyrite is easily recognized during 
 the sulphur determination by the blue ammoniacal filtrate. 
 
 (d} Arsenic. (Method of Reich, modified by McCay.) 0.5 
 gram of pyrite is dissolved in a porcelain crucible with nitric acid. 
 The free acid is volatilized, 4 grams soda are added, and the mass is 
 
 * Taschenbuch fur die Soda-, Pottasche- und Ammoniakfabrikation von Dr. G. 
 Lunge. 2 Aufl. 
 
PYRITE RESIDUUM. 3 
 
 thoroughly dried on a sand-bath, when 4 grams saltpetre are added 
 and the contents are heated to quiet fusion for ten minutes. The 
 fusion is lixiviated with a small quantity of hot water, and to the 
 filtered solution sufficient nitric acid is added to slightly acidify, 
 after which the liberated carbonic acid is expelled by boiling. 
 Silver nitrate is now added, and the solution is carefully neutralized 
 with weak ammonia. All arsenic is obtained in the form of silver 
 arsenate, which is dissolved in dilute nitric acid. The solution is 
 either evaporated in a platinum capsule, dried and weighed as sil- 
 ver arsenate ( Ag 3 As O 4 ), or titrated with ammonium sulpho -cyanide 
 according to the method of Volhard. 
 
 2. Pyrite Residuum. 
 
 The determination of sulphur in pyrite residuum, an operation 
 not infrequently required, can be carried out under the directions 
 given in Example i, except that, in order to avoid evolution of 
 hydrogen sulphide, solution is advantageously effected by nitric 
 acid and only a few drops of hydrochloric acid. 
 
 Lunge* recommends for this purpose the following method : 
 Exactly 2 grams of sodium-bicarbonate, whose strength has been 
 previously estimated by titration, are thoroughly mixed with 3.2 
 grams finely -divided residuum in a nickel crucible of about 30 c.c. 
 capacity. The mixture is heated first for 10 minutes with a small 
 flame just touching the bottom, and afterwards for 15 minutes with 
 a strong flame, without allowing the mass to melt. The crucible 
 should be covered during this operation. The contents are poured 
 out into a porcelain dish, the crucible is rinsed with water, and 
 treated for ten minutes with a concentrated neutral brine in order 
 to avoid subsequent escape of iron oxide through the filter. The 
 undissolved portion is filtered off and washed until the filtrate 
 ceases to give an alkaline reaction. After cooling, the liquid is 
 titrated back with normal acid, using methyl-orange as an indica- 
 tor. The difference between the number of c.c. hydrochloric acid 
 (# ) necessary to neutralize 2 grs. bicarbonate and the number of 
 c.c. () used in back titration, multiplied by the sulphur equiva- 
 lent (i c.c. in acid = 0.016 gr. S) gives the amount of sulphur 
 
 * Taschenbuch fur die Sodafabrikation, etc. 
 
4 CHEMICAL-TECHNICAL ANALYSIS. 
 
 present. Using the above amount of substance, the percentage of 
 sulphur is : 
 
 3. Sulphuric Acid. 
 
 A quantitative determination of the impurities is seldom made 
 except, for example, for storage -battery purposes. The qualitative 
 tests here given for detection of sulphurous acid, hydrochloric 
 acid, and the oxides of nitrogen, lead, iron and arsenic, are accord- 
 ing to the methods of Krauch. 
 
 (# ) Sulphurous acid. To a weak yellow solution of iodine, previ- 
 ously treated with starch paste, the diluted sulphuric acid is added. 
 In presence of sulphurous acid decolorization takes place. Or the 
 sulphurous acid is reduced with zinc or aluminium to hydrogen sul- 
 phide, and the latter detected by means of lead-paper or an alkaline 
 solution of sodium nitroprusside (very delicate). 
 
 (<) Hydrochloric acid. Two grams sulphuric acid are diluted 
 to 30 c.c. and a few drops of a silver nitrate solution are added. 
 Presence of hydrochloric acid is indicated by turbidity. 
 
 (<r) Oxides of nitrogen. A very trustworthy test is the diphenyl- 
 amine test. This is conducted, according to Wagner, in the fol- 
 lowing manner : To i c.c. pure distilled water in a porcelain cap- 
 sule, a few crystals of diphenylamine are added, followed succes- 
 sively by two additions, ^ c.c. each, of the cone, acid under 
 examination. Traces of nitric acid produce a blue coloration after 
 a time. (The same reaction is shown by other oxidizing sub- 
 stances. ) 
 
 (dQ Lead. The acid is mixed with 5 times the volume of 
 strong alcohol. A turbidity after a time indicates the presence of 
 lead sulphate, which is further identified by dissolving the precipi- 
 tate in ammonium acetate, and testing with potassium chromate or 
 hydrogen sulphide. 
 
 (<?) Iron. The acid is boiled with a few drops of nitric acid 
 diluted with a little water. It is allowed to cool, and ammonium 
 sulpho-cyanide is added. A red tint indicates the presence of iron. 
 
 (/) Arsenic. Two grs. cone, sulphuric acid, diluted with an 
 equal volume of water, are warmed with a few pieces of granu- 
 
SULPHURIC ACID AND ANHYDRIDE. 5 
 
 lated zinc until strong evolution of gas begins. A yellow coloration 
 indicates arsenic. Sulphuric acid may contain as high as o. i per 
 cent., and in exceptional cases as high as 0.4 per cent, arsenic. On 
 account of the injurious action of the latter, a quantitative estima- 
 tion is often desirable. For this purpose the following method of 
 Lunge is recommended : 
 
 About 20 grams acid are diluted with an equal volume of water. 
 In order to reduce the arsenic acid present, sulphurous acid is con- 
 ducted into the liquid for some time, until the odor is pronounced. 
 Heat is applied and carbonic acid is conducted in until the odor dis- 
 appears, when carbonate of soda is added to exact neutralization, 
 followed by a small quantity of bicarbonate of soda. The liquid is 
 then titrated with T V normal iodine solution, using starch solu- 
 tion as indicator, (i c.c. iodine solution 0.00495 gr. As. 2 O 3 . ) 
 Any appreciable quantity of iron must previously be removed. 
 
 Fuming Sulphuric Acid and Anhydride. 
 
 Lately there has appeared in commerce fuming sulphuric acid in 
 form of an oily, thick liquid containing a high percentage of SO, 
 (upward of 70 per cent.), or in form of a solid, which is used prin- 
 cipally in the dye industry. Anhydride is a solid mass containing 
 80-90 per cent, free SO S and 10-20 per cent, monohydrate. The 
 analysis is confined principally to the estimation of anhydride and 
 sulphurous acid. In weighing the substance and subsequently dilut- 
 ing, special care is to be observed in preventing on the one hand 
 the absorption of moisture while weighing, and on the other hand 
 in preventing the volatilization of anhydride and sulphurous 
 acid by the heat produced in diluting. The following procedure 
 recommended by Lunge has been found most advantageous : 
 
 The substance is weighed in a thin bulb tube, both ends of which 
 are drawn out to capillaries. The weight of the empty bulb is first 
 ascertained. 3-5 grams of the substance, carefully melted, if neces- 
 sary, in a sand-bath or iron plate, are drawn into the bulb. To 
 effect this a flask with a narrow neck and a caoutchouc stopper with 
 single perforation is used. Through the stopper a tight-fitting glass 
 tube with stopcock issues, over the end of which a rubber tube is 
 drawn. On applying suction with the mouth to this, and then 
 quickly closing the stopcock, a partial vacuum is produced. The 
 
6 CHEMICAL-TECHNICAL ANALYSIS. 
 
 open end of the rubber tube is drawn over the capillary on the 
 bulb, the other end of which is introduced into the liquid to be 
 analyzed. By opening the cock the necessary amount, which, how- 
 ever, should not more than half fill the bulb, is introduced. The 
 capillary is then drawn from the liquid, cleaned, sealed, and 
 weighed in horizontal position. The bulb is now placed open end 
 downward in a small Erlenmeyer flask, whose mouth is closed by 
 the bulb, and which contains sufficient water to deeply immerse the 
 capillary. The sealed end is broken, the liquid is allowed to run 
 out, and the bulb is washed first by washing through the capillary 
 and eventually by drawing water into the entire bulb. When the 
 most concentrated oil (about 70 per cent. ) is used, direct addition 
 to water without loss cannot be accomplished. In this case both 
 ends of the bulb, prepared as above, are sealed, and the bulb is in- 
 troduced into a well-ground glass-stoppered flask, containing con- 
 siderable water. The flask is shaken to break the bulb, and after- 
 wards allowed to stand. The contents of the flask are poured into 
 a graduated flask, diluted to 500 c.c. exactly, and in one portion 
 the total acid is estimated by alkali, while in another the sulphurous 
 acid is titrated with iodine solution.* In the calculation, the result 
 of the titration with caustic soda is expressed in per cent, sulphuric 
 anhydride (a), and that of titration with iodine solution in per cent, 
 sulphurous anhydride (b). The value of (b) is transformed into 
 sulphuric anhydride, and the value (c) so obtained subtracted from 
 a ; the difference (a c) then represents the total amount of sul- 
 phuric anhydride. Moreover, if the sum (a-c) + b be subtracted 
 from 100, the quantity of water of hydration can be ascertained, 
 and the monohydrate present can be calculated in percentage (d). 
 The difference 100 (d + b) yields the percentage of free active 
 anhydride. 
 
 Example. In the examination of a sample of fuming sulphuric 
 acid ther esult of the titration with alkali showed 85.5 percent. 
 SO 3 (a), the titration with iodine 0.6 per cent. SO 2 (b). The 
 value b is changed to SO 3 by the proportion 64 : 80=0.6 : c, and 
 from this c is found to equal 0.75 per cent. The difference a-c= 
 84.75 P er cent - SO 3 . The sum (a-c) 4^=85.3 5 per cent., which 
 
 * In weighing, the stopcock bulb pipettes of Lunge and Rey may also be used 
 to advantage. 
 
NITROSO ACID. 7 
 
 subtracted from 100 gives 14.65 per cent, water of hydration. 
 This, according to the proportion 18 : 981=14.65 : d, corresponds 
 to d 79.76 per cent, monohydrate. There remains, therefore, 
 100 (d + b)=ioo 80.36=19.64 per cent, sulphuric anhydride. 
 
 The acid contains, therefore, 79.76 percent. H 2 SO 4 . 
 
 19.64 " SO 3 . 
 
 0.60 " SO 2 . 
 
 If the fuming sulphuric acid contains no sulphurous acid, the 
 difference roo-a yields the percentage of water of hydration. The 
 quantity of monohydrate corresponding to this value is obtained from 
 the proportion 18 : 98 : : (loo-a) : d, and from the difference 
 100 d the amount of free anhydride is found. 
 
 Nitroso Acid (Nitrated Acid). 
 
 The proportion of total compounds of nitrogen in nitroso acid, a 
 question of great importance in the lead-chamber process, is esti- 
 mated by means of the Lunge nitrometer. The estimation depends 
 on the fact that the acids containing nitrogen, which are dissolved 
 in the sulphuric acid, are reduced by contact with metallic mercury 
 to NO, the amount of which is determined. The nitrometer in its 
 original form presents the following arrangement : The tube (a) 
 (Figure i), divided in ^ or -^ c.cm., is provided with a cup 
 above and has a capacity upward of 50 c.c. Directly below the 
 cup is a three-way cock, whose straight opening establishes commu- 
 nication with the eudiometer, while a second indirect opening allows 
 the contents of the cup to empty through the axis of the stopcock. 
 For this purpose a rubber tube, provided with a screw clamp and a 
 glass tube, is fastened to the stopcock. Finally, the cock can be 
 placed so that the cup communicates with neither opening. 
 
 The tube () is made of strong glass tubing of nearly the same 
 diameter and capacity as (0). Both tubes are attached to a stout 
 rubber tube. The remainder is self-evident. During manipula- 
 tion the tube () is so adjusted that the lower end is somewhat 
 above the stopcock of (0), which is then opened ; mercury is 
 poured into () until the level enters the cup. Since the mercury 
 enters (#) from below, no air-bubbles collect on the glass walls. 
 The cock is closed, the mercury run out of the cup through the side- 
 
CHEMICAL-TECHNICAL ANALYSIS. 
 
 opening, the tube (^) is lowered, and the cock is adjusted to cut 
 off all communication. 
 
 The nitroso acids are now run into the cup from a very small 
 pipette (the stronger acids require 0.5 c.c., the weaker 2-5 c.c.), 
 and the level in the tube (<) is lowered somewhat. The cock is 
 opened, and the acid is allowed to drain into tube (#), care being 
 taken to admit no air. The cup is then rinsed in the same manner 
 twice, first with 2-3 c.c., and again with 12 c.c. absolutely nitroso 
 free, concentrated sulphuric acid. The entire volume of acid intro- 
 duced should not exceed 8-10 
 c.c. Gas evolution is started by 
 removing the tube (0) from its 
 clamp, placing it in an almost 
 horizontal position and suddenly 
 righting a number of times to 
 insure thorough mixture of acid 
 and mercury. It is then shaken 
 for 1-2 minutes until gas evolu- 
 tion ceases. Usually this time 
 suffices. It is allowed to stand 
 until the acid clears, cools off, 
 and the foam disappears, an 
 operation which lasts but a short 
 time. The tube () is raised 
 to bring the mercury level suffi- 
 ciently above that in (a) to cor- 
 respond to the volume of sul- 
 phuric acid in the latter (for 
 every 7 mm. acid i mm. mercury), after which the volume of 
 nitric oxide, which should never exceed 50 c.c., is read off, reduced 
 to o C. and 760 mm. pressure. The calculation of the amount of 
 nitrous oxide is simple, since every c.c. reduced volume equals 
 1.701 mg. N 2 O 3 . Any nitric acid present is thereby also reckoned 
 as N,O S . 
 
 Lunge has prepared tables by means of which the reduced 
 volume, as well as the amount of nitroso acid, may be read off 
 directly. If it should be found desirable, after reading, to ascertain 
 whether the acid column in the eudiometer is compensated for by the 
 
 FIG. i. Lunge's Nitrometer. 
 
NITROSO ACID. 
 
 9 
 
 mercury column in (), the stopcock is opened. Should the level 
 of the acid rise, the pressure was too great. Should it fall, however, 
 the pressure was insufficient. Hence the volume read was in the 
 first instance too small, in the second instance too large. Given, 
 for example, 15.3 c.c., should the acid rise to 15.2 on opening the 
 stopcock, the corrected volume would equal 15. 3 + 0. 1=15. 4 c.c. 
 
 The apparatus is prepared for a new determination by opening 
 the cock and raising the tube (^), thereby forcing out the nitric oxide 
 which enters the cup, followed by the acid containing suspended 
 mercurous sulphate. The moment 
 mercury enters the cup the stop- 
 cock is closed and the acid is al- 
 lowed to issue through the axial 
 perforation. The final traces are 
 removed from the cup with filter- 
 paper, after which the stopcock is 
 re -arranged to prevent communica- 
 tion either way. 
 
 Should a nitroso acid contain an 
 appreciable quantity of sulphurous 
 acid, it is necessary to add to the 
 same in the cup a quantity of potas- 
 sium permanganate. 
 
 The new gasvolumeter of Lunge 
 is preferable to the original nitrome- 
 ter. It differs from the latter prin- 
 cipally in that the decomposition 
 of the nitroso acids and the meas- 
 urement of the gas volume formed do not take place in the same 
 tube, but in separate parts of the apparatus. Further, temperature 
 and pressure readings, as well as the involved calculations, are 
 eliminated in reading the gas volume, and finally the apparatus is 
 useful in a number of other analytical operations. 
 
 As seen in the accompanying illustration (Fig. 2), the one part 
 of the apparatus the reaction vessel, consisting of tubes (.) and 
 (Z>), the stopcock (/) and the cup (//) is very similar to that of 
 the original nitrometer. It differs therefrom, however, in that the 
 tube (/?), used for decomposing the acid, is not graduated, and the 
 
 FIG. 2. Lunge's Gasvolumeter. 
 
10 CHEMICAL-TECHNICAL ANALYSIS. 
 
 stopcock possesses, instead of an axial perforation, a second side- 
 perforation, which establishes communication between the small 
 tube (V) and the tube (Z>). In this part of the apparatus the 
 decomposition of the acid is carried out exactly as before. The 
 second part of the apparatus consists of three tubes (4), (-#), and 
 (C), which are connected with each other by means of a three- 
 way tube. (A~) is a glass measuring tube of 50 c.c. capacity, 
 graduated in ^ c.c. and provided with the double-bored stopcock 
 Qf), which establishes communication of (A} with the straight 
 tube (/), as well as with the rectangular tube (*). () serves 
 as a reduction tube. Under the wide portion, which has a 
 capacity of 100 c.c., the tube, to the extent 100 c.c. to 125 
 c.c., is divided in ^ c.c., and is filled exactly with so much air 
 that the volume of the latter at o and 760 mm. when dry amounts 
 to 100 c.c. The volume V, which represents the space which 
 100 c.c. air at o and 760 mm. pressure would occupy at the observed 
 temperature t and the pressure b, is found by the following equa- 
 
 tion: V= v 73~r ; ; ^ One drop of cone, sulphuric acid 
 
 is now introduced into (} ; mercury is poured in the tube ( C ) until 
 the mark in (J?), representing the volume F, is reached, when it is 
 closed by either carefully sealing the latter, care being taken not to 
 warm (j9), or by closing a previously attached tight-fitting stopcock. 
 The decomposition of the nitroso acid is then carried out in the 
 reaction tube as previously described, and after (A) has been filled 
 completely with mercury to the end of the small tube (/), by 
 raising (C), the tubes (^) and (A) are placed side by side and 
 ( C ) is connected by means of a rubber tube with (<?) in such a 
 manner that the two touch each other glass to glass without enclos- 
 ing air between them. {E} is then raised, (C) is lowered, the 
 stopcocks (/) and (g) are opened, and at the moment that the 
 pressure has driven all the gas over into (A) and the acid issues 
 from (Z>) through (V) and (/) to the stopcock (#), the latter is 
 closed, together with (/), and (JD} and (A) are disconnected. (C) 
 is now raised until the mercury in (J?) rests at precisely 100. By 
 
 * In very exact determinations, I mm. is subtracted for values of / up to 12 ; 
 2 mm. for values from 13-19, and 3 mm. for values from 20-25, to a U w for ex- 
 pansion of the mercury. 
 
BRINE. 11 
 
 means of a double clamp-holder (C) and (^5) are moved up or 
 down in concert until the mercury in (^4) and (jff) reaches the 
 same level, but simultaneously, however, remains at 100 in (^9). 
 Since the gas in (.#) is so far compressed as to occupy the same 
 volume as at o and 760 mm. pressure, the readings in (A) repre- 
 sent the gas reduced to the same normal condition. The tempera- 
 ture in (A") and (^) is supposed to be the same, a condition quickly 
 produced by the mercury. Ten minutes are required before 
 the final adjustment of the apparatus, when large quantities of 
 nitric oxide are used. By the use of these particular reaction tubes, 
 the inconveniences of foam and slime and the compensation for an 
 acid column are avoided. The eudiometer remains clean, in conse- 
 quence of which a large number of determinations can be under- 
 taken without constant cleaning. 
 
 6. Brine. 
 
 The following determinations are usually carried out : 
 
 Specific gravity, total chlorine, sulphuric acid, ferric oxide, 
 alumina, lime, magnesia, and carbonic acid. In addition, qual- 
 itative tests for potassium, bromine and iodine are made, and some- 
 times these constituents are determined quantitatively. 
 
 (a) Specific gravity. This is determined by means of the 
 pyknometer in the usual manner. 
 
 () Total chlorine. 10 c.c. brine are diluted to 1000 c.c. A 
 gravimetric or volumetric determination of chlorine in 25 c.c. is 
 made. 
 
 (c) Sulphuric acid. To 50 c.c. brine a few drops of hydrochloric 
 acid are added. (Sodium chloride is precipitated in this instance 
 from the very concentrated brine solution.) One to two volumes 
 of water are added, and the hot solution is precipitated with barium 
 chloride. 
 
 (//) Ferric oxide and alumina. 250 c.c. brine, previously heated 
 with a small quantity of nitric acid, are precipitated after addition 
 of ammonium chloride with ammonia. The precipitate, of which 
 there is usually a small quantity, is filtered, and both constituents 
 are weighed together. The presence of iron can be ascertained 
 previously in a separate portion of the brine, oxidized with nitric 
 acid, by the addition of ammonium sulpho-cyanide. 
 
12 CHEMICAL-TECHNICAL ANALYSIS. 
 
 (?) Lime is precipitated with ammonium oxalate in the filtrate 
 from d. The precipitate is treated in the usual manner. 
 
 (/) Magnesia. To the filtrate from the lime sodium hydrogen 
 phosphate is added. The precipitate which forms is weighed as 
 magnesium pyrophosphate. 
 
 () Carbonic acid. 1-2 drops methyl-orange are added to ^ 
 liter brine. The solution is then titrated with ^ normal hydro- 
 chloric acid to red coloration. (2HC1 = iCO 2 .) 
 
 (Ji) Potassium, bromine and iodine. The qualitative tests for 
 these three bodies can be carried out in the following manner : 
 
 A large quantity of the brine is evaporated to y$ its original vol- 
 ume. Any salt which separates is filtered off or thoroughly drained. 
 The filtrate is again evaporated, and any salt which separates is 
 removed as before. The mother-liquor is then divided into two 
 portions. In the one, by means of platinic chloride, a test is made 
 for potassium, which is precipitated in form of yellow crystalline 
 potassium -platinic chloride. To the other solution, which must be 
 frequently agitated, chloroform and chlorine-water, drop by drop, 
 are added. Iodine will first be precipitated a fact readily noticed 
 by the violet color of the chloroform. Later, bromine is recog- 
 nized by the lemon or yellow color imparted to the chloroform 
 layer. 
 
 The quantitative estimation of these three bodies will not be 
 described here. 
 
 The results found are arranged according to the same principles 
 which will be considered later under the determination of the more 
 exact composition of boiler-water. 
 
 7. Crude Hydrochloric Acid. 
 
 This substance may contain as impurities : sulphuric acid, sul- 
 phurous acid, chlorine, arsenic and iron compounds, alumina, lime, 
 alkali metals, hydrobromic acid and hydriodic acid. 
 
 The chlorine is usually to be attributed to the presence of nitrous 
 acid in the sulphuric acid. Arsenic and iron compounds arise from 
 the crude sulphuric acid. Qualitative tests for these various impu- 
 rities are made by the usual method. (See also Sulphuric Acid.) 
 
 For the qualitative estimation of arsenic Krauch recommends the 
 following procedure: To i.o gr. hydrochloric acid, diluted with 10 
 
SODA. 13 
 
 c.c. water, 5 c.c. freshly -prepared hydrogen sulphide water are care- 
 fully added, so as to form a supernatant layer. In the absence of 
 arsenic no coloration and no yellow ring should form between the 
 two liquids when warm or cold. 
 
 Of the quantitative determinations particular attention is called to 
 those of arsenic, iron and sulphurous acid. 
 
 (a) Arsenic. In order to reduce any arsenic acid present, sul- 
 phurous acid is conducted into the solution for a protracted period. 
 The latter, after expulsion of the sulphurous acid, is saturated with 
 hydrogen sulphide, when arsenic is precipitated as trisulphide. The 
 precipitate is filtered, thoroughly washed, dissolved from the filter 
 with ammonia, and evaporated in a weighed glass or porcelain dish, 
 after which the trisulphide remaining is dried at 100 and weighed. 
 
 () Iron. A measured quantity of the acid is treated with zinc, 
 free from iron, in a current of carbonic acid, in order to reduce all 
 the iron present. To the copiously diluted acid a 20 per cent, 
 solution of manganous chloride or sulphate is then added, and the 
 liquid is titrated with an accurately standardized, about ^ normal, 
 potassium permanganate solution. 
 
 (c) Sulphurous acid. This is oxidized with permanganate, 
 iodine or hydrogen peroxide to sulphuric acid, and precipitated with 
 barium chloride. Sulphuric acid originally present must likewise 
 be estimated and subtracted from the above. 
 
 8. Soda. 
 
 At present soda is derived principally from two well-known pro- 
 cesses the Le Blanc and the ammonia soda process. That from the 
 former may contain, as chief impurities : sodium sulphate, sodium 
 chloride, sodium silicate, sodium aluminate, sodium hydrate, sodium 
 sulphide, sodium sulphite, ferric oxide, calcium carbonate, silica 
 and carbon. Ammonia soda is mostly very pure, and contains as a 
 rule only sodium chloride (^ to about 2^ percent.), at times 
 sodium bicarbonate, and at the most only traces of sodium hydrate. 
 At the same time it must be admitted that at present the Le Blanc 
 soda comes into commerce in a very pure state on account of the 
 general demand for soda containing not more than 0.4 per cent, 
 matter insoluble in water, o.i per cent, matter insoluble in hydro- 
 chloric acid, and about 0.02 percent, ferric oxide. 
 
14 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Following are the methods of investigation for technical soda 
 selected with regard to its possible impurities. It is hardly neces- 
 sary to state that the simultaneous presence of many of the impuri- 
 ties cited, such as hydrate and bicarbonate of soda, for instance, is 
 excluded. It is an advantage to find out qualitatively the presence 
 of individual constituents such as sodium hydrate, sodium sulphide, 
 and sodium sulphite. 
 
 The qualitative examination for sodium hydrate is similar to the 
 quantitative. The soda solution is precipitated with an excess of 
 barium chloride, and the filtrate is tested for alkali by means of 
 litmus or phenol-phthalein. The presence of sulphide of soda is 
 determined by means of an alkaline solution of sodium nitroprus- 
 side or lead-paper. To test for sodium sulphite a sample is acidified 
 with acetic acid, starch paste is added, and notice is taken whether 
 a slowly-added dilute iodine solution is decolorized. 
 
 Quantitative Examination. 
 
 53 grs. soda (corresponding to one-half the molecular weight) are 
 first dissolved in warm water in a large beaker glass, allowed to 
 stand for ^ hour, and then filtered through a dried and weighed 
 filter into a liter flask. After washing the filter the flask is filled to 
 the mark. The residue is dried at 100 to constant weight, which 
 represents the matter " insoluble in water." Should a more thor- 
 ough examination of this be necessary, the filter is again moistened 
 with water and lixiviated with hot dilute hydrochloric acid. Ferric 
 oxide, alumina, calcium carbonate and magnesium carbonate are 
 dissolved. If the filter now be washed, dried and weighed, it will 
 contain the silica and carbon. By ignition of the filter the carbon 
 is burned off, and the ash which is weighed consists only of silica. 
 In the acid filtrate iron only is usually quantitatively estimated. To 
 accomplish this ammonia is added, and the resulting ferric hydrate 
 is dissolved in i : 4 sulphuric acid, reduced with zinc and titrated 
 with permanganate. The remainder of the insoluble matter, after 
 deducting ferric oxide, silica and carbon, may be considered as cal- 
 cium carbonate. 
 
 Examination of the Aqueous Solution. 
 
 (a) Total active soda (with acid). 50 c.c. solution, representing 
 2.65 grs. soda, are titrated with hydrochloric acid (preferably ^ 
 
SODA. 15 
 
 normal), with addition of methyl -orange, and the result is calculated 
 as sodium carbonate. This includes as sodium carbonate sodium 
 hydrate, sodium sulphide, sodium sulphite, sodium silicate, sodium 
 aluminate, and finally sodium bicarbonate. 
 
 (<) Sodium sulphate. 50-100 c.c. solution are acidified slightly 
 with hydrochloric acid, and the hot solution is precipitated with 
 barium chloride. 
 
 (<r) Sodium chloride. 20-50 c.c. solution are acidified with 
 nitric acid and precipitated with silver nitrate. The presence of 
 considerable quantities of sodium sulphide will influence the accu- 
 racy. 
 
 (X) Sodium hydrate. 100 c.c. soda solution are mixed in a large 
 beaker with a few drops of phenol-phthalein and 150 c.c. of a 10 per 
 cent, barium chloride solution. The solution is copiously diluted 
 and titrated with Tnth normal oxalic acid. Previous filtration is 
 unnecessary. 
 
 (<?) Sodium sulphide. TOO c.c. solution are brought to boiling, 
 and after the addition of ammonia an ammoniacal silver solution is 
 added drop by drop until no further precipitation of silver sulphide 
 ensues. In order to aid this observation the solution is filtered near 
 the end of the operation, and the filtrate is titrated further. This 
 is repeated until only a slight turbidity appears in the filtrate. To 
 prepare the ammoniacal silver solution 13.845 grs. pure silver are 
 dissolved in pure nitric acid, 250 c.c. ammonia are added to the 
 solution, and the whole is diluted to one liter. Every c.c. of this 
 solution represents 0.005 S T - Na.^S. 
 
 (/) Sodium sulphite. 100 c.c. soda solution are acidified with 
 acetic acid, starch paste is added, and the solution is titrated with 
 Tfrth normal iodine solution until the blue coloration appears. 2 
 atoms iodine represent i molecule sodium sulphite, or i c.c. iodine 
 solution = 0.0063 gr. Na.,SO 3 . The sodium sulphide found in (i) 
 calculated into sodium sulphite must be subtracted from this re- 
 sult. 
 
 (g) Sodium silicate and sodium aluminate. 100 c.c. solution are 
 acidified in a spacious porcelain dish with hydrochloric acid and 
 evaporated to dryness. The silica is separated as usual, and in the 
 filtrate the alumina is determined by precipitation with ammonia. 
 
 (^) Bicarbonate. The estimation depends on the fact that 
 
16 CHEMICAL-TECHNICAL ANALYSIS. 
 
 bicarbonate is changed to normal carbonate by the addition of 
 caustic soda. If, therefore, an excess of titrated caustic soda be 
 added to the soda solution, the carbonate be precipitated with 
 barium chloride, and the excess of sodium hydrate be titrated, then 
 the amount of hydrate used represents the quantity of bicarbonate 
 present ; in fact, i molecule sodium hydrate is equivalent to i mole- 
 cule bicarbonate according to the equation 
 
 Na H CO 3 +Na OH=Na 2 CO 3 +H 2 O. 
 
 To conduct this, a separate portion of the soda (about 5 grs.) is 
 weighed and dissolved in a beaker of about i liter capacity, with 
 100 c.c. water which has been previously boiled and cooled to 15- 
 20. Agitation and warming the solution are to be avoided, since 
 the bicarbonate will lose carbonic acid thereby; on the other 
 hand, by crushing the soda in the vessel solution may be acceler- 
 ated. 25 c.c. y?, normal sodium hydrate solution are now added, 
 followed by 150 c.c. 10 per cent, barium chloride and a few drops 
 of phenol -phthalein. About 500 c.c. distilled water are added, 
 and the excess of alkali is titrated with ^ normal oxalic acid. 
 
 Since sodium hydrate usually contains carbonate, 25 c.c. are 
 simultaneously diluted with 100 c.c. water, 150 c.c. barium 
 chloride, and a few drops of phenol phthalein are added, and the 
 solution titrated with ^ normal oxalic acid. Should 24.75 c - c - 
 oxalic acid (instead of 25) be required, they will represent the 
 actual amount of caustic soda in the solution. 
 
 Calculation. If 5 grs. soda were taken, and in titrating 13.5 
 c.c. ^ normal oxalic acid were used, then 24.75 I 3-5 rr:I1 - 2 5 
 c.c. y?, normal oxalic acid, required by the bicarbonate. These 
 correspond to 0.02 X 11.25 0. 225 gr. caustic soda. According 
 to the proportion 4o(NaOH) : 84(NaHCO 3 ) = 0.225 : x, x 
 0.4725 gr. NaHCO 3 or 9.45 per cent, bicarbonate. 
 
 (*') Moisture. This important determination is conducted by 
 heating about 2 grs. soda in a platinum crucible at a low heat, and 
 determining the consequent loss in weight. Any bicarbonate pres- 
 ent is thereby decomposed. In the same manner silica will expel 
 an equivalent quantity of carbonic acid. On account of the com- 
 paratively small error produced, simple desiccation over concen- 
 trated sulphuric acid is also recommended. 
 
SODIUM ALUMINATE. 17 
 
 Freshly -prepared soda should not contain more than J^-^ per 
 cent, moisture. Even well-preserved soda, after some time, should 
 not contain much over i per cent. Stored in moist air, however, 
 the quantity of moisture can rise to 10 per cent. 
 
 Arrangement of the Analytical Results. 
 
 When the insoluble constituents are determined only to the extent 
 mentioned, the calculation is very simple. The amounts of soda 
 corresponding to caustic soda, sodium sulphide, sodium sulphite, 
 sodium bicarbonate furthermore, sodium silicate (Na 2 SiO 3 ) and 
 sodium aluminate (Na 2 Al. 2 O 4 ) are calculated into sodium carbonate, 
 and the sum of these is subtracted from the results obtained under 
 (a). In this manner the true amount of sodium carbonate is ob- 
 tained. This could also be done by a direct estimation of the 
 carbonic acid and subsequent calculation into carbonate of soda a 
 process often preferred. The strength of a soda is expressed in 
 degrees. German degrees represent the strength expressed as car- 
 bonate of soda ; French, or Gay-Lussac, as oxjde of sodium. Des- 
 croizilles degrees show how many parts by weight of sulphuric acid 
 (H.,SO 4 ) are neutralized by 100 parts soda. These degrees bear the 
 following relation to one another: 53.04 German degrees equal 
 31.04 Gay-Lussac or 49 Descroizilles degrees. 
 
 9. Sodium Aluminate. 
 
 This contains, besides its two constituents, small quantities of 
 matter insoluble in water, silica and traces of iron, which are deter- 
 mined in the usual manner. 
 
 The estimation of soda and alumina is carried out volumetrically 
 by the method of Lunge. The method is based on the following 
 process : If to a solution of sodium aluminate hydrochloric acid be 
 added, the soda is neutralized and alumina begins to separate. 
 This is explained by the following reaction : 
 
 Na. 2 OAl 2 3 + 2HC1 + 2 H 2 O = 2 NaCl + A1 2 (OH) 6 . 
 
 Were phenol -phthalein present, the color would disappear as soon 
 as the soda was neutralized. The quantity of acid used, therefore, 
 is a fneasure for the amount of soda present ; in fact, 2 molecules 
 hydrochloric acid correspond to i molecule sodium oxide, or when 
 
 2 
 
18 CHEMICAL-TECHNICAL ANALYSIS. 
 
 YZ normal hydrochloric acid is used, i c.c. of the latter corresponds 
 to 0.0155 gr., Na 2 O. 
 
 If the addition of hydrochloric acid be continued in the presence 
 of methyl -orange as indicator, a permanent red coloration sets in 
 only when all the alumina has redissolved. Hence, according to 
 the formula, 
 
 A1 2 (OH) 6 + 6HC1 = A1 2 C1 6 + 3H. 2 O, 
 
 6 molecules hydrochloric acid are used for every molecule of alu- 
 mina, i c.c. % normal hydrochloric acid, therefore, corresponds 
 to 0.0085 g r - alumina. 
 
 To accomplish this about 0.5 gr. sodium aluminate is dissolved 
 in hot water and titrated to decolorization with ^ normal hydro- 
 chloric acid, using phenol-phthalein as indicator. The acid used is 
 recorded, 12 drops methyl -orange are added, and the solution is 
 titrated with the same acid until it assumes a permanent red color. 
 The calculation of the amount of sodium oxide and alumina is ex- 
 plained by the above statements. 
 
 10. Weldon Mud. 
 
 The investigation of the starting-products for the manufacture of 
 chlorine, pyrolusite, as well as bleaching-lime, is supposed to be 
 known. On the other hand, the examination of Weldon mud 
 according to the procedure of Lunge will be described more fully. 
 In this the amount of manganese dioxide, the total manganese and 
 the " basis" are determined. 
 
 (a) Manganese dioxide. An acid ferrous iron solution, contain- 
 ing 100 grs. crystallized ferrous sulphate (or the equivalent amount 
 of ferrous double salt), and 100 c.c. pure concentrated sulphuric 
 acid to the liter, is accurately titrated with one half normal perman- 
 ganate solution. Thereupon, 25 c.c. iron solution are measured off 
 into a beaker by means of a glass pipette. Ten c.c. of the well-agi- 
 tated mud are drawn into a pipette, the latter is washed externally, 
 the contents are placed with the iron solution in the beaker, and the 
 adhering mud is washed out into the latter. When all has dis- 
 solved, on agitation, about 100 c.c. water are added, and the solu- 
 tion is then titrated with the permanganate solution. Let the 
 amount of the latter solution y, the amount of permanganate 
 
WELDON MUD. 19 
 
 used in titrating 25 c.c. iron solution = x; then the amount of 
 manganese dioxide per liter is found to be : 
 
 2-175 (x-y)- 
 
 (^) Total manganese. Ten c.c. mud, drawn off as in (a), are 
 boiled with cone, hydrochloric acid until chlorine has disappeared. 
 Precipitated chalk is then added to neutralize the excess of acid. 
 A cone, filtered bleaching-lime solution is added, and the mass is 
 boiled for several minutes, after which the red color which appears 
 is removed by the careful addition of alcohol. All the man- 
 ganese is precipitated as dioxide.* This is filtered off and 
 washed until the filtrate no longer reacts with potassium iodide- 
 starch paper. The precipitate, on the filter, is added to 25 c.c. of 
 the acid iron solution, and if all the dioxide refuses to dissolve, an 
 additional 25 c.c. are added. One hundred c.c. water are added, 
 followed by titration with permanganate. The calculation carried 
 out as under (cf) gives the total manganese in the form of dioxide. 
 
 (c) Basis. By this term is understood the monoxides, etc. , con- 
 tained in the mud, which react with hydrochloric acid, but do not 
 generate chlorine. 
 
 Twenty-five c.c. (with very high basis, 50 c.c.) normal oxalic 
 acid solution are diluted to about xooc.c. and heated to 60-80 C. 
 10 c.c. manganese mud are added with the above precautions, and 
 the solution is shaken until the precipitate is a pure white, with no 
 yellow tinge, a change which takes place rapidly at the above tem- 
 perature. The solution is diluted to 202 c.c. (2 c.c. correspond to 
 the volume of precipitate, and are marked on a 200 c.c. flask) and 
 100 c.c. of the filtrate are titrated back with sodium hydrate, using 
 phenol phthalein as indicator. The number of c. c. sodium hydrate 
 solution used = z, and therefore for the original solution = 2z. 
 
 The oxalic acid (i) decomposes the manganese dioxide, yielding 
 manganous oxide and carbonic acid; (2) binds the manganous 
 oxide liberated; (3) saturates the monoxides, including manganese 
 oxide originally present ; (4) forms an excess = 2z. The quanti- 
 ties of oxalic acid used in i and 2 are the same, and together equal 
 
 * When completely precipitated, the filtrate will not turn brown on adding 
 bleaching-lime solution. 
 
20 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the value x y in (#), since the oxalic acid is normal, but the per- 
 manganate only half normal. The value 3 represents the original 
 amount of oxalic acid used, less the quantity (x y) used in i and 2, 
 and the excess 2z. It is therefore equal to: 25 x -f- y 2z 
 respectively 50 x -f y 2z. 
 
 By " basis" is understood the relation of the value of 3 to a, 
 
 v -y 
 
 the latter expressed by * (since the alkali is normal and the 
 
 permanganate one -half normal). 
 
 When 25 c.c. oxalic acid are used, therefore, it = 
 
 25 x -f y 2z 50 2X -f 2y 4z _ 50 4Z 
 x y x y x y 
 
 2 
 
 and when <o c.c. oxalic acid are used 2 
 
 x y 
 
 Boiler- Water. 
 
 The complete analysis of a water used for technical purposes 
 embraces the following determinations : Total solids, silica, ferric 
 oxide, alumina, lime, magnesia, alkali, chlorine, sulphuric acid, 
 carbonic acid and nitric acid. In addition to these, nitrous 
 acid and ammonia may be qualitatively tested for. If necessary 
 the water is filtered through a dry filter before the analysis. 
 
 (a} Total solids. 500 1000 c.c. water are evaporated in a 
 weighed platinum dish and the residue is dried at 160 180, to ap- 
 proximately constant weight. It may be remarked, however, that 
 on account of the ready decomposition of magnesium salts, partic- 
 ularly magnesium chloride, on the one hand, and the difficulty en- 
 countered in completely expelling all the water of crystallization 
 from gypsum and calcium chloride, on the other hand, the results 
 are never concordant. 
 
 (<) Silica, ferric oxide, alumina, lime, and magnesia. 
 
 One liter (sometimes more) water is evaporated, with hydrochloric 
 acid, in a porcelain dish ; the silica is separated, ammonium chloride 
 is added, and the iron and alumina are precipitated with ammonia. 
 
 In presence of a large quantity of magnesia the precipitate is 
 dissolved, re-precipitated, and both constituents are ignited and 
 weighed together. 
 
 In the filtrate the lime is precipitated with ammonium oxalate. 
 
BOILER-WATER. 21 
 
 The precipitate is then carefully heated in a porcelain crucible 
 until the evolution of carbonic acid ceases, and is then ignited over 
 a blast-lamp to constant weight, and weighed as calcium oxide. 
 The magnesia is then precipitated in the nitrate with sodium hydro- 
 gen phosphate in the usual manner. 
 
 (c) Alkalies. These are determined indirectly in the total solids 
 by weighing the sulphate residue. For this purpose the solids are 
 ignited at a low heat in the platinum dish, and then dissolved in 
 dilute hydrochloric acid under cover of a watch-glass. The mass 
 is finally evaporated with 10-12 drops concentrated sulphuric acid, 
 and after expelling the acid it is ignited and weighed. 
 
 If then the sum of the lime and magnesia, previously determined 
 and calculated into sulphates, plus the quantities of silica, ferric 
 oxide and alumina found, be subtracted from the sulphate residue, 
 there remain the alkali sulphates present, which are considered as 
 sodium sulphate and are calculated into sodium oxide. 
 
 (d) Chlorine. Depending on the result of a qualitative test, 
 i^-i liter water, after concentration, is acidified with nitric acid 
 and precipitated in the usual manner with silver nitrate. 
 
 (e) Sulphuric acid. % i liter water, acidified with hydrochloric 
 acid, and, if necessary, concentrated, is precipitated with barium 
 chloride in the usual manner. 
 
 (/") Carbonic acid. The combined carbonic acid present is 
 estimated in ^-i liter by adding methyl -orange and titrating to 
 red coloration with iV normal hydrochloric acid. The calculation 
 is made as normal carbonate ; hence 2HC1 = iCO 2 . The estima- 
 tion of free carbonic acid in a technical analysis may be omitted. 
 
 (g) Nitric acid. The qualitative test is best made with the di- 
 phenylamine reaction. (See Sulphuric Acid.) For quantitative esti- 
 mation the method of Schulze-Tiemann is best employed. In this, 
 by means of ferrous chloride and hydrochloric acid, the nitric acid 
 is reduced to nitric oxide, and the latter is determined volumetric- 
 ally. The details are too well known to describe.* 
 
 The qualitative test for nitrous acid, of which only minute quan- 
 tities are present, is best made by the reaction of Griess. A small 
 quantity of sulphanilic acid solution (5 grs. in 150 c.c. dilute acetic 
 
 * See also Fresenius, Quantitative Analysis, Vol. II., p. 155. 
 
22 CHEMICAL-TECHNICAL ANALYSIS. 
 
 acid) is added to a small quantity of the water in a test-tube and 
 warmed to 80, when a solution of a-napthylamine (.05 gr. in 150 
 c.c. dilute acetic acid) is added. In the presence of nitrous acid a 
 red coloration ensues either immediately or after a few minutes. 
 
 To test for ammonia qualitatively about 5 c.c. Nessler's reagent* 
 are added to 100 c.c. water, and the change noticed from above 
 down through the liquid. Ammonia causes a yellow coloration. 
 When the water is very hard or chalybeate, it is better to precipitate 
 first with pure caustic soda and subsequently examine the filtrate. 
 
 Arrangement of results. Chlorine is bound to sodium and any 
 remainder to calcium. Sulphuric acid is bound to lime, nitric acid 
 to ammonia, any residue to sodium, providing the chlorine has not 
 fully used up the latter, otherwise to magnesia. The remaining 
 lime and magnesia are bound to carbonic acid in the form of 
 carbonates. 
 
 Silica is expressed as such. 
 
 Shorter Procedure. 
 
 It is often desirable to circumvent the execution of a complete 
 analysis by the use of a shortened procedure, which allows a more 
 or less complete insight into the composition of a water. 
 
 As such the method of Kalmann and the direct determination of 
 hardness according to Clark are described. 
 
 The method of Kalmann limits itself to the following determi- 
 nations : 
 
 (a) Combined carbonic acid. This is ascertained by the process 
 described under (/) in the complete analysis. 
 
 (V) Lime. This is determined by the direct precipitation of a 
 measured volume of water by means of ammonium oxalate. The 
 separation of the silica, ferric oxide and alumina is not necessary. 
 
 (?) Magnesia is determined in the filtrate from (&} by the usual 
 precipitation with sodium hydrogen phosphate. 
 
 The various results are reckoned on i liter water. On the basis 
 
 * To prepare this, 50 grs. potassium iodide are dissolved in 50 c.c. hot water 
 and to it is added a hot concentrated mercuric chloride solution until the precipi- 
 tate of mercuric iodide formed no longer dissolves. The solution is filtered, 150 
 grs. caustic potash in concentrated solution are added, and the whole is diluted to 
 one liter. An additional 5 c.c. mercuric chloride solution are added, the solution 
 is allowed to settle, and the clear supernatant liquid is poured off. 
 
BOILER-WATER. 23 
 
 of these results the preparation of water for technical uses can be 
 made. This will subsequently be described more fully. 
 
 Estimation of hardness according to Clark. The hardness of a 
 water depends on the amount of calcium and magnesium salts present. 
 It is divided into temporary hardness, due to bicarbonates of calcium 
 and magnesium, which disappears in consequence of the precipita- 
 tion of the insoluble monocarbonate when the water is boiled, and 
 permanent hardness, which is due to any remaining calcium and 
 magnesium salts. Temporary and permanent hardness represent 
 the total hardness of water. 
 
 The hardness of water is expressed in degrees which are distin- 
 guished as German, French and English degrees of hardness. The 
 German degrees represent the number of milligrammes calcium 
 oxide in 100 c.c. water. Any magnesium oxide is hereby reck- 
 oned in the form of the equivalent amount of calcium oxide. 
 French degrees state the equivalent amount of calcium carbonate, 
 whereas English degrees of hardness express the number of milli- 
 grammes calcium carbonate contained in 70 parts water. German, 
 French and English degrees of hardness stand in the ratio of .56 : 
 11.70. As a rule, the result is expressed in German degrees. 
 
 The method of Clark depends on the fact that soap solutions pre- 
 cipitate all calcium and magnesium salts in the form of insoluble 
 soaps. A slight excess of soap is recognized by the permanent 
 lather formed on the liquid on shaking. 
 
 Preparation of the normal soap solution. 10 grs. finely-shaved 
 Marseilles soap are dissolved in i liter 95 per cent, alcohol. The 
 solution is filtered, and to every 200 grs. solution a mixture of 150 
 c.c. water and 130 grs. alcohol, above strength, is added. The 
 solution so obtained is now standardized in such a manner that 45 
 c.c. correspond to 12 degrees hardness. To accomplish this a 
 solution of normal hardness is prepared which contains 12 mg. 
 calcium oxide in 100 c.c. or an equivalent quantity of barium oxide. 
 Such can be made by dissolving .3686 gr. selenite (CaSO 4 +2H 2 O) 
 or .523 gr. pure crystallized barium chloride in i liter distilled 
 water. To 100 c.c. of this hard water in a glass-stoppered flask of 
 about 200 c.c. capacity, the soap solution is added from a burette 
 until a thick froth lasting five minutes just forms on the surface on 
 shaking. Should less than 45 c.c. of the soap solution be used, as 
 
24 CHEMICAL-TECHNICAL ANALYSIS. 
 
 is usually the case, then from the result obtained in the titration 
 the dilution of the alcohol and water soap mixture, necessary to bring 
 the solution to the required strength, is calculated. After the proper 
 dilution a second titration is made. Should this not yield the de- 
 sired result, the above process is repeated. 
 
 Determination of the hardness. For every determination 100 
 c.c. of the water must be used. However, since the soap solution 
 is suitable only for waters possessing a hardness up to 12, and 
 since also the end reaction is more easily recognized in waters mod- 
 erately hard, it is advisable to use only 50 c.c. of a very hard 
 water and dilute the same with distilled water to 100 c.c. The 
 water is placed in a stoppered flask as before, the soap solution 
 is then added from a burette, and the liquid is shaken. In the 
 place of the above-mentioned end reaction, Kalmann calls atten- 
 tion to the nature of the lather and the perceptible sound pro- 
 duced on shaking. The lather should remain firm, that is, the 
 bubbles should not break immediately after shaking. The sound 
 becomes dull and is not as clear as that produced by water enclosed 
 in glass. 
 
 It often happens that after binding the lime with the fatty acids 
 of the soap, the froth becomes firm and the sound becomes muf- 
 fled. The reading is made at this point, and more soap solution is 
 added. No further change should take place if the end reaction 
 has been reached. When the hardness due to magnesia is not yet 
 neutralized, the bubbles will again become frail and the sound clear. 
 In this case the titration is carried further until the end reaction 
 is reached. The phenomenon is so characteristic that at times it 
 permits of an approximately quantitative estimation of lime and 
 magnesia. 
 
 Since the relation is not constant between soap solution used and 
 hardness, use must be made of the following table. The hardness 
 found is to be estimated on 100 c.c. of the original water. 
 
 The method of Clark gives the total hardness. Should it be nec- 
 essary to determine also the temporary hardness, ^-i liter water 
 is titrated with T V normal hydrochloric acid, using methyl -orange 
 as indicator, and the amount of acid used is computed as lime. The 
 amount of lime in 100 c.c. represents the total hardness. The per- 
 manent hardness is gotten by difference. 
 
BOILER-WATER. 
 
 25 
 
 Table of German Degrees.* 
 
 c.c. 
 Soap- 
 solution. 
 
 Hard- 
 ness. 
 
 c.c. 
 Soap- 
 solution. 
 
 Hard- 
 ness. 
 
 c.c. 
 Soap- 
 solution. 
 
 Hard- 
 ness. 
 
 c.c. 
 Soap- 
 solution. 
 
 Hard- 
 
 ness. 
 
 c.c. 
 Soap- 
 solution. 
 
 Hard- 
 ness. 
 
 1.8 
 
 O. I 
 
 ii. 3 
 
 2-5 
 
 20.4 
 
 4.9 
 
 29.1 
 
 7-3 
 
 37-4 
 
 9-7 
 
 2.2 
 
 0.2 
 
 it- 7 
 
 2.6 
 
 20.8 
 
 S-o 
 
 29-5 
 
 7-4 
 
 37-8 
 
 9-8 
 
 2.6 
 
 o-3 
 
 12. I 
 
 2-7 
 
 21.2 
 
 5-1 
 
 29.8 
 
 7-5 
 
 38.1 
 
 9.9 
 
 3-o 
 
 0.4 
 
 12.4 
 
 2.8 
 
 21.6 
 
 5-2 
 
 30.2 
 
 7-6 
 
 38.4 
 
 10.0 
 
 3-4 
 
 o-5 
 
 12.8 
 
 2. 9 
 
 21. 9 
 
 5-3 
 
 30.6 
 
 7-7 
 
 38.8 
 
 10. I 
 
 3-8 
 
 0.6 
 
 13.2 
 
 3-o 
 
 22. 3 
 
 5-4 
 
 30-9 
 
 7-8 
 
 39-i 
 
 10.2 
 
 4.2 
 
 0.7 
 
 13.6 
 
 3-1 
 
 22.6 
 
 5-5 
 
 31-3 
 
 7-9 
 
 39-5 
 
 I0. 3 
 
 4-6 
 
 0.8 
 
 14.0 
 
 3-2 
 
 23.0 
 
 5-6 
 
 31-6 
 
 8.0 
 
 39-8 
 
 10.4 
 
 5-o 
 
 0.9 
 
 14.3 
 
 3-3 
 
 23-3 
 
 5-7 
 
 32.0 
 
 8.1 
 
 40.1 
 
 10-5 
 
 5-4 
 
 .0 
 
 14.7 
 
 3-4 
 
 23-7 
 
 5-8 
 
 32.3 
 
 8.2 
 
 40.5 
 
 10.6 
 
 5-8 
 
 .1 
 
 15.1 
 
 3-5 
 
 24.0 
 
 5-9 
 
 32.7 
 
 8-3 
 
 40.8 
 
 10.7 
 
 6.2 
 
 .2 
 
 15-5 
 
 3-6 
 
 24.4 
 
 6.0 
 
 33- 
 
 8.4 
 
 41.2 
 
 10.8 
 
 6.6 
 
 3 
 
 15.9 
 
 3-7 
 
 24.8 
 
 6.1 
 
 33-3 
 
 8.5 
 
 41-5 
 
 10.9 
 
 7.0 
 
 4 
 
 16.2 
 
 3-8 
 
 25-1 
 
 6.2 
 
 33-7 
 
 8.6 
 
 41.8 
 
 II. 
 
