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 A manual of quantitative chemical anajys 
 
 3 1924 031 239 548 
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Cornell University 
 Library 
 
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 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924031239548 
 
A MANUAL 
 
 OF 
 
 QUANTITATIVE 
 CHEMICAL ANALYSIS. 
 
 E. F. LADD, B.S., 
 
 Pmfesior of Chemisfyy in -the North Dakota Agncultuml College. 
 
 and Chemist to' the Govemmeni Experiment Station, 
 
 Fargo. N. D. 
 
 FIRST EDITION. 
 FIRST THOUSAND. 
 
 NEW YORK : 
 
 JOHN WILEY & SONS 
 
 London : CHAPMAN & HALL, Limited. 
 
Copyright, 1898, 
 
 BY 
 
 E. F. LADD. 
 
 ROBERT nRTTMMONl), ET-FCTPOTYPFP AWD PRTNTttR, NFW YORK. 
 
PREFACE. 
 
 This little manual is intended for the use of begin- 
 ners in quantitative analysis, and is in no way designed 
 for the use of the professional chemist. 
 
 The methods have been selected to advance the 
 student from the simple analysis to the more complex 
 and difficult, and when he has completed the course 
 as 'laid down here he will be in a position to intelli- 
 gently use and interpret the advanced works of 
 Fresenius, Crookes, and the Encyclopaedias. The 
 methods selected are not the ones that would always 
 give the most reliable results in professional work, but 
 rather are those that represent principles that will aid 
 in developing the reasoning power of the student ; and 
 'for that reason explanations of details and reactions 
 have been largely omitted, and the series of questions 
 at the end of each method will test the student's 
 knowledge of chemistry, and make it necessary that 
 he consult other works to acquaint himself with the 
 reasons for many steps in his work. 
 
IV PREFA CE. 
 
 I lay no claim to originality of methods presented, 
 but rather have brought together a compilation of the 
 methods as used in laboratory work during several 
 years of experience, and such as have been found to 
 give excellent satisfaction in the hands of my own 
 students. 
 
 If the methods herein presented prove as successful 
 in the hands of others as in the hands of my own 
 students, and they are drawn to a further study and 
 a better understanding of the products of nature, the 
 hopes of its author will be more than realized. 
 
 Agricultural College, Fargo, N. D., 
 October, \%iyj. 
 
TABLE OF CONTENTS. 
 
 CHAPTER I. 
 
 PAGE 
 
 Introduction i 
 
 General Directions. Desiccators. Filtering, Washing, 
 and Burning. Weighing. Care of Platinum. Solutions. 
 
 CHAPTER n. 
 
 Gravimetric Analysis g 
 
 Iron. Magnesium, Aluminum, Calcium. Barium. Sul- 
 furic Acid. Chlorin. Copper. Lead. Manganese. Zinc. 
 Phosphoric Acid. Potassium. Sodium. Separation of Potas- 
 sium and Sodium. Carbonic Acid. Dolomite. Feldspar. 
 Gypsum. Mineral Phosphates 
 
 CHAPTER HI. 
 
 Volumetric Analysis 27 
 
 Normal Sulfuric Acid. Normal Sodium Carbonate. Semi- 
 normal Ammonia. Indicators. Iron Determinations. Cal- 
 cium, Chlorin. 
 
 CHAPTER IV. 
 
 Analysis OF Ashes AND Soils 35 
 
 Ash Analysis. Soil Analysis. Nitrogen Determination. 
 
 CHAPTER V. 
 
 Analysis of Ores , 43 
 
 Iron Ores, Zinc Blende. Galena. Coal. 
 
VI TABLE OF CONTENTS. 
 
 CHAPTER VI. 
 
 PAGE 
 
 Electrolysis 49 
 
 Definitions. Arrangement of Apparatus. Co))per. Nickel. 
 Iron. 
 
 CHAPTER VII. 
 
 Sugar, Starches, and Foods 54 
 
 Solutions. Sugar Equivalent of Permanganate Solution. 
 Invert Sugar. Sucrose. Food Analysis. Carbohydrates. 
 Milk Analysis. 
 
 CHAPTER VIII. 
 
 Water Analysis 64 
 
 Solutions. Solids. Free Ammonia. Albuminoid Ammo- 
 nia. Hardness. Nitrates. Chlorin. 
 
 CHAPTER IX. 
 
 Urine Analysis 71 
 
 Urine. Solids. Specific Gravity. Color. Urea. Uric 
 Acid. Indican. Chlorids. Phosphates. Albumen. Sugar. 
 Blood. Bile. 
 
 APPENDIX. 
 Table of the Elements 77 
 
QUANTITATIVE CHEMICAL ANALYSIS. 
 
 CHAPTER I. 
 INTRODUCTION. 
 
 Quantitative analysis may be subdivided into 
 two divisions, according to the methods employed — 
 gravimetric and volumetric analysis. In gravimetric 
 analysis the constituents to be determined are con- 
 verted into compounds of definite composition, which 
 by methods of filtration and washing may be sepa- 
 rated from all others, and after further and appro- 
 priate treatment be weighed. From the known 
 composition of the product as weighed, the amount 
 of the unknown constituent may be calculated. 
 