 7-4 
 
 5 
 
 16.6 
 
 3-9 
 
 25-5 
 
 6-3 
 
 34-0 
 
 8.7 
 
 42.2 
 
 11. i 
 
 7.8 
 
 .6 
 
 17.0 
 
 4.0 
 
 2 5 .8 
 
 6-4 
 
 34-4 
 
 8.8 
 
 42-5 
 
 II. 2 
 
 8.2 
 
 7 
 
 17.4 
 
 4-i 
 
 26.2 
 
 6.5 
 
 34-7 
 
 8.9 
 
 42.8 
 
 H-3 
 
 8.6 
 
 .8 
 
 17.7 
 
 4.2 
 
 26.6 
 
 6.6 
 
 35- 
 
 9.0 
 
 43-1 
 
 ii. 4 
 
 9.0 
 
 9 
 
 18.1 
 
 4-3 
 
 26.9 
 
 6-7 
 
 35-4 
 
 9.1 
 
 43-4 
 
 ii 5 
 
 9-4 
 
 2.0 
 
 18.5 
 
 4.4 
 
 27-3 
 
 6.8 
 
 35-7 
 
 9.2 
 
 43-8 
 
 ii. 6 
 
 9-8 
 
 2.1 
 
 18.9 
 
 4-5 
 
 2 7 .6 
 
 6.9 
 
 36.1 
 
 9-3 
 
 44.1 
 
 11.7 
 
 10.2 
 
 2.2 
 
 19-3 
 
 4.6 
 
 28.0 
 
 7.0 
 
 36.4 
 
 9-4 
 
 44-4 
 
 ii. 8 
 
 10.6 
 
 2-3 
 
 19.7 
 
 4-7 
 
 28.4 
 
 7-1 
 
 36.7 
 
 9-5 
 
 44-7 
 
 ii. 9 
 
 II. 
 
 2.4 
 
 20.0 
 
 4.8 
 
 28.8 
 
 7.2 
 
 37-1 
 
 9.6 
 
 45 - 
 
 12. 
 
 Preparation of Water for Technical Purposes. 
 
 In this the precipitation of constituents of the water which cause 
 hardness is aimed at. Of the different methods proposed for the 
 purpose, only the very useful method of Stingl and Berenger will 
 be more fully described. 
 
 According to this procedure there are precipitated : 
 
 1. The bicarbonate of calcium present in the water, by means 
 of calcium hydrate or sodium hydrate. For every molecule cal- 
 cium bicarbonate, i molecule calcium hydrate or 2 molecules so- 
 dium hydrate are necessary, according to the equations : 
 
 Ca H 2 (C0 3 ) 2 -f Ca (OH) 2 = 2 Ca CO 3 -f 2H 2 O and 
 Ca H 2 (CO 3 ) 2 4- 2 Na OH CaCO 3 -f Na 2 CO 3 + 2 H 2 O 
 
 2. The bicarbonate of magnesium by the same precipitants, of 
 
 * Taken from Kalmann's Kurzer Anleitung zur chem. Untersuchung, etc. 
 
26 CHEMICAL-TECHNICAL ANALYSIS. 
 
 which double the quantities must be taken on account of the solu- 
 bility of normal magnesium carbonate, which is thereby precipi- 
 tated as hydrate. 
 
 Mg H 2 (CO,), + 2 Ca (OH), = 2 Ca CO 3 + Mg (OH), + 2 H 2 O 
 
 and 
 
 Mg H 2 (C0 3 ) 2 + 4 NaOH = 2 Na 2 CO 3 -f Mg (OH), + 2 H 2 O. 
 
 3. All the remaining calcium salts with sodium carbonate, of 
 which i molecule is necessary for every molecule lime. 
 
 Ca Cl, + Na 2 CO 3 = Ca CO, + 2 Na Cl. 
 
 4. All remaining magnesium salts with caustic soda. For every 
 molecule MgO, 2 molecules Na OH are needed. 
 
 Mg Cl, + 2 Na OH = Mg (OH), + 2 Na Cl. 
 
 Evidently, it follows from i and 2 that when sodium hydrate is 
 used for precipitation, an equivalent amount of sodium carbonate 
 is formed in solution, which at times may precipitate the whole of 
 the lime salts present. From this, given the precipitants men- 
 tioned, the three following conditions may be deduced : 
 
 (a) The quantity of soda is greater than that required by ( j) to 
 precipitate the calcium salt. In this instance, in order to avoid 
 the formation of an excess of sodium carbonate, an equivalent part 
 of the sodium hydrate is replaced by calcium hydrate. Therefore, 
 the preparation requires sodium hydrate and calcium hydrate. 
 
 (V) The soda formed is less than the amount required for the pre- 
 cipitation of all remaining lime salts. The purification is then con- 
 ducted with use of caustic soda and soda. 
 
 (c) The soda formed is equal to the amount required for the pre- 
 cipitation of calcium salts. In this instance only caustic soda is 
 necessary for purification. 
 
 In all three instances the quantity of caustic soda required to 
 precipitate any magnesia not present as bicarbonate (4) is added. 
 
 Calculation. The values from the shortened procedure of Kal- 
 mann, or the complete analysis for bound carbonic acid, total lime 
 and total magnesia, are calculated into equivalents of lime. The 
 results so obtained will be : 
 
FUEL. 27 
 
 for bound carbonic acid a g Ca O 
 
 for total lime p g Ca O 
 for total magnesia and total lime 
 
 (total hardness) y g Ca O 
 
 The difference 2a /5 is now found. Should this be positive, 
 there is present the condition described under (a). For purification 
 there are used: (2 a 3) parts by weight lime (dissolved in 800 
 times the quantity of water), and an amount of caustic soda equiva- 
 lent to (y a) parts by weight lime. Instead of using prepared 
 caustic soda, the latter can be produced from slaked lime and soda. 
 For this purpose (y a) parts by weight lime and the equivalent 
 quantity of soda are used. 
 
 Should the difference 2 a /? prove to be negative, condition b 
 exists. 
 
 For purification there is used the quantity of soda equivalent to 
 the difference of (y a) g. lime, and (y-f j3) g. lime, which renders 
 a part of the soda caustic. 
 
 Finally, should the difference 2 a /3=o, condition c exists. 
 
 For purification, a quantity of caustic soda equivalent to (y a] 
 parts by weight lime, is necessary. This may be prepared by 
 adding to (> ) parts by weight lime, as in the case a, an equiva- 
 lent amount of soda.* 
 
 12. Fuel. 
 
 The methods described are applicable to all kinds of fuel an- 
 thracite, bituminous, lignite, etc. 
 
 As a rule, the determinations made in a coal analysis are water, 
 ash, sulphur, and an elementary analysis. In addition to these, 
 nitrogen and phosphorus, as well as the yield of coke, are frequently 
 estimated. 
 
 (#) Water. The estimation of water in fuel. 
 
 The sample must be coarsely ground, about pea size, since during 
 the process of pulverization considerable moisture is given off. Coal, 
 especially anthracite coal, possesses the property of absorbing 
 oxygen upon protracted drying, thereby causing an increase in 
 
 * The derivation of these methods of calculation of Kalmann may be found in 
 the Mittheilung des K. K. technolg. Gewerbe Museum, 1890. 
 
28 CHEMICAL-TECHNICAL ANALYSIS. 
 
 weight. It is best to heat about 2050 grs. material in a weighing 
 tube provided with a well -ground stopper, which is removed during 
 the time of heating, and to weigh the same from hour to hour until 
 no further loss occurs. Should perhaps the last weight show an in- 
 crease, the previous result is accepted. 
 
 (^) Ash. The ignition is best carried out in a muffle, when, as a 
 rule, one hour will be sufficient. Should a muffle not be accessible, 
 about i gr. finely -divided coal is placed in a small platinum capsule 
 and covered with the lid of a larger crucible. Heat is applied at 
 first with a small flame to avoid sintering. Later the lid is re- 
 moved, the capsule is tilted on the triangle, the lid is likewise 
 brought into an inclined position on the capsule, and the latter is 
 heated protractedly to a red heat with an ordinary-sized flame. 
 When the ash appears uniform, which is usually the case after 2-3 
 hours, the capsule is weighed. The ash is now moistened with a 
 few drops of alcohol, when any particles of carbon will rise to the 
 surface, where they may be easily recognized. The alcohol is 
 ignited and driven off, and the capsule is reweighed. This process 
 is finally repeated a second time. Lunge advises the use of a plati- 
 num crucible, which is placed in the round opening of an inclined 
 asbestos plate. Only the part of the crucible protruding beneath is 
 heated. The air used for oxidation does not admix with the gases 
 produced by the flame, and therefore acts more energetically. 
 
 (V) Sulphur. Sulphur is present in fuels in the form of sulphides 
 (mostly pyrite), sulphates (calcium sulphate), and in combination 
 with organic substances. The estimations usually made are : Total 
 sulphur and sulphur present in form of metallic sulphides + sulphates. 
 Sometimes a separate determination of sulphur due to sulphates is 
 also made. 
 
 Total sulphur according to Eschka. About i gr. finely-divided 
 coal is thoroughly mixed in a platinum crucible by means of a thick 
 platinum rod, with 1.5-2 grs. of an intimate mixture of 2 parts pure 
 ignited magnesia and i part anhydrous sodium carbonate. The 
 crucible is inclined on the triangle, or in the perforated asbestos 
 plate, without a lid, and the lower half only is brought to a red 
 heat. Heat is applied for about i hour, with frequent stirring by 
 means of the platinum rod. In that time the mass, at first gray, will 
 have assumed a bright red or brown color. . The contents are cov- 
 
FUEL. 29 
 
 ered with hot water and rinsed into a beaker, the crucible is boiled 
 out again, and bromine water is added until the liquid assumes a 
 bright yellow color. This is done in order to oxidize any remain- 
 ing sulphides. The solution is heated, filtered, and the filtrate is 
 acidified with hydrochloric acid. It. is then boiled in a draught- 
 chamber until the deep brown colored liquid becomes colorless, and 
 is then precipitated with barium chloride. 
 
 The magnesia-soda mixture had better be prepared in quantity. 
 When sulphur is present in small quantity in this mixture, a con- 
 siderable portion is used for a sulphur determination, and the corre- 
 sponding quantity of the latter is subtracted from the total sulphur. 
 
 Sulphur present as sulphides and sulphates. According to 
 Drown, a saturated solution of bromine in caustic soda, sp. gr. 
 1.25, to which sufficient caustic soda to absorb any free bromine 
 has been added, is used to advantage for oxidation. About i 
 gr. of the finely pulverized substance is moistened with 10 c.c. of 
 this solution. It is then heated and acidified with hydrochloric acid. 
 In the space of 10 minutes two quantities, 20 c.c. each, of the solu- 
 tion, are again added, and each time the solution is acidified with 
 hydrochloric acid. After the last addition of acid, the mass is evap- 
 orated to dryness, dried at iio-ii5 in an air-bath to convert 
 silica into insoluble form, taken up with hydrochloric acid, filtered, 
 and the filtrate is precipitated with barium chloride. The method 
 is especially useful for anthracite coal. 
 
 Sulphate sulphur. A considerable quantity of the sample is first 
 incinerated, and a weighed quantity of the ash, 2-3 grs., is lixivi- 
 ated with hot water. In order to oxidize any calcium sulphide 
 formed, the solution is boiled with hydrogen peroxide or a few drops 
 of bromine. It is then acidified with hydrochloric acid and pre- 
 cipitated with barium chloride. 
 
 (d) Elementary analysis. The execution of this is too well 
 known to describe. It is, however, necessary to add special pre- 
 cautions pointed out by Bockmann, and also the authors. 
 
 While the estimation of hydrogen, as a rule, can be carried out 
 with ease and accuracy, a difference in parallel determination of y 2 
 to 24 P er cent - i s noticeable in determining the carbon, even when 
 great care is exercised. The reason for this lies in the already 
 mentioned tendency of carbon to sinter. In order to avoid this as 
 
30 CHEMICAL-TECHNICAL ANALYSIS. 
 
 much as possible, it is advisable to conduct the first part of the 
 combustion slowly. This can be accomplished by at first using a 
 current of air (not immediately of oxygen) and by moderately heat- 
 ing the portion of the tube in proximity to the substance. It is 
 also advisable not to have the substance too finely divided, thereby 
 avoiding an immediate violent action. The finish of the preliminary 
 step, which may be termed coking, is easily observed. The remain- 
 ing operation is then carried out at a high heat in a current of oxy- 
 gen, the flow of which through the wash -bottle is regulated to about 
 20 bubbles in every 10 seconds. 
 
 Charging the combustion tube is done in the usual manner. For 
 many well-founded reasons it has been found decidedly advantageous 
 to substitute for granular copper oxide a series of oxidized copper 
 spirals. The addition of a silver or bright copper spiral is wholly 
 unnecessary on account of the minute quantities of chlorine and 
 nitrogen. On the other hand, an absorbent of the combustion- 
 products of the sulphur is absolutely necessary. In the absence of 
 such, sulphurous and sulphuric acid readily enter the absorption- 
 bulbs, are absorbed, and increase the weight. It is only necessary, 
 according to Fisher, to keep the oxide of copper in the front of the 
 tube at a low red heat, whereby the oxide itself acts as a retainer of 
 the combustion-products of sulphur. Nevertheless, it appears more 
 advisable to fill the front part of the tube, which is allowed to 
 protrude about 28 cm., with dry, coarsely-divided lead peroxide. 
 The latter is placed in a tin case provided with a thermometer, and 
 is heated to 180 during the combustion. 
 
 Further, be it noted that the dehydrated substance had best be 
 used, and that a hydrogen determination be simultaneously con- 
 ducted. The water thus found is deducted from the total water. 
 
 (e) Nitrogen. The method is found under the accurately de- 
 scribed procedure of Kjeldahl in the chapter " Fertilizers." 0.8 i 
 gr. finely-divided coal is used in the determination. 
 
 (/) Phosphorus. This is always determined in the ash, and not 
 the original substance. 12 grs. ash, obtained best by ignition in 
 a muffle, are digested for a considerable length of time with hydro- 
 chloric acid in a porcelain dish, whereby, according to Muck, the 
 phosphorus is quantitatively dissolved. The solution is evaporated 
 to dryness, moistened with hydrochloric acid, and 100-150 c.c. 
 
FUEL. 31 
 
 water are added. It is warmed on a water-bath, filtered into a 
 second porcelain dish, and evaporated repeatedly almost to dryness 
 with addition of nitric acid. The liquid is diluted with water 
 acidified with nitric acid and precipitated in a beaker with molyb- 
 date solution.* The remaining treatment is carried out in the 
 well-known manner more fully described in the chapter on 
 "Fertilizers." 
 
 (g) Coke, i gr. finely-divided coal is weighed in a smooth- 
 walled platinum crucible, which it fills to the height of 30-35 mm., 
 and the crucible is placed on a thin platinum triangle so as to bring 
 its base 3 cm. from the mouth of a Bunsen burner. Strong heat is 
 applied to the tightly-closed crucible from the beginning. The 
 burner, which is provided with a protecting cone, should have a 
 flame 18 cm. in height. Heat is applied until no luminous flame 
 issues from between crucible and lid, an operation lasting 1^-2 
 minutes. The sooty film on the crucible-lid is also weighed. By 
 following these directions accurately results may be obtained which 
 agree within .2-. 4 per cent. 
 
 Arrangement of results. The results are as frequently based on 
 air-dried as on dehydrated material. Oxygen is indirectly deter- 
 mined by deducting the sum of the water, carbon, hydrogen, sul- 
 phur,f nitrogen and ash found from 100. So called " disponible 
 hydrogen ' ' is that which remains upon deducting the quantity of 
 hydrogen used to form "chemically -bound water" with the oxygen, 
 e.g. , y% of the oxygen, together with that present as hygroscopic 
 water, from the total hydrogen. 
 
 Absolute heating value. To calculate this, the formula lately 
 recommended by Schwackhofer is employed, 
 
 SoooC + 2o,oooH + 2qooS-6ooW 
 
 E - calories, 
 
 100 
 
 in which the symbols C, H, S, W represent the percentages of 
 carbon, "disponible" hydrogen, sulphur and water (hygroscopic 
 and chemically bound). 
 
 If the absolute heating value (E) be divided by 637, there results 
 
 * Preparation, see under V, "Fertilizers." 
 f Excluding sulphur existing as sulphate. 
 
32 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the evaporative efficiency, that is, that weight of water at o which 
 is changed to steam at 100 by one kilogram of coal. 
 
 13. Furnace Gases. 
 
 The investigation of gases of a furnace serves to regulate the feed- 
 ing of the latter. Carbonic acid, oxygen, carbon monoxide and 
 nitrogen, the latter by difference, are determined in furnace gases. 
 For this purpose the apparatus of Orsat, whose arrangement is seen 
 in the following illustration, Fig. 3, is best used : 
 
 FiG. 3. Orsat's Apparatus. 
 
 The gas burette A is bound to the leveling flask B, which is filled 
 with water. By raising B, A is filled with water to the uppermost 
 mark ; by lowering B gas is drawn through the tube C, or from the 
 absorption vessels D, E, F; by repeatedly raising B, simultaneously 
 opening the stopcocks of D, E or F, the gas may be led into any 
 of the latter. To establish the necessary communications the cocks 
 D, , F, and the three-way cock A are provided. In order to in- 
 crease absorption the vessels >, E and F are provided with a large 
 
FURNACE GASES. 33 
 
 number of narrow glass tubes. D is used to absorb carbonic acid, 
 and is filled with no c.c. caustic potash solution (sp. gr. 1.20-1.8). 
 E serves to absorb oxygen, and contains pyrogallic acid or thin 
 phosphorus sticks immersed in water. In the latter case black 
 paper surrounds the vessel to protect the contents from the action 
 of light. Finally, for the absorption of carbon monoxide, the vessel 
 Fis filled with cuprous chloride solution prepared by shaking 200 
 grs. commercial cuprous chloride with a solution of 250 grs. am- 
 monium chloride in 750 c.c. water in a stoppered flask, into which 
 there is placed, later, a copper spiral which reaches to the bottom. 
 Before using, i vol. ammonia (sp. gr. 0.905) is added to 3 vols. of 
 this solution. Complete absorption takes place only upon pro- 
 longed contact ; and, furthermore, the reagent must be frequently re- 
 newed. The absorption reagents are kept in the rear tubes, and 
 are brought into those in front only when the apparatus is in use. 
 This is accomplished by establishing communication with the out- 
 side air by means of stopcock #, closing d, e and /, filling A 
 with water by raising B, arranging a to close off A, lowering B 
 and opening the stopcock d. The liquid is thereby drawn from the 
 rear into D. In a similar manner E and F are filled. The tube 
 c, previously provided with a U tube, enclosing raw cotton to 
 exclude dust, is now connected with the chamber from which the 
 gas is to be taken, and by closing d, e and f and lowering B, a 
 volume of gas sufficient to fill to the zero point is drawn.* 
 
 The cock d is opened, B is raised, and the gas in the burette is 
 forced into Z>. As soon as the water reaches the end division the 
 flask is lowered, and the process is quickly repeated in order to 
 bring the gas into thorough contact with the reagents. Finally the 
 water-levels in flask and burette are brought to the same height, the 
 stopcock d is closed, and the volume is read. The decrease in 
 volume gives per cent, by volume of carbonic acid, since the bu- 
 rette is divided into 100 c.c. In the same manner the oxygen is 
 subsequently determined by absorption in , the carbon monoxide 
 in F, and the nitrogen as remainder of 100. 
 
 * To completely remove air contained in the tubes, the gas forced in by lower- 
 ing B is passed out through exit in a, fresh gas is drawn in, and the process is 
 repeated. 
 
 3 
 
34 CHEMICAL-TECHNICAL ANALYSIS. 
 
 For gases rich in hydrogen, such as water-gas, the apparatus of 
 Orsat-Lunge is used. The latter is quite similar to the Orsat appa- 
 ratus. The gas, freed from carbonic acid, oxygen and carbon 
 monoxide, is mixed with a measured quantity of air, and is con- 
 ducted through a capillary containing platinum asbestos or palla- 
 dium asbestos. By heating the latter the hydrogen is burned. The 
 residue is again measured in the burette, and ^ the decrease in 
 volume is reckoned as hydrogen. (2 vols. hydrogen unite with i 
 vol. oxygen,) 
 
II. Cement and Clay. 
 
 THE raw materials for the products of this group are limestone, 
 
 marl and clay. 
 
 1. Lime. 
 
 (a) Moisture. 3-5 grs. sample are heated to constant weight 
 in a drying oven at no 120. 
 
 (<) Silica and clay, ferric oxide, alumina, lime and magnesia. 
 About i gr. powdered sample is uniformly moistened with water 
 in a porcelain dish, covered with a watch-glass, and decomposed by 
 addition of moderately dilute hydrochloric acid. After the evo- 
 lution of carbonic acid has ceased the mass is evaporated to dry- 
 ness on a water-bath with constant stirring, completely dried by 
 heating on an asbestos plate, and covered with sufficient concen- 
 trated hydrochloric acid to completely dissolve all soluble matter. 
 After a half-hour hot water is added, the solution is filtered, the 
 precipitate is washed and weighed as silica and clay. To the hot 
 filtrate, which has been oxidized with bromine water, ammonia is 
 added to slight excess, the solution is boiled for a few moments, and 
 the precipitate formed is filtered off. To free it from any adhering 
 lime, the solution in hydrochloric acid and precipitation with am- 
 monia may be repeated. Ferric oxide and alumina are determined 
 together. A separate iron determination, when necessary, is con- 
 ducted in another portion. The filtrate, now about 200 c.c. in 
 volume, is brought to incipient boiling, the flame is removed, and 
 ammonium oxalate is added to the point of complete precipitation 
 and rapid deposition. A sufficient excess of ammonium oxalate is 
 yet added to convert all magnesia into soluble magnesium oxalate. 
 Finally the solution is diluted to 400500 c.c. and allowed to stand 
 several hours in a warm place. Frequently magnesia is thrown 
 down together with the lime, but by gradual addition of the ammo- 
 nium oxalate the magnesia can be reduced to about .02 per cent. 
 If exact results be required, the precipitation may be repeated a 
 second time. 
 
36 CHEMICAL-TECHNICAL ANALYSIS. 
 
 For this purpose the clear liquid is decanted through a filter, the 
 residue remaining in the beaker is stirred twice with hot water, and 
 the clear liquid is decanted each time through the same filter. The 
 precipitate in the beaker is redissolved in hydrochloric acid, and to 
 the solution ammonia and ammonium oxalate are added in suffi- 
 cient quantity. The reprecipitated calcium oxalate is allowed to 
 stand one hour. The solution is then filtered through the same 
 filter, the latter is washed thoroughly with hot water, dried, ignited 
 for a time at a low heat, and is then ignited over a blast-lamp until 
 constant weight is obtained. It is weighed as calcium oxide.* The 
 filtrate from the lime is made slightly acid with hydrochloric acid 
 and is concentrated on a water-bath to about one-third its volume. 
 One-third the remaining volume of dilute ammonia is added, and 
 when cool the magnesia is precipitated with sodium hydrogen 
 phosphate. After three hours the solution may be filtered. The 
 precipitate is washed with water containing about 3 per cent, 
 ammonia, then dried and ignited in a. platinum crucible. The 
 weight represents Mg 2 P 2 O r 
 
 (V) Oxide of iron and sulphuric acid. 
 
 Both constituents may when necessary be determined in the same 
 operation. For this purpose about 10 grs. powdered sample are 
 placed in a 250 c.c. flask, dissolved in hydrochloric acid, and 
 diluted to the mark. Two hundred c.c. solution are filtered 
 through a dry filter and precipitated with ammonia. The precipi- 
 tate formed is dissolved in sulphuric acid (i 14), diluted with water, 
 reduced with zinc and titrated with permanganate of potash. The 
 filtrate from the sesquioxide of iron is acidified with hydrochloric 
 acid, and the sulphuric acid is determined with barium chloride. 
 
 (d*) Carbonic acid. Carbonic acid, as a rule, can be calculated 
 by considering it bound to the calcium oxide and magnesia which 
 remain after deducting that portion of the former attached to the 
 sulphuric acid found. When large quantities of silica are present 
 in which case lime can exist as calcium silicate a direct determi- 
 nation of carbonic acid is made in the usual manner by absorption 
 in tubes containing soda lime. 
 
 * To check the result, it is advisable to titrate the calcium oxide with hydro- 
 chloric acid. 
 
MARL. 37 
 
 (<?) Alkali metals are present only in traces, as a rule, and their 
 estimation may be omitted. 
 
 (/) Organic matter. For an approximate result the method of 
 Fresenius is useful. By this method the organic matter is deter- 
 mined by combustion in a current of oxygen. For every 58 parts 
 carbon obtained (213 parts carbonic acid) 100 parts organic matter 
 are allowed. 
 
 Marl. 
 
 Limestones containing under 10 per cent, clay, i.e., clay, silica 
 and sesquioxides, yield "fat lime" on being calcined, and are 
 suitable for the preparation of lime cements. Limestones contain- 
 ing over 10 per cent, of such constituents yield "lean lime." 
 They are termed argillaceous limestones or marls. A further dis- 
 tinction is made between calcareous and clayey marls, depending on 
 the predominance of one or the other constituent. 
 
 The analysis of marl is, as a rule, carried out in the manner of a 
 limestone analysis, with the avoidance, nevertheless, of too great an 
 excess of hydrochloric acid and excessive heating when dissolving. 
 In addition, a determination of clay, insoluble in hydrochloric acid, 
 is made. This applies mainly to the determination of soluble silica, 
 coarse and fine sand. 
 
 (a} Soluble silica. The residue, insoluble in hydrochloric acid, 
 obtained from 1-2 grs. sample, is removed from the filter and lix- 
 iviated by boiling several times with renewed portions of caustic 
 soda or chemically pure soda in a porcelain or platinum dish until 
 the filtrate fails to show silica as turbidity upon addition of ammo- 
 .nium chloride followed by boiling. The silica in the alkaline 
 extractions of the residue is determined in the usual manner after 
 precipitation with hydrochloric acid and evaporation to dryness. 
 
 (li) Coarse and fine sand. Hydrochloric acid is added to 50 grs. 
 substance. The solution is boiled ^ hour, and the residue is sub- 
 jected to the washing process described under "Clay." 
 
 The investigation of marl rich in clay may also be conducted by 
 the method described under " Clay." 
 
 Marls which contain 20-30 per cent, clay are best suited, on the 
 average, for the preparation of hydraulic cement. On the other 
 hand, those marls, the clay in which contains an excessive amount 
 of free silica, yield only ordinary hydraulic cements, particularly 
 
38 CHEMICAL-TECHNICAL ANALYSIS. 
 
 when the latter is present, for the greater part, as common sand 
 and not powdered sand. Briefly, the more the clay in a marl is 
 present as silicates, not free silica, and the less coarse sand it con- 
 tains, the better hydraulic cement will it yield. In addition, the 
 requisite proportion of clay to lime must be present. 
 
 By mixing clay with limestone and calcining the mixture until 
 sintered, products are obtained which, upon pulverizing, possess 
 the properties of a hydraulic cement and are known as Portland 
 cement. The limestone is used in form of chalk or marl, and 
 should not contain too much magnesia. While magnesia to an 
 extent of 3 per cent, operates advantageously, considerable quanti- 
 ties are harmful, and about 18 per cent, has a decidedly dis- 
 advantageous effect on the hardness of the cement. 
 
 The clay used is preferably one 'containing little sand (especially 
 coarse sand), much silica, and a rather high amount of iron oxide 
 and alkali. Such clays are usually easily fusible and show the 
 following average composition : 
 
 Percent. 
 
 Silica, . ...... - . ... . . . 59-68 
 
 Alumina, .... '...-, . . . 12-23 
 
 Ferric oxide, .... . . . . . 7~I4 
 
 Lime, . . -75-io 
 
 Magnesia, . . . ' , . ^. . ; " . . . 1-3 
 
 Alkali, . ;. . , T 2-4 
 
 According to Michaelis, it is preferable that the proportion of 
 clay to lime in the mixture be such that in the calcined Portland 
 cement there be 210230 equivalents of alkaline earths and 1525 
 equivalents clay, plus ferric oxide, to 80 equivalents silicate. 
 
 If silica and sesquioxides (as acids) be reckoned on lime, then 
 the following expression is obtained : 
 
 100 (SiO 2 .R 2 O 3 ). 200 CaOand 100 (SiO 2 .R 2 O 3 ). 240 CaO. 
 
 Under 200 CaO disintegration occurs ; above 240 spreading 
 occurs, and it is advantageous not to exceed 220. 
 
 Kosmann states that there should be present in the mixture 
 
 6 Mol. CaO =60.21 per cent. 
 2 SiO 2 = 21.50 " 
 ,1 " A1 2 O 3 = 18.29 " 
 
CLAY. 39 
 
 But on account of the presence of a not inconsiderable quantity 
 of free silica in the limestone and clay, the above proportion must 
 practically be increased 2^-2^ SiO 2 and decreased .$-.66 A1 2 O 3 . 
 
 The extreme limits in the composition of Portland cements, 
 according to Candlon, are : 
 
 Per cent. 
 
 Lime, 58-67 
 
 Silica. ......... 20-26 
 
 Alumina, ..... . . . 5-10 
 
 Magnesia, . . . . . . . . . .5-3 
 
 Sulphuric Acid, . . . . . . . . .5-2 
 
 The chemical investigation of finished cements is conducted in 
 exactly the same manner as that of limestone or marl. Frequently 
 the mere determination of clay (total silicates) is required. For 
 this purpose 2 grs. cement are covered in a capsule with 20 c.c. 
 water and decomposed with hydrochloric acid, to which nitric acid 
 has been added. Thereupon the solution is brought to boiling, 
 precipitated with ammonia, and the precipitate formed is weighed. 
 Good cement should dissolve almost completely in concentrated 
 hydrochloric acid, since, in consequence of the treatment under- 
 gone, the silica is transformed into a soluble modification. 
 
 3. Clay. 
 
 In a broad sense clay is understood to be a hydrated aluminium 
 silicate, which in addition to argillaceous matter can contain among 
 other admixtures unaltered feldspar and silica, frequently also iron, 
 lime, magnesia, alkalies, and minute quantities of manganous oxide, 
 as well as volatile constituents. 
 
 Concerning the part played by the individual constituents, the 
 following may be stated : 
 
 Alumina is the most valuable and distinctive constituent of clay. 
 Its quantity regulates the physical properties of clays (plasticity, 
 shrinking), as well as fusibility. 
 
 Silica frequently operates relatively harmful on the properties of 
 clay. It decreases the plasticity, increases the point of fusibility, 
 and increases the action of fluxes at high temperature. It is con- 
 tained in clay, chemically as well as mechanically bound, and its 
 analysis in latter form is necessary. 
 
 Magnesia, lime, ferric oxide, alkalies, act as fluxes, and in fact 
 
40 CHEMICAL-TECHNICAL ANALYSIS. 
 
 equivalent amounts of these exert the same influence upon the 
 fusibility. Comparatively, magnesia ranks first as a flux, lime 
 second. Alkalies are present mostly in form of potassium oxide 
 and are reckoned as such. Iron influences chiefly the tinge of 
 clay, and changes the color as in the false coloring of pottery. 
 
 Volatile matter. (Loss on ignition.) This is caused by the sul- 
 phur, water, carbonic acid and organic matter present. These, 
 when present in considerable quantity, can influence the plasticity 
 of the clay as well as the density after baking. Much stress is to 
 be laid on the quantitative estimation of sulphur, since even minute 
 quantities (in form of pyrite) can act harmfully. The chemical 
 analysis of clay is divided into the empirical -technical and rational 
 analyses. 
 
 A. Empirical-technical Analysis. 
 
 (a) Moisture. 2-5 grs. sample are dried to constant weight at 
 120. 
 
 (^) Total loss on ignition (water of constitution, organic mat- 
 ter and carbonic acid). 
 
 One to 2 grams dried sample are ignited over a blast-lamp, with 
 air access, to constant weight. 
 
 () Silica, alumina, ferric oxide, manganous oxide, lime and 
 magnesia. About i gram finely pulverized average sample is dis- 
 solved in a platinum crucible by fusion with 6-8 times amount so- 
 dium potassium carbonate mixture. 
 
 Under no circumstances should more than ten times the amount 
 be used. Michaelis states that it is better to use pure sodium car- 
 bonate. In this case fusion sets in at a higher temperature and 
 after all carbonic acid has been evolved. Thereby sputtering is 
 prevented. The fused mass is disintegrated with water, carefully 
 acidified with hydrochloric acid, the solution is evaporated to dry- 
 ness, and the silica is isolated as usual. The purity of the latter is 
 finally tested with hydrofluoric acid. After addition of ammonium 
 chloride, when the estimation of manganese is not taken into con- 
 sideration, the iron and alumina in the filtrate are precipitated in 
 the usual manner by ammonia. Should a separation from manga- 
 nese be required, the filtrate is as nearly as possible neutralized with 
 sodium carbonate and boiled a short time with a concentrated so- 
 lution of sodium acetate or ammonium acetate. 
 
CLAY. 41 
 
 The precipitate, which rapidly settles on removing the heat, is 
 repeatedly decanted with hot water, to which ammonium acetate 
 has been added. It is then thrown on the filter and washed with 
 the water until the filtrate no longer shows traces of chlorine. The 
 precipitate is either directly dried and ignited, or again dissolved in 
 hydrochloric acid, reprecipitated and filtered. When greater accu- 
 racy is demanded, the filtrate is added to that previously obtained. 
 
 Special, care is also to be taken in decanting and washing the pre- 
 cipitate, even when no attempt is made to separate manganese. 
 
 It is not considered superfluous to test the purity of the precipi- 
 tate, according to Mitscherlich, by dissolving the precipitate so 
 obtained in a large excess of a mixture of 8 parts concentrated sul- 
 phuric acid and 3 parts water. If, upon warming in a flask, flakes 
 of silica appear, the latter is filtered, weighed, the weight deducted 
 from that of the alumina -j- ferric oxide and added to that of the 
 silica. The iron in the filtrate can be determined, after reduction 
 with chemically pure zinc, by means of pure permanganate. Should 
 the test of the alumina-ferric oxide precipitate be unnecessary, an 
 aliquot portion is finely pulverized in an agate mortar and fused in 
 a platinum crucible with bisulphate of potash, at first with a low 
 heat and finally at a red heat. The fusion is dissolved in water, 
 sulphuric acid is added, and the iron after reduction with zinc is 
 titrated. 
 
 In the filtrate from the alumina and ferric oxide the manganese is 
 eventually estimated as dioxide by adding bromine water to the cold 
 solution, weakly acid with acetic acid, saturating with ammonia and 
 filtering off the precipitate formed on boiling briskly. The filtrate, 
 acidified with hydrochloric acid, is boiled down, an excess of am- 
 monia is added, the lime is precipitated with oxalate of ammonia as 
 usual, and the magnesia with sodium hydrogen phosphate. 
 
 (V) Alkalies. Two grams finely divided clay, mixed with a 
 little water in a platinum dish, are covered with concentrated 
 sulphuric acid ; hydrofluoric acid is added, and the mass is warmed 
 on a water-bath until all hydrofluoric acid has volatilized. Thereupon 
 the sulphuric acid is almost completely expelled, and the residue is 
 covered with hot water and hydrochloric acid. Thereby the resi- 
 due may be carbonized, but at no time should it be gritty. Sulphuric 
 acid, alumina, ferric oxide and magnesia are now precipitated with 
 
42 CHEMICAL-TECHNICAL ANALYSIS. 
 
 an excess of concentrated baryta water. Excess of baryta in the fil- 
 trate is precipitated with sulphuric acid ; ammonia, carbonate and 
 oxalate of ammonia are then added, and the whole is allowed to stand 
 for some time. The filtrate is evaporated to dryness in a weighed 
 platinum dish. It is then heated in an air-bath, then over a small 
 flame to expel ammonium salts, and is finally ignited. The ignited 
 residue is treated with water, and in event of incomplete solution it 
 is treated in the same manner as before, with small quantities of 
 ammonia, carbonate and oxalate of ammonia. 
 
 This operation, repeated two or three times, suffices to obtain the 
 alkali sulphates in perfectly pure state. They are considered as 
 potassium sulphate, from which potassium oxide is calculated. 
 
 (e) Sulphur. 5 grs. clay are mixed with powdered chlorate of 
 potash ; concentrated nitric acid is gradually added \ the mass is 
 slightly heated and finally boiled with repeated additions of hydro- 
 chloric acid until all nitric acid is decomposed. The excess of acid 
 is then evaporated, water is added, and the sulphuric acid is pre- 
 cipitated with barium chloride. 
 
 B. Rational Analysis. 
 
 The purpose of this is not to determine individual constituents 
 present, but rather to classify the same as distinct characteristic 
 compounds. The amounts of argillaceous matter quartz, feldspar, 
 chalk, etc. are determined thereby. The operation is mostly ap- 
 plied to pure clays for porcelain and pottery. 
 
 To do this, 5 grs. substance are softened in a porcelain dish with 
 about 100150 c.c. water, and boiled with addition of 2 c.c. caustic 
 soda, whereby a fine state of division is obtained. Upon cooling, 
 about 25 c.c. concentrated sulphuric acid are added, after which 
 the contents of the covered vessel are kept in a state of brisk 
 ebullition until sulphuric acid begins to volatilize. In conse- 
 quence, beside the transformation of chalk to calcium sulphate, 
 only the clay matter (silicate of alumina) is decomposed, whereas 
 quartz and feldspar remain unattacked. The mass as obtained is 
 separated from the greater part of the sulphuric acid and sulphate 
 of aluminium by dilution with water and decantation. It is then 
 twice extracted alternately with very concentrated caustic soda and 
 hydrochloric acid. Each time it is filtered upon the same filter 
 
ANALYSIS BY MECHANICAL MEANS. 
 
 43 
 
 upon which the whole residue is finally thrown, washed with hydro- 
 chloric acid, ignited and weighed. The residue consists only of 
 feldspar and quartz. The loss in weight is clay and carbonate of 
 lime. The amount of the latter is ascertained by means of a 
 carbonic acid determination. 
 
 The mixture of quartz and feldspar is decomposed |L 
 
 with sulphuric acid and hydrofluoric acid. In the 
 filtrate the alumina is estimated by precipitation with 
 ammonia, redissolving and reprecipitating, and from 
 the result the feldspar is estimated (i part alumina = 
 5.41 parts feldspar). Quartz is found by difference. 
 
 C. Analysis by Mechanical Means 
 (Suspension). 
 
 Among the apparatus employed, that of Schone 
 claims decided preference on account of the con- 
 cordant results obtained and easy manipulation. It 
 is represented by Fig. 4. The main part is the 
 agitator-funnel, the cylindrical portion of which, BC, 
 the true suspension -chamber, is maintained in the 
 exact proportion represented. The diameter of the 
 lower part, D, must not be more than 5 mm. nor less 
 than 4 mm. in width. The same dimensions must 
 be preserved in the bend, DEF, and in the lower 
 part of the tube, EG. The latter may be widened, 
 but not narrowed, above. The exit-tube, HJKL, is 
 made of barometer-tubing, the inner diameter of 
 which should equal 3 mm. as nearly as possible. The 
 angle at/ should be between 40 and 45. The 
 exit-tube is so arranged at the deepest point on the 
 bend, K, that the passing water-column is directed 
 downward a little obliquely. It should be round, 
 and should possess well-rounded edges and a diameter 
 of i^ mm. The arm, KL, is somewhat over i^ 
 m. long, and serves to measure the pressure under which the water 
 issues at K. It is provided from the lowest point upward with a 
 scale, of which i-io cm. is divided in mm., 10-50 in ^ cm. divis- 
 ions, and the remainder in whole cm. divisions. The entrance- 
 
 FIG. 4. 
 
44 CHEMICAL-TECHNICAL ANALYSIS. 
 
 tube, G, is connected, by means of a conduit, with a water-reser- 
 voir, which, with 25 1. contents, should be at the most 10 cm. high. 
 A stopcock placed in the circuit regulates the flow. By means of 
 a cock an upright tube, bent perpendicular, is inserted in the water- 
 tank. This permits an entrance of air during the flow from the 
 enclosed space and acts as a level-indicator when refilling. 
 
 With funnel and exit-tubes of the above dimensions the velocity 
 in the suspension-chamber may be varied between 0.24 mm. per 
 second. Before using the apparatus the relation between this ve- 
 locity and the height of the water in the pressure-indicator (piezo- 
 meter) must be determined. The velocity is equal to the issue in 
 one second divided by squares of the cross-section of the suspension- 
 chamber. To determine the latter a mark is made above C, and 
 the water is allowed to enter up to that point. 
 
 Fifty c.c. water are then added from a pipette, and the difference 
 in level in the suspension-chamber read off by means of a rule or 
 cathetometer. This height divided into the 50 c.c. added gives 
 the area of the average cross -section of the suspension -chamber. 
 The " piezometer " levels corresponding to a velocity of .2, .5 and 
 2 mm. are measured and recorded for the subsequent determinations. 
 50 grs. of the clay selected and dried at ioo-i2o are softened in 
 water and boiled briskly at least ^ hour, with addition of a few c.c. 
 caustic soda.* 
 
 When the clay has become thoroughly disintegrated, the pasty 
 mass is run through a sieve of 900 meshes. With the aid of a soft 
 brush and agitation any grains of sand greater than .2 mm., as well 
 as pebbles, roots, etc., are separated. That which has passed 
 through the sieve and the washings from the sand are placed in a 
 beaker and allowed to settle, after which the clear liquid is poured 
 off and the settlings are washed into the agitator funnel. Sufficient 
 water only to raise the level in the suspension-chamber to C is 
 used, and simultaneously the stopcock is opened slightly and water 
 is admitted to prevent clogging in the base of the funnel. There- 
 upon water is slowly allowed to ascend the funnel, so that the 
 
 * Clays containing lime are treated, in addition, with cold concentrated hydro- 
 chloric acid in order to remove the carbonates which frequently cement particles 
 together. After carbonic acid evolution has ceased, the acid is completely washed 
 out. 
 
ANALYSIS BY MECHANICAL MEANS. 45 
 
 volume at 10 cm. is completely filled in 500 seconds. The exit- 
 tube is then adjusted and regulated to maintain an influx of a 
 velocity equivalent to .2 mm. in the piezometer. As soon as 
 the receiving beaker-glass receives clear liquid, i.e. the water in 
 the chamber clarifies, the particles operated upon by a current of 
 this velocity have been removed. The receiver is then removed 
 and the piezometer regulated for a velocity of .5 mm. Veloci- 
 ties under .5 mm. require an influx of about 3 liters, and a 
 greater velocity requires 4-5 liters. The liquids in the receivers 
 are allowed to clarify completely, and the supernatant liquid is 
 drawn off with a siphon. The residue is washed into a porce- 
 lain dish, dried and weighed. The residue in the funnel is like- 
 wise emptied into a porcelain dish by inverting the apparatus 
 over the dish and forcing through it a brisk current of water. 
 The quantity is determined by siphoning, drying and weighing. 
 The finest removable particles which take time to settle are de- 
 termined by difference. Coarse sand remaining on the sieve is 
 also weighed. The products obtained are designated as follows : 
 
 (a] Fine clay, (Size) .oi mm.- Current velocity, .2 mm. 
 
 (6) " Schluff " clay, " .01 " -.02 mm. " " .5 " 
 
 (t) Dust, " .02 " -.05 " 2. " 
 
 (of) Fine sand, " .05 " - .2 " Residue in the funnel. 
 
 (<?) Coarse sand, " above .2 " Residue in the sieve. 
 
 Pyrometric Tests. 
 
 The behavior of clay at high temperatures is of vast import- 
 ance in determining the shrinkage, the color, the appearance of 
 flaws, as well as the refractoriness. To study this behavior 
 pyrometers are necessary, in the first place, to measure the tem- 
 perature obtained. For this purpose sheets of pure silver, pure 
 gold, and alloys of the same containing 20 per cent, and upward 
 of gold, besides gold-platinum alloys, are used, from which the 
 following scale has been prepared : 
 
 Pure silver. Melting-point, 960 C. 
 
 Alloy, 80 pts. silver. 20 pts. gold. " " 983 C. 
 
 " 60 " " 40 " " " '* 1006 C. 
 
 40 " " 60 " " " " 1029 C. 
 
 " 20 " " 80 " " " " 1052 C. 
 
 Pure gold. " " 1075 C. 
 
 " 95 "gold. 5 pK platinum. " " HioC. 
 
 90 " " 10 " " " " 1145 C. 
 
46 CHEMICAL-TECHNICAL ANALYSIS. 
 
 For higher temperatures, where alloys of gold and platinum are 
 no longer suitable, Seger has introduced another form of pyro- 
 scope. 
 
 This consists of a series of porcelain glazes containing increas- 
 ing amounts of alumina and silica, and which possess an increas- 
 ing melting-point. 
 
 These substances are shaped in the form of a tetrahedron " Se- 
 ger' s cones." To measure the temperature these are placed in the 
 experimental or in the large furnace. As soon as the point of a cone 
 is inclined in such a manner as to touch the plate upon which it is 
 placed it has reached a corresponding temperature. 
 
 Thirty -six such cones were made and designated with increasing 
 numbers in such a way that the melting-point of No. i corresponded 
 to 1150 (approximately that of alloy of 90 parts gold and 10 
 parts platinum), while No. 20 represented a temperature of 1700. 
 Assuming now that the differences in temperature are equal to one 
 another, then every subsequent number corresponds to an increase 
 of 29. For example, No. 30 corresponds to 2000 C. The 
 compositions of these cones are given by Seger, and they can be 
 obtained through the " Laboratorium fur Thonindustrie in Berlin.* 
 
 For lower temperatures easily -fusible cones have also been pre- 
 pared to replace the expensive alloys. They range from No. . i 
 (960 C.), .9, etc., to i. (1131 C.), making in all a total of 46. 
 
 The numbers corresponding to the temperature required for dif- 
 ferent wares are : 
 
 Bricks, tiles, terra-cotta, etc., ...... to 5 
 
 Earthenware, unglazed, from 3 " lo 
 
 " glazed, "I 
 
 Stoneware, ......... from 5 " 10 
 
 Refractory products, fire-brick, . . . . . " 10 " 20 
 
 Porcelain, " 15 " 20 
 
 (0) Tests for shrinkage, color and flaws. 
 
 A stiff paste is made of the clay with about twenty times its 
 weight of water, and this is rolled into a form of about 8 cm. 
 length, 4 cm. width and i cm. thickness. 
 
 * The temperatures represented by each are to be found in an accompanying 
 explanation. 
 
ANALYSIS BY MECHANICAL MEANS. 
 
 47 
 
 On removing the models so prepared from the moulds they are 
 provided by means of a needle-point with a longitudinal and two 
 perpendicular lateral marks, the distance between which is measured 
 by means of a rule provided with a vernier. The forms are allowed 
 to dry on a wire gauze, after which the distance between marks is 
 again measured. The shrinkage by drying is so obtained. They 
 are then ignited with steadily increasing temperature in a muffle or 
 furnace similar to the Deville blast-furnace, described later, until 
 baked, during which time the temperatures are measured by means 
 of test-cones. The tints, the formation and fusion of flaws corres- 
 ponding to different temperatures, and, further, the shrinkage, are 
 determined. An idea of the porosity can also be formed by making 
 an ink-streak, and observing whether the ink is absorbed or whether 
 a sharply-defined line remains. 
 
 () Determination of refractoriness. This is generally conducted 
 to ascertain the melting-point of a clay, 
 or, moreover, if the clay is to be desig- 
 nated as infusible. 
 
 The latter is taken into account first of 
 all, although it may be stated that the 
 determination of fusibility is similarly 
 conducted. 
 
 The test of refractoriness is made in 
 the Deville blast-furnace, Fig. 5. This 
 consists of the hollow cylinder, A, made 
 of refractive material, surrounded below 
 by a stout wrought -iron plate. This 
 plate has in its centre an opening of 3 
 cm. diameter, which, in turn, is sur- 
 rounded by two rows of small openings 
 of 6 mm. diameter at equal distances 
 from one another. The refractory cylin- 
 der, 35 cm. high, is surrounded by an iron jacket, which is raised 8 
 cm. above the perforated plate, and which rests on an iron plate sup- 
 ported by a tripod. The space between plate and base is provided 
 with a side-opening, C, of 25 mm. width, through which air under 
 pressure is conducted from a cylindrical bellows 50 cm. in diameter. 
 The upturned rim of the plate above is sealed with a sandy non-shrink- 
 
 FIG 5. Deville Oven. 
 
48 CHEMICAL-TECHNICAL ANALYSIS. 
 
 ing clay to prevent escape of air. The combustion-chamber, D, is 
 slightly conical, having 9 cm. diameter below and n cm. above. 
 The strongly-refractory material, about 6 cm. thick, which forms 
 the cylinder consists of about 10 cm. calcined magnesite. The 
 upper portion is filled in with a mixture of 90 parts calcined mag- 
 nesite and 10 parts good kaolin. 
 
 The clay to be examined is moulded into forms similar to those 
 of " Seger' s cones," and these are enclosed in crucibles. These 
 crucibles are made out of strongly-ignited chamotte, consisting of 
 equal parts alumina and fine kaolin, which is then made plastic by 
 means of best quality kaolin. For the sake of cheapness, the sup- 
 ports are made of refractory chamotte, which does not melt below 
 the "Seger cone" No. 36. 
 
 Manipulation. The material under examination is made into 
 small, three-sided pyramids of about i cm. base and 2 cm. height 
 and then dried. Should organic matter be present, the models are 
 ignited for a time at a low red heat. One or two of these pyra- 
 mids are placed simultaneously with the corresponding Seger model 
 into the crucible. Model No. 26 represents in pottery industry the 
 fusibility of those clays which, considered as refractory materials, 
 possess the lowest melting-point. The crucibles are 50 mm. in 
 height, external diameter of 45 mm. and possess walls 5 mm. 
 thick. The lid is 5 mm. thick, and the support is 45 mm. in 
 diameter and 50 mm. high. A layer 7 mm. in height, of a mixture 
 consisting of fine, sifted, best quality and previously suspended 
 Zettlitz kaolin and alumina is poured in the crucible and com- 
 pressed. On this layer samples and ' ' Seger cones ' ' are alternately 
 placed in a circle. By lightly pressing down on them they attain 
 the necessary hold. With a pair of long-armed iron tongs the 
 support is placed over the large hole in the bottom plate ; the 
 covered crucibles are placed upon it and heating is begun. Firing 
 is begun by igniting about 30 grams compressed paper and throwing 
 it into the furnace -chamber. The bellows should not be com- 
 pressed too rapidly, but about 25 times a minute. About 200 
 grams of charcoal, hazel-nut size, are placed on top of the 
 paper. During this operation the paper ash is withdrawn from the 
 furnace. When the charcoal becomes ignited a weighed quantity 
 of broken retort graphite is thrown in. The pieces should be about 
 
ANALYSIS BY MECHANICAL MEANS. 49 
 
 hazel-nut size, and 300 pieces should weigh about i kg. The 
 compression of the bellows is increased to about 50 times per 
 minute, and is continued until the crucible comes plainly into view. 
 . 9-1 kg., usually started with, suffice, when consumed, to have melted 
 model 26. In order to attain higher temperature the amount of 
 fuel with each experiment is varied from 26-40 grams. The 
 exact amount of fuel is not capable of being determined. It de- 
 pends on the heating-power of the graphite, which, however, after 
 several experiments, can be learned. During the firing the furnace 
 is covered with a lid. The crucibles are broken open on cooling. 
 Since the gases in the furnace, depending on whether they possess 
 oxidizing or reducing power, exert a great influence on the appear- 
 ance of the clay, and since, in addition, the determination depends 
 largely on the subjective judgment of the manipulator, therefore, 
 without taking into account the behavior at lower temperatures, 
 only the actual melting-point in Seger's temperature-units will be 
 given. 
 
 (c) Calculation of refractoriness from the analysis : 
 The exact analysis of a clay is also capable of giving an insight 
 into the degree of refractoriness. 
 
 As a standard for this the quotient of refractoriness is deter- 
 mined. This is done by determining the ratio of fluxing material 
 to alumina on the one hand, and that of alumina to silica on the 
 other, and then deriving the corresponding oxygen. Iron oxide is 
 calculated in the form of ferrous oxide. Let a represent the oxy- 
 gen in the alumina, b that in silica, and c that in the fluxing material 
 (ferrous oxide, lime, magnesia, potassium oxide). Then the above 
 
 a b 
 
 ratios become --=.A and --=iB. The quotient of refractoriness 
 c a 
 
 T> 
 
 (^) then equals . A clay is still considered refractory when 
 
 -/TL 
 
 this value lies between 3 and 4. The more refractory, the more 
 these values are exceeded ; the less refractory, the lower the values 
 sink below these limits. 
 
 Example : The Zettlitzer kaolin, considered very refractory, and 
 which possesses the following composition, gives the adjoining 
 oxygen values : 
 
 4 
 
50 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Constituents. 
 
 Oxides. 
 Per Cent. 
 
 Oxygen. 
 Per Cent. 
 
 Silica 
 
 45.68 
 
 24.36 (b) 
 
 Alumina 
 
 78.154 
 
 18.03 (a) 
 
 
 .08 
 
 .02 1 
 
 Ferric oxide 
 
 GO 
 
 18 , , . 
 
 Magnesium oxide .... 
 
 38 
 
 ; I5 h^(c) 
 
 Potassium oxide 
 
 66 
 
 .11 1 
 
 Loss on ignition 
 
 I 7 OO 
 
 
 
 
 
 The comparison of the fluxes with alumina taken as unity yields 
 
 ' -:rr39.i3 (A}. Alumina compared with silica taken as unity 
 .46 
 
 15.03 
 
 Accordingly, the formula of the clay would be 39.19 (A1 2 O s .i.35 
 SiO 2 ) -j- RO, and the quotient of refractoriness F= - z= 
 28,98. 
 
III. Metallurgical Industry. 
 
 1. Iron. 
 
 THE following determinations are made, as a rule, for the various 
 kinds of iron (pig iron, wrought-iron, etc.) : silicon, carbon, man- 
 ganese, phosphorus, sulphur. Concerning sampling, let it be stated 
 that wrought-iron and gray pig-iron can be obtained in desired form 
 by boring, planing or turning, whereas white pig-iron and hardened 
 steel can be broken up with a hammer and subsequently divided in 
 a steel mortar. 
 
 (#) Silicon. Following the method of Brown, 12 grs. iron 
 of white pig-iron and steel a larger quantity are heated with nitric 
 acid (sp. gr. 1.2) until everything has dissolved. 3540 c.c. sul- 
 phuric acid (1:4) are then added, and the whole is heated on a 
 sand- or water-bath until the nitric acid has volatilized. To the 
 chilled liquid 40-50 c.c. water are then carefully added, after 
 which it is heated to complete solution of iron salts and is filtered 
 hot. The residue is washed first with hot water until iron is no 
 longer detectible, and then with hot hydrochloric acid (sp.gr. 1.12) 
 about four times, and finally with hot water to completely remove 
 the hydrochloric acid. The moist filter is consumed in a platinum 
 crucible at a low temperature and then ignited until the silica has 
 become white, a point which with graphitic pig-iron is often not 
 reached for 2-3 hours. Should the silica contain iron, it is fused 
 with sodium-potassium carbonate. 
 
 () Carbon. Total carbon and graphite are usually determined, 
 and bound carbon is calculated by difference. 
 
 (a) Total carbon. The iron is dissolved in neutral cupro-ammo- 
 nium chloride solution, which is prepared by dissolving 300 grs. 
 neutral cupro-ammonium chloride in one liter water or 340 grs. 
 crystallized copper chloride and 214 grs. ammonium chloride in 
 1850 c.c. water. In the residue the carbon is determined as car- 
 bonic acid by combustion. 
 
52 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Procedure. i gr. pig-iron, 3-5 grs. steel or 510 grs. wrought- 
 iron in pulverized condition are placed in an Erlenmeyer flask, and 
 50 c.c. of the above solution are added for every gram of iron. 
 
 The solution is briskly agitated at first at ordinary temperature, 
 later at a temperature of 40 to 50. The iron dissolves rapidly 
 with separation of copper, which later dissolves likewise, leaving a 
 residue consisting solely of carbon, silicide-, phosphide- and sulphide 
 of iron. Should a precipitate of basic salts of iron form, several 
 drops of hydrochloric acid are added to the solution. It is then 
 filtered on an asbestos filter and subsequently on a filter pump. 
 The first portions of the filtrate are tested for carbon, which may 
 have passed through, by dilution with hydrochloric acid and water 
 until transparent. It is then washed first with cupro-ammonium 
 chloride, and later with hot water until chlorine is no longer de- 
 tectible, then with alcohol, finally with ether ; whereupon the pre- 
 cipitate is dried at a low temperature. The carbon on the asbestos 
 filter is oxidized to carbonic acid by treatment with chromic acid 
 and sulphuric acid. To determine the carbonic acid, apparatus for 
 absorption of the latter is used, special care being taken to dry the 
 evolving ga-es with pumice-stone, sulphuric acid and calcium 
 chloride. In the generator of the apparatus is placed the carbon 
 deposit, together with the asbestos-tube, which has been carefully cut 
 with a file. 40 c.c. concentrated sulphuric acid are added, fol- 
 lowed, when cool, by 8 grs. crystallized chromic acid. The flask 
 is then attached to the apparatus and gently warmed. The gases 
 evolved first pass through an upright condenser, then through the 
 drying apparatus, and finally into the absorption vessels, which 
 consist of two tubes containing soda-lime. The second vessel, 
 however, is also filled about y$ its capacity with calcium chloride. 
 In addition, a protecting tube filled with calcium chloride is at- 
 tached. Heating is continued until evolution has ceased and 
 sulphuric anhydride fumes appear in the condenser. An aspirator 
 is then attached, and air, freed from carbonic acid, is drawn through 
 the system for some time. The soda-lime tubes are then detached 
 and weighed. 
 
 Recently methods have been proposed to determine the carbon 
 volumetrically. That of Lunge and Marchlewski is particularly 
 suited to this purpose. According to the latter, .5-5 grs. of the 
 
IRON. 53 
 
 iron under investigation are repeatedly agitated in a flask with a 
 saturated copper sulphate solution for 1-6 hours. The flask is then 
 connected with a condenser and a suitable gasometer and warmed 
 with the quantity of chromic-sulphuric acid mixture necessary to 
 insure oxidation. The authors have constructed for this purpose 
 special forms of generators and gas burettes. An exact description 
 of these would lead too far. They may be found in the Zeitschrift 
 fiir angewandte Chemie, Jahrgang 1891, S. 412. The apparatus is 
 obtainable from J. G. Cramer, in Zurich, C. Desaga, in Heidel- 
 berg, and others. 
 
 (/?) Graphite. 4-5 grs. iron are dissolved by warming with dilute 
 hydrochloric acid. The residue is filtered on an asbestos bed. The 
 latter is washed with hot water until the filtrate, on addition of 
 silver nitrate, no longer opalesces. It is then washed 4-5 times 
 with dilute caustic potash, followed by alcohol, to remove potash, 
 and finally with ether. After drying, the graphite is oxidized like 
 the total carbon with chromic acid and sulphuric acid. 
 
 (<:) Manganese. Of the many methods proposed for this deter- 
 mination, that of Volhard only will be described here. 
 
 Principle. If to a neutral or slightly acid solution of a manga- 
 nese salt, permanganate of potash be added at 80 C., a complete 
 precipitation of the manganese ensues. 
 
 The equation Mn 2 O 7 -f 3MnO = 5MnO 2 , originally proposed for 
 this method, is incorrect under the conditions given, according to 
 Volhard, inasmuch as a precipitate containing manganous oxide, 
 5 MnO a . MnO is formed. If, however, a solution of a zinc, lime or 
 magnesium salt be added, a peroxide containing zinc oxide, lime or 
 magnesia will be precipitated. 
 
 Observing these facts, manganese in iron may be determined by 
 adding zinc oxide to the solution containing all the iron in the ic 
 and all manganese in the ous condition. Ferric oxide is precipi- 
 tated, while an equivalent amount of zinc is dissolved. The solu- 
 tion is then titrated with permanganate of potash. 
 
 Standardization. The permanganate is standardized on iron in 
 the usual manner, and is then calculated into manganese units (of 
 manganous oxide) by use of the equation ioFe(= 2KMnO 4 )= 3Mn. 
 
 Experiment. About 4 grs. sample (less, if it contain much 
 manganese) are dissolved in nitric acid (sp. gr. 1.2) ; the solution 
 
54 CHEMICAL-TECHNICAL ANALYSIS. 
 
 is evaporated to dryness, and the residue is heated for about i hour 
 on a sand- or air-bath. Thereupon it is dissolved in warm hydro- 
 chloric acid; 20 c.c. sulphuric acid (i : i) are added, and the 
 whole is heated until sulphuric acid volatilizes. It is then taken 
 up with water and washed into a 500 c.c. graduated flask. The 
 excess of acid is nearly neutralized with sodium carbonate, and, 
 while being agitated, freshly calcined zinc oxide, suspended in 
 water, is added until the solution, which gradually turns dark brown, 
 suddenly congeals from separation of the entire ferric oxide. Water 
 is then filled in to the mark, and 100 and 250 c.c. respectively of 
 the clear filtrate are withdrawn for titration with permanganate, 
 which should be approximately TO normal. 
 
 The solution to be titrated is heated to about 80 C. It is vig- 
 orously shaken while the permanganate is introduced until the liquid 
 above the flocculent precipitate, which settles rapidly, is of a pink 
 color. It is then boiled, and when the color has disappeared, more 
 permanganate is added until a permanent color remains. 
 
 Modification by Ulzer and Brull* In order to overcome the not 
 inappreciable difficulty of detecting the end reaction of the titration 
 with permanganate, 20 c.c. of a .5 per cent, solution of hydrogen 
 peroxide may be added to the above solution, which has been freed 
 from ferric oxide by means of zinc oxide and filtered. 
 
 This is followed by the addition of caustic soda as long as a pre- 
 cipitate forms, after which it is boiled. Manganese is precipitated 
 as 5MnO r MnO. Upon cooling, oxalic acid of known strength is 
 added, together with pure dilute nitric acid. It is then digested at 
 a low heat until the precipitate redissolves, after which it is heated 
 almost to boiling, and the excess of oxalic acid is titrated with 
 permanganate. 
 
 (</) Phosphorus. To 1-5 grs. iron nitric acid (sp. gr. 1.2) is 
 added, and heat is applied to dissolve it finally. Then to fully 
 oxidize the phosphorus it is boiled with 25 c.c. of a i per cent, 
 potassium permanganate solution. An aqueous solution of 8-10 
 grs. ammonium chloride 'is added to dissolve the manganese perox- 
 ide formed. 
 
 The solution, clarified by reheating, is evaporated to dryness, 
 
 * Contribution of the K. K. Technol. Gen. Mus., Jahrg. 1895, p. 312. 
 
IRON. 
 
 55 
 
 and the residue dissolved by treating with 10-20 c.c. concentrated 
 hydrochloric acid. The solution is evaporated to syrupy consist- 
 ency and 10 c.c. nitric acid are added, followed, after a few 
 moments, by hot water. It is then filtered, washed with water 
 containing nitric acid, nearly neutralized with ammonia, though the 
 liquid is kept clear. The solution, now about 100 c.c., is heated 
 to 70, and precipitated with 25 c.c. molybdate solution. After 
 
 FIG. 6. Apparatus for Determining Sulphur. Johnston and Landolt. 
 
 standing for two hours at a temperature of 40 C. the liquid is 
 filtered off and the precipitate is washed with dilute molybdate 
 solution, containing nitric acid, as long as iron is present. It is 
 then dissolved in ammonia, and precipitated with magnesia mixture 
 in the usual manner. 
 
 (*) Sulphur. Using the less recent directions of Johnston and 
 Landolt, 5 grs. finely-divided iron are introduced into the flask, A, 
 of the accompanying apparatus (Fig. 6). Bromine-hydrochloric 
 
56 CHEMICAL-TECHNICAL ANALYSIS. 
 
 acid mixture is allowed to flow from b into the tube, C,* which is 
 filled with glass beads. The stopcock, g, is closed during the 
 above operation. 5-10 c.c. concentrated hydrochloric acid are 
 run into the flask from the funnel, c. The hydrogen sulphide gen- 
 erated is oxidized by the bromine to sulphuric acid. When the 
 bromine-hydrochloric acid mixture decolorizes, it is run into the 
 flask beneath, and is replaced by fresh solution. When the evolu- 
 tion of gas in A ceases, more hydrochloric acid from C is added, 
 and the flask finally heated, while carbonic acid is run through, 
 which has been washed with an interposed wash-bottle containing 
 mercuric chloride, to absorb any hydrogen sulphide. 
 
 After having been brought to boiling, the bromine solution is 
 allowed to flow into the flask, the glass beads are washed with 
 water, and the solution is evaporated in a porcelain dish. After 
 the bromine and the excess of hydrochloric acid have volatilized, 
 the liquid is diluted with water, filtered, and the sulphuric acid is 
 precipitated with barium chloride. Bromine and hydrochloric acid 
 must, of course, previously be tested for sulphuric acid. Instead of 
 the disagreeable bromine-acid mixture, an ammoniacal hydrogen per- 
 oxide solution, entirely free from sulphuric acid, may be used. 
 
 According to the new and popular procedure of Schulte,f 10 
 grams granulated sample are placed in the flask, A, of the accom- 
 panying apparatus (Fig. 7). The receiver, f t contains 4550 c.c. 
 of a mixture of 25 grs. cadmium acetate and 200 c.c. glacial acetic 
 acid diluted to i liter. Another portion of 10 c.c. of this solution 
 is placed in the cylindrical vessel, H. The apparatus is then ar- 
 ranged as seen in the figure. Thereupon, 200 c.c. hydrochloric 
 acid (i : 2) are placed in the funnel, JB, and allowed to slowly 
 descend into the flask, A. By slowly heating the flask, the iron is 
 brought into solution in about i^-i^ hours. It is now boiled 
 until all hydrogen sulphide has been driven out of A, which will 
 be the case when, after 1-2 minutes, the clatter, due to steam con- 
 densation, is heard in the receiver. The hydrogen sulphide evolved 
 produces a precipitate of cadmium sulphide in f, while under nor- 
 mal conditions no hydrogen sulphide will enter H. In any case, 
 
 * In place of the tube, Winkler absorption coils, containing bromine and hydro- 
 chloric acid, may be advantageously used, 
 f Stahl u Eisen, Jahrg. 1896, S. 865. 
 
ZINC BLENDE. 
 
 57 
 
 the stopper, E, is raised, and a quantity of 57 c.c. copper sul- 
 phate, containing sulphuric acid, is added. This is prepared by 
 dissolving 80 grs. crushed copper sulphate in 750 c.c. water. 175 
 c.c. concentrated sulphuric acid are added, the whole is diluted 
 to one liter, and filtered. Upon the addition of this solution, a 
 rapid and complete transformation of cadmium sulphide to copper 
 sulphide takes place. This may be hastened by agitation. The 
 separated copper sulphide is filtered off and estimated by conversion 
 into oxide or subsulphide. One equivalent of sulphur is reckoned 
 
 FIG. 7. Apparatus for Determining Sulphur. Schulte. 
 
 for every equivalent of copper found. Therefore 63.5 copper 
 (= 79.5 copper oxide = same amount of cuprous sulphide) = 32 
 sulphur. 
 
 Should a small precipitate of cadmium sulphide perhaps appear 
 in H t the two liquids are united and simultaneously precipitated 
 
 with copper sulphate. 
 
 2. Zinc Blende. 
 
 The most important determinations in this are sulphur, zinc" and 
 lead. The following methods, used in most zinc works, are pre- 
 ferable :* 
 
 * Lunge, Taschenbuch fur Sodafabrikation, etc. 
 
58 CHEMICAL-TECHNICAL ANALYSIS. 
 
 (a) Total sulphur. .5 gr. of impalpable sample is covered 
 with about 20 c.c. of a mixture of 3 parts concentrated nitric 
 acid and i part concentrated hydrochloric acid, or else with a sat- 
 urated bromine-hydrochloric acid mixture, and allowed to stand 
 over night, after which it is evaporated almost to dryness and sev- 
 eral c.c. hydrochloric acid introduced, followed by 50 c.c. hot 
 water. It is then filtered and precipitated with barium chloride. 
 
 (^) Zinc. According to the modified Schaffner process, 2.5 grs. 
 finely-powdered sample are treated with 12 c.c. fuming nitric acid 
 in an Erlenmeyer flask, at first in the cold and finally at a low heat, 
 until the red fumes have disappeared, 20-25 c.c. cone, hydrochloric 
 acid are added, and the liquid is evaporated to dryness on a sand- 
 bath. The residue is taken up with 5 c.c. hydrochloric acid and a 
 little water and heated to dissolve soluble portions. Then 50-60 
 c.c. water are added, and heat is applied again to maintain it at 
 6o-7o C. Everything should dissolve but gangue and separated 
 sulphur. A brisk current of hydrogen sulphide is conducted into 
 the solution, accompanied by a subsequent gradual addition of 50- 
 100 c.c. cold water while the liquid is being agitated, in order to 
 completely precipitate all lead and cadmium. Excessive dilution 
 and too prolonged an addition of hydrogen sulphide should be 
 avoided. The precipitate is filtered and washed with TOO c.c. water 
 containing hydrogen sulphide and 5 c.c. hydrochloric acid until a 
 drop of the filtrate no longer shows a trace of zinc when treated 
 with ammonium sulphide. Filtrate and washings are boiled to re- 
 move hydrogen sulphide, and the iron is oxidized by addition of 5 
 c.c. cone, nitric acid and 10 c.c. hydrochloric acid. After partially 
 cooling, the liquid is poured into a graduated flask of 500 c.c, 
 capacity, and 100 c.c. ammonia (sp. gr. .9-.9i) and 10 c.c. satur- 
 ated ammonium carbonate solution are added. In the meantime 
 an ammoniacal zinc solution of known strength is prepared by dis- 
 solving a quantity of chemically pure zinc, approximating the 
 amount of zinc contained in the ore, in a flask of 500 c.c. capacity, 
 by the addition of 5 c.c. nitric acid and 20 c.c. hydrochloric acid 
 and diluting with about 250 c.c. water, 100 c.c. ammonia, and 10 
 c.c. of the above ammonium carbonate solution are added ; the 
 solution is agitated and allowed to stand. In the presence of man- 
 ganese an addition of 10 c.c. hydrogen peroxide should precede 
 
ZINC DUST. 59 
 
 that of ammonia. After thoroughly cooling, both flasks are filled 
 to the mark, and the contents of the one containing the ore are fil- 
 tered through a dry ribbed filter. In titrating 100 c.c. of each so- 
 lution, ore and standard are placed in thick-walled cylinders and are 
 diluted with 200 c.c. water. For titration a concentrated solu- 
 tion of commercial crystallized sodium sulphide is very suitable. 
 The latter is dissolved in 10-20 volumes of water, and should rep- 
 resent approximately .005 .01 gr. zinc per c.c. This solution is 
 run alternately from two adjoining 50 c.c. burettes into the solu- 
 tions, and, in fact, 2-3 c.c. less than required at first. 
 
 Drops of the stirred liquids are then placed on a strip of sensitive 
 lead-acetate paper with a thin glass rod. After 1520 seconds the 
 drops are washed off, the addition of sodium sulphide solution is 
 continued, and the tests with lead-acetate paper are repeated until 
 after an equal period faint but distinct tints of equal intensity appear. 
 It is desirable to contrast the first result, usually approximate, with 
 two or three more. At any rate, the end reactions in both cylinders 
 must be uniform in both vessels and the readings must be made 
 within .05 c.c. 
 
 Let the amount of zinc in the standard solution = a, the number 
 of c.c. sodium sulphide used in titrating 100 c.c. standard solution 
 = b, and the number used in titrating 100 c.c. solution containing 
 
 40 ac 
 ore (= . 5 gr. ore) = c ; then the percentage of zinc = ^ 
 
 In very exact determinations a quantity of ferric chloride cor- 
 responding to that in the ore solution is added to the standard 
 solution to compensate for a possible precipitation of zinc by the 
 ferric hydrate. 
 
 (V) Lead. The precipitated sulphides in b are, if necessary, 
 digested with a fairly concentrated solution of sodium sulphide, 
 diluted and filtered. The residue, plus filter-paper, is dissolved in 
 dilute nitric acid, evaporated with an excess of sulphuric acid, and 
 the lead is determined as lead sulphate. 
 
 3. Zinc Dust. 
 
 The following method of Drewsen, modified by Fraenkel, deter- 
 mines the reducing value only, and therefore small quantities of 
 iron and cadmium present are calculated as zinc. The method 
 
60 CHEMICAL-TECHNICAL ANALYSIS. 
 
 depends on the fact that by the action of sulphuric acid on zinc, in 
 the presence of an excess of bichromate of potash, a part of the 
 chromic acid is reduced to chromic oxide. The unaltered chromic 
 acid is determined iodometrically, and the zinc is calculated from 
 the difference. A ^ normal potassium bichromate solution, con- 
 taining 24.58 grs. of the pure salt in a liter, and a y 2 normal 
 hyposulphite solution are suitable. The latter is exactly standard- 
 ized on the former. In operating, approximately .5 gr. zinc dust 
 is placed in a dry flask of about ^ -liter capacity provided with a 
 stopper. 50 c.c. bichromate solution, next 5 c.c. dilute sulphuric 
 acid (i : 5), are added, and the mixture is agitated. After about 
 5 minutes 10 c.c. more sulphuric acid are added, and the whole is 
 shaken for 10 minutes, when complete solution usually ensues. In 
 order to estimate the chromic acid yet present, 40 p.c. iodide of 
 potassium solution (i : 10) are added, followed by additional 20 
 c.c. sulphuric acid. Separation of considerable iodine ensues. 
 (2CrO 3 = 61). After dilution with 400-500 c.c. water, the iodine 
 is titrated with hyposulphite. To determine the end reaction with 
 precision, hyposulphite solution is added to the brown iodine solu- 
 tion until the latter becomes yellow-green in color. Starch paste 
 is added at this point, whereby the liquid turns deep green. By 
 continued careful titration the color changes gradually into a deep 
 blue until finally the comparatively light-green chromic salt is 
 obtained, at which point the titration is complete. With a little 
 practice, a sharp end reaction is go ten. The difference between 
 the quantity of bichromate solution added and the quantity of 
 hyposulphite solution used in back titration gives the chromic acid 
 reduced by the zinc, from which the zinc can be calculated. 
 
 i K 2 Cr 2 O 7 = 6 I = 3 Zn. 
 
 4. Crude and Refined Copper. 
 
 Great stress has been recently laid on the technical examination 
 of the chemical composition of the kinds of copper named. Certain 
 specifications in this direction are required ; for example, for rail- 
 road consignments. In consequence, various kinds of copper are 
 often subject to quantitative chemical analysis. The analysis offers 
 considerable difficulty when contaminations, usually present in small 
 
CRUDE AND REFINED COPPER. 61 
 
 amount, are present in quantity. When an exact total analysis is 
 desired,* the very reliable method of Fresenius seems to be the 
 simplest one. The method is given here, with a few slight modifi- 
 cations by Fraenkel. 
 
 The foreign elements which are to be determined are : Silver, 
 lead, arsenic, antimony, tin, bismuth, iron, cobalt, nickel, zinc, 
 sulphur, phosphorus and oxygen. The determination of gold may 
 usually be neglected. Copper is calculated with sufficient accuracy 
 by difference. 
 
 100 grs. copper turnings or shavings are taken for the analysis, 
 and, after separation of particles of iron by means of a magnet, are 
 dissolved in nitric acid (sp. gr. 1.2). Solution had best be con- 
 ducted in a beaker of about i liter capacity. The acid is gradually 
 added and warmed toward the end, to effect complete solution. It 
 is filtered, after dilution with water, into a graduated 2-liter flask, 
 washed with hot water, and the flask (^4), not yet filled to the 
 mark, is stood aside. 
 
 The residue is washed from the filter into a porcelain crucible 
 and evaporated to dryness ; the filter ash is added and fused with 
 a mixture of soda and sulphur. .The chilled fusion is lixiviated 
 with hot water, filtered into a graduated flask of 200 c. c. capacity 
 and washed with water to which some sodium sulphide has been 
 added. The filtrate (,#), which is diluted to the mark, is likewise 
 corked up and preserved. The residue (C), together with the filter- 
 paper, is warmed with nitric acid (i : i), diluted with water, fil- 
 tered and added to flask (A), which is then filled to the mark. 
 From the contents of this flask 1000 c.c. are removed for the deter- 
 mination of silver, lead, bismuth, arsenic, tin, antimony, iron, 
 nickel, cobalt and zinc, and the remaining liquid is preserved. 
 This 1000 c.c. represents one-half the original amount of substance 
 taken. It is placed in a beaker, about 4 drops cone, hydrochloric 
 acid are added, and warmed and stirred, in case turbidity ensues, 
 until the liquid clarifies. The separated silver chloride is filtered 
 off and washed. The silver is determined as usual. The lead is 
 determined by adding 85 grs. cone, sulphuric acid to the filtrate, 
 
 * For the simple estimation of the copper, the electrolytic method, by all means, 
 answers the purpose best. 
 
62 CHEMICAL-TECHNICAL ANALYSIS. 
 
 evaporating on a water-bath until nitric acid is completely expelled, 
 dissolving the separated sulphate of copper in water by warming, 
 and filtering off the insoluble sulphate of lead. The latter is 
 washed first with water containing sulphuric acid, and then over a 
 separate receiver with dilute alcohol. The lead is then determined 
 in the usual manner. 
 
 The filtrate from the lead sulphate is heated and then placed in 
 a previously weighed flask (Z>) of about 5 liters capacity. Suffi- 
 cient hot water is added to bring the total volume to 34 liters. 
 About 50 c.c. cone, hydrochloric acid are added, and a brisk con- 
 tinuous current of hydrogen sulphide is conducted in, until com- 
 plete precipitation is indicated by the rapid settling of the precipi- 
 tate and a perfectly colorless supernatant liquid. The precipitate 
 (~) contains all the copper, bismuth, arsenic, antimony and tin. 
 Iron, nickel, cobalt and zinc remain in solution. Flask, solution 
 and precipitate are weighed ; the weight of the flask is deducted 
 and the weight of liquid and precipitate thereby ascertained. The 
 weight of precipitate is found by calculating the copper contained 
 therein into copper sulphide. If this be deducted also, the weight 
 of liquid alone is obtained. As soon as the precipitate has well 
 settled, as much of the clear liquid as possible is drawn off with a 
 siphon. If the remaining liquid, precipitate and flask be now 
 weighed together, the difference between it and the former weight 
 gives the weight of liquid siphoned off. By simple proportion the 
 corresponding quantity of original substance contained therein can 
 be calculated. This solution, filtered if necessary, serves for the 
 determination of iron, nickel, cobalt and zinc. For this purpose it 
 is evaporated as far as possible in a porcelain dish on a water-bath 
 and the excess of sulphuric acid is volatilized over a naked flame. 
 The residue is heated with water and nitric acid, filtered, treated 
 with an excess of ammonia, and the precipitate formed is dissolved 
 in hydrochloric acid and reprecipitated with ammonia. The opera- 
 tion is repeated if necessary, and the precipitate is finally weighed 
 as ferric oxide. To the collected filtrates more ammonia is added, 
 followed by acetic acid to slight acid reaction. Hydrogen sulphide 
 is conducted into the heated solution, whereby cobalt, nickel and 
 zinc are precipitated. These are filtered off, dried, removed as far 
 as possible from the filter, and dissolved in nitric acid and a little 
 
CRUDE AND 11EFINED COPPER. 63 
 
 hydrochloric acid. The filter ash is added, the liquid is evaporated 
 on a water-bath, taken up with water and a little hydrochloric acid, 
 and then exactly neutralized with sodium carbonate, using methyl- 
 orange as indicator. A slow current of hydrogen sulphide is now 
 led in for a brief period. A few drops of dilute, preferably very 
 weak, alkaline sodium acetate solution are added, whereby an ap- 
 preciable darkening of the precipitate should not ensue. A very 
 slow current of hydrogen sulphide is again led in for a few minutes, 
 and the zinc sulphide formed is allowed to settle for a few hours. 
 It is filtered in a double filter, washed with water containing hydro- 
 gen sulphide, and the zinc is determined as sulphide in the usual 
 manner. 
 
 The filtrate from the zinc is best completely evaporated to expel 
 hydrogen sulphide. The residue is taken up with hydrochloric 
 acid and water, filtered if necessary, and the cobalt and nickel are 
 then precipitated with an excess of caustic potash. They are first 
 of all determined together. Should a separation be desired, which 
 as a rule will not be required on account of the preponderance of 
 nickel, one of the usual methods is employed. 
 
 To the residual liquid and precipitate (^) in flask (Z>~) potassium 
 or sodium hydrate is added to slight alkaline reaction. A sufficient 
 quantity of light yellow potassium or sodium sulphide solution is 
 then added, together with TOO c.c. (= one -half) of the liquid in 
 flask (j9). The flask is then placed in a warm place, and frequently 
 agitated to bring all sulphides of antimony, tin and arsenic into 
 solution. It is then diluted to 34 liters with water and weighed, 
 and as much as possible of the clear liquid is withdrawn. The 
 remainder, together with flask and sediment, is weighed, and the 
 amount of copper corresponding to the liquid withdrawn is calcu- 
 lated as before. The flask and precipitate are preserved. 
 
 In order to estimate antimony, tin and arsenic, the liquid is 
 filtered, if necessary, and acidified with hydrochloric acid. The 
 sulphides of these metals and much sulphur are precipitated. These 
 are allowed to settle for a time, and are then filtered and dried. 
 Thereupon precipitate and filter are placed in a flask and extracted 
 with carbon disulphide to free from the greater part of the sulphur. 
 The solution is filtered and the residue is warmed with dilute 
 ammonium sulphide, whereby the sulphides dissolve. After this 
 
64 CHEMICAL-TECHNICAL ANALYSIS. 
 
 has been filtered and the filter has been thoroughly washed it is 
 warmed, and pure hydrogen peroxide is added until the color has 
 disappeared and the sulphur has been thoroughly oxidized. It is 
 now evaporated to dryness in a spacious porcelain dish and oxidized 
 with fuming nitric acid. The latter is expelled as far as possible, 
 and potassium hydrate is added to distinct alkaline reaction, after 
 which the whole is washed into a large silver crucible. A few pieces 
 of stick caustic soda are placed in the crucible, which is heated 
 carefully in a sand-bath until the water has been completely expelled. 
 The residue is then gradually heated to continued fusion, and finally 
 over a naked flame. The crucible contents, now perfectly clear, 
 are lixiviated with water until the insoluble particles have separated 
 as a powder, when about ^ the volume of alcohol is added. The 
 crucible is covered, and the contents are occasionally stirred during 
 the 24 hours in which it is allowed to stand. The undissolved 
 sodium antimonate is filtered and washed with dilute alcohol (i : i), 
 to which a few drops of sodium hydrate solution have been added. 
 Stannate and arsenate of sodium remain in the filtrate (-^). The 
 precipitate of sodium antimonate on the filter is repeatedly covered 
 with a warm solution of tartaric acid in dilute hydrochloric acid 
 until all has dissolved. The solution is diluted, heated and precipi- 
 tated with hydrogen sulphide. Orange sulphide of antimony forms. 
 Should the precipitate be rendered dark from silver sulphide arising 
 from the crucible, it is redissolved by warming with ammonium 
 sulphide, filtered from the sediment and reprecipitated with hydro- 
 chloric acid. The hydrogen sulphide is expelled by conducting 
 into the flask a current of carbonic acid. It is then filtered on a 
 previously dried and weighed filter, after which it is dried and 
 weighed. To expel the last traces of water and sulphur when large 
 quantities of antimony sulphide are concerned, an aliquot portion 
 of the dried precipitate is placed in a porcelain boat, which is 
 introduced into a glass tube and moderately heated. Pure dark -gray 
 trisulphide of antimony is thus obtained. With small quantities it 
 suffices to wash the dried precipitate on the filter repeatedly with 
 carbon disulphide, dry and weigh. 
 
 Hydrochloric acid is added to filtrate (J?) to acid reaction. 
 Thereby a white precipitate of arsenate of tin now and then 
 appears. Without taking notice of this, the tin and arsenic are 
 
CRUDE AND REFINED COPPER. 65 
 
 precipitated with a current of hydrogen sulphide. These are fil- 
 tered on a dried and weighed filter, washed with hydrogen sulphide 
 water, dried and weighed. A separation of tin from arsenic in the 
 precipitate, which usually contains a considerable amount of sulphur, 
 is conducted in the following way : An aliquot portion of the same 
 is placed in a bulb tube bent at a right angle on one side. The 
 straight side is attached to a hydrogen sulphide generator by means 
 of a calcium chloride drying tube. The bent part is connected 
 by a rubber stopper to a Peligot tube filled with ammonia (about 
 i : 2). This tube, finally, may be attached to a second absorption 
 vessel. The bulb is then heated in a current of hydrogen sulphide. 
 Sulphide of arsenic and sulphur which are evolved collect in the 
 ammonia, while sulphide of tin remains in the bulb. The bulb- 
 tube is detached and heated strongly in a current of air, which is 
 conducted through. The sulphide of tin is thereby changed to 
 oxide, and this is weighed on cooling. The tin is calculated 
 from it. 
 
 The solution of sulphide of arsenic is washed into a beaker, 
 acidified with hydrochloric acid, chlorate of potash is added, and 
 the liquid is warmed moderately. Sulphide of arsenic dissolves. 
 Any sulphur remaining is filtered off. The arsenic in the filtrate is 
 determined as magnesium pyroarsenate in the usual manner, and 
 from it the arsenic is calculated. Bismuth is determined by re- 
 peatedly adding a large quantity of water containing sodium sul- 
 phide to the remaining liquid and precipitate in flask (-D), shaking, 
 and drawing off as much liquid as possible. The residue is covered 
 with hydrochloric acid, nitric acid is gradually added, and the 
 whole is allowed to stand in a warm place. A gradual solution of 
 the precipitate takes place, with separation of pure sulphur. Too 
 energetic action causes retention of copper sulphide. The sulphur 
 is filtered off, washed, and the solution is evaporated repeatedly 
 with hydrochloric acid. When the latter is almost completely ex- 
 pelled, water is added, and the small amount of residue remaining 
 is filtered off. The latter consists principally of basic bismuth chlo- 
 ride. To purify the same, it is dissolved in dilute hydrochloric 
 acid, treated with caustic potash to alkaline reaction, potassium 
 cyanide is added, and the bismuth is precipitated with sodium sul- 
 phide, while sulphide Of copper remains dissolved in the cyanide 
 
 5 
 
66 CHEMICAL-TECHNICAL ANALYSIS. 
 
 of potash. The precipitate is thrown on a previously dried and 
 weighed filter, repeatedly washed with carbon disulphide, and 
 weighed as sulphide of bismuth. 
 
 Sulphur is determined by adding ammonia to 400 c.c. of the 
 liquid remaining in (A), until the greater part of the free nitric acid 
 has been neutralized, and after the addition of a few drops of 
 barium nitrate solution is allowed to remain in a warm place. In 
 the presence of appreciable traces of sulphur, probably contained in 
 the form of sulphurous acid in the copper, a small precipitate of 
 barium sulphate is formed which is filtered and weighed. 
 
 In another 400 c.c. solution still in flask (A), the phosphorus is 
 determined. 
 
 To accomplish this the liquid is repeatedly evaporated with 
 hydrochloric acid to expel nitric acid. The residue is dissolved in 
 hot water, placed in a weighed flask of 2 liters capacity, and diluted 
 with hot water to about 1200 c.c. This solution is completely, pre- 
 cipitated at about 70 C. with hydrogen sulphide. The sulphides 
 are allowed to settle and as much clear supernatant liquid as possible 
 is drawn off. Flask, remaining liquid and precipitate are weighed, 
 and, as before, the corresponding amount of copper in the sepa- 
 rated liquid is calculated. The solution is filtered, evaporated to 
 small bulk with repeated additions of nitric acid, and the phos- 
 phorus is determined in the usual manner. (See also Chapter V. , 
 Fertilizers.) The method of Hampe is used to determine, in the 
 bullion, the oxygen which is combined partly with metals and partly 
 with sulphur. The thoroughly cleaned copper is first filed. The 
 filings are sieved through a hair sieve and the iron particles are with- 
 drawn by means of a magnet. The powder is next boiled with 
 dilute caustic potash to rid it of traces of fat, etc. The liquid is 
 poured off, and the powder is washed and hurriedly dried. 
 
 The estimation of oxygen is calculated by loss of weight upon 
 ignition in a current of hydrogen. A hard glass bulb tube, drawn 
 out at both ends, is suitable for this purpose. It is first heated in a 
 current of dry air and then allowed to cool. It is weighed ; 10-20 
 grs. dry copper powder are thereupon placed in the tube, which is 
 reweighed. Dry carbonic acid from a Kipp generator is then con- 
 ducted through the tube. The generator is set in action two hours 
 before use, and to purify and dry the carbonic acid it is led through 
 
CRUDE AND REFINED COPPER. 67 
 
 the following system : A solution of bicarbonate of soda, a tube 
 filled with lumps of bicarbonate, a wash-bottle containing silver 
 nitrate solution, a tube containing pumice-stone saturated with 
 the latter solution, a wash-bottle containing cone, sulphuric acid, 
 and finally a calcium chloride tube. The carbonic acid is allowed to 
 pass through the tube containing the copper for five minutes, after 
 which it is very moderately heated to free from all traces of water. 
 A sublimate of arsenic acid will form when the heat applied is too 
 strong. Pyrogenous products should not form. Upon cooling in 
 carbonic acid, the latter is replaced by air and the tube is weighed. 
 The loss of weight should equal only a few milligrams. A very 
 slow current of pure hydrogen is then conducted over the copper. 
 Thereupon the latter is at first moderately heated, and later to glow- 
 ing, for about fifteen minutes. During the application of heat, 
 water forms, whereas, with impure copper, a sublimate of arsenic, 
 antimony and lead, forms in the bulb and adjacent to it. This sub- 
 limate should in no case issue from the tube. Therefore the tube 
 should be drawn out sufficiently long, and the hydrogen current 
 should be correspondingly slow. When the copper contains sul- 
 phurous acid, some hydrogen sulphide is evolved with the steam. 
 In order to estimate its quantity, the gases are led through an alka- 
 line lead solution or a bromine-hydrochloric acid mixture, and the 
 sulphur is estimated from the sulphuric acid formed. After the 
 copper has thoroughly cooled in hydrogen, dry air is again con- 
 ducted through and the tube is weighed. The loss in weight, less 
 the sulphur evolved as hydrogen sulphide, gives the amount of 
 oxygen present. 
 
IV. Alloys. 
 
 1. Phosphor-Bronze. 
 
 THIS usually contains copper, tin and phosphorus, and frequently 
 also lead and zinc. The presence of other constituents, however, 
 like arsenic and iron, is not excluded,* on account of which a 
 qualitative analysis should always be conducted first. 3 grams of 
 the broken-up alloy, taken for quantitative analysis, are covered 
 with water, and nitric acid is carefully added. Heat is generated, 
 and decomposition takes place. It is brought to a finish by heating 
 with a small flame. It is evaporated to dryness in a porcelain dish, 
 dissolved in nitric acid, and water is added, after which it is filtered 
 and washed out with hot water ( residue A and filtrate B). 
 
 Residue A contains all the tin, together with all phosphorus (as 
 phosphate of tin), some copper and some of the lead. It is ignited 
 and weighed. Thereupon it is fused in a porcelain crucible with 
 carbonate of soda and sulphur. The fusion is lixiviated with hot 
 water. The small residue is filtered off, and estimated either directly 
 as subsulphide of copper by ignition with sulphur in an atmosphere 
 of hydrogen, or else, if necessary, a separation of copper from lead 
 is carried out by means of sulphuric acid in nitric acid solution. 
 The filtrate containing the phosphoric acid and tin is acidified 
 with hydrochloric acid. The sulphide of tin is filtered off, the 
 filtrate evaporated to dryness on a water-bath, and taken up with 
 nitric acid. The phosphoric acid is precipitated with molybdate 
 solution, and the determination is continued in the usual manner. 
 The copper, calculated into cupric oxide, plus the phosphoric 
 anhydride formed from the phosphorus, is deducted from the total 
 residue, and the remainder is calculated as oxide of tin. 
 
 The filtrate B, after addition of sulphuric acid, is evaporated to 
 dryness, to precipitate lead, and the sulphuric acid completely 
 
 # No account of the presence of these is taken in the following method of quan- 
 titative analysis. 
 
WHITE METAL. 69 
 
 expelled. The residue is then taken up with water, washed with 
 water containing sulphuric acid, then with alcohol, and is finally 
 ignited and weighed. Filtrate from the lead sulphate is placed in a 
 250 c.c. graduated flask, and diluted to the mark. In one portion of 
 50 c.c. the copper is estimated as sulphide by means of hydrogen 
 sulphide, while in the remaining 200 c.c. the metals present in less 
 quantity may be determined. For this purpose copper is precipi- 
 tated with hydrogen sulphide, and filtered off. The nitrate is 
 evaporated to dryness, taken up with a few drops of hydrochloric 
 acid, neutralized exactly with sodium carbonate, and hydrogen 
 sulphide is run in. Sulphide of zinc is precipitated. Upon addi- 
 tion of a few drops of a dilute solution of sodium acetate and 
 renewed addition of hydrogen sulphide, the precipitation is com- 
 pleted. The precipitate is allowed to stand for a time, filtered, and 
 determined as zinc sulphide by ignition with sulphur in a current of 
 hydrogen. To the copper contained in the filtrate B, that which was 
 contained in residue A must be added. The same holds good for 
 any lead found in the residue. 
 
 2. White Metal. 
 
 This contains tin, as a rule, as chief constituent, together with 
 antimony and also zinc. Copper and lead are frequently present in 
 minute quantities, although sometimes in large quantities. Arsenic, 
 mercury, nickel and iron may be present. The quantitative analysis 
 covering the presence of tin, antimony, copper, lead and zinc will 
 be described. 
 
 1-2 grs. alloy are dissolved in nitric acid, as previously described, 
 evaporated nearly to drynesss, taken up with dilute nitric acid, 
 filtered, and washed with water containing ammonium nitrate. 
 (Filtrate A. Residue B. ) 
 
 Filtrate A contains copper, lead and zinc, whose separation is 
 conducted as given under Phosphor-Bronze. 
 
 Residue B contains all tin and antimony, besides small quantities 
 of copper, lead and zinc. It is dried, ignited and weighed. A 
 weighed portion of the same is fused with soda and sulphur, and 
 the fusion is lixiviated with water. Should the residue be small, it 
 may be directly ignited with sulphur in a current of hydrogen, and 
 considered as the sulphide of one of the three metals, copper, lead 
 
70 CHEMICAL-TECHNICAL ANALYSIS. 
 
 and zinc, depending on the predominance of one or another as 
 shown by the qualitative tests or the quantitative analysis of filtrate 
 A. Should there be considerable residue, it is dissolved in hot 
 dilute nitric acid, and the individual constituents are separated and 
 determined. The amount of these (in form of oxides) is deducted 
 from the substance used for fusion, whereby tin oxide and antimony 
 oxide (SnO 2 and Sb 2 O 4 ) remain. These are recalculated from the 
 aliquot portion used on the total residue. In order to separate tin 
 and antimony, another portion of the residue B is fused with caustic 
 soda in a silver crucible, and the fusion is lixiviated until the insol- 
 uble portion is powdered. One-half volume of alcohol is added, 
 and allowed to stand 24 hours with repeated stirring. It is then 
 filtered off and washed with dilute alcohol (i : 2). The sodium 
 antimonate remaining in the filter contains a small quantity of cop- 
 per, whereas traces of lead or zinc will remain in solution with the 
 tin, and can be precipitated by careful addition of sodium sulphide. 
 After filtration from this minute precipitate, hydrochloric acid is 
 added to precipitate tin sulphide, which is quantitatively estimated 
 as tin oxide by careful oxidation and ignition with ammonium car- 
 bonate. If this be calculated on the total residue, and subtracted 
 from the sum of the oxides of tin and antimony previously found, 
 there remains the antimony tetroxide, from which antimony is 
 calculated. 
 
 3. Iron Alloys. 
 
 Iron is alloyed with other substances besides those mentioned 
 under the investigation of iron, in order to impart to it certain 
 properties, principally hardness and toughness. Some of these 
 substances are chromium, tungsten, titanium, aluminium and 
 nickel. For instance, there is contained in tungsten steel 9 per 
 cent. W. ; in chromium steel, 2-4 per cent. Cr. ; in ferro-chrom, 
 29-49 per cent. Cr. ; in ferro-aluminium, 6.8-10 per cent. Al., 
 and in nickel steel, 8-10 per cent. Ni. With reference to chro- 
 mium and nickel estimations, ferro-chrom and nickel steel serve as 
 illustrations of such alloys. 
 
 Ferro-chrom. 1-4 grs. of sample, powdered as fine as possible, 
 are boiled ^ hour in a large beaker with 500 c.c. water and 50 c.c. 
 sulphuric acid (i : i). Usually all dissolves. Should a residue 
 remain, however, after continued heating, it is filtered off, washed, 
 
IRON ALLOYS. 71 
 
 incinerated in a platinum capsule, and fused with a mixture of two 
 parts fused borax and three parts soda for three hours at a high 
 heat, preferably in a muffle. The fusion is dissolved in water, 
 acidified with sulphuric acid, and added to the first filtrate. The 
 united filtrates are brought to boiling, and a concentrated perman- 
 ganate solution is added to the same until red coloration sets in. 
 The excess of permanganate is reduced with manganous sulphate, 
 after which it is washed into a liter flask filled to the mark after 
 cooling, well shaken, and filtered through a ribbed filter. An ali- 
 quot part of this solution, which is colored yellow in presence of 
 the smallest quantities of chromium, is treated with 50 or 100 c.c. 
 ferrous ammonium sulphate solution (containing 20 grams of the 
 salt and 10 c.c. sulphuric acid (i : i) to the liter), after which the 
 excess of ferrous salt is titrated back with -& normal permanganate. 
 At the same time the same quantity of ferrous ammonium sulphate 
 solution is titrated with permanganate, and from the quan- 
 tity of the latter now used the first is deducted. The differ- 
 ence represents the ferrous oxide oxidized by the chromic acid from 
 which chromium can easily be calculated. 2CrO 3 = 6 Fe O. 
 
 Nickel steel. 2-4 grs. sample are dissolved in nitric acid (sp. gr. 
 1.2). After dissolving, 1020 c. c. sulphuric acid (i : i) are added, 
 and the whole is evaporated until sulphuric acid begins to volatilize. 
 The residue is dissolved in water, and the solution is gradually 
 poured into a 500 c.c. flask in which 50 c.c. sulphate of ammonium 
 solution (containing 500 grs. of the salt in a liter of water) and 130 
 c.c. cone, ammonia have previously been placed. It is then diluted 
 to the mark, well mixed, and filtered through a ribbed filter. Two 
 hundred and fifty c.c. of the filtrate are taken, and in this the 
 nickel is determined either electrolytically or by precipitation 
 with ammonium sulphide, or hydrogen sulphide,* in a solution 
 slightly acidified with acetic acid. In case copper was present in 
 the nickel steel, it will be found in the ammoniacal solution. The 
 copper, in the solution strongly acidified with hydrochloric acid, 
 may be removed with hydrogen sulphide. Estimation of nickel is 
 then conducted with the filtrate. 
 
 * In the latter case the precipitate of nickel sulphide is dissolved in hydro- 
 chloric acid, with addition of nitric acid or potassium chlorate, and then precipi- 
 tated with caustic potash. It is finally transformed into metallic nickel by reduc- 
 tion in a current of hydrogen. 
 
V. Fertilizers. 
 
 THESE may be divided into three groups, according to their active 
 constituents: i. Phosphate fertilizers; 2. Potash fertilizers; 3. 
 Nitrogenous fertilizers. In addition to these, mixed fertilizers are 
 used which may contain all three constituents. 
 
 Combined methods exist for the estimation of phosphoric acid, 
 potash and nitrogen. These will be described first of all. 
 
 (a) Phosphoric Acid. 
 
 Phosphoric acid may be determined gravimetrically or volumet- 
 rically. The gravimetric methods are the molybdate and citrate 
 methods. In both the phosphoric acid is determined finally as 
 magnesium pyrophosphate. It is determined volumetrically by 
 titration with uranium acetate. 
 
 (a) Molybdate method. Separation from all other bases is 
 accomplished by use of ammonium molybdate, whereby all phos- 
 phoric acid is precipitated in the form of a compound of varying 
 composition. Phosphoric acid is determined from this. 
 
 To do this, 200 c.c. molybdate solution are added to a solution 
 containing phosphoric acid (not exceeding .2 gr. P 2 O 5 ), which is 
 then kept for 15-20 minutes at a temperature of 7080 C. After 
 standing three hours the supernatant liquid is filtered off, and the 
 precipitate, as much as possible of which is allowed to remain in 
 the beaker, is washed with a 1 5 per cent, solution of ammonium 
 nitrate, containing 10 c.c. nitric acid to the liter. The washings 
 are thrown on the same filter. The beaker, holding the main por- 
 tion of precipitate, is placed under the funnel. A warm 2^ per 
 cent, ammonia solution is poured on the filter in just sufficient 
 amount to dissolve the precipitate upon it. It is then washed with 
 cold ammonia of the same strength until a red coloration (molyb- 
 date reaction) no longer appears on adding ferrocyanide of potassium 
 to a drop of the filtrate placed on a porcelain plate. The quantity 
 
FERTILIZERS. 73 
 
 of ammonia used (150 c.c.) should just about suffice to dissolve 
 the precipitate in the beaker on shaking. If not, more ammonia 
 is added, and a clear solution is obtained. To this, for every . i gr. 
 P 2 O 5 , TO c. c. magnesium mixture are added, drop by drop. It is 
 stirred for some time without touching the sides of the beaker, and 
 is filtered after at least three hours' standing. The precipitate is 
 washed with 2 ^ per cent, ammonia until a portion of the filtrate, 
 acidified with nitric acid, opalesces but slightly. Further manipu- 
 lation is conducted in the usual manner. 
 
 Reagents used are prepared as follows : 
 
 Molybdate solution : 150 grams crystallized ammonium molybdate 
 and 400 grams ammonium nitrate are dissolved in a liter of water, 
 and the solution is poured into an equal volume of nitric acid (sp. 
 gr. 1.19). The solution should be kept in the dark. 
 
 Magnesium mixture: 100 grams magnesium chloride and 140 
 grams ammonium chloride are dissolved in 1300 c.c. water, and 
 diluted to two liters with 24 per cent, ammonia. It is filtered after 
 standing in a stoppered flask for several days. 
 
 (j3) Citrate method. By use of this method the precipitation of 
 phosphates of lime, iron, etc. , by ammonia is prevented by citric acid. 
 
 A quantity of solution containing phosphoric acid (not exceeding 
 .2 gr. P 2 O.) is treated with 100 c.c. citrate solution (prepared by 
 dissolving 150 grs. citric acid in water, adding 500 c.c. 24 per cent, 
 ammonia, and diluting to 1500 c.c.). If necessary, more ammonia 
 is added, whereby turbidity must not ensue. The excess is neutral- 
 ized with a few drops of nitric acid, and 25 c.c. magnesium mixture 
 are added. The precipitate is treated as under (a). 
 
 The method is easily carried out and is much used. Since on 
 the one hand some magnesium ammonium phosphate is dissolved 
 by the excess of citric acid, and, on the other hand, small quantities 
 of phosphate of lime, etc., are precipitated, the errors are balanced. 
 
 ( r ) Uranium method. This method, which is considered as 
 universally known, can only be used to determine water-soluble 
 phosphoric acid. It is now rarely used, at any rate. 
 
 (b) Potassium Oxide. 
 
 This is determined as the double salt 2KCl.PtCl 4 by using pla- 
 tinic chloride. It is only necessary that nothing but chlorides be 
 
74 CHEMICAL-TECHNICAL ANALYSIS. 
 
 present, of which those of sodium, calcium and magnesium form 
 platinum salts, soluble in alcohol, whereas that of potassium chlo- 
 ride is insoluble. 
 
 Should there be sulphates present, as is usually the case, they are 
 converted into chlorides by adding a boiling chloride of barium 
 solution (avoiding excess as much as possible) to the liquid, to 
 which i c.c. hydrochloric acid has been added, without regarding 
 a possible residue. The filtrate,' or an aliquot portion of the same, 
 is evaporated down to about 15 c.c. bulk, and sufficient platinic 
 chloride is added to convert all salts present into double salts ( i 
 gr. platinum to .5 gr. substance). It is stirred with a glass rod, 
 evaporated to about 10 c.c., and 90 per cent, alcohol is added. 
 After stirring for a while, and permitting to stand, it is filtered on 
 a filter, moistened with alcohol, and washed with alcohol until the 
 washings have become colorless. 
 
 The precipitate may be dried at 130 and weighed. But since 
 it can contain small quantities of chlorides insoluble in alcohol, it is 
 better to incinerate, filter and place contents in a porcelain crucible, 
 and to ignite the residue separately with small quantities of pure 
 oxalic acid at a high temperature. 
 
 (c) Nitrogen. 
 
 Nitrogen can be present as ammonia (ammonium salts), as nitrates, 
 or as organic nitrogenous compounds. It may finally be present as 
 a combination of two or three of these forms. 
 
 (a) Nitrogen as ammonia. The estimation is carried out by 
 heating with caustic soda and absorbing the ammonia evolved in 
 standardized acid. The operation is well known. When nitrogenous 
 organic matter is simultaneously present, which is partially decom- 
 posed by boiling caustic soda with formation of ammonia, soda- 
 lime or freshly calcined magnesia is used. 
 