 In volumetric analysis the constituent is deter- 
 mined, not by weighing a known product, but rather 
 by means of well-known reactions brought about by 
 means of solutions of a definite and known strength. 
 To determine accurately, then, the amount of the 
 known solution added, is the essential in volumetric 
 analysis. 
 
2 QUANTIl'ATIVE CHEMICAL ANALYSIS. 
 
 Volumetric analysis is quantitative analysis by 
 measure, while gravimetric analysis is quantitative 
 analysis by weight. 
 
 GENERAL DIRECTIONS. 
 
 1. Cleanliness and neatness in every detail is an 
 absolute essential to success. The work-desk should 
 be kept neat and clean, using freely a sponge, which 
 should always be at hand. 
 
 2. Protect all preparations and solutions from dust, 
 from spatterings, and from all unnecessary fumes. 
 See that every piece of apparatus is washed and wiped 
 dry after using, and examine each pi&ce before using, 
 to see that it is perfectly clean. 
 
 3. Read each experiment through carefully before 
 attempting to undertake the work, and be sure you 
 understand every step in the operation, and are able 
 to answer all the questions asked. See that all the 
 necessary apparatus is at hand before beginning, and 
 have everything in place and properly arranged. 
 
 4. No student can make any degree of success who 
 does not keep a neat and legible note-book, in which 
 every detail is written down as soon as observed. All 
 weights and measures should be entered as soon as 
 made, and not kept on a slip of paper to be written 
 up at some future time. One of the greatest short- 
 comings of every young experimenter or chemist is a 
 
INTROD UCTlOtT. 3 
 
 lack of proper notes on work done. Remember that 
 what is perfectly clear to you to-day may be for- 
 gotten by you to-morrow, or next year, when the facts 
 may be needed. 
 
 5. Every piece of apparatus used in the experiment 
 or work should be so labelled as to be readily identi- 
 fied at any time, and no mistake made in the work. 
 
 6. In dissolving or neutralizing substances that 
 effervesce, always add the substance slowly to prevent 
 loss either from frothing or from so rapid efferves- 
 cence as to lose the material by spattering over the 
 sides of the dish. 
 
 DESICCATORS. 
 
 Desiccators should contain a little concentrated 
 sulfuric acid, which from time to time may be re- 
 newed. The cover of the desiccator should be made 
 air-tight by applying about the edges a thin coating 
 of vaseline. 
 
 Some chemists prefer for general use fused anhy- 
 drous calcium chlorid, nearly filling the desiccator 
 with this product. The chlorid needs renewing 
 frequently, and should not be allowed to cake. 
 
 The desiccator should never be allowed to remain 
 uncovered. 
 
 FILTERING, WASHING, AND BURNING. 
 I. Select a funnel of proper size for the work in 
 hand, fold the filter, carefully place in funnel, and 
 
4 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 unless otherwise mentioned moisten the filter with 
 distilled water, and see that the paper fits nicely 
 against all sides of the funnel. This last is essential 
 for success. 
 
 2. The paper in the funnel should not come within 
 one-fourth inch of top of funnel. If paper reaches 
 top of funnel the precipitate cannot be properly 
 washed. 
 
 3. In pouring solutions into funnel, always use a 
 glass rod, pouring the solution down its side. 
 
 4. Washing. — Never add wash-water to the con- 
 tents of the funnel until all the solution has filtered 
 through, then direct the stream of water against the 
 side of the funnel, above the paper, and gradually 
 bring it down, washing the precipitate down toward 
 the centre of the paper. See that all the wash-water 
 is run through before adding a fresh portion. To 
 remove the last particles of adheting precipitate from 
 the beaker, use a glass rod with a small piece of 
 rubber tubing at the end. This rubber-tipped end 
 of the rod must not be used in the solution, and only 
 in the wash-water. 
 
 5. Drying. — Precipitates to be dried in funnel 
 should be covered with glazed paper neatly folded 
 around the edge of the funnel to keep it in place, and 
 then small holes perforated through the paper to per- 
 mit drying. These may then be placed in water-oven 
 and allowed to remain until dry. See that each 
 
MTROD VCTIOM. 5 
 
 funnel is properly labelled before removing it from its 
 stand. 
 
 6. Burning. — Place the weighed crucible upon a 
 piece of glazed paper. Remove the filter and con- 
 tents from the funnel, unfold the filter, and remove 
 carefully all the precipitate, transferring it to the 
 crucible; then fold the filter-paper in, and coil a small 
 platinum wire about it, holding it carefully by the 
 wire over the crucible on the glazed paper, and set 
 the paper on fire, holding above it a funnel so as to 
 form an upward current and to catch any particles 
 that might be carried off mechanically. If the ash of 
 the paper needs further burning, it may now be placed 
 upon the crucible cover and burned, when it should be 
 carefully transferred to the crucible with the main 
 precipitate, and all particles from the glazed paper 
 united with it. When the heat is first applied to the 
 crucible the flame should be moved about, to warm 
 all parts uniformly, to prevent breaking the porcelain 
 or injuring the platinum dish. 
 
 WEIGHING. 
 