 (/?) Nitrogen as nitrates is estimated in an eudiometer graduated 
 into tenths, as nitric oxide, which is caught up after liberation from 
 the nitric acid, which is reduced with ferrous chloride (method of 
 Schulze-Tiemann or Schlosing- Wagner). 
 
 (>) Organic nitrogen. Various methods proposed for this esti- 
 mation have been replaced by the method of Kjeldahl, the modi- 
 fied form of which, by Wilfarth, will be described here. 1-2 grs. 
 substance are covered with 20 c.c. cone, sulphuric acid in a long- 
 
FERTILIZERS. 75 
 
 necked, round-bottom flask of about 150 c.c. capacity. .7 gr. freshly 
 prepared yellow mercuric oxide (or .5 gr. mercury) is added, and the 
 whole is heated on a wire gauze, at first moderately, and finally to 
 a brisk boiling. It is better to fasten the flask in a clamp in an in- 
 clined position in order to avoid loss by sputtering, and also to avoid 
 the direct heating of the frequently uneven bottom of the flask. 
 
 The liquid is heated until colorless. It is allowed to cool and is 
 poured into an Erlenmeyer flask of about 3^ liter capacity, con- 
 taining some water, and is then thoroughly rinsed out. After cool- 
 ing, an excess* of about 30 per cent, caustic soda is added, together 
 with 25 c.c. of a 10 per cent, potassium sulphide solution. The 
 latter precipitates all the mercury in the form of mercuric sulphide 
 and simultaneously decomposes the mercury amides, from which the 
 ammonia is expelled very slowly by alkalies. A few pieces of gran- 
 ulated zinc are added, to prevent bumping on distillation. 
 
 By distilling, all the ammonia is volatilized and is collected in a 
 receiver containing 20 c.c. of half-normal sulphuric acid and 50 
 c.c. of water. The excess of acid is titrated and the nitrogen is 
 calculated (iH. 2 SO 4 is equivalent to 2N). In order to prevent 
 alkali from being carried over, different forms of apparatus have 
 been proposed. As a rule, a bulb tube is placed in the flask 
 and connected with a condenser. Distillation is finished at the end 
 of from 20-30 minutes. The contents of the flask usually heat up 
 considerably, but a loss of ammonia is not to be feared, even when 
 not cooled. 
 
 The most important fertilizers belonging to each of the three 
 groups will now be described. 
 
 1. Phosphate Fertilizers. 
 
 They may be divided into : 
 
 A. Phosphates containing water-insoluble 
 phosphoric acid. 
 
 (a). Crude phosphates. | (). Artificially-pre- 
 
 Mineral phosphates. 
 Bone phosphates. 
 Guano phosphates. 
 
 pared phosphates. 
 Phosphate slags. 
 
 B. Phosphates containing 
 water-sohible phosphoric acid. 
 
 Superphosphates . 
 
 * The amount necessary is easily calculated approximately from the sulphuric 
 acid used. 
 
76 CHEMICAL-TECHNICAL ANALYSIS. 
 
 A. Phosphates Containing "Water-Insoluble Phosphoric Acid. 
 
 Contain phosphoric acid principally in form of tricalcium phos- 
 phate, which, together with iron and aluminium present, is very 
 slowly soluble. 
 
 In order to determine phosphoric acid in crude phosphates of 
 sub-group (0) phosphorite, apatite, bone meal, animal charcoal and 
 Baker guano, 5 grs. substance, finely powdered, are boiled with 20 
 c.c. cone, nitric acid and 50 c.c. cone, sulphuric acid for ^ hour, 
 and the solution, plus residue, is poured into a ^ -liter graduated 
 flask, diluted to the mark and thoroughly agitated, after which it is 
 filtered through a dry ribbed filter. In 50 c.c. of the filtrate the 
 phosphoric acid is determined by the molybdate method. 
 
 Should the citrate method be preferred, however, the substance 
 is dissolved in 30 c.c. concentrated sulphuric acid, instead of the 
 above mixture. The remaining operation is conducted as in p 
 
 (P. 73)- 
 
 A nitrogen determination, according to Kjeldahl, as well as the 
 detection of less valuable phosphates, is usually undertaken in bone- 
 dust. The latter is detected by a high percentage of matter insolu- 
 ble in hydrochloric acid (sand) and presence of ferric oxide and 
 alumina. 
 
 Thomas slag is the most important product of the phosphate slags 
 in sub-group (<). To determine the phosphoric acid in this, 10 grs. 
 powdered material are moistened with water, and stirred with 5 c.c. 
 of a mixture of equal parts sulphuric acid and water. As soon as 
 the mass begins to harden, 50 c.c. concentrated sulphuric acid are 
 added, and the whole is heated for ^ -hour on a sand-bath until 
 white vapors arise. Meanwhile the mass is continually stirred. 
 After cooling, it is carefully diluted with water, washed into a 
 YZ -liter flask, diluted to the mark, well mixed, and allowed to stand 
 several hours, in order to allow gypsum to separate. It is then 
 filtered through a dry ribbed filter, and the phosphoric acid is deter- 
 mined in 50 c.c. filtrate by the citrate method. 
 
 B. Phosphates Containing Water-Soluble Phosphoric Acid. 
 To these belong principally the superphosphates obtained by dis- 
 solving crude phosphates in sulphuric acid, and which contain the 
 monocalcium phosphate CaH 4 (PO 4 ) 2 , which is soluble in water. 
 
FERTILIZERS. 77 
 
 Since the decomposition, however, is never perfect, there are 
 present, beside these, di- and tri calcium phosphate, the quantity of 
 which increases on standing for a long time, due to the action of 
 aluminium and iron compounds present. The latter process is 
 termed phosphoric acid reversion. 
 
 The phosphoric acid in commercial phosphates is, therefore, 
 present in three forms : 
 
 (a) Monocalcium phosphate, CaH 4 (PO 4 \. This is soluble in 
 water, and, together with free phosphoric acid, is estimated as 
 water-soluble phosphoric acid. 
 
 (3) Dicalcium phosphate, CaHPO 4 . This is insoluble in water, 
 but is, on the contrary, soluble in ammonium citrate. At times it 
 is determined, together with the phosphoric acid present in form of 
 iron or aluminium phosphate, as ''citrate-soluble" or "reverted" 
 phosphoric acid. 
 
 (c) Tricalcium phosphate, Ca s (PO 4 ) a , is insoluble in water and 
 ammonium citrate. The phosphoric acid corresponding to this is 
 designated as insoluble phosphoric acid. 
 
 () Estimation of water-soluble phosphoric acid. 
 
 Twenty grams of superphosphate are placed in a liter flask,* and 
 thoroughly agitated for y z hour with 800 c.c. water. The liquid is 
 then diluted to the mark, well mixed, filtered through a dry ribbed 
 filter, and the phosphate is determined by the citrate method in 
 50 c.c. filtrate. 
 
 (/?) Estimation of total phosphoric acid. 
 
 Five grams of superphosphate are suspended in 20 c.c. water, and 
 then boiled with 100 c.c. concentrated nitric acid for ^ hour. 
 The mixture is washed into a ^ -liter flask, diluted to the mark, 
 filtered through a dry ribbed filter, and the phosphoric acid is de- 
 termined in 50 c.c. filtrate by the molybdate method. The estima- 
 tion of citrate-soluble phosphoric acid, concerning the value of 
 which views differ, will not be further described. 
 
 2. Potassium Fertilizers. 
 
 The main source of these is the discarded Stassfurter salts, which 
 consist chiefly of potassium and magnesium salts. The most im- 
 portant are Sylvite, 5KC1 + NaCl ; Carnallite, KC1 + MgCl 2 -f 
 
 * Agitators worked by hand or water-power are very convenient. 
 
78 CHEMICAL-TECHNICAL ANALYSIS. 
 
 6H,O ; Kainite, KC1 -f MgSO 4 -f 3H 2 O ; and Schonite, K 2 SO 4 + 
 MgSO 4 + 6H 2 O. 
 
 In these the per cent, of potassium oxide is usually determined 
 by one of the methods mentioned (p. 73). 
 
 3. Nitrogenous Fertilizers. 
 
 According to the division previously given, there belong in this 
 group ammonium sulphate, potassium and sodium nitrates or a mixture 
 of both (with an average percentage of nitrogen equalling 14.5-16 
 per cent.), dried-blood powder (12-15 per cent. N, about i per 
 cent. P 2 O 5 ), horn meal (7-14 per cent. N, 5-6 per cent. P 2 O 5 ), pow- 
 dered hide (6-10 percent. N). 
 
 4. Mixed Fertilizers. 
 
 These are artificial mixtures of phosphorus, potassium and nitro- 
 genous fertilizers, such as potassium -superphosphate, ammonium- 
 superphosphate, saltpeter -superphosphate or natural products. To 
 the latter belong Peru guano, dried-meat powder, fish-guano and 
 dung. 
 
 Peru guano, formed from bird excrement and carcasses of marine 
 animals, but less weathered than guano phosphate, contains, on the 
 average, 8-n per cent, nitrogen and 10-20 per cent, phosphoric 
 acid. 
 
 Dried meat powder, made out of meat and bones of dead ani- 
 mals, contains 6-7 per cent, nitrogen and 10-15 per cent, phos- 
 phoric acid. Fish guano, made out of fish refuse, contains 5-12 
 per cent. N, 13-16 per cent. P 2 O 5 . 
 
 Dung, the mixture of solid and fluid excrement of cattle, horses, 
 sheep, swine, together with litter, contains all three plant-nour- 
 ishers in varying amounts. They may be confined within the fol- 
 lowing limits: Potassia, .40-. 6 7 per cent.; phosphoric acid, 
 .16-. 28 per cent., and nitrogen, .34-. 83 percent. 
 
VI. Sugar Industry. 
 
 THE investigation of sugar and saccharine products, such as beets, 
 thin juice, molasses, etc., extends as a rule to the estimation of 
 cane sugar, invert sugar, water, alkalinity, ash, and sometimes 
 color. 
 
 Concerning the methods employed for this purpose the follow- 
 ing may be said : 
 
 (a) Cane sugar. This may be determined from the specific 
 gravity or by polarization. 
 
 (a) Specific gravity. Only in pure sugar solutions can sugar be 
 estimated by means of specific gravity. Should other substances 
 be in solution, they effect the specific gravity in different ways. 
 In such solutions only an apparent value (for dry substance) ex- 
 pressed in per cent, of sugar, can be obtained. 
 
 The determination of specific gravity is conducted either with 
 one of the usual forms of applicable apparatus, such as densimeter, 
 pyknometer, hydrostatic balance, in which cases the percentage of 
 sugar corresponding to the specific gravity must be referred to in a 
 corresponding table, or by means of an areometer specially con- 
 structed for the purpose, the saccharometer of Balling or Brix. On 
 account of its graduation direct sugar percentage readings can be 
 made. In this case it is advantageous to use such saccharometers 
 on which the scale is extended over a set of several consecutive 
 spindles, and on which tenths per cent, can be easily read. 
 
 When the saccharometers are used to read volume percentage, 
 an error, provided for on the instrument, due to change in volume 
 by temperature, is taken into account. 
 
 Pyknometers and hydrostatic balance are then used when only 
 small quantities of substance are obtainable. 
 
 (/?) Polarization. It is taken for granted that the principle on 
 which these instruments rest, as well as the arrangement of the 
 same, is known. Recently the apparatus of Soleil-Ventzke-Scheib- 
 
80 CHEMICAL-TECHNICAL ANALYSIS. 
 
 ler and the half-shadow apparatus of Schmidt and Haensch, have 
 come into use. The former is adjusted for a transition color, a 
 pale bluish violet, the latter for an even, faint shadow on both 
 halves. The normal weight for both forms equals 26.048 grams; 
 that is, a solution of 26.048 grs. pure cane sugar in 100 c.c. in 
 a tube 200 mm. in length causes a rotation of 100, or i corres- 
 ponds with .26048 gr. sugar in 100 c.c. With the use of this 
 normal weight and normal tube (200 mm.) the per cent, of sugar 
 can consequently be read off directly. When a 100 mm. or 
 400 mm. tube is used, the degrees are to be doubled or halved. 
 
 Polarization is always preceded by clarification and decoloriza- 
 tion with a solution of lead acetate (basic lead acetate). Cane 
 sugar is dextro -rotary ( + ); invert sugar laevo-rotary ( ). 
 
 () Invert sugar possesses the property of reducing Fehling's 
 solution (see Reagents, p. 90) with separation of suboxide of 
 copper. On the basis of this precipitated suboxide, which is reduced 
 to metallic copper, the amount is determined by a method described 
 later. The results obtained by polarization are influenced by the 
 laevo-rotary power of invert sugar. Therefore, in the presence of 
 the latter a different procedure, that of Clerget,* is followed in the 
 estimation of cane sugar. The description of this is given further 
 on. 
 
 Syrup, molasses, etc. , frequently contain invert sugar. 
 
 (*:) Water. The use of small, flat-bottomed porcelain or enam- 
 eled sheet-iron capsules is advisible for fluid or semi-fluid products. 
 Drying is done on a water-bath or in an air bath at 80-90 to be- 
 gin with. Further drying should take place at 105 under the in- 
 fluence of a current of dry air, in order to expel the last traces of 
 water. Stammer recommends the use of a special apparatus for 
 this purpose. In the absence of the latter an ordinary air-bath is 
 made to answer. 
 
 It is also recommended to mix the substance with a glass rod 
 (4-5 grs. molasses, 8-10 grs. syrup and dense juices) with 20 grs. 
 ignited quartz sand, free from dust, in a small porcelain capsule. 
 This is then weighed and placed in an air-bath at 100 for % hour. 
 It is then thoroughly stirred with a rod until a homogeneous 
 mass is obtained and dried in an air-bath to constant weight. 
 
 * The same method is also made use of in the presence of raffinose. 
 
SUGAR INDUSTRY. 81 
 
 (V) Alkalinity. This is influenced by the presence of free 
 alkali, lime and free ammonia in the saccharine substance. 
 
 It is estimated by titration with normal or one-tenth normal acid, 
 usually nitric acid, and is calculated into per cent. lime. 
 
 The indicator used is usually neutral, bluish-violet litmus tinc- 
 ture, which is added to the liquid. But in using deeply-colored 
 substances, such as molasses, the indicator is not added, but instead, 
 after each addition of acid the liquid is tested with a strip of bluish- 
 violet, sensitive litmus paper. 
 
 (e) Ash. The residue left on ignition of a sugar, including the 
 mechanically admixed impurities in the same, is called the "ash." 
 The residue of a sugar free or freed from these impurities is called 
 the "salts." The latter consists mainly of alkali sulphates or 
 chlorides and carbonates arising from alkali salts of organic acids. 
 Potassium predominates in these alkalies. Sometimes calcium car- 
 bonate, arising from soluble organic calcium salts, is found. 
 These salts hinder crystallization of a part of the sugar and conse- 
 quently cause a loss in the yield ; and furthermore, even though this 
 no longer holds good under the present conditions, one part salts 
 is calculated to yield a decrease of five parts sugar. The complete 
 ignition of a sugar is hard to accomplish by combustion, since the 
 easily fusible alkali salts withhold small particles of carbon from 
 combustion. Too strong a heat should likewise be avoided on 
 account of possible volatilization of alkali chlorides. The inciner- 
 ation is therefore conducted as follows : The weighed sugar is charred 
 in a spacious platinum dish until gas is no longer evolved. The coke 
 is then moistened with water and crushed to a paste with a pestle. 
 After the addition of a little hot water, heating and filtering, the 
 residue on a small filter is repeatedly washed with hot water, and 
 the filter and residue together are incinerated in the platinum dish. 
 The filtrate added to this is evaporated to dryness on a water-bath, 
 moistened with ammonium carbonate, dried at 100 and moder- 
 ately ignited. The clean white residue is weighed. 
 
 In this manner the "ash" (carbonate ash) is ascertained. If 
 the estimation of " salts " also be desired, a weighed quantity of 
 sugar is dissolved in water (about 25 grs. sugar in 250 c.c). The 
 turbid solution is filtered, a portion of the filtrate is evaporated in 
 a platinum dish, charred and heated as before. 
 
 6 
 
82 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Much simpler and quicker is the method of Scheibler. 3-5 
 grs. sugar are moistened with sulphuric acid in a platinum dish. 
 After a few minutes the sugar blackens and decomposes. It is then 
 heated over a very large flame, whereby thorough charring takes 
 place with much swelling, hissing and gas evolution. To com- 
 pletely burn off the remaining coke the dish is placed in a muffle. 
 
 The action of the sulphuric acid converts the salts into sulphates, 
 the weight of which is naturally higher than that of the salts orig- 
 inally present. The increase of weight equals almost exactly 10 
 per cent. , by which the amount found must be decreased. The re- 
 mainder is designated as sulphate ash. 
 
 (/) Color. The Stammer Colorimeter is used for this purpose ; 
 however, the determination is rarely carried out. The crude and 
 refined products of the sugar industry which are subject to investi- 
 gation are beets, beet juice, weak juice, dense juice, filling material, 
 green syrup, molasses, osmosis fluid and cane sugar. 
 
 1. Beets. 
 
 The former assumption, that the sugar content in the juice of the 
 beet bears a fairly constant relation to that of the beets (about 
 i : .95), has been recently proven erroneous for different reasons, 
 and therefore methods have been found for the direct determina- 
 tion of sugar in the beet. The " extraction " and " digestion" 
 methods are recommended for this purpose. 
 
 (<z) Extraction method (Scheibler). An exceedingly fine paste 
 is prepared by rasping a cross section of the beet sample, by hand 
 or machine. 35-40 grs. of this are weighed as quickly as possible 
 on a tared pan and placed in the cylinder of a Soxhlet extractor. 
 In the wide neck, 100 c.c. flask, with which the apparatus is pro- 
 vided, 75 c.c. of absolute alcohol are placed. The residue on the 
 pan is rinsed into the cylinder with absolute alcohol, and then suf- 
 ficient of the latter is added to fill the cylinder almost to the top 
 of its siphon. The flask is attached to the apparatus and heated 
 until extraction is complete. This as a rule is the case after 3-4 
 hours, in which time the alcohol will be siphoned 80-90 times. 
 The water-bath is withdrawn, the flask is allowed to cool, and a 
 sufficient quantity of lead acetate, 510 c.c., is added. It is then 
 diluted to the mark, well mixed and polarized in a 200 mm. tube. 
 
BEETS. 83 
 
 The rotation observed, multiplied by .26048, gives the amount of 
 sugar contained in the weighed paste. If 26.048 grams of beets 
 are used, then direct percentages of sugar are obtained. 
 
 () Digestion method (Rapp and Degner). Like the former, 
 this depends on an alcohol extraction, the difference being that 
 52.1 grs., double the normal weight which is used, are directly 
 placed in a graduated flask of exactly 200 c.c. capacity. The 
 flask is marked down low and is provided with a widened neck into 
 which a condenser, about 50 cm. in length and 10 mm. diameter, 
 can be ground or securely fastened with a tight-fitting cork. 
 Charging in is done with a glass rod, and the particles adhering 
 to this, to the pan and to the neck of the flask, are washed in with 
 a wash-bottle containing 90-92 per cent, alcohol. The flask is 
 filled to four-fifths its capacity with the same alcohol. After ad- 
 justing the condenser, the flask is placed in an inclined position on 
 a water-bath already heated to boiling, and the contents of the 
 former are kept in ebullition for 15-20 minutes. The sugar is 
 thereby completely dissolved in the liquid. The flask is removed, 
 the condenser washed with alcohol and filled about i c.c. above 
 the mark, without cooling. By successive immersions into the hot 
 water-bath, to a point where ebullition begins, a thorough mixture 
 is obtained. It is thereupon allowed to cool in the air for ^-^ hour, 
 and is finally brought to the temperature of the room by immersing 
 in water. To the liquid, which has sunk down below the mark, 10- 
 15 drops of lead acetate are added. It is then diluted to the mark 
 with alcohol, well mixed by shaking, filtered and polarized. The 
 readings made with the use of a 200 mm. tube yield direct sugar per- 
 centage. In order to compensate for the extracted pulp left in the 
 flask, the result obtained is multiplied by .994. The true percent- 
 age is thus obtained. Stammer has in so far modified the opera- 
 tion as to cover an unlimited, usually much larger quantity of the 
 paste with strong alcohol, and to dilute to such a volume that direct 
 percentage of sugar in the beet can be read off in the polariscope 
 after the sugar has become uniformly admixed. The operation re- 
 quires particularly fine pulping of the beet paste in a beet cutting 
 machine. This can only be accomplished in specially fitted labor- 
 atories. 
 
84 CHEMICAL-TECHNICAL ANALYSIS. 
 
 2. Beet Juice, Thin Juice. 
 
 (#) Specific gravity. The estimation is made, as in one of the 
 previously mentioned methods, preferably with Balling's saccharom- 
 eter, in which case the corresponding specific gravity is referred to 
 in the tables. The temperature required is 17.5. 
 
 () Sugar. 100 c.c. juice are as accurately as possible placed in 
 a flask provided with a second mark at no c.c. It is filled to the 
 latter with lead acetate and is frequently shaken. Clarification and 
 decolorization are effected completely after a few moments. In 
 special cases where this quantity of lead acetate does not suffice, 
 correspondingly more, about one-fifth volume of lead acetate, must 
 be added. It is then filtered and polarized in a 200 mm. tube. 
 The angle read off is increased by one-tenth, because of the dilu- 
 tion with lead acetate, and is then multiplied by .26048. The 
 volume percentage that is the grams sugar in 100 c.c. is then 
 obtained. Should the per cent, by weight be desired, it is only 
 necessary to divide the first result by the specific gravity obtained, 
 according to (a). Any bubbles which arise in pouring in the juice, 
 and which are difficult to remove, are preferably depressed by the 
 addition of a few drops of ether. Adhering liquid on the sides of 
 the neck above the mark is removed with a roll of filter paper. 
 
 3. Raw Sugar, Filling Material, Green Syrup, Molasses. 
 
 (#) Sugar. Qualitative tests must be made for invert sugar 
 prior to the sugar estimation. This is done by clarifying 20 grs. 
 substance, dissolved in water, with lead acetate and diluting to 100 
 c.c. 50 cc. clear filtrate are mixed with 50 c.c. Fehling's solution 
 (see Reagents, p. 90), heated on a wire gauze and kept boiling 
 for 2 minutes. Should there be no suboxide of copper formed, or 
 at most an inappreciable amount, the presence of invert sugar is not 
 taken into account and the estimation proceeds as in (a). Should 
 appreciable quantities of invert sugar be present, the estimation 
 proceeds as in (/?). 
 
 (a) Invert sugar is not present. The normal weight is dissolved 
 in a 100 c.c. graduated flask and treated with 2-3 c.c. lead acetate 
 and 1-2 c.c. alum solution. It is diluted to the mark, thoroughly 
 shaken, and filtered. The clear liquid is polarized in a 200 mm. 
 tube. This gives the percentage of saccharose. 
 
RAW SUGAR, FILLING MATERIAL, GREEN SYRUP, ETC. 85 
 
 Alumina in form of a thin hydrate paste is substituted for lead 
 acetate, when purer sugars are used. (See Reagent, p. 90.) When 
 lead acetate is used the alkaline reaction may be neutralized and 
 the slight turbidity destroyed in the filtrate by introducing a glass 
 rod moistened with cone, acetic acid. 
 
 (/?) Invert sugar is present. The operation of Clerget is used, 
 especially in the case of molasses. 
 
 Half the normal weight (13.024 grs.) is dissolved, with addition 
 of 75 c.c. water, in a 100 c.c. flask. 5 c.c. hydrochloric acid sp. gr. 
 1.188 are added. The flask is warmed to 6770 in a water-bath 
 heated slightly above 70. This requires 2-3 minutes. It is then 
 kept, while shaking, as near 69 as possible for 5 minutes. It is 
 quickly cooled, filled to the mark, and bone black or, better, 
 blood charcoal is added, when necessary to decolorize. It is 
 allowed to stand for a few minutes and is then polarized as near 
 20 as possible. The result is doubled when a 200 mm. tube is used. 
 After the sugar has been inverted the liquid shows a strong laevo- 
 rotary power ( 1). 
 
 In addition to this determination, polarization (a) is carried out 
 in the usual manner (-f- P). 
 
 If S equal the sum of the angle before and after the inver- 
 sion (omitting the negative sign of the invert sugar), therefore 
 P -f 1, and t the temperature in centigrade degrees, taken at 
 the time of reading, then the cane sugar R can be calculated from 
 the formula : 
 
 R= ^ IooS 
 
 142.66 y 2 1. 
 
 This formula is based on the fact that pure saccharose, which ro- 
 tates 100 before inversion, shows after inversion a rotation 
 
 t 
 of 42.66 . Therefore, the decrease of rotation of pure 
 
 t 
 saccharose = 142.66 . 
 
 (^) Invert sugar. When the presence of the latter is detected 
 according to (#), the approximate amount is next ascertained. 
 10 grs. substance, dissolved in water, are clarified with lead acetate 
 and diluted to 100 c.c. 10, 8, 6, 4 and 2 c.c. are placed in sep- 
 arate test tubes, 5 c.c. Fehling's solution are added to each, and 
 
86 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the contents are then boiled. Notice is now taken of the tube, 
 whose contents are nearly decolorized. Should this be the case 
 with the one containing 10 c.c., there is less than 1.5 per cent, 
 invert sugar present, and the determination proceeds according to 
 the method of Herzfeld. In the other case the method of Meissl 
 and Hiller is used. For the latter method the number of c.c. in 
 that test tube which is nearly decolorized give simultaneously the- 
 number of grams which, dissolved in 50 c.c., are used in the deter- 
 mination. 
 
 Every c.c. sugar solution (10 grs. to 100 c.c.) corresponds to .1 
 gr. substance. But in the method of Meissl and Hiller ten times 
 the amount of Fehling's solution (50 c.c.) is used. Therefore, ten 
 times the quantity of sugar is also taken. Consequently, every c.c. 
 solution in the test represents i gr. substance in the latter deter- 
 mination. 
 
 Should the test therefore show that decolorization took place 
 with 8 c.c., but that with 6 c.c. a blue tint remained, then 6 grs. 
 dissolved in 50 c.c. are used. 
 
 (a) Method of Herzfeld. A solution, clarified with lead acetate, 
 containing the normal weight in 100 c.c., is used. This is precipi- 
 tated with sodium carbonate when any great excess of lead acetate 
 has been used or when the sample is rich in alkaline earths. 
 
 When precipitation with soda is unnecessary 38.4 c.c. filtered 
 solution diluted to 50 c.c. (= 10 grs. substance) are used. 
 
 When previous precipitation is necessary, 46.07 c.c. solution, 
 increased to 60 c.c. with cone, soda solution, are withdrawn and 
 filtered. 50 c.c. filtrate are then taken, and these also correspond 
 to 10 grs. original substance. The 50 c.c. are placed in a dish or 
 an Erlenmeyer flask with 50 c.c. Fehling's solution, and are heated 
 to boiling for 3-4 minutes over a wire gauze with a triple burner. 
 That moment is accepted as the beginning of ebullition when bub- 
 bles arise from the side as well as from the bottom of the vessel. 
 Boiling is continued for exactly two minutes with the small flame of 
 a single burner. Thereupon the flask or dish is immediately re- 
 moved from the flame, 100 c.c. cold water previously boiled are added, 
 and the contents are rapidly filtered with the aid of a pump, on a 
 weighed asbestos filter (Fig. 8). The precipitate is rapidly washed 
 on the filter with the aid of a feather, and is washed subsequently 
 
RAW SUGAR, FILLING MATERIAL, GREEN SYRUP, ETC. 87 
 
 with 300-400 c.c. hot water. The water is replaced by about 
 20 c.c. alcohol, finally with ether, and the tube is dried in an 
 air-bath at 120-130. The portion of the tube containing the 
 cuprous oxide on the filter is next heated to a low 
 red heat to oxidize and destroy organic substances, 
 and is then reduced by heating slowly in a cur- 
 rent of hydrogen. Reduction is complete in a 
 few minutes. It is allowed to cool in hydrogen 
 and the water collected in the neck allowed to 
 evaporate. It is then placed in a desiccator and 
 weighed after fifteen minutes. The invert sugar 
 is gotten from the amount of reduced .copper by 
 means of the tables (p. 89). 
 
 The following details are yet to be considered : 
 The asbestos must be proof against alkalies and acids 
 and should previously be ignited. It is then sus- 
 pended in water, poured on the glass wool in the 
 tube, and pressed with a glass rod having a flattened 
 end, so that a thin but perfectly solid layer, which 
 filters without use of pump, is formed. It is then 
 washed with alcohol and ether, dried and weighed. 
 
 During filtration a short, thick funnel is loosely 
 placed on the tube. While washing, however, FlGt8< 
 
 the latter is replaced by a funnel attached tightly Asbestos ' Filter - 
 to the tube by means of a rubber stopper. The liquid in the tube 
 should not be allowed to run off entirely. The hydrogen used in 
 reducing must be free from arsenic. The tube is attached to the 
 hydrogen generator by a glass tube in a tightly-fitting rubber 
 stopper, and is inclined upwards somewhat. 
 
 Instead of an asbestos filter, filter paper washed with hydro- 
 fluoric acid may be used. In this case, likewise, 300-400 c.c. hot 
 water are used in washing. It is then incinerated, placed in a 
 Rose crucible, covered with the perforated lid and reduced in 
 hydrogen. When the quantity of cuprous oxide does not exceed 
 . i gr. it may be converted into cupric oxide by ignition in a por- 
 celain crucible, weighed as such, and calculated into metallic 
 copper. 
 
 Method of Meissl and Hiller. This is used when the 
 
88 CHEMICAL-TECHNICAL ANALYSIS. 
 
 amount of invert sugar exceeds 1.5 per cent. The necessary quan- 
 tity of substance is ascertained from the previous experiments. In 
 order to obtain this dissolved in 50 c.c., double the quantity is 
 weighed out, brought to 100 c.c., after clarifying with lead acetate, 
 and 50 c.c. of the filtrate are used. With this quantity the deter- 
 mination of invert sugar is conducted exactly as in the Herzfeld 
 method. 
 
 In order to use the following tables of Meissl and Hiller the approxi- 
 mate ratio of saccharose to invert sugar (R : I) must be ascertained. 
 The method of calculation is apparent from the following consider- 
 ations : The invert sugar can be assumed to be equal to one-half the 
 copper found. If p grs. substance were used and Cu grs. copper were 
 found, then there were contained in p grs. substance approximately 
 
 Cu 
 ioo 
 
 Cu 2 _ 
 grs. invert sugar. Therefore, i grs. invert sugar dissolved 
 
 in ioo grs. substance. Furthermore, had the determination of 
 cane sugar (a /3 p. 85) given r per cent, cane sugar, then the total 
 saccharine matter = r -(- i per cent. To determine the ratio of 
 saccharine and invert sugar in ioo parts sugar, the invert sugar I is 
 next calculated from the proportion (r -f- i) : i = ioo : I. From 
 
 this I = ' or, after substituting the values previously obtained: 
 
 r -f i 
 
 Cu 
 
 IOO . IOO 
 
 2 
 
 I = 
 
 Cu 
 
 p . r -f ioo 
 
 The saccharose then becomes R ioo I. The ratio R : I 
 is now known, and the factor corresponding to this ratio and to 
 the amount of invert sugar approximately found is determined on 
 the tables (p. 90). This factor F substituted in the equation I' = 
 
 - F gives I' the true percentage of invert sugar. 
 
 (V) Water and ash are determined in the manner previously de- 
 scribed. Sugar, water and ash added together and deducted from 
 ioo yields the non -saccharine organic matter. 
 
 (rtQ Alkalinity. That which was previously stated answers in 
 
RAW SUGAR, FILLING MATERIAL, GREEN SYRUP, ETC. 89 
 
 general in this case. When molasses is used, 15-20 grs. are dis- 
 solved and diluted to 250 c.c. 25-50 c.c. of this solution are 
 placed in a graduated cylinder and 12 c.c. litmus tincture are 
 added. If the cylinder be held horizontally over a piece of white 
 paper, a gray-green color is observed in the liquid when the mo- 
 lasses is alkaline. In this case another portion is titrated, as in the 
 method already mentioned. 
 
 To distinguish whether a molasses is neutral, the contents of the 
 cylinder are divided into two parts. To one part one drop nor- 
 mal acid is added, to the other a drop of normal alkali, whereupon 
 the solutions, if originally neutral, should become either red or 
 blue. 
 
 (e) Purity quotient is the sugar contained in 100 parts actual dry 
 substance. 
 
 (/) " Rendement ' ' or Yield is the number which designates 
 how much crystallized cane sugar is capable of being obtained 
 from a raw sugar. The customary calculation in practice funda- 
 mentally assumes 5 parts by weight ; sugar is prevented from 
 crystallizing by i part by weight of soluble salts. The " rende- 
 ment ' ' in Germany and England is therefore obtained by deducting 
 five times the weight of salt content from the cane sugar content. 
 
 The assumption is a rather arbitrary one. 
 
 Tables of Herzfeld. 
 
 Copper, 
 mg. 
 
 Invert 
 Sugar. 
 Per Cent. 
 
 Copper, 
 mg. 
 
 Invert 
 Sugar. 
 Per Cent. 
 
 Copper, 
 mg. 
 
 Invert 
 Sugar. 
 Per Cent. 
 
 Copper, 
 mg. 
 
 Invert 
 Sugar. 
 Per Cent. 
 
 50 
 
 O.O5 
 
 120 
 
 0.40 
 
 190 
 
 0.79 
 
 255 
 
 .16 
 
 55 
 
 O.O7 
 
 125 
 
 0-43 
 
 195 
 
 0.82 
 
 260 
 
 .19 
 
 60 
 
 OOQ 
 
 130 
 
 0-45 
 
 200 
 
 0.85 
 
 265 
 
 .21 
 
 65 
 
 O.I I 
 
 135 
 
 0.48 
 
 205 
 
 0.88 
 
 270 
 
 .24 
 
 70 
 
 0.14 
 
 140 
 
 0-51 
 
 2IO 
 
 0.90 
 
 275 
 
 27 
 
 75 
 
 0.16 
 
 H5 
 
 0-53 
 
 215 
 
 0-93 
 
 280 
 
 3 
 
 80 
 
 0.19 
 
 15 
 
 0.56 
 
 220 
 
 096 
 
 285 
 
 33 
 
 85 
 
 0.21 
 
 155 
 
 0-59 
 
 225 
 
 0.99 
 
 290 
 
 .36 
 
 90 
 
 0.24 
 
 1 60 
 
 0.62 
 
 2 3 
 
 1. 02 
 
 295 
 
 .38 
 
 95 
 
 0.27 
 
 I6 5 
 
 0.65 
 
 235 
 
 1.05 
 
 3 00 
 
 .41 
 
 100 
 
 0.30 
 
 170 
 
 0.68 
 
 240 
 
 1.07 
 
 305 
 
 -44 
 
 105 
 
 0.32 
 
 I7S 
 
 0.71 
 
 245 
 
 1. 10 
 
 3 IO 
 
 47 
 
 no 
 
 0-35 
 
 1 80 
 
 0-74 
 
 250 
 
 1.13 
 
 315 
 
 50 
 
 "5 
 
 038 
 
 1 8 5 
 
 0.76 
 
 
 
 
 
90 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Tables of Hiller. 
 
 R:I. 
 
 Cu 
 
 2 = 200 mg. 
 
 175 mg. 
 
 150 mg. 
 
 125 mg. 
 
 ioo mg. 
 
 75 mg. 
 
 50 mg. 
 
 o : 100 
 
 56.4 
 
 554 
 
 54-5 
 
 53-8 
 
 532 
 
 53 
 
 53-0 
 
 10 : 90 
 
 563 
 
 55-3 
 
 54-4 
 
 53-8 
 
 53-2 
 
 52.9 
 
 52.9 
 
 20 : 80 
 
 56.2 
 
 55-2 
 
 54-3 
 
 53-7 
 
 53-2 
 
 52.7 
 
 52.7 
 
 30: 70 
 
 56.1 
 
 55-1 
 
 54.2 
 
 53-7 
 
 53-2 
 
 52.6 
 
 52.6 
 
 40 : 60 
 
 55-9 
 
 55-0 
 
 54-i 
 
 53-6 
 
 53-1 
 
 52.5 
 
 52.4 
 
 50: 50 
 
 55-7 
 
 54-9 
 
 540 
 
 53.5 
 
 53-i 
 
 52.3 
 
 52.2 
 
 60 : 40 
 
 556 
 
 54-7 
 
 53-8 
 
 53-2 
 
 52-8 
 
 52.1 
 
 51.9 
 
 70: 30 
 
 55-5 
 
 54-5 
 
 53-5 
 
 52*9 
 
 52.5 
 
 5L9 
 
 51.6 
 
 80 : 20 
 
 55-4 
 
 54-3 
 
 53-3 
 
 52.7 
 
 52.2 
 
 5 J .7 
 
 51.3 
 
 90 : 10 
 
 54.6 
 
 53-6 
 
 53 * 
 
 52.6 
 
 52.1 
 
 5L6 
 
 51.2 
 
 91 : 9 
 
 54.1 
 
 53-6 
 
 52.6 
 
 52.i 
 
 51.6 
 
 51-2 
 
 5-7 
 
 92 : 8 
 
 53-6 
 
 53-1 
 
 52.1 
 
 51.6 
 
 51.2 
 
 50-7 
 
 50.3 
 
 93: 7 
 
 53-6 
 
 53-1 
 
 52.1 
 
 512 
 
 50.7 
 
 5 3 
 
 49-8 
 
 94: 6 
 
 53 
 
 52.6 
 
 5i.6 
 
 50.7 
 
 53 
 
 49-8 
 
 48.9 
 
 95: 5 
 
 52.6 
 
 52.i 
 
 5i.2 
 
 50.3 
 
 49-4 
 
 48.9 
 
 48.5 
 
 96: 4 
 
 52.1 
 
 51-2 
 
 50.7 
 
 498 
 
 48.9 
 
 47-7 
 
 46.9 
 
 97' 3 
 
 50-7 
 
 50-3 
 
 498 
 
 48.9 
 
 47-7 
 
 46.2 
 
 45-1 
 
 98: 2 
 
 49-9 
 
 48.9 
 
 4-5 
 
 47.2 
 
 45-8 
 
 433 
 
 40.0 
 
 99: i 
 
 47-7 
 
 47-3 
 
 46.5 
 
 45-1 
 
 43-3 
 
 41.2 
 
 38.i 
 
 Keagents Used in the Methods Described. 
 
 1. Lead acetate. 600 grs. sugar of lead and 200 grs. litharge 
 are covered with two liters of water and allowed to stand, with 
 frequent agitation, for twelve hours in a warm place. The liquid 
 is filtered from the sediment and placed in a reagent bottle. The 
 latter is best provided with a double-bored stopper in which are 
 adjusted a siphon and a soda-lime tube. 
 
 2. Alumina. Commercial aluminium chloride is dissolved in a 
 flask in ioo volumes water and precipitated with ammonia to alka- 
 line reaction. The precipitate of aluminium hydrate is allowed to 
 settle, the supernatant liquid is drawn off, and the precipitate is 
 washed by decantation until alkaline reaction ceases. The alumin- 
 ium hydrate so prepared is preserved as a thick paste. 
 
 3. Fehling's solution. This consists of the two following solu- 
 tions : 
 
 (a) 34.639 grs. crystallized copper sulphate are dissolved in 500 
 c.c. water. 
 
 (^) I 73 grs. Seignette salt are dissolved in 400 c.c. water, ioo 
 c.c. sodium hydrate solution containing 50 grs. caustic soda are 
 
BONE BLACK. 91 
 
 added, and the solution is filtered if necessary. The solutions are 
 kept separate, and are mixed in equal volumes prior to every experi- 
 ment. 
 
 4. Press Cake. 
 
 Sugar. Portions from different parts of the press 'cake under in- 
 vestigation are selected, ground and mixed, and of this uniform 
 stiff mass, so obtained, the normal weight is taken. This quantity is 
 mixed with water, placed in a 200 c.c. flask filled to the mark with 
 a little lead acetate and wash water, and the solution is polarized in 
 a 400 mm. tube. The reading gives the percentage of sugar. The 
 method is not absolutely exact, but suffices for technical purposes. 
 If the volume occupied by the calcium carbonate be taken into con- 
 sideration, 25 grs. may be taken instead of the normal weight, and 
 the readings still considered as percentage. 
 
 5. Lime Saccliarate. 
 
 (a) Sugar. Half the usual weight is placed in a small mortar 
 and ground with a little water to a uniform paste. A little phenol- 
 phthalein is added as indicator, and cone, acetic acid is added while 
 the particles are crushed, and the solution is stirred until the red color 
 disappears. When the decomposition is complete the solution is 
 washed into a 100 c.c. flask, a small amount of lead acetate is 
 added, and the whole is diluted to the mark. It is then filtered and 
 polarized. When a 200 mm. tube is used the reading is doubled, in 
 order to obtain per cent, units. 
 
 (^) Lime. 2-5 grs. are weighed, ground in a mortar and 
 titrated with normal or half-normal acid, using phenol-phthalein 
 as an indicator. The result is expressed in lime units. 
 
 6. Bone Black. 
 
 This substance serves as a decolorizer whose use in sugar factories 
 is undoubtedly diminishing. The investigation includes water, car- 
 bon, sand, clay, carbonate of lime, sulphate of lime, calcium sul- 
 phide and phosphoric acid. 
 
 (a} Water. A weighed quantity, about 10 grs. sample, used in 
 form of a coarse powder, is dried to constant weight, at 140-150 
 in a well-ground, stoppered weighing-bottle. 
 
 (Y?) Carbon, sand and clay. For this purpose, as in the follow- 
 
92 CHEMICAL-TECHNICAL ANALYSIS. 
 
 ing, the finely-powdered and air-dried bone black is used, and since 
 the water is different in this sample from that in the former, a sep- 
 arate water determination is made. The results are reckoned as 
 anhydrous bone black. 
 
 The operation is conducted as follows : 10 grs. substance are 
 moistened with water. 50 c.c. hydrochloric acid are carefully 
 added, and the mixture is heated to boiling for ^ hour. It is 
 then filtered through a dried and weighed filter and washed with 
 hot water until acidity ceases. The filtrate (A~) is collected in a 
 liter flask. The filter and residue are dried to constant weight. 
 The increase in weight represents carbon -f sand -f clay. Filter 
 and residue are now ignited. Sand and clay remain. The carbon 
 is calculated from the difference between this and the former 
 weight. 
 
 (V) Carbonate of lime. The Scheibler apparatus (Fig. 9) is 
 almost exclusively used for this purpose. 
 
 The generation of carbonic acid takes place in flask A, in 
 which the finely -powdered substance is placed and allowed to come 
 in contact with the hydrochloric acid in the gutta-percha cylinder 
 S. The carbonic acid evolved passes through the glass tube, which 
 is sealed in the stopper, and then through the rubber tube r into a 
 thin rubber balloon, X, contained in the flask B. Besides the con- 
 nection with A, the flask B is connected, by means of the glass 
 tube uu, with the graduated tube C, and finally with a third, which 
 communicates with the outer air. This may be established or pre- 
 vented by the pinchcock q. 
 
 The eudiometer C, divided into 25 c.c., communicates below 
 with the tube Z>, whose lower end is provided with an exit tube 
 which extends to the floor of the two-neck flask E. Pinchcock p 
 is placed on a piece of rubber tubing between D and E. By forc- 
 ing air into flask E, preferably with an elastic ball, the water pres- 
 ent in E can be forced into C and D. On the other hand, by 
 opening the pinchcock/ it may be let out of Cand D into E. 
 
 Operation, The normal weight (1.7 grs.) required by the appa- 
 ratus of the finely -powdered bone black is weighed out and placed 
 in the thoroughly dried flask A. The gutta-percha vessel S is then 
 filled with hydrochloric acid of 1.12 density (2 vols. cone, hydro- 
 chloric acid, i vol. water) and carefully placed, with forceps, in A, 
 so that it rests on the glass side in a slanting position. 
 
BONE BLACK. 
 
 93 
 
 After raising the water in C to the zero mark by forcing air into 
 the flask E and simultaneously opening the clip /, A is closed with 
 the well-greased stopper. 
 
 FIG. 9. Scheibler's Apparatus. 
 
 Any air pressure and consequent change in the level of the liquid 
 in C and D are removed by opening the clip q once. The vessel 
 A is taken between thumb and middle finger of the right hand, 
 
94 CHEMICAL-TECHNICAL ANALYSIS. 
 
 while the forefinger presses the stopper. The flask is then inclined 
 sufficiently to allow the acid to escape from the gutta-percha holder. 
 Decomposition, which ensues, is sustained and augmented by care- 
 ful continued shaking of the flask A. Simultaneously the clip/ is 
 opened with the left hand, and as much water is allowed to flow into 
 E as is necessary to bring both levels in tubes C and D to about 
 the same height ; that in D somewhat higher than in C. 
 
 When water in C ceases to descend on prolonged agitation of A, 
 the decomposition is complete. 5-10 minutes are allowed to elapse 
 in order to allow pressure and temperature to equalize, after which 
 the levels in C and D are brought to the same height by carefully 
 opening the clip q. 
 
 The level in C is read off, as well as the temperature of a ther- 
 mometer placed in the apparatus. The direct percentage of car- 
 bonate of lime is found, by means of these two numbers, on the ac- 
 companying tables calculated by Scheibler. 
 
 (</) Sulphate of lime. 500 c.c. of the filtrate A (see &) are 
 nearly neutralized with sodium carbonate, concentrated by evapora- 
 tion and precipitated with barium chloride. The sulphuric acid 
 obtained is calculated into calcium sulphate, 
 
 (<?) Calcium sulphide. About 10 grs. finely-powdered bone 
 black are dissolved in fuming nitric acid or hydrochloric acid and 
 potassium chlorate. The liquid is filtered. The filtrate is diluted 
 to 500 c.c. , and the sulphuric acid in 250 c.c. is determined as 
 before. The sulphuric acid found in (V), deducted from that just 
 found, gives the sulphuric acid corresponding to the sulphur of the 
 calcium sulphide, from which the latter is readily calculated. 
 
 (/) Phosphoric acid. This determination is minutely described 
 in the chapter on Fertilizers. It is of special importance in bone- 
 black waste. 
 
VII, Fermentation Industries. 
 
 IN this chapter the investigation of raw products containing 
 starch, malt, yeast and spirits, will be discussed. 
 
 1. Raw Products Containing- Starch. 
 
 The most important determinations required are starch and total 
 nitrogen. 
 
 (0) Starch. Two methods are in use, in connection with the 
 methods of solution used in practice. The one is conducted with 
 high pressure, the other without. The starch, dissolved in either 
 one or the other way, is eventually inverted and calculated from the 
 dextrose formed. 
 
 () Method of Reinke, with use of high pressure. The finely- 
 divided substance is used in form of a flour, in a separate portion 
 of which the water has been determined. In addition, the water in 
 the original substance must be ascertained. The values found for 
 the flour are recalculated on this. 
 
 Three grs. flour are moistened in a metal or glass beaker with 25 
 c.c. i per cent, solution of lactic acid and 30 c.c. water. The 
 mass is covered with a watch crystal and heated for 2^ hours at 3^ 
 atmospheres in a Soxhlet steam -kettle, or, in the absence of the 
 latter, in a Lintner pressure -flask. After cooling, 50 c.c. hot 
 water are added. The solution is then placed in a 250 c.c. flask 
 and diluted to the mark. After occasional shaking, during a period 
 of a half hour's standing, the solution is filtered. 
 
 200 c.c. of the filtrate, to which 15 c.c. hydrochloric acid (sp. 
 gr. 1.125) have been added, are briskly boiled on a reflux conden- 
 ser for two hours. Upon cooling, the liquid is neutralized with 
 caustic soda to faint acid reaction and diluted to 500 c.c. In order 
 to know once and for all how much alkali to add, 15 c.c. hydro- 
 chloric acid (1.125) are titrated with the former. The quantity 
 
96 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Determination of Grape-Sugar {Dextrose}. F. Allihn. 
 
 Copper. 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose. 
 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dextrose, 
 mg. 
 
 IO 
 
 6.1 
 
 56 
 
 28.8 
 
 I O2 
 
 5L9 
 
 148 
 
 75-5 
 
 194 
 
 99-4 
 
 II 
 
 6.6 
 
 57 
 
 293 
 
 I0 3 
 
 52.4 
 
 149 
 
 76.0 
 
 195 
 
 1 00.0 
 
 12 
 
 7- 1 
 
 58 
 
 298 
 
 I0 4 
 
 52.9 
 
 150 
 
 76.5 
 
 196 
 
 100.5 
 
 13 
 
 7.6 
 
 59 
 
 30-3 
 
 105 
 
 535 
 
 151 
 
 77.0 
 
 I 97 
 
 IOI.O 
 
 H 
 
 8.1 
 
 60 
 
 30.8 
 
 1 06 
 
 54-0 
 
 152 
 
 77-5 
 
 198 
 
 101.5 
 
 15 
 
 8.6 
 
 61 
 
 31.3 
 
 107 
 
 54-5 
 
 153 
 
 78.1 
 
 199 
 
 I02.O 
 
 16 
 
 9.0 
 
 62 
 
 31.8 
 
 108 
 
 55-0 
 
 154 
 
 78.6 
 
 200 
 
 1 02. 6 
 
 17 
 
 9-5 
 
 63 
 
 32.3 
 
 109 
 
 55-5 
 
 155 
 
 79.1 
 
 2O I 
 
 103.2 
 
 18 
 
 IO.O 
 
 64 
 
 32.8 
 
 no 
 
 56.0 
 
 I 5 6 
 
 796 
 
 2O2 
 
 103.7 
 
 19 
 
 10.5 
 
 65 
 
 33-3 
 
 III 
 
 56-5 
 
 157 
 
 80.1 
 
 203 
 
 104.2 
 
 20 
 
 II.O 
 
 66 
 
 33-8 
 
 112 
 
 57-0 
 
 158 
 
 80.7 
 
 2O4 
 
 104.7 
 
 21 
 
 "5 
 
 67 
 
 34-3 
 
 "3 
 
 57-5 
 
 159 
 
 81.2 
 
 205 
 
 105.3 
 
 22 
 
 I2-O 
 
 68 
 
 34-8 
 
 114 
 
 58.0 
 
 1 60 
 
 8i.7 
 
 2O6 
 
 105.8 
 
 23 
 
 12-5 
 
 69 
 
 353 
 
 H5 
 
 58.6 
 
 161 
 
 82.2 
 
 2O7 
 
 106.3 
 
 24 
 
 13.0 
 
 70 
 
 35-8 
 
 116 
 
 59.i 
 
 162 
 
 82.7 
 
 208 
 
 106.8 
 
 25 
 
 '3-5 
 
 7 1 
 
 36.3 
 
 117 
 
 59-6 
 
 163 
 
 83.3 
 
 2O9 
 
 107.4 
 
 26 
 
 14.0 
 
 7 2 
 
 36.8 
 
 118 
 
 60. i 
 
 164 
 
 83.8 
 
 210 
 
 107.9 
 
 27 
 
 14-5 
 
 73 
 
 37-3 
 
 119 
 
 60.6 
 
 165 
 
 84.3 
 
 211 
 
 108.4 
 
 28 
 
 15.0 
 
 74 
 
 37-8 
 
 1 20 
 
 61.1 
 
 1 66 
 
 84.8 
 
 212 
 
 109.0 
 
 29 
 
 15-5 
 
 75 
 
 383 
 
 121 
 
 61.6 
 
 167 
 
 85.3 
 
 213 
 
 109.5 
 
 3 
 
 1 6.0 
 
 76 
 
 38.8 
 
 122 
 
 62.1 
 
 1 68 
 
 85.9 
 
 214 
 
 I IO.O 
 
 3i 
 
 16.5 
 
 77 
 
 39.3 
 
 I2 3 
 
 62.6 
 
 169 
 
 86.4 
 
 215 
 
 110.6 
 
 32 
 
 17.0 
 
 78 
 
 39-8 
 
 124 
 
 63-1 
 
 170 
 
 86.9 
 
 216 
 
 in. i 
 
 33 
 
 '7-5 
 
 79 
 
 403 
 
 125 
 
 63.7 
 
 171 
 
 87.4 
 
 217 
 
 U 1.6 
 
 34 
 
 1 8.0 
 
 80 
 
 40.8 
 
 126 
 
 64.2 
 
 172 
 
 879 
 
 218 
 
 II2.I 
 
 35 
 
 18.5 
 
 81 
 
 4i.3 
 
 127 
 
 64.7 
 
 173 
 
 88.5 
 
 219 
 
 1127 
 
 36 
 
 18.9 
 
 82 
 
 41.8 
 
 128 
 
 65.2 
 
 174 
 
 89.0 
 
 22O 
 
 II3.2 
 
 37 
 
 19.4 
 
 83 
 
 42.3 
 
 129 
 
 65.7 
 
 175 
 
 89-5 
 
 221 
 
 II3.7 
 
 38 
 
 19.9 
 
 84 
 
 42.8 
 
 130 
 
 66.2 
 
 176 
 
 90.0 
 
 222 
 
 II4-3 
 
 39 
 
 20.4 
 
 85 
 
 43-4 
 
 J3 1 
 
 66.7 
 
 177 
 
 9-5 
 
 223 
 
 II4.8 
 
 40 
 
 20.9 
 
 86 
 
 43-9 
 
 132 
 
 67.2 
 
 178 
 
 91 i 
 
 224 
 
 II5-3 
 
 4i 
 
 21.4 
 
 87 
 
 44-4 
 
 !33 
 
 67.7 
 
 179 
 
 91.6 
 
 225 
 
 "5-9 
 
 42 
 
 21.9 
 
 88 
 
 449 
 
 134 
 
 68.2 
 
 1 80 
 
 92.1 
 
 226 
 
 116.4 
 
 43 
 
 22.4 
 
 89 
 
 45-4 
 
 135 
 
 68.8 
 
 181 
 
 926 
 
 227 
 
 116.9 
 
 44 
 
 22.9 
 
 90 
 
 45-9 
 
 136 
 
 69-3 
 
 182 
 
 93-1 
 
 228 
 
 117.4 
 
 45 
 
 23-4 
 
 9i 
 
 46.4 
 
 137 
 
 69.8 
 
 183 
 
 93-7 
 
 22 9 
 
 118.0 
 
 46 
 
 23-9 
 
 92 
 
 46.9 
 
 138 
 
 70.3 
 
 184 
 
 94-2 
 
 230 
 
 118.5 
 
 47 
 
 24.4 
 
 93 
 
 474 
 
 *39 
 
 708 
 
 185 
 
 94-7 
 
 231 
 
 1190 
 
 48 
 
 24.9 
 
 94 
 
 47-9 
 
 140 
 
 7L3 
 
 1 86 
 
 95-2 
 
 232 
 
 119.6 
 
 49 
 
 254 
 
 95 
 
 48.4 
 
 141 
 
 71.8 
 
 187 
 
 95-7 
 
 233 
 
 1 20. 1 
 
 50 
 
 25-9 
 
 96 
 
 48.9 
 
 142 
 
 72.3 
 
 188 
 
 96.3 
 
 234 
 
 120.7 
 
 51 
 
 26.4 
 
 97 
 
 49-4 
 
 H3 
 
 72.9 
 
 189 
 
 96.8 
 
 235 
 
 121. 2 
 
 52 
 
 26.9 
 
 98 
 
 49-9 
 
 144 
 
 734 
 
 190 
 
 97-3 
 
 2 3 6 
 
 121.7 
 
 53 
 
 27.4 
 
 99 
 
 5-4 
 
 H5 
 
 73-9 
 
 191 
 
 97-8 
 
 237 
 
 122.3 
 
 54 
 
 27.9 
 
 100 
 
 50.9 
 
 146 
 
 74-4 
 
 192 
 
 98.4 
 
 2 3 8 
 
 122.8 
 
 55 
 
 28.4 
 
 IOI 
 
 51.4 
 
 147 
 
 74-9 
 
 193 
 
 98.9 
 
 239 
 
 1234 
 
 added is then made less than that required to fully neutralize. The 
 dextrose is determined with Fehling's solution in 50 c.c. of neu- 
 
RAW PRODUCTS CONTAINING STARCH. 
 