 I. Always test the balance before each weighing to 
 see that it is in perfect adjustment. If the swing of 
 the needle is not the same to each side of the zero, 
 then the balance should be brought into adjustment 
 before attempting to weigh. 
 
6 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 The student should never attempt to make adjust- 
 ment of the balance, but call upon the instructor. 
 
 2. The balance should be brushed off and kept 
 clean. Salts or liquids should not be allowed to come 
 in contact with the pans. 
 
 3. When not in use, return the weights to their 
 proper place in the weight-box. Make two readings 
 of weights. F"irst read the weights missing from 
 weight-box, then return the weights from the pan to 
 their proper place, reading them again. In this way 
 the student has a check upon his weighings. 
 
 4. The balance-case should always be closed during 
 the final weighings before using the rider, and thus 
 protect the pans from any currents of air. 
 
 5. Never trust to memory the weights of sub- 
 stances, but make a memorandum of all weighings at 
 the time of taking the readings of the weights from 
 the pan. 
 
 CARE OF PLATINUM. 
 
 1. Never heat the platinum dish in contact with 
 iron. Use only platinum or pipe-stem triangles. 
 
 2. Do not fuse pure metals in a platinum crucible 
 or salts of the silver, arsenic, copper, and zinc groups. 
 
 3. Do not fuse the sulfid of metals in platinum. 
 
 4. Do not use aqua regia or free chlorin on plati- 
 num ware. 
 
IN TROD UCTION. 7 
 
 5. Alkalin nitrates, hydrates, or cyanids should 
 not be fused in platinum. 
 
 6. Keep the dish always perfectly bright and clean, 
 and for this purpose there is nothing better than fine 
 sea-sand free from the sharp grit. Use only the 
 moistened finger for applying the same. Occasionally 
 fusing with a little KHSO, and then carefully polish- 
 ing with sand will be found a good method for clean- 
 ing badly tarnished platinum ware. 
 
 7. Never allow a smoky flame to be used with 
 platinum, or if the reducing flame comes in contact 
 with the platinum there is soon formed a gray film, 
 and the platinum is injured. 
 
 SOLUTIONS. 
 
 Nearly all the solutions required are mentioned in 
 connection with the method of analysis. A few stock 
 solutions may be required, the methods of prepara- 
 tion of which are given here. 
 
 Molybdate Solutions. — Dissolve lOO grams of molyb- 
 dic acid in 417 c.c. of ammonia, sp. gr. 0.96. Pour 
 the solution into 1250 c.c. of nitric acid, sp. gr. 
 exactly 1.20. The solutions should be united slowly, 
 and always in the order given above. Let the mix- 
 ture stand for several days in a warm place and then 
 decant the solution from the sediment and preserve 
 for use. 
 
8 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Magnesia Mixture. — Of recently ignited MgO, dis- 
 solve" 22 grams, or no grams crystallized MgCl, in 
 dilute HCl, avoiding any excess. When dissolved 
 add a slight excess of calcined magnesia and boil, to 
 precipitate iron, and then filter and add 280 grams 
 of ammonium chlorid, 700 c.c. of NH.OH, sp. gr. 
 0.96, and make up to 2000 c.c. with distilled water. 
 
CHAPTER II. 
 
 GRAVIMETRIC ANALYSIS. 
 
 I. Iron (Fe ; 56). 
 
 Weigh out 0.3 gram pure iron wire, place in 
 beaker of about 250 c.c. capacity, add water and 
 nitric acid, heat slowly to dissolve, avoid much excess 
 of HNO3, and to the hot solution add NH,OH slowly 
 and with constant stirring until slightly alkalin; boil 
 for a few minutes, allow ppt. to settle, filter, and wash 
 thoroughly with hot distilled water. Dry this ppt. 
 thoroughly in the steam-oven, then transfer ppt. to a 
 tared porcelain crucible; burn filter-paper and add 
 ash to crucible, cover the crucible and ignite, at first 
 slowly, .then intensely, with blast-lamp ; cool in desic- 
 cator, and weigh as Fe^O,. 
 
 Formula. — FejO, : Fe, :: ppt. : x\ 
 
 X = amount of Fe in ppt 
 
 *M '. X :: 100 : y\ 
 y = per cent Fe. 
 
 * M in all cases indicates the mass or amount of original sub- 
 stance weighed out. 
 
 9 
 
lO QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Questions. — Why dry ppt. before igniting ? Why 
 add HNO,? Is there any danger of loss by volatih'z- 
 ing the iron? 
 
 2. Magnesium (Mg; 24). 
 Of magnesium foil or powder weigh out about .15 
 gram, add water and HCl slowly to dissolve the Mg, 
 beat to bring all into solution, then add NH^Cl and 
 NH,OH in slight excess. If ppt. forms add more 
 NH.Cl till redissolved. To this solution add Na,HPO. 
 as long as ppt. forms, stir carefully without touching 
 sides of beaker, and allow to stand until the solution 
 above ppt. is perfectly clear. Filter and wash out 
 beaker with portions of the filtrate, and then wash 
 with dilute ammonia water (i pt. NH^OH to 3 pts. 
 H,0) until filtrate gives no coloration with HNO, 
 and AgNO,. Dry thoroughly, remove ppt. to tared 
 porcelain crucible, burn filter-paper and add the ash 
 to the crucible and its contents, and ignite, at first 
 slowly, then to intense heat; cool, and weigh as 
 Mg,P,0,. 
 
 Formula. — Mg,P,0, : Mg, :: ppt. : x; 
 X = amount of Mg in ppt. 
 
 M : X :: 100 : y\ 
 y = per cent Mg. 
 
 Questions. — Why add HN,C1? Why not ignite in 
 platinum crucible? WhyaddNH,OH? Why wash 
 with NH,OH water? What is composition of ppt.? 
 
GRA VIME TRIC ANAL YSIS. 1 1 
 
 3. Aluminum (Al; 27). 
 
 Weigh out about one gram dry alum A1K(S04), 
 I2H,0 and dissolve in about 100 c.c. distilled water; 
 add 25 c.c. NH^Cl, then NH.OH to slight alkalinity, 
 avoiding much excess, and heat to drive off any excess 
 of NH,OH. Allow to stand until ppt. subsides, and 
 then filter and wash thoroughly; dry, transfer ppt. to 
 tared platinum crucible, ignite filter-paper, add ash, 
 ignite carefully, and finally- with full blast ; cool, and 
 weigh as alumina, Al^Og. 
 
 Formula. — Al^O, : Al, :: ppt. : x\ 
 
 X = amount Al in ppt. 
 
 M \ X ^•. 100 '. y; 
 y = per cent Al. 
 
 Questions. — Why add NH.Cl? Why avoid excess 
 of NH.OH? Why ignite intensely at close? What 
 is composition of ppt. ? 
 
 4. Calcium (Ca; 40). 
 
 Weigh out about 0.5 grams CaCOj, add 50 c.c. H^O, 
 and slowly HCl, and heat to dissolve Ca and to drive 
 off excess of acid; add NH,OH until slightly alkalin 
 and then (NH,),CA to ppt. all the Ca; allow to 
 stand twelve hours, filter, and wash with hot water 
 containing a little ammonia; dry, and transfer ppt. to 
 
12 QUANTITATIVE CHEMICAL ANALYSIS.. 
 
 tared platinum crucible: burn filter-paper, add ash 
 .to the crucible, and ignite, at first slowly and finally 
 with full blast; cool, and weigh as CaO. 
 
 Formula. — M \ ppt. :: lOO : x\ 
 
 X = per cent CaO. 
 
 By igniting at low heat the ppt. may be weighed as 
 CaCOj, then converted into CaO it may then be dis- 
 solved in HCI, and H,SO, added to form CaSO., 
 and determined in this form. 
 
 Questions. — What is the composition for the first 
 ppt. of Ca? What change takes place in crucible by 
 heating ppt. at low heat? With intense heat? Why 
 not weigh as CaCO,? Why was NH.OH added? 
 Why add NH.OH to wash-water? Why not filter at 
 once? Why have solution hot when (NH,),C,0, is 
 added? 
 
 5. Barium (Ba; 137). 
 
 Weigh out about i gram barium chlorid that has 
 been well dried, add 150 c.c. water, i c.c. HCI, and 
 heat to drive off excess of acid. To the hot solution 
 add diluted H^SO, until slightly acid, and with con- 
 stant stirring keep near boiling for ten minutes; then 
 allow ppt. to settle and decant on to a firm filter- 
 paper. To the ppt. add boiling water and a few 
 drops of HjSO., then decant, add hot water to the 
 ppt., and filter, washing carefully with boiling water 
 
GRA VT METRIC ANAL YS/S. 1 3 
 
 on the filter until filtrate gives no turbidity with BaCl,. 
 Dry ppt. and then remove it to tared platinum cruci- 
 ble; burn filtrate carefully, putting ash on crucible; 
 cover, adding a drop of H^SO,, and ignite ; then transfer 
 ash to crucible, and heat low for some time, and 
 finally raise temperature to low redness; cool, and 
 weigh as barium sulfate. 
 
 Formula. — BaSO, : Ba :: ppt. : x; 
 
 X = amount of Ba in ppt. 
 
 Mix:: loo : j/; 
 y = per cent Ba. 
 
 Questions. — Why must there be an excess of HCl? 
 Why remove ppt. from filter before igniting? Why 
 ignite at low red heat? Why have solution dilute 
 before adding precipitant? 
 
 6. Sulfuric Acid (SO,; 80). 
 
 Weigh out about one gram copper sulfate, and add 
 100 c.c. water, a few drops of HCl, and 20 c.c. 
 NH,C1; then heat to boiling, remove lamp, and add 
 drop by drop BaClj until in slight excess, stirring con- 
 stantly. Allow to stand in warm place for twelve 
 hours. Decant through filter, add boiling water to 
 ppt. and a few drops of H^SO, ; boil, decant ; add more 
 boiling water, filter, and wash thoroughly. Be sure 
 to allow each portion of wash -water to pass through 
 
14 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 before adding more. Dry ppt., transfer to tared cru- 
 cible, burn, filter, and moisten ash vtith H^SO, on 
 crucible cover; dry and ignite, then transfer ash to 
 crucible, and heat very low and finally at dull red heat 
 for ten minutes; cool, and weigh as BaSO,. 
 