 97 
 
 Determination of Grape-Sugar {Dextrose} . F. Allihn* Continued* 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dex- 
 trose, 
 mg. 
 
 Copper, 
 mg. 
 
 Dextrose, 
 mg. 
 
 240 
 
 123.9 
 
 285 
 
 148.3 
 
 330 
 
 I73.I 
 
 375 
 
 198.6 
 
 420 
 
 224.5 
 
 241 
 
 124.4 
 
 286 
 
 148.8 
 
 331 
 
 173-7 
 
 376 
 
 199.1 
 
 421 
 
 225.1 
 
 242 
 
 125.0 
 
 287 
 
 149.4 
 
 332 
 
 174.2 
 
 377 
 
 199.7 
 
 422 
 
 225.7 
 
 243 
 
 125.5 
 
 288 
 
 149.9 
 
 333 
 
 174.8 
 
 378 
 
 200.3 
 
 423 
 
 226.3 
 
 244 
 
 I26.O 
 
 289 
 
 150.5 
 
 334 
 
 175-3 
 
 379 
 
 200.8 
 
 424 
 
 226.9 
 
 245 
 
 126.6 
 
 290 
 
 151.0 
 
 335 
 
 175.9 
 
 380 
 
 201.4 
 
 425 
 
 227.5 
 
 246 
 
 I27.I 
 
 291 
 
 151.6 
 
 336 
 
 176.5 
 
 38i 
 
 2O2.O 
 
 426 
 
 228.0 
 
 247 
 
 127.6 
 
 292 
 
 152.1 
 
 337 
 
 177.0 
 
 382 
 
 202-5 
 
 427 
 
 228.6 
 
 248 
 
 I28.I 
 
 293 
 
 152.7 
 
 338 
 
 177.6 
 
 383 
 
 203.1 
 
 428 
 
 229.2 
 
 249 
 
 128.7 
 
 294 
 
 153-2 
 
 339 
 
 I78.I 
 
 384 
 
 203.7 
 
 429 
 
 229.8 
 
 250 
 
 129.2 
 
 295 
 
 153.8 
 
 340 
 
 178.7 
 
 385 
 
 204.3 
 
 430 
 
 230.4 
 
 251 
 
 129.7 
 
 296 
 
 154.3 
 
 34i 
 
 179.3 
 
 386 
 
 204.8 
 
 431 
 
 231.0 
 
 2 5 2 
 
 I3 .3 
 
 297 
 
 154.9 
 
 342 
 
 179.8 
 
 387 
 
 205.4 
 
 432 
 
 231.6 
 
 253 
 
 I 3 0.8 
 
 298 
 
 155.4 
 
 343 
 
 180.4 
 
 388 
 
 2O6.O 
 
 433 
 
 232.2 
 
 254 
 
 I3M 
 
 299 
 
 156.0 
 
 344 
 
 180.9 
 
 389 
 
 206.5 
 
 434 
 
 232.8 
 
 255 
 
 I3L9 
 
 3 00 
 
 156.5 
 
 345 
 
 181.5 
 
 390 
 
 2O7.I 
 
 435 
 
 233-4 
 
 2 5 6 
 
 I3 2 4 
 
 3 OI 
 
 I57-I 
 
 346 
 
 I82.I 
 
 39i 
 
 207.7 
 
 436 
 
 233-9 
 
 257 
 
 ^33-0 
 
 3 02 
 
 157.6 
 
 347 
 
 182.6 
 
 392 
 
 208.3 
 
 437 
 
 234-5 
 
 2 5 8 
 
 133-5 
 
 303 
 
 158.2 
 
 348 
 
 183.2 
 
 393 
 
 2088 
 
 438 
 
 235.1 
 
 259 
 
 I34.I 
 
 34 
 
 158.7 
 
 349 
 
 183.7 
 
 394 
 
 209.4 
 
 439 
 
 2357 
 
 260 
 
 134.6 
 
 35 
 
 159-3 
 
 35 
 
 1843 
 
 395 
 
 2IOO 
 
 440 
 
 236.3 
 
 26l 
 
 I35-I 
 
 306 
 
 159.8 
 
 351 
 
 184.9 
 
 396 
 
 2IO.6 
 
 441 
 
 236.9 
 
 262 
 
 135.7 
 
 37 
 
 160.4 
 
 352 
 
 1854 
 
 397 
 
 2II.2 
 
 442 
 
 237-5 
 
 263 
 
 136.2 
 
 3 08 
 
 160.9 
 
 353 
 
 186.0 
 
 398 
 
 2II.7 
 
 443 
 
 238.1 
 
 264 
 
 136.8 
 
 309 
 
 161.5 
 
 354 
 
 186.6 
 
 399 
 
 212.3 
 
 444 
 
 238.7 
 
 265 
 
 137.3 
 
 310 
 
 162.0 
 
 355 
 
 187.2 
 
 400 
 
 212.9 
 
 445 
 
 239-3 
 
 266 
 
 137.8 
 
 3 11 
 
 162.6 
 
 356 
 
 l877 
 
 401 
 
 213.5 
 
 446 
 
 239.8 
 
 267 
 
 138.4 
 
 312 
 
 163.1 
 
 357 
 
 188.3 
 
 402 
 
 2I4.I 
 
 447 
 
 240.4 
 
 268 
 
 138.9 
 
 313 
 
 163.7 
 
 358 
 
 188.9 
 
 403 
 
 214.6 
 
 448 
 
 241.0 
 
 269 
 
 139.5 
 
 3'4 
 
 164.2 
 
 359 
 
 189.4 
 
 404 
 
 215.2 
 
 449 
 
 241.6 
 
 2 7 
 
 1400 
 
 315 
 
 164.8 
 
 360 
 
 190.0 
 
 405 
 
 215.8 
 
 450 
 
 242.2 
 
 2 7 I 
 
 140.6 
 
 3i6 
 
 165.3 
 
 361 
 
 190.6 
 
 406 
 
 216.4 
 
 45 ! 
 
 242.8 
 
 272 
 
 141.1 
 
 317 
 
 165.9 
 
 '362 
 
 I9I.I 
 
 407 
 
 217.0 
 
 452 
 
 243.4 
 
 273 
 
 141.7 
 
 3i8 
 
 166.4 
 
 363 
 
 I9I.7 
 
 408 
 
 217-5 
 
 453 
 
 244.0 
 
 274 
 
 142.2 
 
 319 
 
 167.0 
 
 364 
 
 192.3 
 
 409 
 
 218.1 
 
 454 
 
 244.6 
 
 275 
 
 1428 
 
 320 
 
 167-5 
 
 365 
 
 192.9 
 
 410 
 
 2l8j 
 
 455 
 
 245-2 
 
 2 7 6 
 
 H3-3 
 
 321 
 
 I68.I 
 
 366 
 
 193.4 
 
 411 
 
 219.3 
 
 456 
 
 2457 
 
 277 
 
 143-9 
 
 322 
 
 168.6 
 
 367 
 
 194.0 
 
 412 
 
 219.9 
 
 457 
 
 246.3 
 
 2 7 8 
 
 144.4 
 
 323 
 
 169.2 
 
 368 
 
 194.6 
 
 413 
 
 220.4 
 
 458 
 
 246.9 
 
 279 
 
 I45.o 
 
 3 2 4 
 
 169.7 
 
 369 
 
 I95-I 
 
 414 
 
 22I.O 
 
 459 
 
 247.5 
 
 280 
 
 1455 
 
 325 
 
 170-3 
 
 370 
 
 195-7 
 
 415 
 
 221.6 
 
 460 
 
 248.1 
 
 28l 
 
 146.1 
 
 326 
 
 170.9 
 
 37i 
 
 196.3 
 
 416 
 
 222.2 
 
 461 
 
 248.7 
 
 282 
 
 146.6 
 
 327 
 
 171.4 
 
 372 
 
 196.8 
 
 417 
 
 222.8 
 
 462 
 
 249.3 
 
 283 
 
 147.2 
 
 328 
 
 172.0 
 
 373 
 
 197.4 
 
 418 
 
 223.3 
 
 463 
 
 249.9 
 
 284 
 
 147.7 
 
 329 
 
 172.5 
 
 374 
 
 198.0 
 
 419 
 
 2239 
 
 
 
 tralized solution, corresponding to . 24 gr. substance. For this pur- 
 pose, according to Allihn, 30 c.c. copper sulphate solution and 30 
 
 7 
 
98 CHEMICAL-TECHNICAL ANALYSIS. 
 
 c.c. alkaline Seignette solution are diluted in a porcelain dish of 
 200 c.c. capacity with sufficient water to bring the total volume, 
 after adding the sugar solution under examination, to 145 c.c. in 
 this instance 35 c.c. This solution is boiled. 50 c.c. dextrose 
 solution are run into the boiling liquid, which is held in ebullition 
 for two minutes from the moment that boiling again sets in. 
 
 Further treatment is conducted in exactly the same manner as 
 described in the determination of invert sugar. In the accompany- 
 ing tables of Allihn are found the values for dextrose corresponding 
 to the copper obtained. To calculate into starch, the quantity of 
 dextrose is multiplied by .9. 
 
 The method is applied mainly to the determination of starch in 
 potatoes. 
 
 (/?) Method of Marcker, without the use of high pressure. 
 
 Solution of the starch is here accomplished by diastase. 3 grs. 
 substance, previously extracted in a Soxhlet apparatus with ether, 
 if necessary, to free from fat, are boiled with looc.c. water for ^ 
 hour on a reflux condenser. The solution is cooled to 65 and 10 
 c.c. malt extract (prepared according to directions given below) 
 are added. The solution is kept at 65 for ^ hour. Thereupon 
 the solution is again boiled for ^ hour, again cooled to 65, and 
 allowed to remain at this temperature for ^ hour after addition of 
 another 10 c.c. malt extract. Finally it is boiled, cooled, diluted 
 to 200 c.c. and filtered. 200 c.c. filtrate are inverted with 15 c.c. 
 hydrochloric acid (1.125), then neutralized and diluted to 500 c.c. 
 
 50 c.c. are reduced with Fehling's solution. The remaining 
 operation is conducted precisely as in (a). 
 
 From the dextrose values found in the tables, that amount is to be 
 deducted, which corresponds to 1.6 c.c. malt extract contained in 
 50 c.c. The difference multiplied by .9 gives the starch in .24 gr. 
 flour. 
 
 Preparation of malt extract. 100 grs. bruised kiln -dried malt 
 are covered with i L. water and macerated, with occasional agita- 
 tion, for a period of 6 hours. It is thereupon filtered. The filtrate 
 keeps better on addition of a little chloroform. 
 
 Dextrose value of the malt extract. 50 c.c. are diluted with 150 
 c.c. water and boiled on a reflux condenser in a flask with 15 c.c. 
 hydrochloric acid (1.125) for two hours. It is then nearly neu- 
 
STARCH. 99 
 
 tralized, diluted to 500 c.c., and 50 c.c. treated, as heretofore, with 
 Fehling's solution. The dextrose value, corresponding to the cop- 
 per found, multiplied by .32, gives the amount of dextrose corres- 
 ponding to 1.6 c.c. malt extract, which is to be deducted. 
 
 (<) Total nitrogen. The determination is conducted according 
 to the method of Kjeldahl, in precisely the same manner as under 
 Nitrogen Fertilizers (p. 78). i gr. substance is used. By multi- 
 plying the nitrogen found by 6.25 the crude proteids are obtained. 
 
 2. Starch. 
 
 The investigation includes chiefly the determination of water, 
 the detection of impurities and adulterants, as well as establishing 
 the raw product from which it was made. 
 
 For the latter purpose use is made chiefly of the microscopic 
 method of investigation, which, however, will not be further de- 
 scribed here.* A starch determination can be conducted by in- 
 verting 2.53 grs. substance by boiling with 200 c.c. water and 
 20 c.c. hydrochloric acid (1.125) for three hours. The dextrose 
 formed is determined with Fehling's solution, as before. Accord- 
 ing to Sachsse, 100 grs. dextrose equal 91.67 grs. starch. The 
 operation is seldom conducted. 
 
 (a) Water. About 10 grs. starch are weighed out, dried at first 
 for an hour at 40-50, and then for 3-4 hours to constant weight 
 at 120 C. 
 
 (^) Impurities and adulterants. These may be both organic 
 and inorganic in nature : 
 
 (a) Inorganic matter. This is ascertained from the amount of 
 ash present, and is estimated by an ash determination. Mineral 
 adulteration is usually done with sand, gypsum, chalk, heavy spar 
 and clay. 
 
 (/?) Organic. The starch is dissolved with malt extract and the 
 residue is examined. It contains such organic impurities as 
 wood particles, fibres, coal-dust, chaff, fungus spores, etc. Organic 
 adulterants can hardly be else than cheaper grades of starch 
 which are added to the finer, and which are determined micro- 
 scopically. 
 
 * An excellent reference is the small book of V. Hohnel, " Starch and Ground 
 Products." 
 
100 CHEMICAL-TECHNICAL ANALYSIS. 
 
 3. Malt. 
 
 For this investigation the combined method of E. Jalowetz, pre- 
 pared at the Congress of Agriculture and Forestry in Vienna, 1890, 
 will be discussed. 
 
 (#) Water. 45 grs. malt are weighed off in form of whole 
 grains and are bruised as nearly quantitatively as possible in a special 
 mill. The substance, which is placed in watch crystals provided 
 with clasps, is heated in an atmosphere of dry hydrogen in a drum- 
 shaped water-bath. If the latter is inaccessible, it is dried in a 
 well -ventilated air-bath at 98-104. In the first case drying re- 
 quires 6 hours ; in the latter, 3-4 hours. It is finished when the 
 loss in weight no longer exceeds .25 per cent. 
 
 Very moist malt is dried at 40-50. 
 
 (<) Extract. 50 grs. whole malt are weighed out and ground, 
 without loss, in a malt mill. It is then washed with about 200 c.c. 
 water of 45 C. temperature, in a weighed beaker of about 500 c.c. 
 capacity, and is kept in a water-bath at the same temperature for a 
 half hour. The temperature of the bath is thereupon increased i 
 from minute to minute, so that after a period of 25 minutes a tem- 
 perature of 70 is reached. The mash is kept at this temperature 
 until saccharizing is complete, which is usually the case in about 
 y 2 hour. The end reaction is ascertained by means of iodine tests 
 which are calculated in this manner : A drop of mash is placed on 
 a porcelain dish. A drop of iodine solution is added and allowed 
 to stand for a while. The first test is made 10 minutes after 
 saccharizing has begun ; that is, after the mash has attained a tem- 
 perature of 70. Further tests are made at intervals of 510 min- 
 utes. Saccharizing is considered finished when the iodine tests 
 show a weak red or a pure yellow color. The time consumed, up 
 to this moment, is named the * ' time of saccharizing. ' ' The mash 
 is now removed from the water-bath, cooled, and treated with 
 approximately 200 c.c. cold water. On the balance, the weight of 
 the mash is increased by addition of water to 450 grs. It is mixed 
 and filtered into a dry flask through a ribbed filter. The filter should 
 be capable of receiving the entire quantity of mash at once. The 
 first portion of about 100 c.c. is replaced in the filter and the 
 density of the subsequent filtrate is determined with a pyknometer. 
 The latter, filled with the wort, should stand about one hour in a 
 
MALT. 101 
 
 bath at 17.5. By means of the density, the corresponding ex- 
 tract e, that is, the extractive matter in 100 c.c, is sought for in 
 Balling's tables. 
 
 The extract E of the air-dried malt is found by means of the 
 
 W E 
 
 formula (100 e) : e (400 -| ) : - where W equals the 
 
 amount of water expressed in per cent. 
 It then becomes : 
 
 e (400 + ^ 
 
 E=2. 2 - 
 
 ioo e 
 
 In ioo parts by weight of wort there are e parts extract, and ioo 
 E parts water. The total weight of the mash equaled 450 grs. , /. e. ,400 
 
 W 
 grs. water and 50 grs. malt, with Wfi water, hence in all 400 -f 
 
 grs. water. If the percentage of extract in the malt equal E, then in 
 50 grs. malt there are contained grs. extract. The previously con- 
 structed proportion is hereby sufficiently explained. 
 
 {c) Maltose. The estimation of maltose is conducted gravi- 
 metrically by reduction with Fehling's solution. 
 
 30 c.c. of the wort obtained as in (b} are diluted to 200 c.c. 25 
 c.c. of the dilute solution are run into 50 c.c, boiling Fehling's 
 solution. It is kept boiling for 4 minutes, the suboxide of copper 
 is filtered through an asbestos filter, and the remaining operation is 
 conducted as heretofore. The maltose corresponding to the copper 
 found is determined from the tables of Wein (see page 102). 
 
 Let the maltose be m, then the original 30 c.c. wort contain 8m 
 grams maltose. Furthermore, if the extract in ioo grs. be e, then 
 the extract in 30 c.c. or 30 d grams (d=density) = .3 . d . e. In 
 order to find the maltose M in E grs. extract, use is made of the pro- 
 portion : 
 
 .3. d. e: SmrzrE: M. 
 
 Therefore the percentage of maltose is 
 
 8m E 
 
 -rjTarr 
 
 (d} Diastatic value. The estimation depends on the fact that 
 a malt extract of known value inverts more starch the higher its 
 
102 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Weirf s Tables for the Determination of Maltose. 
 
 Copper, 
 nig. 
 
 Maltose, 
 nig. 
 
 Copper. 
 mg. 
 
 Maltose, 
 mg. 
 
 30 
 
 25-3 
 
 170 
 
 149-4 
 
 40 
 
 33-9 
 
 1 80 
 
 158.3 
 
 50 
 
 42.6 
 
 I 9 
 
 167.2 
 
 60 
 
 51-3 
 
 2OO 
 
 I76.I 
 
 70 
 
 60. 1 
 
 2IO 
 
 185.0 
 
 80 
 
 689 
 
 220 
 
 193-9 
 
 90 
 100 
 
 Hi 
 
 230 
 24O 
 
 202.9 
 2II.8 
 
 1 10 
 
 95-5 
 
 250 
 
 220.8 
 
 120 
 
 104.4 
 
 260 
 
 229.8 
 
 I 3 
 
 "34 
 
 270 
 
 238.8 
 
 I 4 
 
 122.4 
 
 280 
 
 247-8 
 
 15 
 
 I3L4 
 
 290 
 
 256.6 
 
 160 
 
 1404 
 
 300 
 
 265.5 
 
 diastatic value. The determination is conducted with a normal 
 starch and a malt extract. 
 
 Starch solution. To prepare this, a soluble starch is used. The 
 latter is prepared by adding sufficient 7 ^ per cent, hydrochloric 
 acid to cover any desired quantity of prime potato starch. This is 
 allowed to stand 7 days at ordinary temperature or 3 days at 40. 
 The acid is drawn off and the residue is washed with cold water by 
 decantation until acidity ceases. It is then air dried. 2 grs. of 
 this starch are dissolved in hot water. The solution will remain 
 clear for a number of days, but can be used even after it has 
 become turbid. 
 
 Malt extract. 25 grs. kiln-dried malt or crushed green malt are 
 extracted with 500 c.c. water at ordinary temperature for 6 hours. 
 It is then filtered. The solution is refiltered as long as the filtrate 
 comes through turbid. When green malt is used, the filtrate is 
 diluted with an equal volume of water before use. 
 
 Experiment. Introduce 10 c.c. starch solution in each of 10 test- 
 tubes. There is then added to each of these . i, .2 i c.c. malt 
 extract. They are well shaken and the diastase is allowed to act 
 at the surrounding temperature for i hour. After this time has 
 elapsed 5 c.c. Fehling's solution are added to each of the tubes, 
 which are then well shaken and placed for 10 minutes in boiling 
 water. The tube in which all the copper oxide is reduced is easily 
 
SPIRITS. 103 
 
 recognized. In this one the liquid over the suboxide appears 
 faintly blue, whereas in the next higher it is yellow, and in the next 
 lower it is deep blue. In very exact determinations, another test is 
 made between the two limits found by increasing the malt extract 
 by .02 c.c. and observing similar conditions. The fermenting 
 value of a malt is made equal to 100, according to Lintner, when 
 .1 c.c. of the malt extract, prepared as above, just reduces 5 c.c. 
 Fehling's solution. It is graded in the same proportions as the ex- 
 tract used increases, /'. ^., .2 c.c. malt extract 50; .5 c.c. malt 
 extract = 20, etc. The fermentation values obtained are doubled 
 when green malt, which is diluted with an equal volume of water, 
 
 is used. 
 
 4. Yeast. 
 
 Determination of fermentation value. 50 grs. yeast, together 
 with 400 c.c. 10 per cent, cane sugar solution, are placed in a flask 
 and closed with a rubber stopper, to which there is attached a small 
 sulphuric acid drying apparatus. Flask, contents and drying appa- 
 ratus are weighed and heated in a water-bath at exactly 30 C. 
 After 24 hours the loss in weight, due to the evolution of carbonic 
 acid, is determined. 
 
 According to Heyduck, compressed yeast free from starch, and 
 of which 5 grs. are used for analysis, should yield 812 grs. car- 
 bonic acid. -4904 gr. carbonic acid corresponds to i gr. cane 
 
 sugar decomposed. 
 
 5. Spirits. 
 
 (a) Alcohol. When pure spirits are used, this can be deter- 
 mined by certain areometers and alcoholometers. For this purpose 
 the officially adopted instruments are preferably used. The nor- 
 mal temperature is set at 12 R. in Austria and at i2| R. in Ger- 
 many. Readings are made at any temperature, and from the ap- 
 parent strength and the thermometer reading the true strength is 
 interpolated by means of tables which accompany the instruments. 
 The true volume of the spirits, on the basis of the true strength, 
 may be determined, by the use of another table, from the apparent 
 volume, at the prevailing temperature. A third table contains the 
 numbers for calculation of the weight of spirit into true volume. 
 
 When impure spirits are examined, such as fermented mashes, this 
 method is not suitable. The alcohol is in this case determined by 
 
104 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the method of distillation. For this purpose 100-200 c.c. liquid 
 to be tested are placed in a flask with an equal volume of water 
 and are distilled off exactly one-half. The distillate contains all the 
 alcohol originally present in the same quantity of liquor as before 
 distillation. The alcohol may be determined as heretofore by find- 
 ing the density of the distillate with an alcoholometer or a pyk- 
 nometer. 
 
 (^) Fusel oil. The most convenient methods are that of Rose 
 and that of Traube (using stalagmometer). The latter is less re- 
 liable, but can be rapidly executed and is often sufficiently exact. 
 
 (a) Method of Rose (modified by Stutzer and Reitmair). This 
 depends on the following principle : On shaking a mixture of 
 ethyl alcohol and water with chloroform, a certain portion of the 
 former dissolves in the chloroform, which thereby experiences an 
 increase in volume. When the alcohol contains fusel oil this is also 
 dissolved. Therefore a greater increase of volume takes place. 
 The amount of this latter increase affords a means of establishing 
 the quantity of fusel oil. 
 
 The agitator used consists of a glass tube, sealed at one end, 
 while the other possesses a pear-shaped enlargement, provided with 
 a tightly fitting stopper. The middle of the tube is contracted 
 and graduated. There are two different sizes of this apparatus. 
 In the smaller form of Herzfeld the graduation begins at 20 c.c. 
 and extends to 26. In the larger one it begins at 50 c.c. and ex- 
 tends to 56. Both are divided in .05 c.c. 
 
 Experiment. The thoroughly dry apparatus is suspended in 
 water of exactly 15 C. and chloroform of 15 C. is added as far 
 as the lowest division (20 or 50 c.c.). 100 (or 250) c.c. of 
 the spirits under investigation, diluted exactly to 30 per cent, 
 alcohol volume, and i c.c. (or 2.5) sulphuric acid (sp. gr. 1.286) 
 are added. The entire contents of the burette are run into the pear- 
 shaped bulb. It is then shaken continuously and briskly about 150 
 times, after which it is again suspended in water at 15 C. After 
 the chloroform has settled and the particles have been removed 
 from the walls by tapping with the finger, the chloroform volume is 
 read off on the scale. From this the " basis" is deducted. The 
 * ' basis' ' is the increase in volume which the chloroform shows 
 when shaken with pure ethyl alcohol free from fusel oil. 
 
SPIEITS. 105 
 
 Since this is also dependent on the source of the chloroform 
 employed, it must be determined anew when a different chloroform 
 is used. The same sulphuric acid must also be used in all deter- 
 minations. 
 
 The requisite pure alcohol is best prepared by fractional distilla- 
 tion, because even the commercial product known as "purest" is 
 often unsatisfactory. The remaining operation is conducted as be- 
 fore. If now the "basis" be deducted from the increase of vol- 
 ume furnished by the spirits under investigation, the difference af- 
 fords the increase due to fusel oil. From this the per cent, volume 
 of fusel oil in the original spirits (not the 30 per cent ) may be 
 found, when the smaller apparatus is used, by means of the follow- 
 ing formula : 
 
 d (ioo-fa) 
 
 150 
 
 where d represents the difference between the increase of vol- 
 ume found and the "basis," and a, the water or alcohol added 
 which was necessary to dilute 100 c.c. original spirits to 30 per 
 cent, volume. The formula depends on observations made by 
 Stutzer and Reitmair, which show that every .15 c.c. increase in 
 volume corresponds to .1 per cent, volume in the 30 per cent, 
 alcohol.* 
 
 In using this method the following points should be observed : 
 The spirits under examination must equal exactly 30 per cent, by 
 volume, /. e., .96564 sp. gr. The most extreme limits allowable are 
 29.9530.05 per cent, volume, because only .1 per cent, by 
 volume alcohol causes an increase in volume of the chloroform of 
 rfc .03 c.c. corresponding to .02 per cent, by volume of fusel oil. 
 The quantity of water which is necessary to dilute spirits greater 
 than 30 per cent, by volume to 30 per cent, is found in a set of 
 tables (also given in the " Chemiker Kalender "). 
 
 The temperatuie must be kept as near 15 as possible while 
 measuring the liquid and observing the volume. The utmost limits 
 are 14.5-15.5. As a correction for 15 for every .1 below 
 normal temperature .01 c.c. is added. Above normal this amount 
 
 * In the larger apparatus .15 c.c. increase in volume represents .04 per cent, 
 fusel oil. 
 
106 CHEMICAL-TECHNICAL ANALYSIS. 
 
 is deducted. When fine spirits are investigated, in which minute 
 quantities of fusel oil exert a great influence on the value, Stutzer 
 and Reitmair recommend a concentration by fractional distilla- 
 tion when small quantities are present. 
 
 Since this concentration can only be extended to .15 per cent, 
 by volume, it is necessary beforehand to ascertain if this limit is 
 not already overstepped in the original product. Should this not 
 be the case, 1000 c.c. spirits are added to 100 grs. dry potash, or 
 if the spirits contain lower than 90 per cent, by volume of alcohol 
 more potash is added. It is placed in a large distilling bulb and 
 distilled from a salt-bath after 2-3 hours. The first 500 c.c. which 
 distil over are collected separately, as are every subsequent 100 c.c. 
 After all has distilled over, the flask is allowed to cool, 200250 c.c. 
 water are added and 100 c.c. are distilled off. This aqueous dis- 
 tillate is used to dilute the last fraction which contains the entire 
 fusel oil, providing that the latter in the original spirits did not ex- 
 ceed . 1 5 per cent. This fraction is placed in the agitator. The 
 " basis" determination can be conducted with one of the inter- 
 mediate fractions which is diluted to 30 per cent, by volume. 
 When liquids are examined which contain substances having an 
 influence on the volume increase (aldehydes, ether varieties, 
 volatile acids and others increase ; ethereal oils decrease the vol- 
 ume), such as brandy, liquors, etc., a distillation with potassium 
 hydrate must be carried out in order to free from these. For this 
 purpose 200 c.c. sample .are placed in a spacious distilling bulb. 
 Four-fifths of the volume is distilled off, the distillate is caught in a 
 200 c.c. flask and diluted to the mark with water of 15 temperature. 
 
 (/3) Traube's method, using the stalagmometer. This depends 
 on the observation that the size of the drops, that is the vol- 
 ume of the drop which issues from a capillary tube on a circular 
 smooth surface, bears a definite relation to the quantity of fusel oil 
 present. The apparatus consists of a bulb drawn out at both ends 
 to a tube. One tube, the exit tube, is widened at the end to a disk 
 which bears a capillary widened below to a cone-shaped opening. 
 A constant volume is confined between two marks placed on the 
 tubes. On the instrument is etched the number of drops which 
 this volume yields when filled with a 20 per cent, pure spirit of a 
 definite temperature. The correction for the above directions, at a 
 
METHYL ALCOHOL (WOOD SPIRIT). 107 
 
 different temperature, is to be found in an explanation which ac- 
 companies the apparatus. 
 
 The spirits to be investigated are diluted to 20 per cent, volume. 
 The requisite quantity of water is to be found in the tables referred 
 to under Rose's method, after the density has been determined 
 with a pyknometer. When ethereal oils are present in the spirits, 
 it must be distilled first and the distillate then diluted. After the 
 liquid has arrived at the temperature of the room, it is forced 
 into the well-cleaned and dried apparatus by suction until the upper 
 mark is reached. Care must be taken that no air bubbles enter. The 
 liquid is then set at the upper mark and allowed to run out to the 
 lower mark. Meanwhile the drops are counted. The last adhering 
 drop is taken into account. According to Traube, the maximum 
 error should not exceed .2 of a drop for every 100 c.c. By this 
 operation .1 to .05 per cent, fusel oil can be determined. When 
 smaller quantities, as low as .02 per cent., are present, he advises 
 a concentration by agitation with ammonium sulphate solution, 
 which dissolves fusel oil. By distillation of this the fusel oil is 
 obtained in more concentrated form. The calculation is made 
 from the difference between the number of drops counted and 
 that designated on the instrument, corrected for prevailing tem- 
 perature. The next lower difference on the accompanying tables 
 is found and the fusel oil of the 20 per cent, spirit is gotten in per 
 cent, by interpolation. If the amount of fusel oil in the tables = 
 b and the water necessary to dilute 100 c.c. original substance to 20 
 per cent, volume = a, the fusel oil in per cent, by volume (f ) in 
 the original spirits would be 
 
 (100+ a) b 
 
 100 
 
 6. Methyl Alcohol (Wood Spirit). 
 
 This finds use in thedyestuff industry, as well as for "denaturiz- 
 ing ' ' spirits of wine. 
 
 Impurities usually present in wood spirit are : Aldehyde, ace- 
 tone, methyl acetate, dimethylacetal, allyl alcohol and ethyl alco- 
 hol. The quantitative estimation of acetone alone will be de- 
 scribed here. 
 
 The methods applied here are based on the fact that in the pres- 
 
108 CHEMICAL-TECHNICAL ANALYSIS. 
 
 ence of alkali, acetone is changed to iodoform by iodine, whereas 
 methyl alcohol and the other substances present do not bring about 
 this formation. According to the method of Messinger, which is 
 to be described, a definite quantity of iodine is added to form the 
 iodoform, and the excess of iodine is titrated back. 11.5 c - c - 
 wood spirit are placed in a 250 c.c. bottle. 20 c.c. normal alkali 
 are added and followed by 2030 c.c. -5- normal iodine solution. 
 The whole is shaken briskly for ^ minute. The alkali is now 
 exactly neutralized with hydrochloric acid (20 c.c, normal acid) 
 and the excess of iodine is titrated back with a T V normal hypo- 
 sulphite solution, using starch paste as an indicator. 
 
 The number of grams acetone in 100 c.c. wood spirit (y) is 
 found by the equation : 
 
 m 
 y= n . 7.612, 
 
 where m represents the quantity of iodine used in the formation of 
 iodoform, and n, the quantity of wood spirit used in the analysis, 
 expressed in c.c. 
 
VIII. Fats, Waxes and Mineral Oils. 
 
 FATS are mixtures of triglycerides of monobasic fatty acids. 
 Vegetable and animal waxes are fatty acid esters of higher fatty 
 alcohol. Mineral waxes and mineral oils consist of hydrocarbons. 
 
 The groups named, representing different chemical constitu- 
 tions, show characteristic behavior towards alkalies. Fats are 
 saponified on treatment with alkali into salts of fatty acids (soaps) 
 and glycerin, both of which are soluble in water. Fats are there- 
 fore completely saponifiable. Vegetable and animal waxes yield 
 salts of fatty acids soluble in water, and insoluble higher fatty alco- 
 hols, by this treatment, and are termed incompletely saponifiable. 
 Mineral waxes and oils are not changed by alkalies ; they are unsa- 
 ponifiable. 
 
 A. Fats. 
 
 1. General Methods of Investigation. 
 
 Although the fats represent mixtures of many triglycerides, the 
 quantity of the same in every kind of fat is a fairly constant one. 
 In consequence of these so-called constants, slightly varying values 
 can be determined for each fat. These would lead with certainty 
 to the identification of the same. Of these constants there will be 
 described : 
 
 (0) The saponification number. This indicates how many 
 milligrams potassium hydrate are necessary to saponify one gram of 
 fat, and is therefore a representation of the capacity of saturation 
 of the fatty acid contained in the fat. 
 
 (3) Hiibl's iodine number. This represents the quantity of 
 iodine which a fat is capable of absorbing and serves as a measure 
 for the unsaturated acids present (oleic acid, linoleic and linolenic 
 acid series). 
 
 (^ The acetyl number, which is a measure for the oxy fatty 
 acids and the fatty alcohols present. 
 
110 CHEMICAL-TECHNICAL ANALYSIS. 
 
 (</) The acid number, which expresses the number of milligrams 
 potassium hydrate used to neutralize the free fatty acids in a gram 
 of fat. It serves, therefore, as a measure for the free fatty acids 
 contained in the fat. 
 
 (#) Saponification Number . {Kottstorfer 1 s Number. ) 
 
 There are necessary to determine the saponification number : 
 
 (a) An about ^ normal hydrochloric acid, exactly standardized 
 by titration with potassium hydrate. 
 
 (/3) An alcoholic potash solution, prepared by dissolving in a 
 little water 30 grs. caustic potash, purified by alcohol, and then 
 diluting to i liter with alcohol free from fusel oil. After stand- 
 ing one day it is filtered into a flask. A 25 c.c. pipette, provi- 
 ded above with a piece of rubber tubing and a clip, is inserted 
 into the single perforation of a tightly-fitting rubber stopper. 
 When pure alcohol is used the solution will never become brown, 
 but can at the utmost assume a pale yellow tint on standing for 
 months. 
 
 To conduct the operation 1-2 grs. are placed in a wide-necked 
 flask of 150-200 c.c. capacity. For the purpose of weighing, a 
 small bottle with a lip is preferable. Introduce 50-60 drops oil 
 from the weighing-bottle into the flask and reweigh the bottle. 
 25 c.c. alcoholic potash are now allowed to flow from the pipette 
 into the flask. The drops which issue finally are counted, in order 
 to observe equal conditions, A reflux condenser is then inserted 
 through a suitable cork in the flask and the contents are heated to 
 boiling in a water-bath and agitated from time to time. Saponifi- 
 cation is complete in 15 minutes as a rule, but with difficultly 
 saponifiable fats ^ hour is required. A few drops of phenol - 
 phthalein are added,* and the excess of alkali is titrated with ^ 
 normal hydrochloric acid. 
 
 Since the standard of the alcoholic potash alters somewhat, 25 
 c.c. are titrated anew with hydrochloric acid prior to each experi- 
 ment. The same conditions as heretofore are to be observed, 
 namely, the same period of heating on the water-bath, etc. The 
 difference between the number of c.c. hydrochloric acid used for 
 
 * It is advisable to use alkali blue when the solutions are colored. 
 
FATS. Ill 
 
 this and the previous titration is expressed in milligrams K O H 
 and calculated on i gr. fat to obtain the saponification number. 
 
 (<) v. HilbV s Iodine Number. 
 
 Whereas iodine acts but slowly on fats, unsaturated fatty acids 
 readily form chlor-iodine addition products on treatment with an 
 alcoholic solution of iodine and mercuric chloride. 
 
 The materials necessary for this operation are : 
 
 () Iodine solution. 25 grs. iodine and 30 grs. mercuric chlor- 
 ide are each separately dissolved in 500 c.c. 95 per cent, alcohol 
 free from fusel oil. The latter solution is filtered if necessary. 
 They are then united.* The liquid should stand 24 hours be- 
 fore using, because the standard rapidly alters at first. A 2 5 c.c. 
 pipette may be inserted, as before. 
 
 (/?) Sodium hyposulphite solution. It is made approximately 
 TS normal. The standard is best established with a potassium bi- 
 chromate solution containing 3,874 grs. to the liter, 10 c.c. of 
 this solution equal . i gr, iodine. 
 
 (y) Chloroform. 10 c.c. of this, mixed with 10 c.c. Hiibl's 
 solution, should require, after 2-3 hours, the same amount of hypo- 
 sulphite as this quantity of iodine solution used alone. 
 
 (f5) Potassium iodide solution, i part potassium iodide to 10 
 parts water. 
 
 (??) Starch solution. Freshly prepared i per cent, starch paste. 
 From .15-. i8gr. drying oils, -25-.35gr. non-drying oils, or .8-1 gr. 
 solid fats is placed in a 500 c.c. flask, provided with a tight-fitting 
 stopper. 10 c.c. chloroform and 25 c.c. iodine solution are added. 
 Should the liquid on shaking remain turbid, more chloroform is 
 added. Should the liquid become colorless on brief standing, 
 another measured portion of iodine solution is added, so that, in 
 fact, on standing 6 hours the liquid still appears dark brown. Sub- 
 sequently 20-25 c - c - potassium iodide and 200-300 c.c. water are 
 added. Any red precipitate of mercuric iodide which forms is re- 
 dissolved by addition of more potassium iodide. Sufficient hypo- 
 sulphite is added, with frequent agitation, to render the aqueous 
 liquid and the chloroform light in color. Starch paste is then 
 
 * Waller states that Hiibl's iodine solution is much more stable when 25 c.c. 
 hydrochloric acid (sp. gr. 1.19) are added to 500 c.c. of the same. 
 
112 CHEMICAL-TECHNICAL ANALYSIS. 
 
 added, and the solution is carefully titrated to disappearance of 
 the blue color. A similar experiment is simultaneously conducted 
 with 25 c.c. iodine solution by titrating hyposulphite. From the 
 difference the iodine absorbed is found and calculated into per cent. 
 Results are concordant when sufficient iodine is added. The 
 excess should about equal half the iodine absorbed. Titration 
 should be made after the solution has stood 6 hours. Longer stand- 
 ing does not in any way influence the accuracy of the result. 
 
 (V) Acetyl Number. 
 
 The acetyl number of Ulzer and Benedikt expresses the number of 
 milligrams potassium hydrate which are necessary to saponify the 
 acetyl groups in i gr. acetylized fatty acids. 
 
 To determine this the free fatty acids must first be isolated from 
 the fats, for which purpose 30 grs. fat are placed in a flask with 
 6070 c.c. alcohol and 10 grs. potassium hydrate, dissolved in a 
 little water. This is boiled on a water-bath with a reflux condenser 
 to complete saponification. The latter is finished when, after addi- 
 tion of some water and shaking, the liquid remains perfectly clear. 
 The excess of alcohol is evaporated on a water-bath. The remain- 
 ing soap is dissolved in warm water and is poured into a beaker of 
 i L. capacity. The solution is boiled with dilute sulphuric acid 
 until the fats are completely melted. A current of carbonic acid 
 is meanwhile run through to prevent bumping. Thereupon the acid 
 fluid is siphoned off and the fats are again boiled with water. 
 The acid liquor is again siphoned, and the operation is repeated 
 until the liquid siphoned off no longer reacts acid. The acids are 
 filtered on a hot-water funnel through a dry filter, and are acetylized 
 by boiling 2 hours with an equal volume acetic anhydride in a flask 
 provided with a reflux. The contents of the flask are poured into 
 a beaker of about i L. capacity, are mixed with 500-600 c.c. water, 
 and boiled for ^ hour. As before, carbonic acid is conducted 
 through a capillary extending nearly to the bottom. After a time 
 the water is siphoned off and the boiling with water is repeated 
 three times, whereby all acetic acid is removed. Finally, the 
 acetylized acids are filtered in an air-bath at about 80 through a 
 dry filter. In a portion of the acetylized acids the saponification 
 number is taken as in (a]. This gives the "acetyl saponification 
 
FATS. 
 
 113 
 
 number." In another portion the "acetyl acid number" is 
 determined in the manner described below, in the method for 
 acid number. The difference between the two gives the acetyl 
 number. If a fat contain no oxy fatty acids, its acetyl number 
 will equal zero. 
 
 (</) Acid Number. 
 
 About 10 grs. fat are slightly heated in a flask with about 50 c.c. 
 pure acid-free 95 per cent, alcohol while the liquid is agitated. 
 Upon cooling, phenol-phthalein is added, and the solution titrated 
 with y? normal alkali until the red color appears. The number 
 of milligrams potassium hydrate used, calculated on i gr. fat, 
 yields the acid number. When free fatty acids are used the acid 
 number is identical with the saponification number. Frequently 
 the acid number of a fat is expressed in Burstyn degrees. These 
 express the number of c.c. normal alkali necessary to combine with 
 the free acids present in 100 c.c. of the fat. The determination 
 of acid number is also made use of in examining other fats, such as 
 those used as lubricants. 
 
 The following tables* contain the iodine numbers and saponifica- 
 tion numbers of the most important fats : 
 
 Fats. 
 
 Iodine Number. 
 
 Saponification Number. 
 
 Min. 
 
 Max. 
 
 Mean. 
 
 Min. 
 
 Max. 
 
 Mean. 
 
 Olive oil 
 
 79 
 I0 3 
 
 87.3 
 
 102 
 
 82 
 9 8 
 170 
 
 H0.5 
 122 
 I2 3 
 
 S l 
 
 26 
 
 35-5 
 4 6 
 
 88 
 
 112 
 
 I0 3 
 
 112 
 
 85-9 
 IO4 
 
 I8 3 
 157.5 
 134 
 166 
 
 52.4 
 
 9-35 
 35 
 44 
 55 
 
 82 83 
 
 I8 5 
 I8 7 
 I 9 
 
 I9 1 
 176 
 
 175 
 187.4 
 I 9 
 I8 9 
 175 
 200 
 
 253 
 221 
 
 193 
 
 I 9 6 
 I 9 2 
 
 I 9 7 
 
 198 
 
 183 
 
 179 
 
 I95- 2 
 193 
 I 94 
 194 
 202.5 
 262 
 227 
 206 
 
 193 
 190 
 I 94 
 
 195.5 
 1 80 
 177 
 192 
 
 I9I-5 
 192 
 182187 
 201.5 
 
 257 
 224 
 197 
 190.9 
 
 Sesame oil 
 
 I 08 109 
 9496 
 
 I 08 109 
 
 84.5 
 100 101 
 
 178 
 
 150 
 128 
 
 144148 
 51.5 
 
 8-5 
 33 
 39 
 49 
 
 Peanut oil (Arachis 
 oil) 
 
 Cotton oil 
 
 Castor oil 
 
 Rape-seed oil 
 
 Linseed oil 
 
 Hemp-seed oil 
 
 Sunflower-seed oil...... 
 Cod-liver oil 
 
 Palm oil 
 
 Cocoanut oil 
 
 Butter fat 
 
 Tallow 
 
 Bone fat 
 
 
 * The maximum and minimum values expressed in the tables are those found 
 only in isolated cases. Normal values are those under the heading " Mean." 
 
 8 
 
114 CHEMICAL-TECHNICAL ANALYSIS. 
 
 In addition to the determinations mentioned, the density is 
 usually taken. This is done with the liquid fats in a pyknometer. 
 Since, however, the densities of one and the same fat may vary 
 considerably, and, moreover, since these are approximately the same 
 for different fats, it is only seldom that they offer a reliable insight. 
 
 Certain features will be stated, in the chapters devoted to wax, 
 mineral oils and soaps, concerning determination and estimation 
 of unsaponifiable constituents of common resin and colophonium 
 
 rosin. 
 
 2. Classification of FatH. 
 
 This is represented in the following scheme : 
 
 a. Liquid fats. 
 
 a. Drying oils. 
 
 ft. Non-drying oils. 
 
 y. Fish oil. 
 
 rf. Fluid waxes. 
 
 b. Solid Fats. 
 
 (<z) Liquid Fats. 
 
 (a) Drying oils. These consist mainly of glycerides of linoleic 
 acid and linolenic acid. In thin layers they dry to varnish-like 
 masses in the air, thereby absorbing much oxygen, but they do not 
 yield ela'idin. 
 
 (/?) Non-drying oils. They contain much olein, and dry with 
 the utmost difficulty in the air or at higher temperatures. They 
 absorb little oxygen and give ela'idin. 
 
 (y) Fish oils, obtained from the fats of fish, absorb much oxy- 
 gen, do not dry to a varnish, and yield little or no ela'idin. They 
 give intense colorations with caustic soda, sulphuric acid, nitric 
 acid and phosphoric acid, of which that obtained with sulphuric 
 acid serves to distinguish them from other oils. It is obtained by 
 warming 5 vols. oil with i vol. glacial phosphoric acid. By this 
 treatment, all fish oils, whether mixed or not, give an intense red, 
 brown-red or brown-black shade. 
 
 (<5) Liquid waxes from the oils of marine animals consist mainly 
 of esters of monatomic alcohols, and contain only a small amount 
 of glycerides.* They are, like true waxes, only partially saponi- 
 
 * The classification of these under the fats is, therefore, a more or less arbitrary 
 one. 
 
CLASSIFICATION OF FATS. 115 
 
 fiable, and possess, in consequence, a very low saponification 
 number. The unsaponified portion is solid and consists of mona- 
 tomic alcohols. They contain only 60-65 P er cent, fatty acids, as 
 against 95 per cent, in other oils. They absorb little oxygen in air, 
 do not dry, and give no elaidin, 
 
 Recognition of drying and non-drying oils. Since the thorough 
 drying of the oils in air, spread on glass plates in thin layers, re- 
 quires too long a period, the determination can hardly furnish a 
 means of recognition. On the other hand, the following methods 
 are suitable elai'din tests. This depends on the fact that glycerides 
 of the oleic acid series are transformed by nitrous acid into the 
 solid glycerides of the elaidic acid series, whereas those of the 
 linoleic series, etc., remain liquid. 
 
 10 grs. oil, 5 grs. nitric acid, 40-42 Be. and i gr. mercury are 
 placed in a test-tube and are shaken continuously for 3 minutes to 
 dissolve the mercury. The liquid is then allowed to stand for 20 
 minutes, and is then shaken for i minute. From this point olive 
 oil will, for instance, solidify in i hour, peanut oil in i hour and 
 20 minutes, sesame oil in 3 hours and 5 minutes, whereas linseed 
 oil and fish oil give a red pasty foam and hemp- seed oil remains 
 unaltered. 
 
 Copper may be used in place of mercury. 
 
 Maiimene* s test. This depends on the phenomenon that sul- 
 phuric acid, mixed with drying oils, heats up considerably more 
 than with non-drying oils. The test is conducted as follows : 50 
 c.c. oil are placed in a 100 c.c. beaker. The temperature is taken 
 with a thermometer, and from a pipette 10 c.c. cone, sulphuric 
 acid of the same temperature are run in during a period of i min- 
 ute, while the liquid is being stirred with the thermometer. To 
 prevent loss of heat the beaker containing the oil may be placed in 
 a second larger beaker, with cotton placed between. It is stirred 
 until the temperature ceases to rise. Should the rise equal more 
 than 70, drying oils can be considered present with certainty. 
 As examples,* olive oil shows a rise of 41-43 in temperature, 
 rape -seed oil 51-60, and linseed oil 104-111. 
 
 Iodine number. The non-drying oils possess lower iodine 
 
 * According to Allen. 
 
116 CHEMICAL-TECHNICAL ANALYSIS. 
 
 numbers than the drying oils. The iodine number, in consequence, 
 serves as a convenient and safe means of identification, providing 
 that fish oils are absent. These are non-drying, and yet possess a 
 high iodine number. 
 
 () Solid Fats. 
 
 Recognition of solid fats is accomplished chiefly by : 
 
 (a) Specific gravity. This is best determined by the method of 
 Gintl, who uses a small cylindrical, flat-bottomed pyknometer, the 
 opening of which may be closed with a ground glass plate. When 
 filling in the molten fat an excess is allowed to remain above the top. 
 After cooling, the plate is slipped on and screwed down. The ex- 
 cess is wiped off with a cloth dipped in petroleum ether. The 
 weights of empty and filled flasks are determined in the usual 
 manner. 
 
 According to the method of Hager for the determination of 
 specific gravity, the molten fat is allowed to drop a short distance 
 into a glass dish filled with 6090 per cent alcohol. The solidified 
 drops are placed' in the liquids which serve to determine specific 
 gravity. For densities less than water a mixture of water and alco- 
 hol, and for greater densities a mixture of glycerin and water or 
 alcohol, or alcohol and water respectively. Glycerin or glycerin 
 and water are added until the drop just floats on the liquid, which is 
 set in rotation. Finally the liquid is poured through glass wool, 
 and the specific gravity, which is equal to that of the fat, is then de- 
 termined with areometer or pyknometer. The determination of 
 ithe specific gravity of molten fats may be conducted with the 
 Westphal balance. The vessel containing the fat is placed in a 
 paraffin bath. 
 
 (/3) The melting point and solidification point of a fat and of 
 isolated fatty acids. Fuller directions will be given in the discus- 
 sion of tallow and wax. 
 
 (f) The behavior in the refractometer. The latter is used 
 chiefly in testing butter, fat and lard. For apparatus and descrip- 
 tion see Benedikt and Ulzer, Analyse der Fette und Wachsarten, 
 3. Aufl. 
 
 (rf) Saponification and iodine numbers. The saponification and 
 iodine numbers of the most important fats are given in the tables, 
 p. 113. 
 
EXAMINATION OF A FEW COMMON FATS. 117 
 
 0?) Volatile fatty acids. These are determined by the Reichert- 
 Meissl number, which represents the number of c.c. T V normal 
 alkali which are necessary to neutralize the volatile fatty acids in 
 5 grs. fat. 
 