 Formula. — BaSO, : SO, :: ppt. : x\ 
 X = amount SO, in ppt.' 
 
 M : X :: loo : y\ 
 y = per cent SO,. 
 
 Questions. — Why acidify with HCl? Why have 
 solution hot when BaCl, is added? Why add HN,C1? 
 Why not burn ppt. and paper together? Why is such 
 extreme care in details necessary? 
 
 7. Chlorin (CI; 35-4). 
 
 Weigh out about .25 gram NaCl that has been 
 heated to expel moisture, dissolve in 75 c.c. water, 
 and add slowly AgNO, containing a few drops of 
 HNO, ; heat nearly to boiling and stir vigorously, and 
 continue until ppt. settles, leaving liquid above clear; 
 filter, wash with hot water containing a few drops of 
 HNO3 until wash-water gives no turbidity with HCI; 
 dry ppt., transfer all of ppt. to tared porcelain cruci- 
 ble, burn filter-paper carefully, and add ash to cruci- 
 ble, then a few (four) drops of HNO, and a drop or 
 two of HCl; dry, ignite very gently, moving burner 
 
GRA VIME TRlC ANAL VSIS. 1 S 
 
 about under ciucible until ppt. just begins to fuse 
 about the edges of crucible; then cool and weigh, 
 avoiding direct sunlight. 
 
 Formula. — AgCl : CI :: ppt. : x; 
 
 X = amount of CI in ppt. 
 
 M : X v. loo : y; 
 y = per cent CI. 
 
 Questions. — Why not use platinum crucible? Why 
 not add HNO3? Why avoid sunlight? Why ignite so 
 low? 
 
 8. Copper (Cu; 63.2). 
 
 Weigh out about one gram of well-desiccated cop- 
 per sulfate, add 100 c.c. hot water and heat to boiling. 
 The solution should be clear, and to the hot solution 
 add drop by drop a dilute solution of NaOH, using 
 but slight excess of reagent. Stir constantly, and 
 continue to heat for ten minutes; allow ppt. to 
 subside, and then decant on to filter; add water, and 
 boil ppt. again. Filter, and wash thoroughly with hot 
 water, dry in steam-oven, transfer ppt. completely to 
 tared crucible, burn filter, add ash, and ignite in- 
 tensely; cool, and weigh as oxid. 
 
 Formula. — CuO : Cu :: ppt. : x; 
 
 X =; amount of Cu in ppt. 
 
 M \ X :: 100 : y\ 
 y = per cent Cu. 
 
l6 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Should the ppt. adhere firmly to sides of beaker it 
 may be dissolved off with a few drops of HNO, pre- 
 cipitated again with NaOH and added to filter. 
 
 Questions. — Why decant and boil with H,0 instead 
 of filtering at once? Why heat to boiling before add- 
 ing NaOH? Why use but slight excess of reagent? 
 
 9. Lead (Pb; 207). 
 
 Weigh out about one gram Pb(N03)j, dissolve in 75 
 c.c. water, and add slowly H^SO, in slight excess, 
 and then add an equal volume of alcohol ; mix well 
 and allow to stand for twelve hours; filter, wash with 
 alcohol (3 volumes alcohol and i volume 11,0), dry, 
 and remove carefully all the ppt. to a tared crucible. 
 Burn filter, moisten with HNO, and HjSO,, dry and 
 ignite, and transfer the well-burned ash from crucible 
 cover to crucible with ppt., and heat only to low 
 redness; cool and weigh. Observe that the reducing 
 flame does not come in contact with ppt. 
 
 Formula. — PbSO, : Pb :: ppt. : x; 
 
 X = amount of Pb in ppt, 
 
 M : X \: 100 : y; 
 y = per cent Pb. 
 
 Questions. — Why burn filter completely before unit- 
 ing with ppt.? Why wash with alcohol? Will the 
 presence of NH^OH salts or HNO, interfere in this 
 
GJiA VIME TRIC ANAL YSIS. 1 7 
 
 method? Why? How prevented? Why add alcohol 
 before adding reagent? 
 
 10. Manganese (Mn; 55). 
 
 Weigh out about .5 gram MnClj, dissolve in 100 
 c.c. of water, add a few drops HCl, then NH,OH in 
 excess, then Na^HPO^ in large excess; dissolve the 
 white ppt. with H^SO,, heat to boiling, and add 
 NH^OH in excess. Place on water-bath for one 
 hour, when the ppt. forms crystalline scales and is rose- 
 colored. Filter, and wash with hot water containing 
 a little NHjOH. Dry, and transfer to tared porcelain 
 crucible, adding ignited filter ash, and burn at bright 
 red heat, when the ppt. is converted into a nearly 
 white powder, Mn,PjO,. 
 
 Formula. — Mn^P^O, : Mn, :: ppt. : x; 
 X = amount of Mn in ppt. 
 
 M : X :: 100 : y. 
 y = per cent Mn. 
 
 Questions. — Why redissolve ppt. with H,SO,? Why 
 add to solution NH,OH? Why heat for one hour? 
 Is ppt. soluble in H,0? 
 
 II. Zinc (Zn; 65). 
 
 Dissolve about one gram pure zinc sulfate in 100 
 c.c. H^O in porcelain dish, heat to boiling, and add 
 
1 8 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Na,C0.5 slowly, with stirring, until an excess of reagent 
 is added. Allow to settle and decant through filter, 
 and boil the ppt. three times with water and decant- 
 ing of each separate portion of water; finally, transfer 
 ppt. to filter, and wash with hot water. Dry, transfer 
 ppt. to crucible, burn ash, add to ppt., and ignite 
 gently at first, and finally to full redness; cool, and 
 weigh as ZnO. 
 
 Formula. — ZnO : Zn :: ppt. : x; 
 
 X = amount of Zn in ppt. 
 
 M : X " lOO : y; 
 y = per cent Zn. 
 
 Questions. — Why use porcelain dish in place of 
 beaker? What is composition of ppt. ? 
 
 12. Phosphoric Acid (PjO^; 142). 
 
 Weigh out about .5 gram ammonium phosphate 
 well dried, dissolve in 75 c.c. H,0, add 12 c.c. NH,C1, 
 and then "magnesia mixture" slowly with con- 
 stant stirring, but do not touch sides of beaker until 
 an excess of reagent is added. Allow to stand fifteen 
 minutes and add 25 c.c. NH^OH, and stand in warm 
 place for about twelve hours. Decant on to filter, 
 using some of filtrate for purpose if necessary, and 
 wash well with ammonia water (i to 3) until washing 
 gives no reaction for CI. Dry ppt. and treat the 
 same as in Mg, weighing as Mg^PjO,. 
 
GRA VIME TRIG ANAL VSlS. 1 9 
 
 Formula. — Mg^I^O, : P^O, :: ppt. : x\ 
 X = amount of P,0, in ppt. 
 
 M : X :: loo : y\ 
 y = per cent P5O5. 
 
 Questions. — Why add NH^Cl? What is " magnesia 
 mixture "? Why not let rod touch sides of beaker ? 
 Why add NH,OH after adding reagent? How shall 
 we test for CI in wash-water, and why? 
 
 13. Potassium (K^O; 94). 
 Weigh out about .3 gram of potassium chlorid, 
 the salt having been previously heated and cooled 
 in a desiccator. Dissolve in porcelain evaporating- 
 dish with as little water as convenient (j to 8 c.c), add 
 platinic chlorid to slight excess, and evaporate almost 
 to dryness on water-bath ; then add 40 c.c. 80 per cent 
 alcohol, and allow to stand for one hour; then decant 
 on weighed filter and add fresh alcohol, and repeat two 
 or three times, and then transfer to filter and wash 
 with ether; l ry, cool in desiccator, and weigh. From 
 total weight deduct weight of filter-paper, or 9. Gooch 
 crucible with asbestus filter may be used. Ppt. is 
 KjPtCl,,. In place of alcohol a mixture of alcohol 
 and ether is preferable (2 to i). 
 
 Formula. — K^PtCl, : K^O :: ppt. : x; 
 X — amount of K,0 in ppt. 
 
 M : X :: loo : y; 
 y = per cent K^O. 
 
20 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Questions. — Why use mixture of alcohol and ether? 
 Why not use absolute alcohol? May K be determined 
 as a sulfate? Why not ignite ppt.? 
 
 14. Sodium (Na,0; 62). 
 
 Weigh out of Na.jCO„ about .4 gram; dissolve in 
 water in tared porcelain dish, add slowly a slight excess 
 of HCl, evaporate to dryness on water-bath, moisten 
 with HCl, dry, and then heat gently at 110° for ten 
 minutes; then bring heat up till dull redness, moving 
 the flame about constantly to all parts of dish ; cool, 
 and weigh as sodium chlorid. 
 
 Formula. — 2NaCl : Na,0 :: ppt. : x; 
 X = amount Na^O in ppt. 
 
 Mix :: 100 : y; 
 y = per cent K^O. 
 
 Questions. — Why heat ppt. so carefully at first? 
 Why moisten ppt. with HCl and evaporate? Why 
 not heat to convert direct into Na,0? 
 
 15. Separation of K and Na. 
 
 Weigh out .5 gram of mixed salts, dissolve in 50 
 c.c. water, add HCl to the solution, then Ba (0H)„ as 
 long as ppt. forms; boil for three minutes, filter while 
 hot, and wash with boiling water. To filtrate add a 
 
GRA VIMS TRIG A If At YSIS. 2 1 
 
 few drops of NH.OH and then (NH J^CO, to ppt. Ba,- 
 filter, and evaporate to dryness in porcelain dish, 
 gradually raising heat to dull redness to drive off 
 ammonia salts. Dissolve with 15 c.c. H^O, add a few 
 drops of NHjOH if ppt. forms, filter into tared dish, 
 wash, and evaporate to dryness; heat to dull redness, 
 cool, and weigh total alkalis as chlorids. Dissolve 
 residue with 10 c.c. water and add platinic chlorid as 
 in K determination, precipitating K and Na. After 
 evaporating dissolve out Na with alcohol, leaving 
 K^PtCl, to be treated and weighed as in potash. 
 