 About 5 grs. fat are placed in a 200300 c.c. flask on a water- 
 bath with about 2 grs. stick potash and 50 c.c. of 70 per cent, 
 alcohol and saponified.* The flask and contents are shaken from 
 time to time. 
 
 The alcohol is volatilized after complete saponification until a 
 thick soap remains. This is dissolved by warming with 100 c.c. 
 water. 40 c.c. sulphuric acid (i : 10) and a few pieces of pumice- 
 stone are added to the flask, which is then connected with a Liebig 
 condenser by means of a bulb tube. It is first heated with a small 
 flame until the fats have melted to a clear layer, after which it is 
 distilled for a half hour and exactly no c.c. distillate are collected 
 in a graduated flask. After shaking, 100 c.c. are filtered off in a 
 measuring flask, emptied into a beaker and titrated with iV normal 
 alkali, using phenol-phthalein as indicator. The quantity of the 
 alkali used is increased T V and calculated on 5 grs. fat. 
 
 The Reichert-Meissl number is principally used to identify butter 
 and cocoanut oils. Butter has a number between 26-29; cocoa- 
 nut oil, 7. 
 
 3. Examination of a Few Common Fats. 
 
 O) Olive Oil. 
 
 The iodine number and saponification numbers are taken. Should 
 these correspond to the mean values given in the table, the oil may 
 be considered pure. Should the saponification number correspond, 
 but the iodine number lie above 85, adulteration with sesame oil, 
 peanut oil, or cotton-seed oil has been attempted. The methods, 
 specially described, may be used for detecting their presence. 
 
 Should the saponification number be low and the iodine number 
 high, the adulterant is presumably rape-seed oil. In this case a 
 test for mineral oil must also be made. When used for machine 
 oil the acid number should not exceed 16. 
 
 * Kreiss and some others recommend the use of sulphuric acid instead of 
 potash. 
 
118 CHEMICAL-TECHNICAL ANALYSIS. 
 
 () Rape-seed Oil. 
 
 The normal values for iodine and saponification numbers, as a 
 rule, suffice for identification. Drying oils and fish oil raise the 
 iodine and saponification numbers. Rosin oil and mineral oil 
 lower the same. When used for lubricating purposes the acid 
 number should not exceed 6. 
 
 (c} Castor Oil. 
 
 Iodine number and saponification number, acetyl number and 
 density, serve to determine the purity. The acetyl number 
 should not exceed 15.2; the density, .960 .966. Castor oil must 
 completely dissolve in two parts by volume of 95 per cent, alcohol, 
 and remain insoluble in petroleum ether. 
 
 (</) Sesame Oil. 
 
 This is frequently adulterated with cotton-seed oil. Iodine num- 
 ber, saponification number and density do not afford sufficient means 
 for identification. The Livache test is particularly suited to this 
 purpose. It depends on the fact that the increase in weight due to 
 oxygen absorption is perceptibly less in the presence of cotton -seed 
 oil than in the genuine article.* 
 
 The test of Livache is conducted by precipitating the solution of a 
 lead salt with zinc. The precipitate is quickly washed with water, 
 alcohol and ether, and dried in a vacuum over sulphuric. Two 
 quantities of lead powder, each i gr. , are spread out on two large 
 watch crystals. The weight of each lead powder and crystal are 
 taken and 20 drops of oil placed on one of the watch crystals from 
 a finely-drawn-out pipette. On the other is placed the same quan- 
 tity of the fatty acids of the same in such a manner that the drops 
 do not flow together. Both watch crystals are again weighed in 
 order to obtain the weight of oil and fatty acids and are set in 
 a place protected from dust. They are allowed to remain in the 
 light on the average seven days at ordinary temperature. When 
 this time has elapsed, the increase in weight of each is determined 
 and reckoned in percentage of substance taken. Presence of cot- 
 ton-seed oil is detected by this means. 
 
 * The increase in weight of the oils and fatty acids of oils, such as sesame 
 and most of the others, in the same time, is of nearly equal percentage. 
 
EXAMINATION OF A FEW COMMON FATS. 119 
 
 Detection of sesame oil mother oils. According to Baudouin, 20 
 c.c. oil under investigation are placed in a test-tube containing .1 
 gr. cane sugar and 10 c.c. hydrochloric acid (sp. gr. 1.19). It is 
 well shaken for a minute and allowed to settle. The layer of 
 liquid, which separates immediately, as a rule, shows an intense red 
 color in the presence of sesame oil, whereas, in absence of same, 
 the aqueous layer remains colorless at least 2 minutes and the oily 
 layer appears green or yellow. 
 
 Villavecchia and Fabris attribute the red coloration to the fur- 
 furol formed from the laevulose, which is formed by the action of 
 hydrochloric acid on cane sugar, and demonstrate this by showing 
 that a 2 per cent, alcoholic solution of furfurol gives the same re- 
 action. They therefore propose the use of this reagent in place of 
 cane sugar. 
 
 (<?) Arachis Oil. {Peanut Oil.) 
 
 This is characterized by the iodine number and saponification 
 number given in the tables as well as the rise of temperature, which 
 equals 45.5-51.4 with Maumene's test. Additions of peanut oil 
 to other oils can be detected, according to De Negri and Fabris, 
 by the fact that the soap solutions obtained in the saponification 
 number solidify comparatively easy. An olive oil diluted with 
 10 per cent, peanut oil after determination of the saponification 
 number gives a turbid liquid which subsequently deposits a pre- 
 cipitate of the potassium salt of arachidic acid. 
 
 The presence of arachidic acid, which melts as high as 75, in 
 peanut oil can be serviceable in detecting the latter when present 
 in other oils. The procedure of Renard, modified by De Negri 
 and Fabris, is conducted as follows : 
 
 10 grs. sample are saponified. The fatty acids are separated 
 with hydrochloric acid, dissolved in 50 c.c. 90 per cent, alcohol, 
 and precipitated in the cold with a solution of lead acetate. It 
 is decanted after standing 12 hours. The residue is digested with 
 ether to separate lead oleate, and the precipitate, consisting of lead 
 palmitate and lead arachitate, is separated from the liquid by decan- 
 tation. It is finally filtered, and the precipitate is washed with ether 
 until the filtrate no longer shows a residue on evaporation. The 
 lead salts are decomposed in a separatory funnel with hydrochloric 
 acid (i : 5). Ether is added, the liquid is agitated, and when the 
 
120 CHEMICAL-TECHNICAL ANALYSIS. 
 
 two layers have separated the aqueous portion is run off. The 
 ethereal layer is then withdrawn, the ether is distilled off, and the 
 residue, consisting of fatty acids, is dissolved in 50 c.c. hot, 90 per 
 cent, alcohol. Upon cooling, a copious crystalline precipitate of 
 arachidic acid separates. It is filtered and washed at first with 90 
 per cent, alcohol, and later with 70 per cent, alcohol, is weighed, 
 and the melting point is taken. The latter usually is 7071, be- 
 cause the acid is not quite pure. 
 
 (/) Tallow. 
 
 In addition to the constants, the determination of the freezing 
 point of the fatty acids, the so-called " titer test" is of especial 
 importance. In order to obtain concordant results, the following 
 method was proposed by Wolf bauer : 
 
 25 c.c. potassium hydrate, sp. gr. 1.509 (125 grs. stick potash in 
 100 c.c. water), are stirred with 120 grs. molten sample in a beaker. 
 The temperature should be only slightly above the melting point of 
 the tallow. It is placed in a compartment at 100 after being agita- 
 ted, mixed, and covered with a watch glass. It is permitted to remain 
 there, with occasional stirring, until the saponification is complete, 
 and a drop, warmed with 50 per cent, alcohol, completely dis- 
 solves, which is the case after about 2 hours. 150 c.c. boiling 
 Water are stirred into the soap, which is then poured into a dish, 
 treated with 165 c.c. sulphuric acid, sp. gr. 1.143 ( 22 c - c - cone, 
 sulphuric acid and 150 c.c. water), and boiled until the fatty acids 
 form a perfectly clear layer. 
 
 The acid liquid is withdrawn entirely with a siphon and the fatty 
 acids are boiled with weak sulphuric acid (5 c.c. cone, sulphuric 
 acid in 100 c.c water), which is then again withdrawn, after which 
 they are twice boiled out with 100 c.c. water. The fatty acids are 
 eventually dried for 2 hours at 100. The solidified acids are 
 melted in a water-bath and filled to within i ^ cm. into a thin wall 
 test-tube of 15 cm. length and 3.5 cm. diameter. The test-tube 
 is then suspended in a specimen bottle by means of a cork. There- 
 upon a thermometer, graduated in one-fifth degree as far as 60, is 
 inserted through a cork into the fatty acids in such a manner that 
 while four-fifths cm. distant from the bottom it is submerged to 35th 
 division. 
 
WAXES. 
 
 121 
 
 The clear mass is stirred with the thermometer until no longer 
 transparent, and until the thermometer-reading on repeated stirring 
 no longer changes. The thermometer is then fastened. The 
 mercury begins to rise, due to liberation of latent heat of fusion. 
 The highest mark which it touches, and at which it becomes station- 
 ary, is read off and taken as the freezing point. The difference be- 
 tween two determinations should not exceed .1. Frequently the 
 iodine number of the fatty acids of tallow is taken. The number 
 multiplied by 1.1102 gives the oleic acid in the fatty acids. When 
 used for lubricating purposes, tallow should not contain more than 
 .5 per cent matter insoluble in chloroform. 
 
 B. Waxes. 
 
 As has been mentioned, waxes are of animal and vegetable origin. 
 They are partly saponifiable and separate insoluble higher fatty 
 alcohols. Mineral waxes are unsaponifiable. The saponification 
 number affords a sure basis of distinction. 
 
 1. Vegetable and Animal Waxes. 
 
 Following determinations are chiefly resorted to in examining 
 vegetable and animal fats : Acid number, saponification number, 
 ester number (the difference between saponi- 
 fication and acid numbers), specific gravity, 
 melting point and freezing point. These de- 
 terminations are generally conducted accord- 
 ing to the methods previously mentioned. 
 
 The specific gravity can be determined, in 
 addition to the methods already given, with 
 the Sprengel tube. This is a U tube (Fig. 10) 
 of about 1 8 c.c. capacity and n mm. exter- 
 nal diameter, which tapers at both ends to 
 narrow bent tubes a and ^, of which the one 
 is longer and is provided with a mark, m. 
 The molten fat or wax is brought into the 
 tube by suction, during which operation the 
 longer bent tube is dipped in the fat. It is 
 now brought into a water-bath of constant 
 
 . , i j FIG. 10. Sprengel Tube. 
 
 temperature until the wax ceases to expand, 
 
 and the excess in the shorter arm is removed with filter paper 
 
122 CHEMICAL-TECHNICAL ANALYSTS. 
 
 until the longer arm is just filled to the mark. It is allowed to 
 cool, and the tube is cleaned and weighed. The experiment is 
 repeated with water at the same temperature or at 15. The melt- 
 ing point, according to Pohl, is usually determined by finding the 
 temperature when the wax fuses. To this end the bulb of a ther- 
 mometer is dipped for a moment in the fat or wax, which is heated 
 slightly above its melting point so that a film will remain on re- 
 moving. The thermometer is allowed to stand a while and is then 
 inserted through a cork into a long, wide test-tube so that the bulb 
 rests i cm. from the bottom. The test-tube is held with a test-tube 
 holder 2-3 c.c. over a tin shield or an asbestos plate which is care- 
 fully heated with a burner. The point is noticed at which the wax 
 becomes transparent when a drop of molten wax will appear at the 
 lower end. 
 
 Frequently the molten fat is drawn into a thin walled, not too 
 narrow, capillary tube, so that a column of 12 cm. is formed. The 
 end is then sealed, and the tube is fastened on a thermometer so 
 that the column of fat is on a level with the mercury bulb. 
 
 As soon as the substance has solidified better after 24 hours 
 the thermometer is placed in a 3 cm. wide test-tube containing the 
 heat conductor (glycerin). The temperature is taken the moment 
 the fat flows to a clear liquid. 
 
 Examination of Beeswax for Adulterants. 
 
 (0) Determination of total acid number. In consequence of 
 the difficulty experienced in the saponification of many waxes with 
 alcoholic potash, especially when they contain paraffin or ceresin, 
 too low results are often obtained. Benedikt and Mangold there- 
 fore determine the total acid number instead of the saponification 
 number, that is, the number of milligrams caustic potash required 
 to neutralize i gr. of the mixture of fatty acids and alcohol which 
 is set free from the wax by saponification of the wax and subsequent 
 decomposition of the soap obtained by boiling with dilute hydro- 
 chloric acid. The mixture is termed "decomposed wax." In 
 order to prepare the latter 20 grs. potassium hydrate are dissolved 
 in 15 c.c. water in a hemispherical capsule of 350500 c.c. capac- 
 ity. The solution is heated to boiling, when about 20 grs. pre- 
 viously-melted wax are stirred in. The solution is heated 10 min- 
 
WAXES. 123 
 
 utes, with constant, brisk stirring, over a small flame. 200 c.c. 
 water are added, the mass is heated and acidified with 40 c.c. 
 hydrochloric acid, previously diluted with a little water. There- 
 upon it is boiled until the upper layer becomes perfectly clear. It 
 is allowed to cool and is boiled out three times with portions of 
 water, to the first of which hydrochloric acid has been added. The 
 cake is finally removed, wiped off with filter paper, is melted in a 
 drying oven and filtered. The filtered fat is poured, still liquid, 
 on a watch crystal, and is broken up after cooling. For the esti- 
 mation of total acid number 68 grs. of the decomposed wax so 
 obtained are covered with alcohol free from acid, are heated on a 
 water-bath, and titrated after addition of phenol-phthalein. Even 
 when a large amount of ceresin is present, the saponification is 
 usually complete. The total acid number lies somewhat lower than 
 the saponification number, about 92.8 on an average, according to 
 v. Hiibl. 
 
 (ft) Determination of ceresin and paraffin. 
 
 The quantity of paraffin or ceresin present may approximately be 
 ascertained on the basis of the total acid number S by means of the 
 following formula : 
 
 100 S 
 
 P=IOO -^1T' 
 
 where P = paraffin or ceresin and 92.8 the average total acid 
 number of pure beeswax. 
 
 The test of A. u. P. Buisine is useful in the exact determination 
 of the paraffin or ceresin. This depends on the fact that the fatty 
 alcohols, on heating with soda-lime, disengage hydrogen with for- 
 mation of the sodium salts of corresponding fatty acids according 
 to the equation : 
 
 C 15 H 31 CH. 2 OH -f NaOH = C 1B H 81 COO Na + 2 H 2 
 Cetyl alcohol. Sodium palmitate. 
 
 A subsequent extraction with ether or petroleum ether removes, 
 beside paraffin and ceresin, only the hydrocarbons of the wax.* 
 
 To accomplish this, 2-10 grs. sample are melted in a small porce- 
 lain crucible, and to it is added an equal volume of powdered 
 caustic potash. It is stirred, and on cooling a hard mass is obtained 
 
 * The quantity of hydrocarbons in beeswax varies between 12-14.5 per cent. 
 
124 CHEMICAL-TECHNICAL ANALYSIS. 
 
 which is pulverized and uniformly mixed with 3 parts soda-lime 
 (for i part wax). 
 
 The mixture is now heated in a small flask or a test-tube, at 250, 
 for 2 hours. The powdered residue, if necessary, together with 
 the adhering broken glass, is powdered and extracted in a flask or 
 extractor with ether or petroleum ether. The liquid is filtered, if 
 required, the solvent is distilled off, and the last adhering traces are 
 vaporized in a current of air. The residue is weighed. If p 
 the percentage of hydrocarbons found, C the ceresin or paraffin, 
 then, according to Mangold, if the hydrocarbons in genuine wax 
 be taken at 13.5 per cent. : 
 
 _ IPO p 1350 
 86.5 
 
 (c} Determination of stearic acid. Stearic acid heated with 
 alcohol dissolves, together with ceresin, but, unlike the latter, it 
 does not separate so readily on cooling. 
 
 Therefore, if i gr. wax be boiled for several minutes with 10 c.c. 
 80 percent, alcohol in a test-tube 18-20 mm. wide, and allowed to 
 cool to 1820, then, upon adding water to the solution, filtered 
 into a similar test-tube, the liquid becomes slightly turbid if it con- 
 tain pure wax, whereas, when stearic acid is present, a flocculent 
 precipitate is formed. Even with only i per cent, stearic acid a 
 perceptible precipitate is formed. On the strength of the acid 
 number, the stearic acid may be approximately calculated. The 
 acid numbers of pure beeswax and stearic acid are respectively 20 
 and 195. Let that of the sample = S. Then the stearic acid 
 
 K __ IPO (S 20) ^ 
 
 175 
 
 The absence of other acids, including those of rosin, is taken for 
 granted. 
 
 (dQ Determination of neutral fat. 
 
 Since pure wax yields no glycerin, but fats contain an average of 
 10 per cent., the neutral fat may be approximately determined on 
 the strength of the amount of glycerin present, by multiplying the 
 latter, which is found by the permanganate method (see Glycerin, 
 p. 141) by 10. 
 
 e~ Determination of carnauba wax. 
 
MINERAL OILS. 
 
 125 
 
 When present, this wax decreases the acid number, while the 
 ether number remains unchanged. Specific gravity and melting 
 point are increased. 
 
 (/) Determination of rosin. The most applicable qualitative 
 test for rosin is the reaction of Morawski and Storch (see Mineral 
 Oils, p. 129). The methods of Twitchell or Gladding (see 
 Soaps, p. 137) may be used for quantitative purposes, but in this 
 case myricyl alcohol and other unsaponified matter must previously 
 be removed from the saponified sample. 
 
 2* Mineral Waxes. 
 
 Melting point, freezing point and specific gravity are the tests 
 applied to mineral wax. The methods employed by buyer and 
 seller should be identical, because the results obtained by different 
 methods differ not inconsiderably. The insolubility of ceresin and 
 paraffin in boiling acetic anhydride distinguishes these from the 
 fatty alcohols. The latter remain entirely dissolved in the heat and 
 partially in the cold. 
 
 The loss of weight of ozokerite (earth wax) on heating at 150 
 is also determined. It should not exceed 5 percent. The earthy 
 constituents are determined by dissolving in benzine and weighing 
 the residue. 
 
 The following table contains the most important data of the 
 most common waxes : 
 
 Wax. 
 
 Specific 
 Gravity at 
 i5. 
 
 Melting 
 Point. 
 
 Freezing 
 Point. 
 
 Acid 
 Number. 
 
 SaponiSca- 
 tion. 
 
 Iodine 
 Number. 
 
 Carnauba wax 
 
 0.9900.999 
 
 8 3 -85 
 62 -6 5 
 81 83 
 
 44 A. 7 
 
 8o 81 
 60.5 62 
 80.5 81 
 43.40-44.2 
 
 y. 
 
 4-8 
 18.621 
 
 05-17 
 
 8095 
 9197 
 
 6377.9 
 125.8 134.6 
 
 13.5 
 8 n 
 
 Chinese wax 
 
 0.926 0.970 
 0.942 0.960 
 vai 
 0.918 0.922 
 
 Paraffin 
 
 y considerab 
 61 78 
 
 'Ceresin 
 
 
 
 C. Mineral Oils. 
 
 Mineral oils are either distillation products of bituminous coal or 
 bituminous shales, etc., or else their origin is crude petroleum, 
 from which they are likewise gotten by distillation. Their use is 
 mainly for lubricating and illuminating purposes. The higher dis- 
 
126 CHEMICAL-TECHNICAL ANALYSIS. 
 
 tillation products of petroleum or shale, termed ' ' heavy oils, ' ' 
 are used as lubricants; while the lower boiling fractions of shale 
 oil are used for illuminating purposes under the names solar oil, 
 illuminating oil, and those from crude petroleum as petroleum. 
 
 The gas oils, likewise from shale oil, are used mainly in oil gas 
 factories, while the lowest distillation products (light shale oil, pho- 
 togen on the one hand ; gasoline, naphtha, benzine on the other) 
 are used as solvents for fats, etc. 
 
 1. Mineral Lubricants. 
 
 The viscosity, specific gravity, flash point, burning point, acidity, 
 rosin, fatty oils, rosin oils, and, if necessary, coal-tar oils, are the 
 tests usually undertaken. 
 
 (#) Viscosity. The viscosity or body of an oil is measured by 
 comparing the time it takes for a given quantity of oil to flow from 
 a narrow opening, with the time it takes an equal amount of water 
 to flow out. The latter is taken as i. 
 
 The most convenient of the viscosimeters is that of C. Engler 
 (Fig. n). The vessel containing the oil under investigation con- 
 sists of a smooth box (A) of brass, provided with a lid (A'}. The 
 form and dimensions are indicated in the figure. Connected with 
 the conical bottom is a 20 mm. long tube (a) which is almost ex- 
 actly 3 mm. in width. It is usually made of brass. It may be 
 opened and closed by means of a plug (<). 
 
 Four level-marks (V) serve to measure off the oil sample and to 
 give means for keeping the level in the box horizontal. Filled to 
 the mark, the apparatus should hold 240 c.c. The box (A} is sur- 
 rounded by a jacket (BB) made of brass, and is open at the top. 
 This serves to hold suitable fluid, by which the contents of A can 
 be brought to the desired temperature. 
 
 The thermometers / and t' record the temperature of the oil to be 
 tested and the liquid in the jacket. The apparatus rests on a tripod. 
 The measuring flask C, under the exit-tube, is provided in its neck 
 with the marks 200 and 240. The neck is enlarged, in order to 
 shorten the escaping column. 
 
 Regulation of the apparatus. 240 c.c. water are placed in the 
 box, which is previously cleaned with ether, alcohol and water, and 
 plugged. The temperature is brought to 20. To do this the 
 
MINERAL LUBRICANTS. 
 
 127 
 
 water contained in the jacket {BB} is maintained at this tempera- 
 ture until the inner thermometer registers exactly 20. In the mean- 
 while the flask is allowed to drain. It is then placed under the 
 vent and the plug is withdrawn. The time is recorded in seconds, 
 by a second-watch or chronometer, which elapses while the flask is 
 filled to 200. Before allowing the oil to run out, it must have come 
 to complete repose. The time required to issue should lie between 
 
 FIG. ii. Viscosimeter of Engler. 
 
 50 and 55 seconds when the apparatus is properly constructed. 
 The mean is taken of three determinations, which should not differ 
 by more than % minute. This time is taken as i. 
 
 Oil test. In the next operation all moisture is removed from the 
 box by drying and rinsing with alcohol, then with ether. The ap- 
 paratus is filled to the mark with the oil in question. Only thin 
 oils can be filled in with a measuring flask. It is then brought to 
 
128 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the desired temperature by heating the jacket (BB~}, which con- 
 tains water or oil. The temperature must remain constant at least 
 3 minutes before the operation is begun. Determination of the 
 time of issue is then conducted as before. 
 
 The lowest grade for an oil which is to be used as a lubricant is, 
 according to Engler, a degree of viscosity of 2.6 at 20, water rrr 
 i. With viscosity determination of lubricants the rule holds good 
 that the temperature used should lie near that which the oil will 
 assume while in use (machine oil 50, cylinder oil 150). 
 
 In order to maintain an even temperature above 50 for a longer 
 period, the later forms of apparatus are provided with a ring burner 
 the gas flames of which heat the liquid in the jacket. In addition, 
 the rod of the plug issues from an opening in the lid, so that it can 
 be withdrawn without removing the lid. The liquid for the 
 jacket and the oil, in this case as well as with the older forms 
 of apparatus, should be heated to the required point and poured in. 
 
 Fatty oils as well as lubricants are subjected to the viscosimetric 
 test. In many cases, such as rape-seed oil, the viscosity is so large 
 and so constant that it can serve as a test for purity. 
 
 (b) Specific gravity is determined with an areometer or a pyk- 
 nometer. 
 
 (V) Flash and burning points. A crucible 6 cm. upper diameter 
 and 6 cm. high is filled with oil to within i cm. of the rim. 
 
 The mercury bulb of a thermometer is then immersed with the 
 end i cm. above the bottom, which is best accomplished by first 
 resting the thermometer on the bottom and subsequently raising the 
 same i cm. The crucible is warmed in a sand-bath, and when the 
 temperature has overstepped 120 a small flame, preferably a pea- 
 sized flame of a burner, is passed over the surface of the oil at the 
 same height as the crucible rim at every increase of 5. As soon 
 as the first faint explosion of oil -vapor saturated air ensues the 
 flash-point has been reached. The flame is enlarged, and when the 
 temperature has increased io 15 it is passed over the surface at 
 every 2 increase until quiet ignition takes place. The burning 
 point is so obtained. Draughts are prevented by screens of paste- 
 board. 
 
 The burning point of spindle oils should not lie under 150; 
 that of machine oils (transmission oils) not below 170. 
 
PETROLEUM (ILLUMINATING OIL). 129 
 
 (//) Acidity. Mineral oils should be entirely free from acids. 
 The acid remaining after the refining process is detected by shak- 
 ing about 100 c.c. oil with an approximately equal volume of tepid 
 water to which several drops of methyl orange have been added. 
 The aqueous layer, after settling, will appear red. 
 
 (<?) Resins. Incompletely refined oils resinify readily. A test 
 for resinous matter can be conducted by placing 20 c.c. sample, to- 
 gether with 10 c.c. sulphuric acid and 20 c.c. petroleum benzine, 
 in a cylinder divided into 50 c.c., agitating and allowing to settle. 
 The increase in volume of the sulphuric acid is read off. With 
 good oils the increase usually amounts to 1.2-2.4 c.c., that is 612 
 per cent, of the oil volume. Under no conditions must it exceed 
 2.4 c.c. (12 per cent.). 
 
 (/) Fatty oils. Fatty oils are easily detected by the notice- 
 able saponification number which they possess. A quantitative de- 
 termination is conducted by the method which will be described 
 later (p. 132). 
 
 () Rosin oil. For qualitative purposes the test of Storch- 
 Morauski is to be recommended: 1-2 c.c. oil are shaken with 
 i c.c. acetic anhydride. The liquid is allowed to settle, the acetic 
 anhydride is pipetted off and treated with a drop of sulphuric acid 
 (sp. gr. 1.53). In the presence of rosin oil a violet color is pro- 
 duced. The freezing point of an oil, which in use is subjected to 
 winter temperature, is usually taken. Furthermore, the lubricating 
 value is frequently determined by means of special complicated ap- 
 paratus. 
 
 2. Petroleum (Illuminating Oil). 
 
 The valuation of petroleum as an illuminant is estimated by use 
 of specific gravity, flash point, viscosity and distillation tests. 
 
 (a) Specific gravity. The areometer, less frequently the pyk- 
 nometer, is used. Finer American oils have an average specific 
 gravity .800; Galician oil .So5~.82o ; and finer qualities Russian 
 kerosene .8i5~.8 20. In general, too low a specific gravity indicates 
 admixture with low-boiling oils, and, in consequence, danger from 
 fire. A high specific gravity indicates imperfect separation from 
 high-boiling oils. To use specific gravity alone as a criterion is 
 altogether too unreliable. 
 
 (<) Flash point. Since 1882 the apparatus of Abel has been 
 
130 CHEMICAL-TECHNICAL ANALYSIS. 
 
 used in the official testing of petroleum. It consists mainly of a 
 petroleum receiver provided with a lid and warmed externally 
 with a water-bath. The petroleum is filled in up to a designated 
 mark. A thermometer inserted into the lid is immersed in the 
 petroleum. In addition it is provided with openings which can be 
 opened or closed by a slide worked simultaneously by means of a 
 small piece of mechanism, with a small lamp suspended on trun- 
 nions. As 'the slide is made to recede, the small flame comes di- 
 rectly over the middle opening, and is there in direct contact with 
 the petroleum vapors. As the slide is made to close the opening, 
 the flame recedes. The water in the water-bath is heated to 54.5- 
 55. Continuous manipulation is started as soon as the petroleum 
 approaches the expected flash point, and is repeated for every half 
 degree rise in temperature until a sudden flash of blue light an- 
 nounces ignition. Exact description and instructions accompany 
 the apparatus, on account of which a closer description is not ne- 
 cessary here. The minimum flash point allowed in Germany is 
 
 21 C. 
 
 (<r) Viscosity. According to Engler, the viscosity of illuminat- 
 ing oil bears a direct relation to the speed of absorption in the 
 wick. To conveniently determine this speed in an oil, therefore, 
 the viscosity is taken. The Engler apparatus, possessing, however, 
 a i. 8 mm. exit (instead of 3 mm.), is used. 
 
 (X) Distillation test (distillation curve). This is conducted in 
 a distilling bulb of the following dimensions : Diameter of lower 
 part 6.5 cm., diameter of neck 1.6 cm., length of neck 15 cm. 
 The side tube should be 10 cm. long, .6 cm. wide, and attached at 
 an angle of 75. The distance from the place of attachment to 
 the level of the 100 c.c. oil, with which the flask is filled, should 
 be 9 cm. The side tube is attached to a condenser of i cm. aver- 
 age width and 45 cm. length. 100 c.c. petroleum are placed in 
 the bulb with a pipette and are heated to boiling. A wire gauze 
 is set under at first, but it is removed when the temperature has as- 
 cended above 150. Distillation is conducted so that 2-2^ c.c. 
 distil every minute. The fractions between every 25 or 50 are 
 weighed or measured. As soon as a temperature of 150 is reached 
 the temperature is allowed to sink at least 20 by removing the 
 lamp. The contents are again brought to boiling, and are distilled 
 
PRODUCTS OF THE FAT INDUSTRY. 131 
 
 until the above temperature is again reached. This is repeated 
 until nothing more distils up to that point. Results agreeing within 
 i per cent, are thus obtained. The main fraction, 150-300, is 
 termed normal illuminating oil. The amount of same in especially 
 well refined illuminating oils can reach 80 and even 90 volume per 
 cent. A good illuminating oil should contain (according to Beil- 
 stein) not more than about 5 per cent, fraction under 150 and not 
 more than about 15 per cent, fraction above 270. 
 
 The test for acids can be conducted according to the method 
 described under lubricating oil. The behavior toward cone, sul- 
 phuric acid is at times used as a test for purity of petroleum. On 
 mixing with an equal volume of cone, sulphuric acid, and allowing 
 to separate, the petroleum layer should be rather lighter and the 
 sulphuric acid at the most only yellow, but never brown. The rise 
 of temperature on mixing should not exceed 5. A rise of temper- 
 ature of 2050 ensues when distillates from bituminous shales, 
 
 rosin, etc., are present. 
 
 3. Gas Oil. 
 
 An approximate means of determining the gas contained in gas 
 oil can be found in a gasification on a small scale by gasifying a defi- 
 nite quantity of the oil in a red-hot retort into which it is dropped, 
 and measuring the gases formed. The Italian customs authorities 
 prescribe the use of the method of Nasini and Villavecchia in test- 
 ing gas oils. 100 grs. oil are distilled under reduced pressure (40 
 mm.) to a temperature of 210 and the distillate so obtained is 
 distilled under normal pressure to 310. The fraction should not 
 exceed 20 per cent, of the total oil used. 
 
 D. Products of the Fat Industry. 
 
 1. Materials Used in Oiling Wool. 
 
 Fatty oils, oleic acid, especially emulsion of oil and oleic acid, 
 with small quantities of ammonia or soda and water, are used for 
 this purpose. The fatty oils are also replaced in part by mineral 
 oils, due to the fact that 80 parts mineral oil with but 10 parts oleic 
 acid and 10 parts ^ per cent, solution of soda emulsify very well. 
 Mineral oil, when present, is frequently the cause of spots in the 
 cloth. The oils from the scouring water are also used under the 
 names elam, extract oil. The examination of other products em- 
 
132 CHEMICAL-TECHNICAL ANALYSIS. 
 
 braces the determination of unsaponifiable matter, neutral fat, free 
 fatty acids, alkali salts of fatty acids, and occasionally water and 
 alcohol. 
 
 (#) Unsaponifiable matter. Qualitative test. A piece of stick 
 potash, pea-size, is dissolved in 5 c.c. 95 per cent, alcohol. Three 
 drops substance to be tested are added and the whole is boiled for 
 a minute. Should turbidity ensue on addition of 3 c.c. water, un- 
 saponifiable matter is present. 
 
 Quantitative determination. About 10 grs. substance are dis- 
 solved in 50 c.c. 95 per cent, alcohol, and to this are added 3 grs. 
 caustic potash, dissolved in a very little water. By heating with a 
 reflux on a water-bath for an hour, fatty acids and neutral fats are 
 saponified.- It is then diluted with 30 c.c. water and extracted in 
 a separatory funnel with petroleum ether. Addition of alcohol as- 
 sists the separation of the two layers. The soap solution so ob- 
 tained is run off and extracted a few more times with petroleum 
 ether. The collected petroleum extractions are shaken 12 times 
 with a little water in order to free from dissolved soap. The petro- 
 leum ether is then filtered through a dry filter into a weighed flask. 
 The solvent is then distilled off as much as possible, and the last 
 adhering traces are removed by immersing the flask in a hot water- 
 bath and conducting into it a current of air from a blast bellows. 
 After about 15 minutes the flask is removed from the water-bath, is 
 allowed to cool, and weighed. Air is repeatedly run through for 
 10 minutes at a time until the weight of the flask is nearly con- 
 stant. The increase in weight represents the unsaponifiable mat- 
 ter of mineral oil nature. 
 
 (^) Total fatty acids. The soap solution contained in (#) is 
 decomposed with dilute hydrochloric acid and shaken out with ether 
 in a separatory funnel. The ether layer is separated, distilled, and 
 the fatty acids in the residue are determined as in (a). 
 
 (c] Free fatty acids. About 10 grs. sample are dissolved in 50 
 c.c. alcohol (if necessary by heating) and titrated with normal 
 alkali, using phenol -phthalein as indicator. The amount of alkali 
 solution used is first of all recorded. 
 
 (d} Alkalies. The alkalies present in form of fatty acid salts 
 are determined by heating 5-10 grs. sample with water, adding an 
 excess of standardized sulphuric acid (about ^ normal), separat- 
 
SOAPS. 133 
 
 ing from the precipitated fat (fatty acids, neutral fat, unsaponifi- 
 able matter) by filtration or extraction with petroleum ether, and 
 titrating back the excess of acid in the aqueous layer. 
 
 The nature of the alkali can be qualitatively proved in another 
 portion. Attention is also called to the not infrequent presence of 
 ammonium soaps. 
 
 O) Mean molecular weight of the fatty acids. The determina- 
 tion is necessary to determine the exact quantities of free fatty 
 acids, soaps and neutral fats. For this purpose the total fatty acids 
 obtained as in () are dissolved in alcohol and titrated with normal 
 alkali, using phenol-phthalein as indicator. Let g the weight of 
 fatty acids, u the number of c.c. normal alkali used, then M, the 
 mean molecular weight, is gotten by the formula : 
 
 M= I00 g. 
 u 
 
 Water and alcohol are sometimes present in wool oiling mate- 
 rial. They are determined together by placing about 30 grs. 
 ignited quartz sand in a platinum capsule and finding the weight of 
 capsule -f- sand -f small glass rod. About 5- grs. sample are 
 weighed out in the dish and admixed by stirring. It is dried at 
 100 and the loss of weight is noted. 
 
 Calculation of the quantities of free fatty acid, soap and neutral 
 fat present : 
 
 () The amount of normal alkali used in (<:} is multiplied by the 
 quotient of 1000 into the mean molecular weight. The free fatty 
 acids are thus obtained. 
 
 (/3) The quantity of alkali found, according to (//), is reck- 
 oned into fatty acids present in the form of soap, by means of the 
 mean molecular weight. 
 
 (>) If the free acids, as found in (a), as well as the fatty acids 
 found present as soap, as in (/?), be subtracted from the total fatty 
 acids, there remains that which is present as neutral fat and which 
 can be reckoned into neutral fat with sufficient accuracy by multi- 
 
 100 
 plying by ---. 
 
 2. Soaps. 
 
 Soaps are mainly alkali salts of fatty acids, in fact, sodium and 
 potassium salts. 
 
134 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Soda soaps are hard and come into the market under the name of 
 compact soaps, cut or filled soaps. Potash soaps are soft and are 
 known as soft soaps. Lately, however, hard potash soaps (Schicht's 
 patent) have appeared. For many industrial purposes, substances 
 such as rosin (rosin soaps), borax, water-glass, sodium alumin- 
 ate, soda (to increase alkalinity), are added to soaps. Further- 
 more, adulterants, such as chalk, heavy spar, starch, clay, etc., 
 etc., are frequently encountered. 
 
 Analysis of Pure Soaps. 
 
 These may contain, beside the alkali salts of fatty acids, free 
 alkali, alkaline carbonates, free fatty acids and neutral fats.* In ad- 
 dition, a considerable quantity of water is always present. 
 
 (a) Water. About 5 grs. of soap, removed from the center, 
 in form of shavings, are dried at 50 for 1-2 hours. The temper- 
 ature is then gradually raised to 100-110 and the soap is dried to 
 constant weight. 
 
 Soft soaps are placed in a 100 c.c. beaker containing a small gl^ss 
 rod, and the bottom of which is covered 1.3 cm. deep with ignited 
 quartz sand. Beaker + sand + rod are weighed, f About 5 grs. 
 soap are added and the whole is reweighed. 25 c.c. alcohol are 
 added, and the mass is heated on a water-bath and stirred. The 
 beaker is then placed in a drying oven and dried to constant weight 
 at 110. 
 
 () Total fat and total alkali. 
 
 10-20 grs. fine cut soap are dissolved in about 100 c.c. hot water 
 in a beaker. An excess of standardized sulphuric acid is added (50 
 80 c.c. normal acid) and the whole is heated in a water-bath con- 
 taining boiling water until a clear layer of fatty acids is formed. It 
 is now allowed to cool. In case the fatty acids refuse to solidify 
 a weighed quantity of wax, paraffin or stearic acid, approximately 
 equal in weight to the soap taken, is added, and the mass is re- 
 heated and again allowed to cool. The fatty acid cake, now solid, 
 is removed from the beaker with a glass rod, and is washed off with 
 water. The washings are caught in the beaker. It is externally 
 
 * Manifestly, a simultaneous presence of free alkali and free fatty acid is im- 
 possible. 
 
 f All weighings should be made as nearly as possible at the same time, because 
 the quantity of water in soaps readily changes. 
 
SOAPS. 135 
 
 dried with filter paper and kept in a cool place. The solution re- 
 maining in the beaker is filtered, the filter is washed well, and the 
 filtrate is titrated back, using methyl orange as an indicator. The 
 total alkali, representing that combined with fatty acids, free alkali 
 and alkaline carbonates, is calculated from the acid required for 
 decomposition. 
 
 The total fat is determined by dissolving the particles adhering 
 to the beaker in ether, filtering the latter through the previously em- 
 ployed filter into a weighed glass vessel containing a glass rod. After 
 the ether has been volatilized, the fatty acid cake is also placed in 
 the vessel and is heated with a small flame, with constant stirring, 
 until the crackling sound, caused by escaping steam, has ceased, 
 and the vapors of fatty acids have begun to make their appearance. 
 Upon cooling, the glass dish is weighed and the added paraffin, 
 etc. , is deducted. The total fat is thus obtained. Any neutral fats, 
 as well as fatty acids, will be present. 
 
 (c) Alkaline carbonates and free alkali. 
 
 Qualitative test. A portion of soap is warmed and dissolved in 
 alcohol, filtered, and any residue is w r ashed with alcohol. Free 
 alkali is detected by the red color which will form on addition of 
 phenol-phthalein to the filtrate. On the other hand, the residue 
 on the filter is dissolved in water and tested for alkaline carbon- 
 ates by warming with phenol-phthalein. 
 
 Quantitative determination. About 10 grs. soap are treated as 
 above, care being taken, however, in washing with the alcohol, 
 which is best done by using a hot water funnel during filtration. 
 
 The alcoholic filtrate, as well as the aqueous solution of the well- 
 washed residue, is titrated with ^ normal acid, using phenol-phthal- 
 ein as indicator in the first instance and methyl orange in the 
 second. 
 
 After the free alkali and alkali carbonate have been deducted from 
 the total alkali found, as in (^) (everything calculated as alkali ox- 
 ide), there remains the alkali which is bound to the fatty acids. 
 This can also be directly determined by dissolving a weighed quan- 
 tity of soap in water, decomposing it with an excess of hydro- 
 chloric acid, thus using the separated fat in a moistened filter, 
 washing, dissolving the fatty acid in alcohol by placing filter and 
 contents in a beaker with alcohol, and finally titrating with alkali, 
 using phenol-phthalein as indicator. 
 
136 CHEMICAL-TECHNICAL ANALYSIS. 
 
 As a rule the alkali in hard soaps is calculated as sodium oxide 
 and that of soft soaps as potassium oxide. On the assumption that 
 both potash and soda are present in a soap, 5 grs. of the latter are 
 burned in a platinum dish until only a charred mass remains. This 
 is covered with water, filtered and washed. In the aqueous filtrate 
 a check determination of total alkali may be conducted by titration 
 with hydrochloric acid, after which a determination of potassium 
 is made in the usual way with platinic chloride. (See Fertilizers, 
 
 P- 73-) 
 
 (*/) Free fatty acids. When the alcoholic soap solution does 
 not change color on addition of phenol-phthalein (a proof of the 
 absence of free alkali), free acid, which may be present, can be de- 
 termined by titration with caustic soda. 
 
 (>) Neutral fat. A considerable quantity of fine shaved soap is 
 weighed off, dried and extracted in a Soxhlet extractor with ether. 
 In order to remove traces of soap which may perchance have gone 
 into solution, the ethereal extract is shaken out 23 times with 
 water in a separatory funnel. Then, if necessary, it is filtered, the 
 ether is volatilized, and the residue is weighed after the usual treat- 
 ment in a current of air. It also contains any free fatty acids 
 which may have been present. The latter may be deducted after 
 determination (//) has been made, or they may be directly titrated. 
 
 Summary of analysis. The percentage of fatty acids must not be 
 placed as such in the analysis, but must first be reckoned into 
 anhydrides. No great error is experienced in simply deducting 
 3.25 per cent, from every 100 parts fatty acid.* 
 
 In order to ascertain the nature of the fat from which a soap has 
 been made the separated fatty acids are tested for melting point, 
 freezing point, specific gravity, iodine number, saponification num- 
 ber, etc. 
 
 Determination of Foreign Admixtures in Soaps. 
 
 (a} Examination of residue insoluble in alcohol. 
 
 To determine the total amount of the same, a weighed quan- 
 tity of soap is dried and warmed on a water-bath with 8-10 
 times the quantity of alcohol. It is then filtered through a weighed 
 
 * Instead of this a quantity of water, equivalent to the alkali which is bound to 
 fatty acids, may be deducted. 
 
SOAPS. 137 
 
 filter, washed with alcohol, dried and weighed. The residue is ex- 
 tracted with cold water and the solution is tested for chlorides, sul- 
 phates, carbonates, silicates and borates of the alkalies. If neces- 
 sary, quantitative determinations of these constituents may be made 
 in the usual manner. 
 
 The residue from the aqueous extraction is ignited to destroy or- 
 ganic matter, is weighed, and the ash is qualitatively and quantita- 
 tively examined. It is advisedly examined for chalk, clay, in- 
 fusorial earth, etc. 
 
 Any organic matter, such as dextrine, contained perhaps in the 
 residue from the alcohol extraction, is dissolved in cold water and 
 can be reprecipitated from its aqueous solution by alcohol. Starch 
 can be detected under the microscope as well as by the blue colora- 
 tion with iodine. 
 
 () Glycerin, quantitative estimation, i-io grs. soap are dis- 
 solved in water or in methyl alcohol when organic substances, in- 
 soluble in methyl alcohol, are present. The solution is filtered, 
 the alcohol is volatilized, the fatty acids are separated with dilute 
 hydrochloric acid, and the glycerin in the acid filtrate is estimated 
 according to the method of Benedikt and Zsigmondy. (See Gly- 
 cerin, p. 141.) 
 
 (V) Rosin. In the qualitative test for rosin in soaps, or in the 
 fatty acids separated from the latter, the reaction of Storch and 
 Morowski (p. 129) is used. The method used in the quantitative 
 estimation of rosin in the mixture of the latter with fatty acids, 
 which is separated by mineral acids, has, until recently, been that 
 of Gladding. It depends on the fact that the silver salts of fatty 
 acids are insoluble in ether, whereas silver resinate is soluble in 
 the latter. Lately preference has been given the method of Twitchell. 
 It depends on the property of fatty acids forming esters when 
 hydrochloric acid gas is conducted into their solution, whereas 
 rosin does not react under the same conditions. 
 
 2-3 grams rosin-fatty acid mixture are dissolved in 10 times the 
 volume of absolute alcohol in a flask. A brisk current of hydro- 
 chloric acid gas is led in. Meanwhile, the temperature is kept under 
 20 by good cooling. At first the gas is rapidly absorbed. After 
 a period of about % of an hour the esters formed separate on the 
 surface and further absorption ceases. The flask is withdrawn from 
 
138 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the cooling mixture, is allowed to stand ^ hour, is diluted with 5 
 times the volume of water, and boiled until the acid solution clari- 
 fies. The resinic acids can be determined either gravimetrically or 
 volumetrically. 
 
 (a) Gravimetric method. The contents of the flask are placed 
 in a separatory funnel and shaken up with petroleum ether. The 
 acid layer is drawn off, the petroleum ether layer is washed and 
 shaken up with a solution of 5 grs. caustic potash, dissolved in 5 
 c.c. alcohol and 50 c.c. water. The resin is saponified and the soap 
 formed remains dissolved in the aqueous layer which separates com- 
 pletely from the petroleum ether layer. The soap solution is drawn 
 off and the petroleum ether is washed first with dilute potassium 
 hydrate solution and then with water. 
 
 The collected aqueous extractions are decomposed with dilute 
 hydrochloric acid. The precipitated resinic acids are dissolved in 
 ether, the ether is distilled off, and the residue is dried at 100 
 and weighed. 
 
 (/5) Volumetric method. The contents of the flask are shaken 
 up with about 75 c.c. ether in a separatory funnel, the acid layer is 
 drawn off, and the etherial layer is washed with water until acid re- 
 action with litmus paper has ceased. 50 c.c. alcohol are added 
 and the solution is titrated with ^ normal alkali, using phenol - 
 phthalein as indicator. The resinic acids are saponified, whereas 
 the fatty esters remain unattacked. The resinic acid equivalent is 
 taken as 346 in the calculation. 
 
 3. Turkey-Bed Oil. 
 
 Turkey-red oil is a product of reaction between concentrated 
 sulphuric acid and chilled castor oil,* to which ammonia has been 
 added in quantity sufficient to impart the property of forming a 
 complete emulsion when a sample is shaken with water. Turkey- 
 red oil contains a water-soluble constituent consisting of " ricinol- 
 sulphuric acid," and which can be salted out of its aqueous solu- 
 tion with salt, very dilute sulphuric acid and hydrochloric acid. 
 The " ricinoleic sulphonic " acid is not decomposed by boiling 
 water or alkali solutions, whereas, when boiled with dilute acids, it 
 
 * Sometimes other oils. 
 
TURKEY-RED OIL. 139 
 
 is converted into ricinoleic acid and sulphuric acid. That portion 
 of turkey-red oil which is insoluble in water consists mainly of 
 ricinoleic acid, and contains, in addition, some neutral fat, and per- 
 haps polyricinoleic acids, together with anhydrides of ricinoleic 
 acid and the above mentioned acids. Good castor oil should yield 
 a fairly permanent emulsion with water, should dissolve to a clear 
 solution in ammonia, and should not become turbid thereafter on 
 addition of much water. 
 
 Chemical Examination. 
 
 According to Benedikt, this applies principally to the determin- 
 ation of total fat. In more exact analyses, the neutral fat, sulphonic 
 acid, ammonia, soda and sulphuric acid are determined by the 
 methods employed by the above author. 
 
 (a) Total fat. By this is understood the sum of the water-insol- 
 uble constituents of the acidified oil (fatty acids, oxy fatty acids 
 and neutral fat) and the oxy fatty acids obtained by the decomposi- 
 tion of the soluble fatty sulphonic acids. About 4 grs. sample are 
 stirred with 20 c.c. water, which are gradually added, in a thin 
 hemispherical glass dish of about 125 c.c. capacity, which has pre- 
 viously been weighed, together with a small glass rod. When the 
 liquid is turbid, a drop of phenol -phthalein is added, followed by 
 ammonia to faint alkaline reaction. It is now mixed with 15 c.c. 
 of sulphuric acid, is diluted with an equal volume of water and 
 68 grs. stearic acid are added, whereupon it is heated to faint 
 ebullition. When the fatty acids have separated in a clear layer, 
 it is allowed to cool. The solid cake is raised with a glass rod, 
 rinsed with water, and placed on filter paper. The fat particles 
 attached to the walls are collected by heating the liquid in the dish 
 until the particles have united to i or 2 drops. The dish is re- 
 moved from the water-bath and inclined, so that the drops reach 
 the glass walls, where they immediately solidify and cling. The 
 liquid is now poured off, the fat cake is placed in the rinsed dish 
 and heated with a small flame in a manner similar to that employed 
 in the total fat estimation in soap (p. 134). The cooled-off cake 
 residue is weighed and the weight of stearic acid added is deducted. 
 
 (^) Neutral fat. About 30 grs. sample are dissolved in 50 c.c. 
 water, 20 c.c. ammonia and 30 c.c. glycerin are added, and the 
 mass is shaken out twice with quantities of 100 c.c. ether. Small 
 
140 CHEMICAL-TECHNICAL ANALYSIS. 
 
 traces of soap, which are taken up by the ether, are removed by 
 shaking with water. The ether is then distilled off and the residue 
 is dried first in a water-bath, then in an air-bath, and is finally 
 weighed. 
 
 (t~) Soluble fatty acids. (Fatty sulphonic acids.) 5-10 grs. 
 sample are dissolved in 25 c.c. water in a pressure flask. 25 c.c. 
 fuming hydrochloric acid are added, and the flask is heated in an 
 oil-bath at 130150 for an hour. Its contents are then diluted 
 with water, poured into a beaker and filtered from the fat layer. 
 To insure easy manipulation an indefinite quantity of stearic acid 
 may be added, the solution heated, and again allowed to cool. A 
 sulphuric acid determination is made in the filtrate by means of 
 barium chloride. The sulphuric acid found in (<?) is deducted 
 from this, and the remainder is calculated into ricinol-sulphuric 
 acid. (80 parts sulphuric acid correspond to 378 parts ricinol- 
 sulphuric acid.) 
 
 (</) Ammonia and soda. 15-20 grs. oil are dissolved in ether 
 and shaken out 4 times with quantities of 5 c.c. dilute sulphuric 
 acid. A part of the collected extractions is distilled with potas- 
 sium hydrate to determine ammonia, and in another portion the 
 soda is determined as sodium sulphate. This is obtained by evap- 
 orating the solution on a water-bath, volatilizing the sulphuric acid, 
 and igniting the residue with additions of ammonium carbonate. 
 
 (e) Sulphuric acid. The sulphuric acid present in form of sul- 
 phate of ammonia or soda is determined by shaking the ethereal 
 solution of the oils several times with small quantities of a saturated 
 solution of salt, which is free from sulphuric acid. The collected, 
 diluted and filtered extractions are precipitated with barium chlo- 
 ride. When an insight into the source of a turkey -red oil is de- 
 sired, especially whether the substance in question is a castor oil 
 turkey -red oil, the iodine number and acetyl number are taken of 
 the total fats (#), to which, however, no stearic acid has been 
 added. 
 
 An iodine number considerably under 70 and an acetyl number 
 under 140 indicate admixture with other oils. 
 
 4. Glycerin. 
 
 (a) Crude glycerin. For determination of glycerin in crude 
 glycerin the acetin method is preferred. It depends on the phe- 
 
GLYCERIN. 141 
 
 nomenon that glycerin on boiling with acetic anhydride is quanti- 
 tatively transformed into triacetin. If the latter be then dissolved 
 in water, and the free acetic acid be neutralized with sodium hy- 
 drate, the dissolved triacetin can be saponified with caustic soda 
 and the excess of the latter titrated back. 
 
 The necessary reagents are : 
 
 () ^ normal to normal hydrochloric acid accurately standard- 
 ized. 
 
 (/?) Dilute alkali, not standardized, which contains not more 
 than 20 grs. sodium hydrate to the liter. 
 
 (/) Concentrated, about 10 per cent, alkali, best preserved in a 
 flask provided with a 25 c.c. pipette, i 1.5 grs. sample are 
 weighed out in a wide-necked, small, round-bottom flask of about 
 100 c.c. capacity. 7-8 grs. acetic anhydride are added, with about 
 3 grs. dehydrated acetate of soda. The mass is boiled on a reflux 
 for iij4 hours. It is then allowed to cool somewhat, is diluted 
 with 50 c.c" water, and likewise heated on a reflux until the oil is 
 completely dissolved. The solution is now filtered into a 400600 
 c. c. wide-necked flask. Usually a copious flocculent white precipitate 
 remains on the filter. The solution is allowed to cool, phenol- 
 phthalein is added, after which it is neutralized exactly with dilute 
 alkali. This is accomplished when the yellow color changes to 
 reddish yellow. Dilute acid and cold solution must be used, as 
 otherwise the triacetin will be saponified. 25 c.c. of the concen- 
 trated 10 per cent, alkali is then added from the pipette. The 
 final adhering drops are counted the same for each experiment. It 
 is boiled for a quarter of an hour and titrated back with hydro- 
 chloric acid. Exactly the same amount (25 c.c.) of alkali is then 
 titrated with the hydrochloric acid, and from the difference the 
 alkali used by the triacetin is found. This is then calculated into 
 glycerin. (3 molecules NaOH represent i molecule glycerin.) 
 