 Formula for Kfi.—KJ'tCl : K,0 :: ppt. : x; 
 X = amount K^O in ppt. 
 
 M : X :: loo : j/; 
 y = per cent K^O. 
 « 
 Formula for Na,0.— K,PtCl„ : 2KCI :: ppt. : x; 
 X = amount KCl in total alkalis. 
 Total alkalis — jr = ppt. as NaCl. 
 2NaCl : Na,0 :: amount NaCl : x\ 
 X = amount Na^O in ppt. 
 
 M : X \: 100 : y\ 
 y = per cent Na^O. 
 
 Questions. — Why weigh ppt. first as chlorids? How 
 was Na separated from K? Vl/hy not evaporate solu- 
 tion fully to dryness after adding platinic chlorld? 
 
22 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 i6. Carbonic Acid (CO,; 44)- 
 
 A. Weigh into a tared platinum crucible about 1.5 
 grams well dried and pulverized marble, mix with 
 about four times its weight of powdered borax, and 
 fuse. Loss is taken as CO,. This method is not 
 applicable in many cases, and is at best only an 
 approximation. 
 
 B. About one gram of the carbonate is placed in a 
 flask of 200 c.c. capacity, fitted with a rubber stopper 
 having three perforations. Through one perforation is 
 
 . passed a small separatory funnel containing dilute HCl. 
 A second opening has a small glass tube connected 
 with a U tube containing KOH solution, and this 
 connected with another tube having H,SO,. These 
 tubes and reagents are for drying the air that may 
 be drawn through the apparatus during the analysis. 
 The third opening has a bent glass tube connected 
 with a U tube containing concentrated H,SO^ to 
 serve as a drying agent for evolved gas; this is at- 
 tached to a KOH bulb containing strong KOH solu- 
 tion (i to i), and to the end of this is attached a small 
 U tube containing H,SO, to prevent any moisture 
 from entering the KOH bulb, and the whole attached 
 to a suction-pump. (In place of the pump one may 
 use a large bottle, properly arranged, filled with water 
 and inverted.) When ready for starting, the KOH 
 bulb should be carefully weighed and again attached 
 
GRAVIMETRIC ANALYSIS. 2^ 
 
 in the circuit, and the dilute HCl allowed to flow 
 drop by drop into the flask upon the marble or other 
 carbonate, and when the decomposition is complete 
 the flask, on a sand-bath, should be gently heated, 
 and the suction-pump started very slowly, drawing 
 through a continuous stream of air, CO,, free. When 
 all the gas in the apparatus has been drawn through 
 the KOH bulb the pump may be shut off, the bulbs 
 removed and again weighed. The increase in weight 
 is due to CO,. This method is very accurate and reli- 
 able if the work is carefully done and all leaks avoided. 
 Questions. — Why use H^SO, in U tubes? Why is 
 not method A satisfactory? 
 
 17. Dolomite. 
 
 Of the well pulverized and dried mineral weigh out 
 about one gram, put into porcelain dish, add a little 
 water, and then HCl with a few d-rops of HNO,. 
 Evaporate to dryness, moisten with HCl, add water, 
 and heat on water-bath; filter, wash with hot water, 
 dry, and ignite residue as SiO,. 
 
 Iron and Alumina. — To the filtrate above add 
 NH.Cl and NH.OH until alkalin, heat to drive off 
 excess of NH,; filter, wash with hot water, dry, ignite, 
 cool, and weigh as Al,Oj and Fe^O,. 
 
 Lime. — -To the filtrate above add NH,OH and 
 (NH,),C,0.. The completion of the determination is 
 the same as for Ca, which see. 
 
24 QUANTITATIVE CHEMICAL AA'ALYSIS. 
 
 Magnesia. — To the above filtrate add Na,HPO, and 
 NH^OFI and treat ppt. as in magnesium, whicli see. 
 
 Volatile Matter. — Weigh out in tared platinum 
 crucible about .5 gram of dolomite; heat intensely 
 until no further loss in weight. Loss is CO, and 
 other volatile matter. 
 
 18. Feldspar (Orthoclase and Albite). 
 
 Of the finely pulverized and dried mineral weigh 
 out about one gram, add 13 grams of a mixture in 
 equal parts of potassium and sodium carbonates and 
 fuse in platinum crucible, and cool quickly. Place the 
 crucible in porcelain dish, boil with HjO and HCl in 
 excess, evaporate on water- bath to dryness, and heat 
 at 120° for one hour, to render SiO, wholly insoluble. 
 Moisten the dry mass with HCl, add H,0, heat to 
 boiling for ten minutes, filter, and wash. The resi- 
 due is dried, ignited, cooled, and weighed as SiO,. 
 
 Deternaine iron, alumina, lime, and magnesia in 
 filtrate in same manner as in dolomite. 
 
 The alkalis must be determined in a separate por- 
 tion, as follows : Weigh out about . 5 gram of the min- 
 eral, add .5 gram NH,CI and four grams. of calcium 
 carbonate, and heat in platinum crucible the well- 
 mixed mass at first gently and then at low redness for 
 one and one-half hours; then cool and put crucible 
 in porcelain dish, add H,0, and boil for twenty min- 
 utes, replacing water from time to time; filter, and to 
 
GRAVIMETRIC ANALYSIS. 2$ 
 
 filtrate add HCl and evaporate to dryness and heat 
 residue for some time at 120°; pulverize residue in 
 mortar, add H,0, boil, filter, and wash into the fil- 
 trate. Determine alkalis as for separation of K and 
 Na, which method see. 
 