 () Determination of glycerin in fats and soaps. 
 
 When glycerin in strongly alkaline solution is oxidized at ordi- 
 nary temperature with potassium permanganate, it is completely 
 transformed into oxalic acid : 
 
 C 3 H 8 3 +30 2 = C 2 Hp 4 +C0 2 + 3 H 2 0. 
 
 On this reaction rests the method of Benedikt and Zsigmondy, 
 which will be described here in the modified form of Herbig and 
 Mangold. 
 
142 CHEMICAL-TECHNICAL ANALYSIS. 
 
 2-3 grs. fat are saponified in pure methyl alcohol with potassium 
 hydrate. The alcohol is volatilized, the residual soap is dissolved 
 in hot water and is decomposed with dilute hydrochloric acid. It 
 is then heated until the separated fatty acids form a clear layer. 
 To liquid fat some paraffin had best be added. It is cooled 
 thoroughly, filtered off into a liter flask, and washed well. With 
 soaps, the method described (p. 137) is followed up to this point. 
 The solution is exactly neutralized with caustic potash and phenol- 
 phthalein. 10 grs. more caustic potash are added, and as much 5 
 per cent, potassium permanganate solution is added in the cold as 
 would represent approximately i^ times the theoretical amount. 
 (For every part glycerin 6.87 parts potassium permanganate.) 
 
 The liquid will then no longer appear green, but blue or black. 
 It is allowed to stand ^ hour at ordinary temperature. Hydrogen 
 peroxide, in not too great an excess, is added, until the supernatant 
 liquid becomes colorless. It is diluted to the mark, is shaken 
 briskly, and 500 c.c. are filtered off through a dry filter. To de- 
 compose the hydrogen peroxide the liquid is boiled for ^ hour, 
 cooled to about 60, and after addition of sulphuric acid the oxalic 
 acid formed is titrated with permanganate. 
 
 In place of filtration, the filtrate, after acidifying with acetic 
 acid, may be precipitated with calcium chloride. When filtered it 
 may be determined either gravimetrically by ignition to calcium 
 oxide, or it may, after decomposition with sulphuric acid, be titrated 
 with permanganate, as above. 
 
IX. Mordants and Tanning Materials. 
 
 A. Mordants. 
 
 THE substances which are most used for mordanting are com- 
 pounds of aluminium, chromium, iron, tin, antimony and copper. 
 
 1. Alumina Mordants. 
 
 To these belong sulphate of aluminium, alum, sodium aluminate, 
 aluminium acetate. 
 
 (a) Sulphate of aluminium A1 2 (SO 4 ) 3 -f i8H,O. This is prin- 
 cipally examined for iron and free sulphuric acid. 
 
 The qualitative test is the red color produced by a sulphocyanide 
 of potassium solution. The latter is added to the solution of the 
 sample, which has been oxidized with a little nitric acid. Lunge* 
 states that the method may be advantageously employed for the 
 colorimetric determination of iron. 
 
 To conduct this there are necessary (a) a 10 per cent, potassium 
 sulphocyanide solution, (/?) pure ether, (y) an ammonium alum solu- 
 tion, containing 8.606 grs. iron alum and 6 c.c. pure cone, sulphuric 
 acid to the liter. For the experiment i c.c. of this solution, di- 
 luted to 100 c.c., is used. This dilute solution contains .01 gr. 
 iron in a liter, (d) pure nitric acid free from iron, (?) several cylin- 
 ders for shaking. These are divided in T \j c.c. to 25 c.c., and 
 should have about 5 c.c. free space above this. They should be 
 nearly alike in height and diameter. 
 
 When small quantities of iron only are present, as is usually the 
 case with good commercial material, 1-2 grs. of the aluminium sul- 
 phate under examination are dissolved in a little water and exactly 
 i c.c. nitric acid (d) is added. The solution is heated, allowed to 
 cool, and is diluted to 50 c.c. At the same time i c.c. nitric acid 
 (<$) is diluted alone to 50 c.c. with water. Exactly 5 c.c. alumin- 
 
 * Zeitschrift fur angewandte Chem., Jahrg. 1894, p. 669, and 1896, p. 3. 
 
144 CHEMICAL-TECHNICAL ANALYSIS. 
 
 ium sulphate solution in question are placed in one cylinder (A}, 
 and in the other cylinder (.Z?) are placed 5 c.c. of the diluted ni- 
 tric acid. A quantity, say i c.c., dilute iron solution (}) is added 
 to the latter, and the same quantity of water is added to (A) in 
 order to preserve the same dilution. Thereupon 5 c.c. sulpho- 
 cyanide solution () are added to each cylinder, followed by 10 
 c.c. ether (/3), the stoppers are inserted, and the cylinders vig- 
 orously shaken until the aqueous layer has become colorless. 
 
 The intensity of the colors of the ethereal layers are thereupon 
 compared. Rough differences can be instantly observed. At the 
 same time, one or more tests are made with greater or smaller 
 amounts of the diluted iron dilution. When shades are about 
 alike, the comparisons are best made after standing a few hours. 
 The accuracy can be easily brought to .1 c.c. iron alum solution, 
 however, only when the total iron present is equivalent to the iron 
 in 2 c.c. iron alum solution at the most. For the purpose of com- 
 parison, observation had best be made in transmitted light, prefer- 
 ably from above, through the entire column of ether. To this end 
 the cylinder is placed on a white foundation. Should the sulphate 
 of aluminium contain a large amount of iron, a considerably more 
 dilute solution must be used for examination. When about ^ per 
 cent, iron is present (the maximum amount allowed in use of the col- 
 orimetric method), only . 2 gr. sample is dissolved in 250 c.c. 5 c.c. 
 of this solution (= .004 gr. sample) are used in the experiment. 
 
 Free sulphuric acid is qualitatively tested for by treating the 
 powdered and dried substance with 10 times its weight of absolute 
 alcohol, whereby the free acid is extracted by the alcohol, in which 
 it may be recognized by means of litmus paper. An approximate 
 quantitative result is obtained by titration with T ^ normal alkali. 
 A frequently required exact quantitative estimation of the free sul- 
 phuric acid is made by dissolving 1-2' grs. aluminium sulphate in 
 5 c.c. water. 5 c.c. neutral saturated ammonium sulphate solu- 
 tion are added, and the mixture is stirred frequently during an in- 
 terval of one quarter of an hour. Thereupon the entire aluminium 
 sulphate is precipitated in the form of ammonium alum by the 
 addition of 50 c.c. 95 per cent, alcohol, whereas the entire free 
 sulphuric acid remains in solution. The solution is filtered. The 
 residue is washed with 50 c.c. 95 per cent, alcohol, the filtrate is 
 
CHROMIUM MORDANTS. 145 
 
 evaporated on a water-bath, and the residue, dissolved in water, is 
 titrated with T \j- normal alkali. 
 
 () Alum. The examination for iron oxide and free sulphuric 
 acid is conducted as in (0). Direct extraction of sulphuric acid 
 with alcohol can, however, be resorted to in the latter determina- 
 tion. Large quantities of sodium alum can be detected in the pres- 
 ence of potassium alum by the greater solubility of the former in 
 water. (Sodium alum dissolves in 2 parts water ; potassium alum 
 in 10 parts water.) Potassium alum K 2 SO 4 . A1 2 (SOJ 8 -f 24 H 2 O 
 and sodium alum Na 2 SO 4 . A1 2 (SO 4 ) 3 -f 24 H 2 O are principally used. 
 
 (V) Sodium aluminate. The examination according to Lunge 
 was described in Chapter I., p. 17. 
 
 (//) Aluminium acetate. Alumina is determined in the usual 
 manner. The estimation of acetic acid is made by distilling with 
 phosphoric acid and titrating the distillate with normal alkali, using 
 phenol -phthalein as indicator. 
 
 2. Chromium Mordants. 
 
 Potassium and sodium bichromates are most frequently used ; the 
 fluoride comes next, whereas chrome-alum is less frequently used. 
 
 (#) Potassium and sodium bichromates. In both materials the 
 chromic acid is determined, as well as the sulphates, which frequently 
 occur in sodium bichromate. 
 
 (a) Chromic acid. The estimation is conducted either volu- 
 metrically, preferably iodometrically, or gravimetrically, by pre- 
 cipitation with ammonia after the reduction of the chromic acid 
 with hydrochloric acid and alcohol. 
 
 (/?) Sulphuric acid. The solution reduced, as directed above, 
 is precipitated with ammonia, and the sulphuric acid in the filtrate 
 is precipitated with barium chloride. 
 
 In potassium bichromate the sulphuric acid is present as potas- 
 sium sulphate, and in sodium bichromate as sodium sulphate. 
 
 () Fluoride of chromium. Chromium is determined by pre- 
 cipitation with ammonia. 
 
 (c) Chromium alum. As impurities it fnay contain organic 
 matter, tarry matter, gypsum and sulphate of sodium in considerable 
 quantities. 
 
 10 
 
146 CHEMICAL-TECHNICAL ANALYSIS. 
 
 3. Iron Mordants. 
 
 These are used in form of ferrous and ferric mordants ; in fact, 
 as green vitriol in the first instance, and as ferric nitrate containing 
 basic ferric sulphate, produced by the oxidation of the ferrous sul- 
 phate by nitric acid in the latter instance. 
 
 In both instances a determination of total iron is made by pre- 
 cipitation with ammonia after oxidation with nitric acid, and a de- 
 termination of ferrous oxide by titration with permanganate in sul- 
 phuric acid solution. 
 
 In the ferric nitrate, furthermore, the sulphuric acid is estimated 
 with chloride of barium after precipitation of the iron with ammonia 
 and the nitric acid is estimated by the usual methods. 
 
 4. Tin Mordants. 
 
 Both stannous chloride (tin salt) SnCl 2 -f 2H 2 O and stannic 
 chloride SnCl 4 are used. 
 
 (#) Stannous chloride. Pure tin salt dissolves completely in 5 
 times its weight of absolute alcohol ; the oxidized salt gives a fine 
 pulverous or flocculent precipitate, which dissolves on addition of 
 alcoholic hydrochloric acid. Adulterants remain in the form of 
 crystalline fragments. 
 
 Stannous oxide (stannous chloride). Method of Goppelsoder 
 and Trechsel, modified by FraenkeL* 
 
 3-4 grs. tin salt are dissolved in 30-40 c.c. 10 per cent, hydro- 
 chloric acid and diluted to 500 c.c. 50 c.c. solution and 50 c.c 
 one-tenth normal potassium bichromate solution are placed in a 
 stoppered flask, and after 15 minutes 1015 c - c - potassium iodide 
 solution and 510 c.c. hydrochloric acid (both i : 10) are added. 
 After a half-hour action it is diluted with about 200 c.c. water, 
 and the precipitated iodine is titrated back with one-tenth normal 
 hyposulphite solution. The stannous salt is calculated from the 
 difference in c.c. between the bichromate added and the hyposul- 
 phite used in back titration. i SnCl 2 = i SnO = 2 I. When 
 exactly one-tenth normal solutions are used, the difference need 
 only be multiplied by .01125 and calculated into per cent, in 
 order to obtain the amount of crystallized tin chloride present. 
 (SnCl 2 +2 H 2 0.) 
 
 * Contribution from the K. K. tech. Gewerbe- Museum, 1892. Volume 7. 
 
TANNING MATERIALS. 147 
 
 () Tin chloride. This comes into the market in solid form or 
 in form of solutions containing 10-20 per cent. tin. It is to be 
 tested particularly for iron and nitric acid. Stannous chloride is 
 detected by means of mercuric chloride. Total tin, .5-1 gr. salt 
 or 24 c.c. solution are diluted to 100200 c,c. with water, and 
 in case stannous chloride is present a weak iodine solution is added 
 to yellow coloration. Ammonia is then added until the solution 
 faintly opalesces, after which the tin is precipitated with an excess 
 of a saturated solution of Glauber salt. The liquid is heated to 
 boiling for a while and the voluminous precipitate is decanted sev- 
 eral times with hot water. It is then thrown on a filter, is thor- 
 oughly washed, ignited, and weighed as tin oxide. 
 
 5. Antimony Mordants. 
 
 Chiefly to be considered are : Tartar emetic (potassium anti- 
 monyl tartrate) K.SbO.C 4 H 4 O 6 -f %H 2 O and De Haen's salt 
 Sb F1 3 . (NH 4 ) 2 SO 4 . The potassium antimony oxalate has been 
 used very little recently. 
 
 An antimony determination suffices as a rule. This is conducted 
 gravimetrically in the usual manner by precipitation with hydrogen 
 sulphide. A volumetric method consists of tit ration with iodine 
 solution: .5 gr. sample is dissolved in about 50 c.c. water and 
 made slightly alkaline with bicarbonate of soda solution. A pre- 
 cipitate which might form is removed by addition of Seignette salt. 
 Starch paste is then added to the solution, which is titrated until a 
 blue color of short duration is formed (i Sb 2 O 3 = 4 I). The acids 
 present are best determined after precipitation of the antimony 
 with hydrogen sulphide. Oxalic acid is recognized by the precipi- 
 tate in acetic acid solution by calcium chloride. 
 
 6. Copper Mordants. 
 
 Blue vitriol is principally used, and sometimes copper acetate. 
 The copper is estimated in the usual manner. Iron should be 
 tested for qualitatively and its quantity estimated. 
 
 B. Tanning Materials. 
 
 Chemically, tanning substances are not yet sufficiently understood 
 to allow of their precipitation in isolated conditions or in the form 
 of characteristic compounds. In consequence, the customary 
 methods cannot be claimed to be exactly scientific. 
 
148 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Practically they yield approximate satisfactory results, providing 
 that the material present which tans is designated as the tanning sub- 
 stance ; that is, those organic substances which are absorbed from 
 their solutions by the hide. Hereby a number of different chem- 
 ical substances under the general name of ' ' Tanning Substance ' ' 
 are usually determined. 
 
 Of the customary methods, the procedure of Simand and Weiss, 
 of the Vienna Experimental Station, will be described. This has re- 
 cently become popular. According to these chemists a portion of 
 the solution containing tannin is evaporated and the constituents 
 soluble in hot water are then weighed. In another portion the 
 non -tannins, soluble in hot water, are estimated by evaporating the 
 solution from which the tannins have been withdrawn by hide 
 powder. The remaining substance is found from the difference. 
 
 1. Tannin Extracts. 
 
 (#) Water and ash. 2-3 grs. extract are evaporated, if neces- 
 sary, in a platinum dish, and are dried to constant weight at 100. 
 The loss of weight represents water. The residue is ignited and 
 weighed as ash. 
 
 (<) Matter soluble in hot water. A weighed amount of the ex- 
 tract containing at least 10-12 grs. of the dry material is dissolved 
 in water, placed in a liter flask, and upon cooling is diluted to the 
 mark and filtered. 100 c.c. clear filtrate are evaporated in a 
 weighed platinum dish, are dried to constant weight at 100, and 
 weighed. The residue is ignited, the ash is deducted, and the dif- 
 ference is considered as soluble organic matter (tanning substances 
 and non -tanning substances). 
 
 (c} Organic matter insoluble in hot water. If the percentages 
 of ash, water and organic- matter soluble in water found as in (a) 
 and (<) are deducted from 100, the organic matter insoluble m hot 
 water is obtained. 
 
 (//) Non-tannins. A tube 22.5 cm. wide, 12 cm. high, not too 
 thin, open at both ends and possessing rounded edges, is closed at 
 the lower end with a cork, which should not extend too far into the 
 tube. This is charged with 6 grs. hide powder in such a way as to 
 be evenly distributed without the presence of any marked gaps at 
 the^ walls. The tube, as prepared, which should still possess an 
 
RAW PRODUCTS. 
 
 149 
 
 JftiMcr 
 
 empty space 3 cm. high above the powder, is placed in a beaker 
 13-14 cm. high and 5 cm. wide. The beaker is gradually filled 
 with the solution prepared as in (), without allowing the solution 
 to touch the powder from above. After a few hours the solution 
 will have risen from below in the inner tube, above the surface of 
 the hide powder. By means of a tight-fitting rubber stopper, con- 
 taining one perforation, a siphon filled with water (described be- 
 low) is inserted in such a way in the upper part of the tube con- 
 taining hide powder as to dip into the liquid, but somewhat above 
 the upper surface of the hide powder. The liquid, now clear, is 
 gradually drawn off. The first 30 c.c. liquid are discarded. The 
 following 100 c.c. are evaporated and dried to constant weight. 
 If the ash be deducted from the resulting residue, the difference 
 gives the non-tanning matter. 
 
 The siphon previously referred to is a 
 glass tube twice bent at right angles, one 
 arm of which is short and is placed in the 
 tube containing the hide powder, whereas 
 the other is twice the length of the tube 
 containing the powder and extends down- 
 wards. The horizontal part of the tube is 
 about 4 cm. long. 
 
 (e) Tanning substances. They are deter- 
 mined by deducting the non-tanning sub- 
 stances (d) from the matter soluble in hot 
 water (<). 
 
 2. Raw Products. 
 
 In order to make the above described 
 methods applicable to raw products used in 
 tanning (barks, wood, etc.), a solution con- 
 taining i 1.2 grs. dry material in 100 c.c. 
 is prepared by exhausting the material in 
 question with water. 
 
 For extraction the following apparatus FIG. 12. Extraction Appara- 
 
 ,-,-,. , , . . ,,. ._ tus for Tanning Materials. 
 
 (rig. 12) was prepared by the Vienna Ex- 
 perimental Station. A is a wide-mouth flask of more than i liter 
 capacity. In this the mantle B is inserted through a hole in the 
 stopper. The former is made of sheet copper, which is tin-plated. 
 
150 CHEMICAL-TECHNICAL ANALYSIS. 
 
 On the upper end a low copper ring C is joined, and in the trough 
 so formed is fitted the sheet copper, tin-plated, cover, D. A rub- 
 ber ring, E y set in the trough, and two diametrically opposite 
 bayonette clasps, serve to make the jacket steam-tight when the 
 cover is adjusted. The cover is closed by a cork stopper, through 
 which a fairly wide tube issues to a condenser. Inside the cover 
 a tin plate is soldered, which is depressed somewhat toward the 
 center, and which is provided with pea-sized perforations, so that 
 the condensed water-drops are equally distributed. In the space 
 formed inside of the jacket and lid the vessel G is placed as a re- 
 ceptacle for the material. This, as well as the siphon, issuing from an 
 opening in the bottom, and the perforated floor H y is made of tin. 
 
 The vessel G is sufficiently large to conveniently hold the neces- 
 sary quantity of material to be extracted. According to Eitner, 
 Weiss and Anderen, of pine and oak bark, quebracho wood, etc. , 
 50-60 grs. should be extracted; of gall nuts, valonia, etc., 20-25 
 grs. should be extracted. 
 
 A similar apparatus, but made of glass, was also prepared by the 
 Vienna Station. Both forms are obtainable from Stefan Baumann, 
 Vienna, VIII, Florianigasse n. 
 
 The examination of the extract so obtained is conducted in ex- 
 actly the same manner as that described under tanning extracts. 
 The objection made to the above procedure is that the concentrated 
 solutions prepared in the heat precipitate difficultly soluble tannin 
 upon cooling, thereby causing loss. A method based on a similar 
 principle, in which, however, much more dilute solutions are used, 
 has been perfected by v. Schroeder. As far as we know the Vienna 
 method is at present the most popular, and among other countries it 
 is practiced in England. 
 
X. Textile and Dyeing Industries. 
 
 THIS section embraces a large number of raw materials and sub- 
 stances used technically, which may be arranged in the following 
 groups : Textile fabrics, bleaching materials, wool-oiling material, 
 thickening material, dressing and finishing materials, tanning mate- 
 rials, mordants and dyes. Some of these groups, such as wool- 
 oiling material, tannins and mordants, have already been treated of 
 in previous chapters. 
 
 Others are brought into commerce in so many different forms 
 and kinds that only a few instances will have to suffice. 
 
 1. Textile Fibers. 
 
 The best means of distinguishing the textile fibers is the micro- 
 scope, for the use of which reference only will be made to the ex- 
 cellent little work of v. Hohnel.* The chemical points of differ- 
 ence between animal and vegetable fibers are : 
 
 (a) Behavior when burned. When animal fibers are burned 
 they disseminate the peculiar odor of burning nitrogenous matter. 
 They burn much slower than vegetable fiber. 
 
 The former leave a voluminous, difficultly combustible coke, and 
 the latter incinerate easily and completely. 
 
 (/3) Behavior toward alkalies. Boiling with a 10 per cent, solu- 
 tion of potassium or sodium hydrate dissolves animal fibers, whereas 
 vegetable fibers remain practically unattacked. 
 
 (y) Behavior toward acid. After treatment for 23 hours with 
 dilute acid, especially sulphuric acid (sp. gr. 1.03-1.04), and sub- 
 sequent drying at about 100, vegetable fibers are destroyed (carbon- 
 ized), while animal fibers are scarcely attacked. 
 
 Chloride of magnesium and chloride of aluminium solutions 
 which give off acid above 100 react similarly. 
 
 * Die Microscopic der technisch verwendeten Faserstoffe von F. v. Hohnel, 
 Wien, 1887. 
 
152 CHEMICAL-TECHNICAL ANALYSIS. 
 
 (d) Behavior toward nitrating mixture. According to Peltier, 
 the fibers under examination are immersed for about ^ hour in a 
 mixture of equal volumes cone, sulphuric acid and cone, nitric acid, 
 after which they are washed with much water. Silk is thereby 
 completely dissolved, wool is colored yellow or light brown, 
 whereas vegetable fibers change neither in color nor structure, but 
 yield highly combustible gun-cotton when dried. 
 
 (a) Half- "Woolen Yarns and Fabrics. 
 
 Moisture, fat and cotton are determined in these, and the wool is 
 obtained by difference. 
 
 (a) Moisture. About 10 grs., if necessary, more, are dried at 
 100 to constant weight. 
 
 (/2) Fat. The sample dried according to (a) is extracted in a suit- 
 able apparatus with ether. The ethereal solution, filtered, if necessary, 
 is placed in a weighed flask, the ether is distilled off, and the last 
 traces are removed by a current of air until a nearly constant 
 weight is obtained. The fat so obtained may, if necessary, be 
 tested for saponifiable and unsaponifiable constituents. Soaps, if 
 present, do not dissolve in the ether. They may be determined by 
 extraction with alcohol subsequent to the extraction with ether. 
 
 (>) Cotton. The dried sample, freed from fat, is placed in a 
 boiling-hot 10 per cent, solution of caustic potash; the boiling is 
 continued for 15 minutes, when the whole is poured into a 
 beaker filled with distilled water. The remaining cotton is re- 
 moved, wrung out, well washed, and finally dried at 100 to con- 
 stant weight. 
 
 (<J) Sheep's wool is estimated by the difference reckoned on 100. 
 
 (b) Half-Silk. 
 
 In fabrics containing silk and cotton, the cotton can be estimated 
 by the method described under (a, y). 
 
 (c) Shoddy. 
 
 This consists of a mixture of unused wool fibers and more or 
 less already used fibers, which sometimes contain cotton. 
 
 To determine the animal fibers, shoddy, like half- wool, is subjected 
 to the alkali treatment. Microscopically, shoddy can be detected 
 by the fact that, while in the main it consists of uniformly col- 
 
BLEACHING MATERIALS. 153 
 
 ored fibers, other differently colored fibers are present, which 
 shows that a uniform dyeing process was not used. Besides this, 
 innumerable gaps, as well as wool fibers of very different charac- 
 ter, can usually be detected in shoddy. A separation of the differ- 
 ent fibers present, and these, with an approximate idea of the rela- 
 tion of one to the other, can also be conducted with the micro- 
 scope, but requires considerable practice.* 
 
 (d) Oxycellulose. 
 
 This is formed by the action of many oxydizing agents, such as 
 chlorine, bleaching lime, hydrogen peroxide, potassium perman- 
 ganate, and chromic acid on cotton, and can, therefore, frequently 
 arise in the bleaching process. Its production must be carefully 
 avoided on account of the consequent weakening of the cotton 
 fiber, which becomes especially evident in the subsequent treatment 
 with alkalies, soda or soap. 
 
 The property of oxycellulose of absorbing basic dye can be made 
 use of as a test, according to Witz. The cotton to be tested is 
 placed in a ^ per cent, solution of methylene blue. Those por- 
 tions which are changed to oxycellulose are colored more or less 
 blue. Better than this method is the power of oxycellulose to re- 
 duce Fehling's solution. For this purpose, the fabric,f which is 
 prepared by repeated boiling with water, or, better, by digesting 
 with malt infusion at 65, is boiled for 5 minutes, stirring con- 
 stantly with a mixture of equal parts Fehling's solution, to which 
 an equal volume of water has been added. Thereupon the fabric 
 is washed. Those parts containing oxycellulose are recognized by 
 the rose color which arises from deposited cuprous oxide. This be- 
 comes more intense the more oxycellulose is present in the fabric. 
 
 The yellow color produced on oxycellulose spots by warming the 
 fabric with alkaline /3-naphthol solution can be used as a test. How- 
 ever, this reaction is less sensitive. 
 
 2. Bleaching- Materials. 
 
 Sulphurous acid, sodium bisulphite and hydrogen peroxide are prin- 
 cipally used to bleach animal fibers. Beside these, chloride of lime 
 
 * See Dr. F. R. v. Hohnel. Die Microscopic der technisch verwendeten 
 Faserstoffe, Wien. 
 
 f Starch especially is often difficult to remove. 
 
154 CHEMICAL-TECHNICAL ANALYSIS. 
 
 is used in bleaching vegetable fibers. It is taken for granted that 
 the examination of all these substances is known.* Recently salts 
 of persulphuric acid (persulphates) have been used as bleaching 
 agents. The bleaching action depends on their strongly oxidizing 
 properties. The following reaction of decomposition of the am- 
 monium salts demonstrates this : 
 
 (NH 4 ) 2 S 2 8 +H 2 = (NH 4 ) 2 S0 4 +H 2 S0 4 +0. 
 
 The estimation of the active oxygen, according to Ulzer, is con- 
 ducted as follows : f 
 
 About .3 gr. sample is decomposed by addition of an excess 
 of ferrous ammonium sulphate solution (11.5 g rs -) an d dilute sul- 
 phuric acid. The solution is boiled for y>, hour in a current of 
 carbonic acid or in a flask provided with a Bunsen valve, and the 
 excess of ferrous salt is titrated back with permanganate. From 
 the ferrous ammonium sulphate oxidized, the active oxygen can be 
 calculated, and from this, by the above equation, the persulphate 
 is found. 
 
 Ammonium persulphate is the common form. 
 
 3. Sizing Materials. 
 
 These serve on the one hand for the preparation of dressings, on 
 the other hand for the laying on of coloring matter in calico print- 
 ing. The different kinds of starch and flour, dextrin, gums, traga- 
 canth, albumin, casein, and many others, are used. The investiga- 
 tion of these products is often difficult and uncertain. Starch, 
 dextrin and a few reactions for gums only will be described. 
 
 (a) Starch. 
 
 The chemical examination of starch has already been described 
 in Chapter VI. Microscopic means are employed to distinguish 
 between the different varieties. 
 
 (b) Dextrin. 
 
 Dextrin is obtained by the action of dilute acids on starch at 
 high temperature, also by heating per se ; and it contains, in addi- 
 tion, water, ash, maltose, starch, and other organic substances. 
 The determinations of these constituents, as well as the acidity, are 
 conducted according to Hanofsky as follows : 
 
 * Contribution from the K. K. tech. Gewerbe- Museum, Jhrg. 1895, p. 310. 
 f See Appendix. 
 
SIZING MATERIALS. 155 
 
 25 grs. dextrin are placed in a flask of 500 c.c. capacity and are 
 well shaken with cold water, filled to the mark, allowed to settle, 
 and are filtered through a ribbed filter. In the filtrate, maltose, 
 dextrin and acidity are determined. 
 
 () Maltose. This is determined by the cuprous oxide, which 
 it has the power to precipitate from Fehling's solution. 
 
 Since the power of reduction changes with the concentration, the 
 latter must be made the same always. A test is made, therefore 
 (similar to that of invert sugar, p. 85,), to determine how much 
 of the solution is required to reduce 10 c.c. Fehling's solution. 
 In the actual determination 12 c.c. less are taken, and are diluted 
 with sufficient water to bring the total volume to 5758 c.c. The 
 liquid is run into a porcelain dish in which 10 c.c. Fehling's solu- 
 tion have previously been placed. It is heated to boiling, and is 
 kept in that state exactly 4 minutes. The precipitated cuprous 
 oxide is thrown on the asbestos filter, and is treated further in the 
 usual manner. Using the concentration referred to, 113 copper 
 100 anhydrous maltose, the percentage of maltose so found = M. 
 
 (/?) Dextrin. 50 c.c. solution are diluted to 200 c.c., and are 
 heated to incipient boiling on a reflux with 15 c.c. hydrochloric 
 acid (sp. gr. 1.125) for two hours. Dextrin and maltose are 
 thereby changed to dextrose, the solution is filtered into a 500 
 c.c. flask, is nearly neutralized with caustic soda, and diluted to the 
 mark. The dextrose in 25 c.c. is determined with Fehling's solu- 
 tion. If the dextrose in per cent. = D, the dextrin will be 
 
 .9 (D-i.05 M), 
 since 20 parts dextrose correspond to 19 parts maltose. 
 
 (7) Acidity. 50 c.c. solution are titrated with one-tenth nor- 
 mal alkali, using phenol-phthalein as indicator. The quantity of 
 one-tenth normal alkali calculated in 100 grs. substance is desig- 
 nated the acidity. 
 
 (fl) Starch. 2.5-3 g rs - dextrin are mixed with 200 c.c. water 
 and are treated with 15 c.c. hydrochloric acid (sp. gr. 1.125), as 
 in (/3). The solution is nearly neutralized, diluted to 500 c.c., 
 and likewise treated for the dextrose in 25 c.c. Maltose, dextrin 
 and starch are converted into dextrose. If the percentage of dex- 
 trose = D, then the percentage of starch will be 
 
 9 (D-D)- 
 
156 'CHEMICAL-TECHNICAL ANALYSIS. 
 
 (77) Water and ash are determined in the usual manner. If the 
 water = W per cent, and the ash A per cent., the " other organic 
 constituents ' ' present will be 
 
 TOO (Mdtose+Dextrin+Starch-fW + A). 
 
 (c) Gums. 
 
 Of the many kinds of gums, gum arabic, gum Senegal and gum 
 tragacanth are chiefly used. 
 
 These three varieties can be distinguished in pure condition by 
 their appearance. Gum arabic is more easily, gum Senegal less 
 readily soluble in water, whereas gum tragacanth is scarcely soluble 
 at all, but swells up to a slimy mass, which distributes itself through- 
 out a sufficient quantity of water. Gums are frequently adulterated 
 with dextrin. 
 
 Lieberman has proposed the following tests for the detection of 
 gum Senegal and dextrin in gum arabic. The gum is dissolved in 
 hot water, treated with an excess of caustic potash and some 
 copper sulphate, slightly warmed and filtered. The milky filtrate 
 is boiled. A perceptible precipitate of cuprous oxide indicates the 
 presence of dextrin. 
 
 The precipitate formed by the action of caustic potash in the 
 copper sulphate, and which contains the gum acids, is washed with 
 water, dissolved in dilute hydrochloric acid, and precipitated with 
 alcohol. It is allowed to settle for %-i day, when the supernatant 
 liquid is poured off. The precipitated gum in the vessel is washed 
 with alcohol, dissolved in hot water, and to it are added an excess 
 of caustic potash and some copper sulphate. A balled-together 
 precipitate, quickly ascending to the surface, indicates gum arabic, 
 whereas a more divided, fine flocculent precipitate discloses gum 
 Senegal or an admixture of the same. In the first instance, in ad- 
 dition, an aqueous solution, boiled with caustic potash, should turn 
 amber yellow. If the amber color arise in the second case under 
 the same conditions a mixture of Senegal gum and gum arabic is 
 present, whereas a faint yellow or no color indicates Senegal gum 
 alone. 
 
 4. Finishing Materials. 
 
 The number of substances used for dressings is very large and is 
 on the increase. In consequence only the most important will be 
 
FINISHING MATERIALS. 157 
 
 selected, and the part which they play in finishing will be men- 
 tioned. 
 
 () Sizing material. These were treated of in the previous 
 chapter. 
 
 (/3) Substances which make the goods soft, pliable and hygro- 
 scopic : Glycerin, grape sugar, fats, tallow, stearin, paraffin, cocoa- 
 nut oil, wax, ozokerite, calcium chloride, zinc chloride, sodium 
 and ammonium salts. 
 
 (y) Loading materials. Gypsum, chalk, barium sulphate (per- 
 manent white), sulphate of magnesium, sodium and zinc, talc, 
 china clay, magnesium chloride, barium chloride, barium carbon- 
 ate, lead sulphate. 
 
 (<S) Coloring matters. Ultramarine blue, Berlin blue, indigo 
 blue, indigo carmine, all kinds of blue cotton-dyes, ammoniacal 
 cochineal, black, gray and brown mineral pigments. 
 
 (>?) Antiseptics. Phenol, creosote, salicylic acid, tannin, cam- 
 phor, oxalic acid, zinc salts, boracic acid, borax, alums, aluminium 
 sulphate, formic acid, etc. 
 
 (e) Water-proof materials. Fats, varnishes, resins, paraffin, 
 tannin, basic aluminium acetate and aluminium soaps. Besides 
 these there may be contained materials which render the fabric fire- 
 proof, such as boric acid, phosphates, silicates, etc., and such as 
 impart metallic lustre to the goods : metallic sulphides, metal- 
 dust, etc. 
 
 With this array of substances no general method of investigation 
 of finishing materials can be given. 
 
 In the following, the analysis of two simple, frequently occurring 
 products are described : 
 
 (0) Finishing material containing starch paste and chloride of 
 magnesium. 
 
 (a) Starch. 1020 grs. material are heated for three hours to 
 incipient boiling in a 500 c.c. flask with 200 c.c. water and 20 c.c. 
 hydrochloric acid (sp. gr. 1.125). To avoid evaporation of the 
 water a reflux is used. Upon cooling, the contents are poured into 
 a 500 c.c. measuring-flask, and an excess of caustic soda is added 
 to precipitate all the magnesia capable of precipitation by alkali. 
 The solution is filled to the mark and is rapidly filtered through a 
 dry filter. In 25 c.c. filtrate the dextrose formed by inversion is 
 
158 CHEMICAL-TECHNICAL ANALYSIS. 
 
 estimated by means of Fehling's solution, as is described under 
 starch (p. 99). 
 
 (/?) Magnesia and chlorine. The determination of these constit- 
 uents in the ash is not possible on account of the easy decomposi- 
 tion of magnesium chloride. The presence of starch likewise in- 
 terferes with the precipitation. The latter is therefore inverted 
 with dilute nitric acid as in (a) and in one portion the chlorine, and 
 in another portion the magnesa are determined by the usual methods. 
 
 O) Water and ash. An exact determination of these constitu- 
 ents cannot be accomplished on account of the easy decomposition 
 of magnesium chloride and the tenacity with which water adheres. 
 Nevertheless, approximate results can be obtained by drying a 
 weighed portion at about 100 to almost constant weight and in- 
 cinerating the residue. The water of crystallization of magnesium 
 chloride is for the greater part still present after drying. 
 
 () Finishing material, containing starch paste, fat and sulphate of 
 zinc. 
 
 () Starch, zinc oxide and sulphuric acid. 1020 grs. material 
 are inverted as before with hydrochloric acid, separated from the 
 fat by nitration through a moistened filter, and diluted to 500 c.c., 
 after approximate neutralization with caustic soda. The starch is 
 determined as before in 25 c.c. of this solution. Other measured 
 portions are used for the determinations of zinc oxide and sulphuric 
 acid by the usual methods. 
 
 () Fat. Since the fat separated in (a) does not usually answer 
 for further examination, a larger portion of the finishing material 
 is preferably taken. It is inverted with hydrochloric acid, and the 
 separated fat is extracted repeatedly by shaking with ether. The 
 collected ethereal extractions are freed from ether by distillation and 
 the last portions of the solvent are removed by a current of air, 
 after which the residue is weighed. It contains the total fat. In 
 the latter, the usual constants, such as saponification number, iodine 
 number, etc. , can be determined in addition to unsaponifiable por- 
 tions of the fat. The nature of the latter is thus ascertained. 
 
 5. I>ye-Stuffs. 
 
 These are divided into natural and artificial dye stuffs, according 
 to their origin. According to their use, they may be divided into 
 basic, acid, mordant and direct cotton dye-stuffs. 
 
DYE-STUFFS. 159 
 
 To these are added a number of dye-stuffs formed directly on the 
 fiber, such as "vat" dyes, diazotized dyes and aniline black. 
 Each of these groups represents a special dyeing process, which 
 will be briefly discussed here. 
 
 Basic dyes, applied to cotton. The material to be dyed must first 
 be mordanted. Mordanting is usually conducted in the following 
 manner : The cotton is first placed in a bath of tannin at 60 for 
 about 12 hours, after which it is thoroughly wrung out and placed 
 in a bath of tartar emetic, 10-20 grs. per liter, or the correspond- 
 ing amount of antimony salt [SbFl 3 . (NH 4 ). 2 SO 4 ]. Thereupon it is 
 washed well and dyed in the bath containing the dye at a tempera- 
 ture of 5060 until the bath is exhausted. 
 
 Applied to wool. Takes place in a bath which is either neutral 
 or slightly acidified with acetic acid. The bath is gradually heated 
 to boiling. 
 
 Applied to silk. Takes place in neutral, slightly acid (acetic) 
 or separate soap bath, with gradually heating to about 70. 
 
 Among the basic dyes belong fuchsin, auramin, malachite green, 
 victoria blue, methyl violet, etc. 
 
 Acid dyes find use chiefly in dyeing wool. Dyeing is conducted in 
 a bath containing 24 per cent, sulphuric acid, or 2-5 per cent, 
 sulphuric acid and 10-15 P er cent. Glauber salt, or 5-10 per cent, 
 sodium bisulphate. A gradual rise in temperature and eventually 
 continuous boiling are required. 
 
 The group of basic dyes is very extended. There may be men- 
 tioned, for instance : Ponceau, naphthol black, alkali blue, patent 
 blue, acid fuchsin, acid violet. 
 
 Mordant dye-stuffs. The dyeing of cotton as well as of wool re- 
 quires previous mordanting. Aluminium, chromium and iron mor- 
 dants are chiefly used. Mordanting wool is accomplished by boil- 
 ing 1-2 hours in the solution of the mordant (3-4 per cent, potas- 
 sium bichromate, 6 10 per cent, aluminium sulphate, 4-6 per cent, 
 ferrous sulphate) with the addition of sulphuric acid (i per cent.), 
 acid potassium tartrate (3-8 per cent.), or oxalic acid (1-2 per 
 cent).* 
 
 Cotton mordanting must be accomplished by an artificial fixation 
 
 * Recently lactic acid has also found use. 
 
160 CHEMICAL-TECHNICAL ANALYSIS. 
 
 with chemical precipitants. The cotton is first placed in a fairly 
 strong solution of the mordant (aluminium sulphate, aluminium 
 acetate, chrome alum, chromium fluoride, ferric nitrate). It is then 
 pressed out and passed through a bath containing soda, chalk, am- 
 monium carbonate, etc. Finally it is well washed. 
 
 Iron and tin baths are used mostly for silk. As a rule, a simulta- 
 neous ''weighting" occurs, and sometimes also the silk becomes 
 colored, as, for instance, with acetate of iron and tannin. In such 
 cases the operation must be repeated several times. 
 
 Dyeing mordanted goods is conducted in neutral baths. On ac- 
 count of the insolubility of many mordant dyes, the bath must be 
 kept in motion during the process of dyeing. Also, in order to 
 insure uniform dyeing, the temperature must increase very slowly. 
 To the mordant dyes belong the large group of alizarin dyes and 
 most of the natural dye-stuffs, blue wood, yellow wood, red wood, 
 cochineal, etc. 
 
 Direct cotton dye-stuffs. (Benzidine colors also dye vegetable 
 fibers directly.) Dyeing is usually conducted in weak alkaline 
 baths (soda, soap, 2-5 percent.; borax, sodium aluminate, 5-10 per 
 cent. , and sometimes in neutral, salt, Glauber salt, or weakly acid 
 baths). The operation usually takes place at a boiling tempera- 
 ture. This group is also very large. To it belong, among others, 
 benzopurpurin, chrysamin, benzoazurin, diamine blue, diamine 
 black. 
 
 "Vat" dyeing is almost exclusively conducted with indigo.* 
 The insoluble indigo blue or indigotin contained therein must 
 first be transformed in the vat into soluble indigo white. Reducing 
 agents mostly used are ferrous sulphate (iron vat), zinc dust (zinc 
 vat), hyposulphurous acid (hydrosulphite vat). The fabric im- 
 pregnated with indigo white is rapidly colored blue by oxidation 
 in the air. 
 
 Diazotized dyes. Benzidine dye-stuffs can be diazotized in the 
 fiber and developed in a bath containing dissolved phenols, naph- 
 thols or amines. A new color is formed which is similar to the 
 original, but more perfect, and which is distinguished for its fast- 
 ness. The developers mostly used are phenol, resorcin, /S-naphthol, 
 
 * Recently the artificially prepared indophenol has come into use. 
 
DYE-STUFFS. 161 
 
 m. phenylenediamine, naphthylamine ethers, amido diphenylamine, 
 and others. The colors produced are also called ingrain or devel- 
 oped colors. As an example, the diazotizing of primuline, first 
 attempted, may be mentioned. The goods are dyed as usual at 
 first. They are then washed and placed in a diazotizing bath con- 
 taining in 200 parts water i part sodium nitrite and the requisite 
 quantity of sulphuric or hydrochloric acid (sulphuric acid, about 
 twice as much, and hydrochloric acid, about three times as much 
 as the quantity of sodium nitrite). The diazotizing bath is kept cool 
 by addition of ice. After short immersion, the goods are rinsed in 
 cold water and are placed in the developing bath. This may con- 
 sist of an alkaline solution of phenol, resorcin, /3-naphthol, a solution 
 of m. phenylaminediamine hydrochloride, etc. The developing 
 bath is usually kept cold. The goods are subsequently rinsed. 
 
 Somewhat different from this is the production of insoluble azo 
 dye-stuffs on fiber which has not been previously dyed. 
 
 The colors so produced are termed " ice colors." They are pre- 
 pared for dyeing, especially for the printing, of cotton goods. 
 The goods to be dyed are first impregnated with an alkaline 
 solution of a-naphthol, and are then drawn through a diazo solu- 
 tion. In this manner there is produced in the filter an azo dye- 
 stuff which is quite fast toward water and very fast toward acid 
 and alkali. As an example, the production of the very beautiful 
 paranitraniline red may be mentioned. 144 grs. ,9-naphthol are dis- 
 solved in 10 liters water, and 145 grs. caustic soda (sp. gr. 1.333), 
 with addition of 500 grs. turkey-red oil. The goods are impreg- 
 nated with this solution and dried. They are afterwards placed in 
 the diazotizing bath. The latter is obtained by dissolving in a 
 boiling solution of 69 grs. paranitraniline in 200 c.c. hydrochloric 
 acid and 200 c.c. water. To the cooled solution i liter cold 
 water, and, after thorough cooling, 500 grs. ice are added. It is 
 then diazotized with 250 c.c. twice normal nitrite solution, is di- 
 luted to 10 liters and treated with 300 grs. sodium acetate before 
 using. The goods, which are removed from the diazotizing bath, 
 are well rinsed, slightly soaped at 40, and dried. 
 
 Aniline black is a dye-stuff which is formed on the fiber by the 
 oxidation of aniline. Potassium bichromate or chlorate are usually 
 used as oxidizers. It can be produced on cotton, wool or silk. 
 
 11 
 
162 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Method of Testing. 
 
 The best means of determining the value and strength of a dye- 
 stuff is by comparative dye tests. To this end a " type " or stand- 
 ard sample may be employed for comparison ; or, when a choice is to 
 be made between several kinds of the same dye, the process may be 
 undertaken with all the samples. In the first case dyeing is con- 
 ducted under the same condition until the same shade is obtained, 
 and a comparison is made between the amounts of dye used. They 
 are merely proportional to the value of the dye-stuff. In the second 
 case dyeing is conducted with dyes in quantity of equal price and 
 the colors produced are compared. A process of dyeing is selected 
 which is as simple as possible, and which gives reliable value for the 
 strength of the dye and the clearness of the shade. In order, for 
 instance, to avoid mordanting the cotton, wool may be used with 
 basic dyes. The quantity of mordant is rather taken somewhat 
 higher than required in actual practice when mordant dyes are used. 
 Wool is mordanted in the manner previously mentioned. Strips of 
 cotton calico* printed with iron and aluminium mordants are prefer- 
 ably used instead of cotton. The quality of dye chosen should 
 not be too large, because lighter shades are more easily compared. 
 In case the bath is not exhausted, a second, and, if necessary, a third 
 sample is placed in the same, until exhaustion is complete. 
 
 The samples to be dyed should possess equal weight, and for 
 carded wool, cotton yarns or calico, should equal about 10 grs. If 
 necessary, they are first mordanted and dyed in porcelain or glass 
 vessels. In order to preserve uniform heat, the vessel is placed in 
 an oil- or glycerin -bath. The quantity of water used is about 50 
 times the weight of the goods when these are wool, and 30 times the 
 weight when cotton is used. The evaporated water is replaced from 
 time to time. To prepare the dye-stuff solution, i gr. per liter of 
 coal-tar colors is used, and 10-20 grs. dye-wood extracts per liter. 
 10-20 grs. insoluble dye-pastes are weighed off, mixed with one 
 liter water, and thoroughly shaken before using. The dye-stuff solu- 
 tion is added from a burette or pipette and manipulated as pre- 
 viously stated. After dyeing, the goods are washed, and, if neces- 
 sary, soaped. If, for example, in one case 70 c.c., in another 
 
 * These may be readily purchased. 
 
DYE-STUFFS. 
 
 163 
 
 56 c.c. of two solutions containing blue wood extract (in both cases 
 TO grs. extract per liter) were used, their value will be the reverse : 
 56 : 70 or 80 : 100. 
 
 Tests for impurities. Inorganic admixtures are easily recognized 
 by the increased ash. The nature of these is determined in the 
 examination of the latter. Organic impurities, such as starch and 
 dextrin, remain behind on extraction with alcohol in many cases, 
 and can thus be determined quantitatively. 
 
 FIG. 13. Indigo Extraction Apparatus. 
 
 Special Methods of Investigation. 
 
 Special methods of investigation are also applied, in addition to 
 the dye tests, to certain natural dye-stuffs. Of these the examina- 
 tion of indigo for indigotin, according to Schneider, will be men- 
 tioned. This depends on the solubility of indigotin in naphthalene. 
 30-50 grs. pure naphthalene, which has been previously melted to 
 expel water, are placed in the Erlenmeyer flask, K, of the accom- 
 panying apparatus (Fig. 13). The Erlenmeyer flask may be re- 
 placed by a wide-necked test-tube. 
 
164 CHEMICAL-TECHNICAL ANALYSIS. 
 
 Thereupon about .3 gr. of air-dried indigo is placed in the ex- 
 traction capsule H (these are for sale by Schleicher and Schull), 
 mixed with ignited bar-sand by means of a spatula, or by shaking, 
 and covered with a small paper plate. It is then hung in the flask 
 by two wires which are inserted into the sides of the capsule. The 
 wires are pressed against the inner walls by the cork *$*. Through 
 a hole in the latter there is placed a condenser-tube R, provided 
 with a slanting end extending into the capsule, and which may 
 have an opening at a in order to facilitate the issue of the naph- 
 thalene vapors. This is not indispensable, however. The naph- 
 thalene is now gradually brought to boiling, when the vapors, 
 which are condensed in the tube, drop into the capsule and extract 
 the indigotin.* Any solidified naphthalene in the tube may be re- 
 moved by heating. Heat is applied until the naphthalene which 
 flows from the capsule remains nearly colorless for a time. It 
 is then allowed to cool, the contents of the flask are covered with 
 ether, and after all soluble matter has gone into solution the residue 
 is thrown on a dried and weighed filter, is well washed with ether, 
 dried at 100 and weighed as indigotin. In a separate portion of 
 the sample the water is determined by drying at 100, and the ash 
 is determined by first subliming off the indigotin with a small 
 flame and afterwards igniting briskly to constant weight. 
 
 Becognition of Dye-stuffs. 
 
 The behavior of the dye-stuff with acids, alkalies and reducing 
 agents serves as a means of identification. The reactions bearing 
 on this, most of which depend on changes of color and decolor- 
 ization, and which can also be used to identify a dye on the fiber, 
 are specially treated of in the excellent work of G. Schultze and 
 P. Julius, i.e., " Tabellarische Uebersicht der kiinstlichen organ - 
 ischen Farbstoffe. ' ' A detailed description at this point would be 
 too extensive. 
 
 * Indigo red is also extracted by naphthalene, but on subsequent treatment with 
 ether it dissolves, while indigo-blue remains undissolved. 
 
XI, Products of the Coal-Tar Industry. 
 
 I. Crude Benzene. 
 
 (0) DETERMINATION of petroleum hydrocarbons. 
 
 100 grs. crude benzene are nitrated with a mixture of 150 grs. 
 nitric acid (42, Be.) and 220 grs. concentrated sulphuric acid. 
 The product obtained is carefully washed with water and very di- 
 lute alkali, after which it is dried and subjected to fractional dis- 
 tillation. The petroleum hydrocarbons, which distil up to 150, 
 are measured. 
 
 (<) Fractional distillation. 100 c.c. crude benzene are placed 
 in a distilling bulb in which a thermometer is placed in such a 
 manner that the upper end of the mercury reservoir is parallel with 
 the lower point of contact of the exit tube. Connected with the 
 distilling bulb is a condenser, at the end of which a measuring 
 cylinder is placed. Heat is now gently applied, and the tempera- 
 ture at which the first drop goes over is recorded as the beginning 
 of boiling. Distillation is continued rapidly and yet in such a 
 manner that the drops may be counted as they run into a cylinder. 
 The volume of the distilled fluid is read off every 5. At 100 
 the flame is removed, the tube is allowed to drain, and the volume 
 of the distillate is recorded. Thereupon distillation is continued 
 until complete. 
 
 The following table shows the course of distillation of 90, 50 
 and 30 per cent, benzene : 
 
 
 
 
 
 
 
 Amount Distilled in c.c. up to 
 
 
 yj 
 
 Cf. p . 
 
 
 q ./- p 
 
 
 
 85 
 
 900 
 
 95 
 
 100 
 
 105 
 
 "5 
 
 120 
 
 
 90 per cent. 
 50 " 
 
 82 
 88 
 
 20 
 
 72 
 
 5 
 
 84 
 30 
 
 9 
 5o 
 
 ? 5 
 64 
 
 t 
 
 94 
 
 .882 
 .880 
 
 30 " 
 
 
 
 ... 
 
 2 
 
 12 
 
 30 
 
 42 
 
 92 
 
 90 
 
 .875 
 
 2. Crude Xylol. 
 
 Determination of the three xylols according to Lewinstein. The 
 method, which is little used, practically depends on the difference 
 
166 CHEMICAL-TECHNICAL ANALYSIS. 
 
 in behavior of these substances with dilute nitric acid, and, further- 
 more, with cone, and fuming sulphuric acid. 
 
 100 c.c. crude xylol are boiled, while constantly agitated, with 
 40 c.c. nitric acid (sp. gr. 1.4) and 60 c.c. water for ^ i hour. 
 As soon as the evolution of red fumes has ceased, the acid is sepa- 
 rated from the hydrocarbons in a separatory funnel. The latter are 
 washed with dilute alkali and distilled in a current of steam. 
 
 The solution of the hydrocarbons (# ) in the distillate, consisting 
 of metaxylol and hydrocarbons of the fatty series, is measured and 
 thereupon shaken for a half-hour with i ^ times the volume cone, 
 sulphuric acid. Metaxylol is thereby dissolved as sulphonic acid, 
 whereas the aliphatic hydrocarbons remain. If their volume (b} 
 be deducted from the previous volume (#), the difference (a-b) 
 will equal the metaxylol present. 
 
 To determine the paraxylol, 100 c.c. crude xylol are shaken for 
 half an hour with 120 c.c. cone, sulphuric acid. Ortho- and meta- 
 xylol dissolve as sulphonic acids. When, upon further addition of 
 sulphuric acid, the latter remains colorless, the volume of the un- 
 dissolved oil, which consists of paraxylol and aliphatic hydrocar- 
 bons, is read off. Let this == c. The oil is now drawn off from 
 the acid and shaken with an equal volume of fuming sulphuric acid, 
 containing 20 per cent, anhydride. Paraxylol dissolves and the 
 fatty hydrocarbons remain unattacked. If their volume = d, then 
 the difference, c-d, will yield the amount of paraxylol present. 
 
 If the sums of the volume percentages of meta- and paraxylol 
 and the aliphatic hydrocarbons be added, and their sum subtracted 
 from 100, the difference will represent orthoxylol. 
 
 3. Crude Anthracene. 
 
 The determination of anthracene by the method of Luck (modi- 
 fied by Meister, Lucius and Briining) depends on the property of 
 anthracene to yield anthraquinone on oxidation with chromic acid 
 in acetic acid solution. The latter compound is not attacked by 
 further action of chromic acid and of sulphuric at 100. On the 
 contrary, the other constituents of anthracene (acenaphthene, fluo- 
 rene, phenanthrene, carbozol, fluoranthene, etc.), are either com- 
 pletely destroyed or converted into sulphonic acids, which are solu- 
 ble in water or alkalies, i gr. crude anthracene is covered with 
 
CRUDE CARBOLIC ACID. 167 
 
 45 c.c. glacial acetic acid in a 500 c.c. flask. The flask is pro- 
 vided with a double-bored stopper, through one opening of which 
 a separatory funnel is inserted, while through the other there issues 
 an adapter, which is connected with a condenser. To the boiling 
 solution of anthracene, 15 grs. chromic acid in 10 c.c. glacial 
 acetic acid and 10 c.c. water are gradually added. The chromic 
 acid is added at intervals of 2 hours. The solution is boiled 2 
 hours, stood aside for 12 hours, diluted with 400 c.c. water, and 
 after 3 hours is filtered from the separated anthraquinone. This 
 is washed first with pure water, then with boiling alkali, and 
 finally again with water. It is then rinsed from the filter into a 
 small flat porcelain dish. The water is evaporated, and the 
 residue, after being dried at 100, is heated on a water-bath with 
 10 times the volume of fuming sulphuric acid (68 Be.). The 
 solution so obtained is allowed to stand for 12 hours in a moist 
 place, is diluted with 200 c.c. cold water, and the pure anthra- 
 quinone formed is filtered off. The latter is washed as before, 
 rinsed into weighed capsules, dried at 100 and weighed. There- 
 upon the anthracene is volatilized by heating, and any remaining 
 ash is deducted from the weight first obtained. The anthraquinone 
 so found is then calculated into anthracene. 207.5 anthraquinone 
 = 177.58 anthracene. 
 
 4. Crude Carbolic acid. 
 
 Determination of phenol. 120 grs. crude acid are distilled from 
 a small bulb, which is attached to a condenser, until about 8 grs. 
 remain.* The distillate is dissolved in ether and shaken out with 
 10 per cent, caustic soda in a separatory funnel. The ethereal 
 layer is washed several times with dilute alkali, and the aqueous 
 layer is washed several times with ether. The united alkaline 
 extractions are decomposed with hydrochloric acid (i : i), which 
 is added to acid reaction, and extracted with ether. After the 
 ethereal solutions have been washed with water and the acid liquid 
 with ether in a separatory funnel, the ethereal solutions are placed 
 in a weighed flask. The ether is distilled off as far as possible, and 
 
 * This procedure is suitable because the subsequent extraction with ether is 
 more easily accomplished, and a sharper separation of the two layers is obtained. 
 
168 CHEMICAL-TECHNICAL ANALYSIS. 
 
 the last traces are removed by attaching the flask to a dephlegmator 
 or Linnemann column and heating the same over a wire gauze until 
 an inserted thermometer indicates above 100. The contents are 
 then allowed to cool and are weighed, together with the flask. 
 
 5. Dimethyl Aniline. 
 
 The approximate determination of monomethyl aniline can be 
 accomplished by the rise in temperature on mixing with an equal 
 volume of acetic anhydride. 
 
 Every degree rise in temperature corresponds to approxi- 
 mately ^ per cent, monomethyl aniline. On mixing pure di- 
 methyl aniline with acetic anhydride, a depression of )^ is ob- 
 served. Each test requires 4 c.c. 
 
 The monomethyl aniline may be more exactly determined by the 
 method of Nolting and Boasson by allowing nitrous acid to act on 
 the product. Monomethyl aniline is thereby converted into ether- 
 soluble methyl-phenyl-nitroso amine C 6 H 5 N (NO) (CH 8 ), whereas 
 dimethyl aniline hydrochloride is converted into the hydrochloride 
 of nitroso dimethyl aniline C 6 H 4 (NO).N (CH 3 ). HC1, which can- 
 not be extracted by ether from its aqueous solution. According 
 to Nietzki, 30 grs. dimethyl aniline are dissolved in 80 grs. cone, 
 hydrochloric acid and about y 2 liter water. The solution is well 
 cooled and 38 grs. sodium nitrite are run in. After a while the 
 solution is repeatedly extracted with ether, the ethereal solutions 
 are united, the ether is evaporated off, and the residual oil is dried 
 over sulphuric acid and weighed. The nitroso amine found, when 
 multiplied by .786, gives the monomethyl aniline originally present. 
 
Appendix. 
 
 A. White Paint (White Lead). 
 
 A WHITE paint consists of a white pigment ground in a suitable 
 oil, usually linseed oil. A very common form, and for general 
 uses the best, is that termed " white lead," which is essentially the 
 pigment white lead 2PbCO 3 .Pb(OH) 2 ground with linseed oil. 
 Other pigments, not necessarily adulterants, which may be ad- 
 mixed or per se are barium sulphate, lead sulphate, zinc oxide, zinc 
 carbonate, zinc sulphide, strontium sulphate, calcium sulphate, 
 calcium carbonate, magnesite, kaolin and silica. These and others 
 are brought into the market in one form or another under various 
 names. Mineral oils, rosin oil, etc., may be present with the dry- 
 ing oil of the paint. These may be detected, after separation from 
 the pigment, by other methods given in the chapter on Oils. 
 
 Analysis. 
 
 In a small Erlenmeyer flask about 5 grs. paint are weighed out. 
 This is repeatedly washed by decantation with pure ether until a 
 few drops of the latter leave no non-volatile residue on evapora- 
 tion. The residue is thrown on a filter or else freed from adher- 
 ing traces of ether by a current of air. The collected ethereal ex- 
 tractions are evaporated, and, after expelling the last traces of ether 
 in the usual way, the residual oil is weighed, and if necessary ex- 
 amined. The weight of the residue is gotten by difference. It is 
 then subjected to analysis by the following scheme (see table on page 
 170). 
 
 The residue may contain PbSO 4 , 2PbCO 3 .Pb(OH) 2 , BaSO 4 , 
 CaSO 4 , CaCO 3 , BaCO 3 , ZnCO 3 ,'ZnO, SiO 2 , clay, etc. It is covered 
 with hot acetic acid, diluted, heated and filtered. 
 
 B. Manganese Dioxide, Bleaching Lime, Etc. 
 
 The simplicity of the Lunge nitrometer (Fig. i) and its prin- 
 ciple furnish a more extended use of the same in quantitative an- 
 
170 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 I* 
 
 li 
 II 
 
 O B 
 
 5 " 
 
 3- 
 
 2 
 
 11 
 
 2"2-c 
 
 =* "S 
 s l^ 
 
 g:-ig 
 
 55** 
 
 tl 
 li 
 
 "&*. 
 
 S- -g . . 
 
 : S?a oS 
 
 - d-S 
 E2|g 
 
 iliii 
 
 M ^3 ; g 
 
 d- 13 ^^^ 
 
 gs^.l 
 IS ill 
 
 fe^-^ 
 
 iliii 
 
 51111 
 
 BSff.rf 
 
 lal 
 Is*P.S 
 
 h^l 
 
 Illii 
 
 2 8 1-5 
 
 v -a 
 iJ 
 
 2 
 
 3 1 
 
 -S 5 
 
 ^H3 
 
 1^ 
 
 c . . 
 
 O T3 
 
 2 S 
 %% 
 
 B a<C 
 ^ = fl 
 
 Mi 
 
 s 
 ^888 
 
 ^1 
 
 ^ S 3 
 
 ^.S-g 3 .2-OT3 : 
 B-S.l^ 
 
 
 
 
 w-. 
 
 BJiJrf-g 
 
MANGANESE DIOXIDE. 171 
 
 alysis. In fact a quantitative method is insured wherever, under 
 convenient conditions, an equivalent in form of gas is evolved by 
 the chemical decomposition of a substance. Such substances are 
 manganese dioxide, bleaching lime, hydrogen peroxide, etc., etc. 
 For the purpose of the estimation of their value either the original 
 nitrometer (Fig. i), or, even more convenient, the later form of 
 gasvolumeter, may be used. A slight modification, a generator 
 similar in principle to that in Fig. 9, is used. A plain, thick, 
 wide-necked bottle, with a perforated, well-ground stopper, which is 
 provided with a small internal receiver, is connected with the 
 opening in the stopcock (Fig. i) by the stout rubber tube. Since 
 the volume read off is displaced air, the zero point taken need not 
 necessarily be the zero mark on the apparatus. The apparatus is 
 adjusted as usual, and the readings are reduced to o C. 760 mm. 
 pressure. Decomposition is complete in the generator when in 
 agitating the latter the mercury meniscus does not change. 
 
 1. Manganese Dioxide. 
 
 When manganese dioxide, in very finely divided condition, and 
 hydrogen peroxide are brought together in acid solution the de- 
 composition which ensues is expressed by the equation 
 
 Since i c.c. oxygen at o C. 760 mm. weighs 1.43003 mg., 
 every c.c. oxygen obtained when reduced to the same conditions 
 will equal .00389 gr. MnO 2 . 
 
 Operation. About .19 gr. substance is placed in the genera- 
 tor, and shaken with dilute sulphuric acid in order to decom- 
 pose any carbonates present. Somewhat more than 3.7 c.c. of a 
 2 percent, hydrogen peroxide solution (i.e., the theoretical amount 
 for the above quantity of substance) are poured into the little cup 
 which is placed in the generator. The mercury in both tubes is 
 placed on the same level and read off. The cup on (a) and the 
 side tube are put into communication when the generator flask is 
 attached. The stopcock is then turned to establish communication 
 between the eudiometer (a) and the generator, whereby no change 
 in the mercury level must occur. The contents of the generator 
 are then mixed, and after decomposition has taken place the mur- 
 
172 CHEMICAL-TECHNICAL ANALYSIS. 
 
 cury* levels are again adjusted, the apparatus is allowed to stand 
 for a while, f the volume is read off, reduced, and calculated into 
 manganese dioxide by means of the above data. 
 
 2. Bleaching- Lime. 
 
 Reaction takes place between bleaching lime and hydrogen per- 
 oxide as follows : 
 
 CaOCl 2 +H 2 O 2 CaCl 2 +H 2 
 
 Therefore every volume of oxygen evolved represents an equal 
 volume of "active " chlorine in the bleaching lime. The latter is 
 prepared for use as usual by weighing 7-8 grs. in a weighing bottle. 
 The contents are poured into a porcelain mortar, rubbed to a thick 
 paste, diluted with water to a thin paste and poured into a liter 
 flask through a funnel. The flask is filled to the mark. 40-50 c.c. 
 of this turbid solution are used. The hydrogen peroxide, which is 
 placed in the little cup, is first made alkaline by careful addition of 
 sodium hydrate. The operation is conducted as above. 
 
 3. Hydrogen Peroxide and Permanganate. 
 
 Since 5 H 2 O 2 +2 KMnO 4 -f 3 H 2 SO 4 =8H 2 O + K 2 SO 4 -f 2 MnSO 4 + 
 5O 2 , the value of either one or the other can be determined by using 
 an excess of one or the other in the operation. Then every c.c. 
 oxygen reduced to o C. 760 mm. =: 2.8243 mg. KMnO 4 or 
 1.5194 mg. H 2 O 2 , as the case may be. 
 
 C. Asphalt and Asphaltic Substances. 
 
 Under this heading may be understood natural bitumens, varying 
 in physical properties from hard, resonant, vitreous masses to soft, 
 sticky masses. The former are known under the technical name of 
 asphalt, and the latter under the name of maltha. With more or 
 less mineral matter, which, likewise, can vary in physical and chem- 
 ical composition, they belong to the product which, when admixed 
 with suitable constituents and subjected to various processes, form 
 the basis of artificial paving. Little is known regarding the origin 
 of these substances and the nature of their organic constituents. 
 
 * Instead of mercury, a salt solution or water may be employed. 
 f As soon as temperature, etc., are uniform, on standing, hydrogen peroxide 
 evolves oxygen. 
 
ASPHALT AND ASPHALTIC SUBSTANCES. 173 
 
 A very exhaustive and interesting research is that of Clifford Rich- 
 ardson,* who has shown that the bitumen proper consists of hydro- 
 carbons of the series C n H 2n , and probably of lower series ; that 
 they contain very little, if any, oxygen, and that maltha is con- 
 verted into asphaltum by reactions in which sulphur plays a prom- 
 inent part. He has also subjected various isolated constituents to 
 the usual processes of examination of oils, and has materially added 
 to the data used in the analysis of asphalt. 
 
 A general description of analysis will be given, together with a 
 few analytical results. The analysis includes the estimation of 
 water, substances soluble in petroleum ether or petrolene, sub- 
 stances soluble in carbon bisulphide or turpentine, called asphaltene, 
 organic matter not bitumen, and mineral matter. The method de- 
 scribed and results appended are those of Laura A. Linton :f 
 
 (<?) Water. 2-5 grs. substance, divided as finely as possible or 
 spread over as large a layer as possible, are dried over sulphuric 
 acid in a desiccator, or, better, in a current of dry air at a temper- 
 ature not exceeding 50 C. The substance is reweighed, and the 
 remaining results are based on anhydrous material. 
 
 (^) Petrolene. 2-5 grs. substance, depending on the amount of 
 bitumen present, are weighed on a tared filter paper, which has 
 been fitted into a much larger funnel, provided on its exit tube 
 with a stopcock. The contents are repeatedly extracted with 
 petroleum ether every 'few minutes. To remove the last traces 
 digest several hours. The filter and contents and counterpoise are 
 dried in a steam-bath and weighed. The loss in weight represents 
 petrolene. 
 
 (c} Asphaltene. i. The filter and contents are replaced on the 
 funnel and extracted in a similar manner with turpentine. After 
 complete exhaustion, which, at times, is tedious, the contents are 
 washed with alcohol, dried and weighed as before. The difference 
 represents asphaltene soluble in turpentine. 
 
 2. The process is repeated, using chloroform for extraction. 
 The difference represents asphaltene soluble in chloroform. 
 
 The three fractions are summed up as " total bitumen." 
 
 * Journal Soc. Chem. Industry, Vol. xvii., p. 13 (1898). 
 
 f Journal Amer. Chem. Society, Vol. xvi., p. 809; Vol. xviii., p. 275. 
 
174 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 (d) Mineral matter. The residue is ignited in a platinum dish, 
 cooled and weighed. In case carbonates are present, the ash must 
 be recarbonated by ignition with ammonium carbonate. 
 
 (<?) Matter not bitumen is that which remains when the sum of 
 the percentages obtained in a, b, c and */are deducted from 100, 
 
 
 
 
 
 
 c 
 5 
 
 62 
 
 C 
 
 |g 
 
 S - 
 
 8 
 
 
 i 
 
 1 
 
 || 
 
 II 
 
 4) 
 
 e 
 
 1 
 
 S.2 c 
 
 si 
 
 !! 
 
 1 
 
 
 o 
 
 i 
 
 |*S 
 
 jj 
 
 
 PQ 
 
 III 
 
 |M 
 
 1 
 
 
 PLH 
 
 H^ 
 
 u ta 
 
 
 1 
 
 
 MO 
 
 c 
 
 
 
 
 
 
 H 
 
 ^ 
 
 O c 
 
 i 
 
 Trinidad asphaltum.,... 
 
 35-40 
 
 I2 3 
 
 5.29 
 
 17.59 
 
 52.99 
 
 i : 10 
 
 10.96 
 
 36.1 
 
 Scyssel asphaltic rock 
 
 
 
 
 
 
 
 
 
 (Eastern France)* 
 
 7-49 
 
 3-95 
 
 37 
 
 4.32 
 
 1 1.8 
 
 1:31 
 
 
 88.2 
 
 Sandstonef asphaltic 
 
 
 
 
 
 
 
 
 
 rock ( locality un- 
 
 
 
 
 
 
 
 
 
 known) 
 
 5.12 
 
 2 
 
 27 
 
 2.27 
 
 7.79 
 
 
 .75 
 
 01.86 
 
 
 ) 
 
 
 / 
 
 
 / *O-7 
 
 
 */ *? 
 
 -y v^ 
 
 Water. 
 86.87 
 
 D. Food Stuffs. 
 
 Under this head will be considered a few types of food stuffs, 
 such as milk, flour, coffee and pepper. Armed with the general 
 methods it is quite possible, using such modifications and precau- 
 tions as good judgment dictates, to conduct the investigation of 
 
 other substances. 
 
 1. Milk. 
 
 1. The average composition of new cow's milk is : 
 
 Fat. Casein. Albumin. Milk Sugar. Ash. Solids. 
 
 3.50 3.98 .77 4.00 .17 13.13 
 
 Its average specific gravity is 1.029-1.039. 
 
 2. Products made from cow's milk may contain one, several or 
 all of these constituents, with or without necessary additions. They 
 depend on the operation which the milk undergoes, and the nature 
 and quantity of material added to yield the products desired. 
 Under this head come : a. Cream, skim-milk, buttermilk, curd, 
 whey, butter, cheese, milk sugar, casein, koumiss, b. Condensed 
 milk, preserved milk, lactated foods. 
 
 * This belongs to the class of asphaltic limestones, and can contain as much as 
 91.3 per cent, calcium carbonate, 
 f Analysis by author. 
 
FOOD STUFFS. 175 
 
 3. Finally, milk may contain alteration products, such as lactic 
 acid, etc., and preservatives, such as borax, salicylic acid, bicar- 
 bonate of soda, ultramarine, etc. Practically, the main adulterant 
 used is water. 
 
 A description of an analysis embracing all these substances is for 
 the present purpose too extended. 
 
 For a complete analysis of milk the following apparatus should 
 be prepared, and if possible all parts of the analysis should be con- 
 ducted at once : 
 
 1. Sp. gr. hydrometer, hydrostatic balance or pyknometer. 
 
 2. Porcelain or platinum capsule of about 50 c.c. capacity, 
 weighed together with ignited bar-sand and a small glass rod. 
 
 3. Small weighed platinum dish or crucible. 
 
 4. A weighing bottle of convenient form and two separately 
 dried and weighed filter papers. 
 
 Operation, The specific gravity is taken at 15.5 C. 60 F. 
 
 (0) Solids. 10 c.c. milk, the weight of which is equal at 15.5 
 C. to the sp. gr. with the decimal point moved one place to the 
 right, are placed in the platinum dish with the sand, are evaporated 
 to dryness with occasional stirring on a water-bath, and are finally 
 dried at 105 in an air-bath to constant weight. 
 
 () Ash. The contents of the second crucible, 10 c.c., are 
 evaporated to dryness, incinerated and weighed. In more exact 
 work the dry mass is simply charred, washed with water and fil- 
 tered. After incinerating the charred mass, the washings are added 
 and evaporated to dryness. In this case volatile portions, such as 
 salt, are retained. 
 
 (c) Fat, casein and albumin. Hoppe-Seyler method. 10 c.c. milk 
 are diluted to 50 c.c. in a small beaker with water. The solution is 
 warmed to 45 and 1-2 c.c. of 10 per cent, acetic acid are added. 
 Casein and fat are precipitated in form of curd, whereas albumin 
 remains in solution. The precipitate is filtered on a weighed filter, 
 dried at 105 in a weighing bottle and reweighed. The weight of 
 bottle+filter deducted from the latter weight gives the weight of 
 casein and fat. 
 
 The filter is placed in a suitable form of extractor,* which is put 
 
 * The Thorn extractor is very suitable. 
 
176 
 
 CHEMICAL-TECHNICAL ANALYSIS. 
 
 into operation for 6-8 hours. The niter and contents are then 
 placed in a perfectly clean weighing bottle, dried at 105, and re- 
 weighed. Bottle plus filter plus casein minus bottle plus filter 
 gives the weight of casein. Casein plus fat minus casein = fat. 
 The filtrate containing albumin is boiled for several minutes. The 
 precipitate formed is collected in another weighed filter, is washed, 
 dried and weighed. 
 
 (*/) Milk sugar. Ritthausen method. 10 c.c. milk are diluted 
 to about 100 c.c. with water in a beaker of about 200 c.c. capacity. 
 Everything except soluble salts and milk sugar is precipitated by 
 the addition of 10 c.c. copper sulphate solution (69.28 grs. copper 
 sulphate per liter) and sufficient sodium hydrate solution to in- 
 completely precipitate the copper. The precipitate formed, 
 together with liquid, is thrown on a ribbed filter of about 200 c.c. 
 capacity, and filtrate and washings are collected in a 500 c.c. flask 
 and diluted to the mark. 200 c.c. filtrate are boiled with 25 c.c. 
 each of Fehling's solutions for 6 minutes and the cuprous oxide 
 formed is treated as on page 86. The milk sugar. is found by 
 reference to the following table : 
 
 Table for Milk Sugar. 
 
 Weight of Copper. 
 
 Milk Sugar. 
 
 ioo Parts of Milk Sugar 
 Precipitate of Copper 
 
 Reduction Ratio. 
 
 mg. 
 
 mg. 
 
 Oxide. 
 
 
 392.7 
 
 300 
 
 130.9 
 
 :7-43 
 
 363.6 
 
 275 
 
 132.2 
 
 :7-5 
 
 333-0 
 
 250 
 
 133.2 
 
 :7-56 
 
 300.8 
 
 225 
 
 133-7 
 
 :7-59 
 
 269.6 
 
 200 
 
 134.8 
 
 :7-65 
 
 237-5 
 
 175 
 
 135-7 
 
 17.70 
 
 204.0 
 
 ISO 
 
 136.0 
 
 = 7-72 
 
 171.4 
 
 I2 5 
 
 I37.I 
 
 :7-78 
 
 138.3 
 
 100 
 
 138.3 
 
 :7-8 5 
 
 All weights of constituents are calculated into per cent. 
 
 For very many purposes only one or two of these constituents 
 are wanted. In the technical analysis of milk, adulteration with 
 water and by skimming are guarded against by estimation simply of 
 specific gravity, total solids and fat. Necessarily quicker and 
 shorter methods are required. For the estimation of fat the method 
 
BUTTER. 177 
 
 of Leffmann-Beam* and Chevalier f are there substituted. These, 
 however, require special forms of apparatus. 
 
 Albuminoids may be determined by the Kjeldahl (see p. 74) 
 or some modified method, such as the Gunning method (see p. 182), 
 or by combustion with soda-lime (see p. 74). In any case nitro- 
 gen is calculated from ammonia obtained, and is multiplied by the 
 factor 6.25 to obtain total albuminoids. 
 
 Condensed milk. This may or may not contain cane sugar. The 
 latter is a common form and contains about 25.51-30.05 percent, 
 water, 6. 60-10.08 per cent, fat, 44.47-53.27 percent, cane and milk 
 sugars, 10.11-12.04 per cent, casein, and 1.80-2.09 P er cent 
 salts. J For analysis, definite portions are diluted and analyzed as 
 heretofore. Cane sugar will be present with the milk sugar, and 
 may, if necessary, be determined after inversion. (See p. 86. ) 
 
 2. Butter. 
 
 Butter consists of butter fat, curd, water, milk sugar and salt. 
 A complete analysis is conducted as follows : 
 
 About 5 grs. uniform sample are weighed, together with a suitable 
 weighing bottle, which has previously been weighed. A short 
 glass rod, flattened at one end, is weighed in also. With this im- 
 provised spatula, about half the butter is placed on a tared filter 
 paper and extracted with chloroform in an extractor. The weigh- 
 ing bottle, spatula and remaining butter are reweighed, and the 
 quantity used is gotten by difference. The quantity, number 2, 
 remaining in the bottle is also calculated. 
 
 (a) Fat. Quantity i is extracted for a period of about 6 hours with 
 chloroform. The curd, milk sugar and salt, plus filter paper, are 
 dried and weighed, and their combined weight, deducted from 
 quantity i, gives fat, plus water, which is calculated into per cent. 
 In order to obtain the percentage of fat, the water percentage found 
 in (r) is deducted. 
 
 (/) Curd, salt and milk sugar. The residue on the filter con- 
 sists of milk sugar, salt and curd. It is washed with hot water and 
 the collected washings are diluted to a definite volume. Aliquot 
 
 * Leffmann-Beam Milk Analysis, 
 f Becke, Milch Priifungs-Methoden, p. 40. 
 J Battershall. Food Adulterations and Its Detection, p. 53. 
 12 
 
178 CHEMICAL-TECHNICAL ANALYSIS. 
 
 portions are used for milk sugar (see above) and salt (p. 177) deter- 
 minations. The filter, plus curd, is dried at 105 and reweighed. 
 The curd is found by deducting the weight of filter paper from the 
 above weight. 
 
 (V) Water. Quantity 2 is dried to constant weight. 
 
 All results are calculated to percentage. 
 
 Examination of butter fat is most important, as this is the only 
 means of distinguishing genuine butter from substitutes. For this 
 purpose the filtered fat is used, and the constants determined are 
 viscosity.* Reichert-Meissl number, p. 117; iodine number, p. 
 in ; Kottstorfer number, p. no. The behavior in the refracto- 
 meter is also a valuable criterion. For constants see p. 113. 
 
 Tea, Coffee and Cocoa. 
 
 The analysis of genuine tea and coffee is rarely conducted for 
 the purpose of determining their values as producers of beverages. 
 On the other hand, the estimation of caffein in the manufacture of 
 that substance and the disclosure of foreign admixtures of organic 
 nature, foreign leaves in the case of tea, foreign and artificial beans 
 in the case of coffee, coloring matter (facings), Prussian blue, tur- 
 meric, indigo, etc., and of substances of inorganic nature, mineral 
 matter, weighting material, etc., often demand investigation of 
 chemical and microscopic nature, f 
 
 3. Tea. 
 
 The analysis of twenty -three teas in Russian commerce by Drag- 
 gendorf gave a mean : 
 
 Per cent. 
 Water, ......... 10.00 
 
 Extract, ......... 32.67 
 
 Theine, caffein, . . . . . . . . 1.90 
 
 Tannin (four determinations), ..... 11.42 
 
 Ash, . . . 6.23 
 
 (#) Moisture. 12 grs. powdered sample are dried to constant 
 weight in a weighing bottle. 
 
 (^) Extract. 5 grs. sample are boiled with 500 c.c. water for 
 one hour on a reflux condenser. An aliquot portion is drawn off, 
 
 * Dr. Neuman Wender, Journal Amer. Chem. Society, Vol. xvii., p. 719. 
 f Foods, Composition and Analysis. A. W. Blyth. 
 
COFFEE. 
 
 179 
 
 evaporated to dryness and weighed. Adulteration with spent leaves 
 lowers the percentage of extract. The determination is not very re- 
 liable, because genuine tea can contain from 26-40 per cent, extract. 
 (<:) Theine, caffein. 5 grs. sample are boiled on a reflux with 
 water for several hours. The liquid and leaves are evaporated with 
 some magnesia to pasty condition. This is exhausted with chloro- 
 form, and the latter is separated and distilled off. The residue is dis- 
 solved in a little boiling water, evaporated to dryness at a gentle 
 heat, and weighed. 
 
 (*/) Tannin. The process (p. 149) may be employed.* 
 (<?) Ash. 1-5 grs. sample are incinerated in a platinum dish. 
 There is no danger of volatilization since the leaves readily incin- 
 erate at low temperatures. The ash is cooled and weighed. It 
 should equal 5.17-7.02 per cent. It is lixiviated with hot water, 
 and the soluble portion is removed by filtration on an ashless filter. 
 Filter and contents are replaced in the dish, ignited, cooled and 
 weighed. The insoluble portion is gotten directly, and the soluble 
 portion is obtained by difference. The former should be 2.64-4.22 
 per cent, and the latter 1.33-2.87 percent. Another characteristic 
 is about i per cent, manganous oxide. 
 
 4. Coffee. 
 
 The analysis comprises the estimation of water, caffein, fat, fiber, 
 ash. The following averages were obtained by Konig : 
 
 
 
 
 
 
 T3 
 
 
 
 
 B 
 
 
 
 
 
 O 
 
 c 
 
 
 
 
 I 
 
 
 "v> 
 
 'i 
 
 1 
 
 Sugar. 
 
 
 M 
 
 
 
 
 I 
 
 
 
 
 
 Per 
 cent. 
 
 Per 
 
 cent. 
 
 Per 
 cent. 
 
 Per 
 
 cent. 
 
 Per 
 
 cent. 
 
 Per 
 cent. 
 
 Per cent. 
 
 Unroasted coffee 
 Roasted coffee 
 
 11.23 
 1.15 
 
 13.27 
 1448 
 
 18.17 
 19.89 
 
 3-92 
 4 75 
 
 12.07 
 13.98 
 
 I.2I 
 
 1.24 
 
 ( Telus 
 
 .66 < gums and 
 
 
 
 
 
 
 
 
 (^ dextrin. 
 
 Water, ash and caffein are estimated as in tea. 
 
 (a) Fat. 2-3 grs. finely powdered sample are placed in an 
 
 * A more reliable method is that of Councler and Schroeder, Zeit. fur anal. 
 Chem., 25, 121. 
 
180 CHEMICAL-TECHNICAL ANALYSIS. 
 
 extractor with petroleum ether and extracted for several hours. The 
 petroleum ether is distilled off, and the residue, which is quite 
 pure, is dried and weighed. 
 
 Fiber* 2 grs. substance are washed several times by decantation 
 with ether and boiled for ^ hour on a reflux with 200 c.c. 1.25 per 
 cent, sulphuric acid in an Erlenmeyer flask. The solution is filtered 
 through linen, and the filtrate is refiltered through a Gooch crucible. 
 The two residues are washed, reunited and boiled in the same flask 
 with 200 c.c. 1.25 per cent, caustic soda. Filtration and washing 
 are conducted as before. The contents of the linen are washed 
 with alcohol into the crucible and then washed with ether, dried at 
 110 and weighed. It is then incinerated and the ash is deducted. 
 Adulterants may be inorganic coloring matter, etc., in which case, 
 the percentage and nature of the ash would give some indication. 
 Organic adulterants consist of artificial beans, which are usually 
 made of flour, chicory and sugar caramel, which forms on the 
 roasted bean when the unroasted bean is treated with sugur solu- 
 tions. Roughly, the presence of the first named may be detected 
 by covering the sample with water. Natural beans float, whereas 
 artificial beans sink. The test is not always conclusive. The coffee 
 bean contains no starch, and therefore flour in any form can be 
 recognized by the starch reaction. Chicory maybe suspected when 
 the ash contains much over .03 per cent, chlorine. Careful incin- 
 eration is advised in this case. Burnt sugar or caramel is detected 
 by the rapid darkening of water on which a little coffee is sprinkled. 
 Comparative microscopic examinations afford the safest clues. 
 
 5. Cocoa and Chocolate. 
 
 Cocoa, the ground product of the decorticated cocoa bean, 
 forms the basis of all cocoa preparations. The average composi- 
 tion, according to J. A. Wanklyn, is : 
 
 Per cent. 
 
 Fat (cocoa butter), 50.00 
 
 Theobromin, . . . . . . . . 1.50 
 
 Starch, . . . . . , . . . 10.00 
 
 Albumin, etc., . . . . . . 18.00 
 
 Gum, . . . .. . . . . . . 8.00 
 
 Coloring matter, . . .' . . . ; . 2.60 
 
 Water, . 6.00 
 
 Ash, . . . 3.60 
 
 * U. S. Dept. Agriculture Bulletin, No. 13. 
 
COCOA AND CHOCOLATE. 181 
 
 When incorporated with refined sugar it forms chocolate. Fre- 
 quently the expressed and "defatted" substance is used for the 
 above. Both varieties, mixed with various kinds of starch, sugar 
 and flavoring extracts, constitute cocoa preparations. In soluble 
 cocoa preparations the former is previously defatted, treated with 
 ammonia to destroy the cellular structure, and then with necessary 
 reagents to transform the albuminoids to a soluble form. 
 
 The use of the above substances in moderation is for many 
 reasons allowable, but their abuse is considered adulteration. Min- 
 eral matter, weighting material, etc., may be present as adulterants. 
 
 The analysis embraces the determination of water, fat, starch, 
 theobromin, sugar, nitrogenous matter and ash. 
 
 (a) Water. 2-5 grs. rasped or powdered sample are dried to 
 constant weight at 105. 
 
 (&) Fat. 2 grs. rasped or powdered sample are, if necessary, 
 mixed with sand and extracted with ether. The ether is distilled 
 off and the fat is dried at 100 and weighed. If previous "de- 
 fatting" and addition of foreign fat be suspected, the usual constants 
 are determined. The iodine number of genuine cocoa butter is 
 about 34, Kottstorfer's about 200. 
 
 (V) Sugar. The residue from (^) is extracted with cold water and 
 an aliquot portion is inverted. The remaining operation is as on 
 p. 86. 
 
 (d) Starch. The residue from (V) is boiled with water and in- 
 verted. In an aliquot portion of the solution the starch is deter- 
 mined as in p. 99. To determine the nature of the starch a mi- 
 croscopic examination is necessary. 
 
 (e) Theobromin is determined asunder theine, caffein (p. 179), 
 except that the sample is first defatted with petroleum ether and the 
 final extraction is done with boiling 80 per cent, alcohol. The 
 residue left on expelling the latter is, if necessary, purified with 
 petroleum ether, dried and weighed. 
 
 (/) Nitrogenous matter is determined by the Kjeldahl process, 
 
 p. 74- 
 
 ( g) Ash. 5 grs. sample are incinerated in a platinum dish and 
 weighed. The fact that the dry cocoa bean contains about 1.5 per 
 cent, of phosphoric acid is of importance. 
 
182 CHEMICAL-TECHNICAL ANALYSIS. 
 
 6. Flour and Other Cereals. 
 
 The analyses comprise the determination of water, ash, starch, 
 fat, nitrogenous matter, water extract and wood fiber. Adulterants 
 would mainly be present in form of inorganic weighting material. 
 
 (#) Water. 2-5 grs. sample are dried at 105 to constant 
 weight. 
 
 () Ash. 2-5 grs. sample are incinerated in a platinum dish, 
 cooled and weighed. Frequently the ash is difficult to free from 
 carbon particles. In this case careful addition now and then of 
 crystals of pure ammonium nitrate aids the incineration. 
 
 (<r) Starch is determined after inversion, as usual. (See p. 99.) 
 From the copper obtained, that produced by inversion of a cold 
 water extract of an equal amount of flour must be deducted. The 
 difference is then calculated into starch. 
 
 (*/) Nitrogenous matter, which consists mainly of glutin, is de- 
 termined as on p. 74, or by a modification known as the Gunning 
 method. This differs only in the process of decomposition, which 
 requires heating with 3040 c.c. of a semi-fluid mass, obtained by 
 warming two parts cone, sulphuric acid and one part ground potas- 
 sium sulphate. The liquid is heated briskly until it becomes per- 
 fectly clear. In the remaining operation addition of sulphide of 
 sodium is unnecessary. 
 
 (<?) Fat. 5 grs. dried sample are extracted with ether in an extrac- 
 tor, and after expulsion of the latter the residue is dried and weighed. 
 
 (/) Water extract. 10 grs. flour are covered with 500 c.c. 
 water and briskly shaken. 250 c.c. are filtered into a platinum 
 dish, evaporated to dryness, dried and weighed. The residue, 
 which contains sugar, gum, dextrin, albumin and phosphate of 
 potash, should equal about 5 per cent. On ignition it should con- 
 sist entirely of potassium phosphate. In a portion of the liquid, corre- 
 sponding to the flour used in the starch determination, the reducing 
 power in copper units is determined after inversion. (See <:.) 
 
 Of) Wood fiber. The determination is of more use in the an- 
 alysis of whole or crushed cereals. The determination is conducted 
 as on p. 1 80. 
 
 The percentage values of wheat flour are by no means constant. 
 TOO parts, according to Wanklyn, contain: water 16.5 per cent., 
 fat 1.2 per cent., glutin, etc., 12.0 per cent., starch, etc., 69.6 per 
 cent., ash .7 per cent. 
 
SPICES, ETC. 
 
 183 
 
 Spices, Etc. 
 
 Unless supplemented by a careful microscopic examination in the 
 search for adulterants the chemical analysis of spices, etc., is of 
 little value except in the matter of discovering the addition of in- 
 organic substances, sand, etc. Water, ash, starch, fat (oils) and 
 fiber determinations furnish the analytical data. The example 
 
 selected is : 
 
 7. Pepper. 
 
 Adulterations in form of various ground seeds, dust, sand, ground 
 husks and shells, starch, flour, etc., etc., are found in cheaper 
 grades. 
 
 (0) Water. 2-5 grs. sample are dried at 105 and weighed. 
 
 () Ash. The residue from the above is incinerated and 
 weighed. 
 
 (<r) Starch. The substance is first washed with alcohol and then 
 treated precisely as under starch (p. 99.) The solution is accu- 
 rately neutralized and diluted to 500 c.c. before it is reduced with 
 Fehling's solution. 
 
 (//) Fats, etc. i. Total ether extract.* 2 grs. sample are ex- 
 tracted in a large Soxhlet apparatus with absolute ether for 24 
 hours. The extract is washed into a weighed capsule and the 
 ether is allowed to evaporate spontaneously, but not too rapidly. 
 It is then^iried over night in a desiccator and weighed. 
 
 2. Volatile oil. The residue is heated to no-for several hours 
 and is reweighed. The difference represents volatile oil. 
 
 (<?) Fiber is determined as on page 180. 
 
 Black pepper is the dried unripe fruit of piper nigrum, and white 
 pepper is the dried ripe fruit of the same deprived of its outer 
 black covering. The following analyses f of both kinds in whole 
 conditions will give a good basis of comparison : 
 
 
 Water. 
 
 Ash. 
 
 Volatile 
 Oil. 
 
 Ether 
 Extract. 
 
 Starch. 
 
 Crude 
 Fiber. 
 
 Whole black. 
 
 8.15 
 
 2.91 
 
 1.48 
 
 8.68 
 
 33.92 
 
 8.74 
 
 Whole white 
 
 I O.6o 
 
 1.34 
 
 1.26 
 
 9.02 
 
 43-10 
 
 4.20 
 
 
 
 
 
 
 
 
 * U. S. Dept. Agriculture Bul'etin No. 13, p. 165. 
 f Bulletin loc. cit. 
 
Index. 
 
 Acetone, estimation of in methyl alcohol, 
 
 107. 
 
 Alcohol, 103, 107. 
 Alumina as a reagent, 90. 
 Aluminium acetate, 145. 
 sulphate, 143. 
 
 detection of iron in, 143. 
 Aniline black, 161. 
 Animal charcoal (see Bone black). 
 Asphalt and asphaltic substances, 172. 
 analysis of, 173. 
 determination of asphaltene, petro- 
 
 lene, water, 173. 
 matter not bitumen, mineral matter 
 
 in, 174. 
 table of analyses of, 1 74 
 
 Baker guano, 76. 
 
 Beeswax, examination of for adulterants, 
 
 122. 
 
 determination of carnauba wax, 
 neutral fat, stearic acid, in, 
 124. 
 
 ceresin and paraffin in, 123. 
 specific gravity of, 121. 
 total acid number of, 122. 
 Beets, estimation of sugar in, 82, 83. 
 Bleaching lime, 169, 172. 
 
 materials, 153. 
 Boiler-water, 20. 
 
 analysis of according to Kalmann, 
 
 22. 
 
 determination of alkalies, chlorine, 
 sulphuric acid, carbonic acid, 
 nitric acid in, 21. 
 ammonia in, 22. 
 total solids, silica, ferric oxide, 
 alumina, lime and magnesia 
 in, 20. 
 
 estimation of hardness of, 23. 
 preparation of, 25. 
 Bone black, 76, 91. 
 
 determination of carbonate of lime 
 
 in, 92. 
 
 sulphate of lime, calcium sul- 
 phide, phosphoric acid in, 94.' 
 water, carbon, sand and clay 
 
 in, 91. 
 Bone meal, 76. 
 
 Brine, n. 
 
 determination of lime, magnesia, 
 
 carbonic acid in, 12. 
 specific gravity of, 1 1 . 
 total chlorine, sulphuric acid, 
 ferric oxide and alumina in, 
 II. 
 
 qualitative tests for potassium, bro- 
 mine, iodine in, 12. 
 Butter, 177. 
 
 analysis of, 177. 
 
 determination of fat, curd, salt, 
 
 milk sugar, water in, 177. 
 Butter fat, constants, 178. 
 examination of, 178. 
 
 Cane sugar, estimation of by inversion, 
 80,85. 
 
 by means of specific gravity, 79. 
 
 by polarization, 79. 
 Camallite, 77. 
 Castor oil, 118. 
 Chrome alum, 145. 
 Chromium fluoride, 145. 
 
 mordants, 145. 
 Clay, 39. 
 
 analysis by suspension, 43. 
 
 calculation of refractoriness from 
 analysis of, 49. 
 
 determination of refractoriness of, 
 
 47- 
 
 empirical-technical analysis of, 40. 
 pyrometric tests for, 45. 
 rational analysis of, 42. 
 Coal, coke, etc., 27. 
 
 and coke, absolute heating value of, 
 
 3*. 
 
 Cocoa and chocolate, 180. 
 
 determination of water, fat, sugar, 
 starch, theobromin, nitrogenous 
 matter, ash, 181. 
 Coffee, 179. 
 
 average composition of, 179. 
 estimation of fiber in, 180. 
 
 water, ash, caffein in, 179. 
 Coke, evaporative efficiency of, 32. 
 Condensed milk, 176. 
 Copper, crude, 60. 
 mordants, 147. 
 
186 
 
 INDEX. 
 
 Crude anthracene, 1 66. 
 benzene, 165. 
 carbolic acid, 167. 
 copper, 60. 
 
 determination of antimony, tin, 
 arsenic in, 63. 
 
 bismuth, 6 $. 
 
 iron, nickel, cobalt, zinc in, 62. 
 
 oxygen, phosphorus in, 66. 
 
 silver, lead in, 61. 
 
 sulphur in, 66. 
 
 Dextrin, 154, 155. 
 
 determination of acidity of, 155- 
 maltose, starch in, 155- 
 water, ash, 156. 
 Dimethyl aniline, 168. 
 Dried blood powder, 78. 
 
 meat powder, 78. 
 Drying oils, 114. 
 
 Maumene's test for, 115- 
 Dung, 78. 
 Dye-stuffs, 158. 
 
 basic, acid, mordant, 159. 
 
 direct cotton, "vat," diazotized, 
 1 60. 
 
 method of testing, 162. 
 
 Farth wax (see Ozokerite). 
 Ela'idin tests for oils, 115. 
 Evaporative efficiency of coke, 32. 
 
 Fats, 109. 
 
 determination of acid number of, 
 
 "3- 
 
 acetyl, 112. 
 
 Hiibl's iodine number of, ill. 
 Reichert- Meissl number of, 117. 
 saponification number of, I IO. 
 Fehling's solution, 90. 
 Ferro-chrom, analysis of, 70. 
 Fertilizers, 72. 
 
 determination of nitrogen in, 74. 
 phosphoric acid in, 72, 73. 
 potassium oxide in, 73. 
 mixed, 78. 
 nitrogenous, 78. 
 phosphate, 75. 
 Filling material, 84. 
 Finishing materials, 156. 
 Fish guano, 78. 
 Flour and other cereals. 
 
 determination of water, ash, starch, 
 nitrogenous matter, fat, water ex- 
 tract, wood fiber in, 182. 
 Food stuffs, 174. 
 Freezing point of fatty acids, 1 20. 
 
 Fuel, 27. 
 
 determination of ash, sulphur, total 
 
 sulphur in, 28. 
 nitrogen, phosphorus in, 30. 
 elementary analysis of, 29. 
 Fuming sulphuric acid, 5. 
 
 estimation of sulphuric anhydride 
 
 and sulphurous acid in, 5. 
 Furnace gases, 32. 
 
 Gas oil, 131. 
 Glycerin, 140. 
 
 determination of in fats, 141. 
 
 soaps, 137, 141. 
 Green syrup, 84. 
 Gums, 156. 
 
 de Haen's salt, 146. 
 Half- silk fibers, 152. 
 
 -woolen yarns and fabrics, 152. * 
 Hardness of water, determination of, 24. 
 Hide, powdered, 78. 
 Horn meal, 78. 
 
 Hiibl's iodine number for fats, ill. 
 Hydrogen peroxide and permanganate, 
 172. 
 
 Ice colors, 161. 
 
 Illuminating oils (see Petroleum). 
 
 Indigo, 163. 
 
 Ingrain colors, 161. 
 
 Invert sugar, 80, 85. 
 
 estimation of, 85, 86, 87. 
 Iron pyrites, I. 
 
 determination of sulphur in, I. 
 
 copper, arsenic, moisture in, 2. 
 
 Kainite, 78. 
 
 Kottstorfer's saponification number, no. 
 
 Lead acetate as a reagent, 90. 
 Lime, 35. 
 
 determination of alkalies, organic 
 
 matter in, 37. 
 carbonic acid, oxide of iron 
 
 and sulphuric acid in, 36. 
 moisture, silica, clay, ferric 
 oxide, alumina, lime and 
 magnesia in, 35. 
 saccharate, 91. 
 
 estimation of sugar, lime in, 91. 
 
 Malt, loo. 
 
 diastatic value of, 101. 
 estimation of maltose in, 101. 
 
 water in, 100. 
 extract, loo. 
 
INDEX. 
 
 187 
 
 Maltose in dextrin, determination of, 
 
 155- 
 
 in malt, determination of, 101. 
 Manganese dioxide, 171. 
 
 bleaching lime, etc., 169. 
 Marl, 37. 
 
 determination of soluble silica, 
 
 coarse and fine sand in, 37. 
 Materials used in oiling wool, 131. 
 Maumene's test for drying oils, 115.. 
 Mean molecular weight of fatty acids, 
 
 133- 
 
 Meat powder, dried, 78. 
 Methyl alcohol, 107. 
 
 estimation of acetone in, 107. 
 Milk, 174. 
 
 analysis of, 175. 
 
 determination of albuminoids in, 
 
 177. 
 
 milk sugar in, 176. 
 solids, ash, fat, casein, albu- 
 min in, 175. 
 Mineral lubricants, 126. 
 acidity of, 129. 
 
 determination of flash- and burning- 
 points, specific gravity of, 128. 
 resins, fatty oils, rosin oils in, 
 
 129. 
 
 waxes, 125. 
 Mixed fertilizers, 78. 
 Molasses, 84. 
 
 Nickel steel, analysis of, 71. 
 
 Nitrogen, determination of by Gunning 
 
 method, 182. 
 Kjeldahl method, 74. 
 Nitrogenous fertilizers, 78. 
 Nitroso acid, 7. 
 Non-drying oils, 1 14. 
 
 Oil, arachis, 119. 
 
 castor, 1 1 8. 
 
 fish, 114. 
 
 olive, 117. 
 
 rape- seed, 118. 
 
 sesame, 118. 
 Oils, saponification equivalent of, 109, 
 
 no. 
 
 Orsat apparatus, 32. 
 Oxy cellulose, 153. 
 Ozokerite, 125. 
 
 Pepper, 183. 
 
 determination of water, ash, starch, 
 
 fats, fiber in, 183. 
 Persulphate, 154. 
 Peru guano, 78. 
 
 Petroleum, 129. 
 
 distillation point of, 1 10. 
 determination of flash-point, specific 
 
 gravity of, 129. 
 viscosity of, 130. 
 Phosphor-bronze, 68. 
 
 determination of tin, phosphorus, 
 
 lead in, 68. 
 copper, zinc in, 69. 
 
 Phosphoric acid determination of in fer- 
 tilizers, 72, 73. 
 Phosphorite, 76. 
 Portland cement, 38. 
 
 composition of, 38. 
 Potassium alum, 145. 
 bichromate, 145. 
 fertilizers, 77. 
 nitrate, 78. 
 
 Press cake, estimation of sugar in, 91. 
 Pyrites^ see Iron Pyrites), 
 residuum, 3. 
 
 determination of sulphur in, 3. 
 
 Raw sugar, 84. 
 Refined copper, 60. 
 Rendement or yield of sugar, 89. 
 Resins in mineral lubricants, test for, 1 29. 
 Ritthausen's method for determination 
 
 of milk sugar, 176. 
 
 Rosin in beeswax, determination of, 125. 
 soaps, detection and estimation of, 
 137- 
 
 Saccharose (see Cane Sugar). 
 Shoddy, 152. 
 
 Soaps, determination of alkali carbon- 
 ates and free alkali in, 135. 
 free fatty acid, neutral fats in, 
 
 136. ' 
 
 glycerin in, 137. 
 rosin in, 137. 
 water, total fat, total alkali in, 
 
 *3S- 
 
 solution, preparation of normal, 23. 
 Soda. 13. 
 
 determination of moisture in, 16. 
 sodium sulphate, chloride, hy- 
 drate, sulphide, sulphite, sili- 
 cate and aluminate, bicar- 
 bonate in, 15. 
 total active soda in, 14. 
 qualitative tests for sodium hydrate, 
 
 sulphide and sulphite in, 14. 
 quantitative estimation of, 14. 
 Sodium aluminate, 17, 145. 
 
 estimation of soda and alumina 
 in, 17. 
 
188 
 
 INDEX. 
 
 Sodium bicarbonate, 145. 
 
 nitrate, 78. 
 Specific gravity of solid fats and waxes, 
 
 determination of, 116, 121. 
 Spices, etc., 183. 
 Spirits, determination of alcohol in, 103. 
 
 fusel oil in, 104, 106. 
 Stannous chloride, determination of 
 
 stannous oxide in, 146. 
 Starch, 99, 157. 
 
 determination of in raw products, 
 
 95, 98. 
 Sugar, 79. 
 
 determination of ash of, 8l. 
 cane sugar, 79. 
 specific gravity of, 79. 
 water in, 80. 
 estimation of alkalinity of, 81, 88. 
 
 "salts" in, 8r. 
 general methods of investigation, 
 
 79-. 
 
 polarization of, 79. 
 quantitative estimation of, 79, 80 
 
 84. 
 
 Sulphuric acid, qualitative tests for sul- 
 phurous acid, hydrochloric acid, 
 oxides of nitrogen, lead, iron, 
 arsenic in, 4. 
 quantitative estimation of arsenic 
 
 in, 5. 
 anyhydride (see Fuming Sulphuric 
 
 Acid). 
 Super-phosphates, 76. 
 
 estimation of total phosphoric acid 
 
 in, 77. 
 water-soluble phosphoric acid 
 
 in, 77- 
 Sylvite, 77. 
 
 Table for invert sugar by Herzfeld, 89. 
 
 Killer, 90. 
 
 milk sugar, 176. 
 
 of analyses of coffee, 179. 
 
 constants for common waxes, 
 
 I2q. 
 German degrees of hardness of 
 
 water, 25. 
 iodine numbers and saponifica- 
 
 tion numbers of fats, 113. 
 
 Tallow, 120. 
 Tanning extracts, 148. 
 
 estimation of water and ash, 
 matter soluble in hot 
 water, organic matter 
 insoluble in hot water, 
 non-tannins in, 148. 
 tanning substances in, 
 
 149- 
 materials, 147. 
 
 raw products for, 149. 
 Tartar emetic, 147. 
 Tea, coffee and cocoa, 178. 
 
 determination of moisture, extract, 
 
 178. 
 theine, caffein, tannin, ash, 
 
 179. 
 Thin juice, 84. 
 
 estimation of specific gravity of, 84. 
 
 sugar in, 84. 
 Thomas slag, 76. 
 Tin chloride, 147. 
 
 salt (see Stannous Chloride). 
 Turkey- red oil, 138. 
 
 chemical examination of, 139. 
 determination of solid fatty acids, 
 ammonia and soda, sulphuric 
 acid in, 140. 
 total fat, neutral fat in, 139. 
 
 Water (see Boiler- water). 
 Waxes, 121. 
 
 liquid, 114. 
 
 mineral, 125. 
 
 vegetable and animal, 1 21. 
 Weldon mud, 18. 
 
 determination of manganese dioxide 
 
 in, 1 8. 
 total manganese, "basis" in, 
 
 19. 
 
 White metal, 69. 
 White paint. 169. 
 
 analysis of, 169. 
 
 scheme for analysis of. 170. 
 Wood spirit (see Methyl Alcohol). 
 
 Xylol, crude, 165. 
 Yeast, 103. 
 
UNIVERSITY OP CALIFORNIA LIBRARY 
 
 THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 NOV 4 1916 
 SEP 13 1925 
 
 5 1931 
 
 APR 5 - 
 REC'D JLD 
 
 30m-l,'15 
 

 237357 
 
 
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