 19. Gypsum^ 
 
 Moisture and Water of Crystallisation. — Of the 
 well-pulverized material weigh out in platinum crucible 
 about 2.5 grams, add a little (NHJ^CO,, and gradually 
 heat to 150° to drive off all the ammonia salts; cool 
 and weigh. Loss in weight is calculated as moisture 
 and water of crystallization. 
 
 Weigh out about one gram of the finely pulverized 
 gypsum, add HCI, and heat on water-bath (50 c.c. 
 H3O and 10 c.c. strong HCl). Continue the digestion 
 for one hour or more, then filter, using a weighed 
 filter; wash, dry, and weigh filter and residue; then 
 ignite and weigh again, calculating loss as organic 
 matter and the residue as clay and sand. 
 
 Make the filtrate ud to 200 c.c; divide into two 
 parts A and B. 
 
 Sulfuric Acid. — Nearly neutralize A with NajCOj, 
 heat solution nearly to boiling and add BaClj, and pro- 
 ceed as under H^SO, determination. From the sul- 
 furic acid calculate the per cent of gypsum. 
 
 Iron and Alumina. — To B add HNO, to oxidize 
 
26 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 any iron from ferrous to ferric condition, and determine 
 iron and alumina as in dolomite. 
 
 Lime. — To the above filtrate heated to boiling add 
 (NH,)jC,04, and determine lime as in dolomite. 
 
 Carbonic Acid. — In one gram of the finely-pulver- 
 ■ized gypsum determine the CO, as under carbonic 
 acid, and from this calculate the per cent of calcium 
 carbonate contained in the gypsum. 
 
 20. Mineral Phosphates. 
 
 Apatite. — Pulverize finely and dry to ioo°. Of the 
 dry mineral weigh out one gram in a porcelain dish, 
 add lOO c.c. concentrated HCl and evaporate to dry- 
 ness on water-bath; moisten residue with HCl, add lO 
 c.c. of dilute HNO,, and evaporate again to dryness. 
 To the' residue add 50 c.c. water and 5 c.c. HNO„ 
 filter, and make up to 200 c.c. To 50 c.c. of filtrate 
 add about 15 grams dry ammonium nitrate, heat, 
 add 50 c.c. of " molybdate solution," and keep at a 
 temperature of 65" for one hour or in a warm place at 
 about 60° for several hours. Filter and wash with a 
 solution of ammonium nitrate. Dissolve the ppt. on 
 the filter with ammonia and hot water, nearly neu- 
 tralize solution with HCl, cool, add " magnesia mix- 
 ture ' ' slowly, and treat as in previous determination 
 
 of PA- 
 
 The determination of bases may be made as in 
 dolomite and feldspar if desired. 
 
CHAPTER III. 
 
 VOLUMETRIC ANALYSIS. 
 
 Briefly, volumetric analysis is quantitative analy- 
 sis by measure instead of by weight, as in gravimetric. 
 For volumetric work, three things are essential: 
 
 1st. Solutions, the chemical power of which is abso- 
 lutely known — called " Standard Solutions." 
 
 2d. Carefully graduated vessels called " burettes." 
 
 3d. A means of detecting by the eye the end reac- 
 tion. This is usually made possible by means of an 
 indicator. 
 
 There are also three important classes of reactions 
 to be considered: 
 
 1. Where the determination is effected by satura- 
 tion or by neutralization with substances of opposite 
 chemical properties, as acids and alkalis. 
 
 2. Where the determination is made by processes 
 of reduction or oxidation, using agents of known 
 power, as potassium permanganate, potassium bichro- 
 mate, iodin, etc., as oxidizing agents, and ferrous and 
 stannous compounds and sodic thiosulfate as reducing 
 agents. 
 
 27 
 
28 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 3. Where the determination is effected by precipi- 
 tation in some insoluble and definite combination, as 
 in the case of silver and chlorin. 
 
 Many determinations are best made wholly or in 
 part by means of volumetric methods. For this pur- 
 pose standard solutions are necessary, and they are 
 usually made of such strength that looo c.c. would 
 contain an amount exactly equivalent to one gram of 
 hydrogen, and are known as normal solutions; that 
 is, are of such strength that i c.c. of any of the acids 
 will exactly neutralize i c.c. of any of the bases. 
 Such solutions are made by weighing the equivalent 
 of the molecular weight of univalent acids and 
 bases, or one-half of the molecular equivalent of 
 divalent acids or bases, and bringing the solution to 
 1000 c.c. by the addition of distilled water. Semi- 
 normal would be half this strength, tenth normal 
 (^^ir) one-tenth this strength, and others in the same 
 manner. A normal solution of NaOH would contain 
 40 grams NaOH per 1000 c.c, and would just neutral- 
 ize an equal amount of normal HCl solution contain- 
 ing 36.37 grams HCl. For volumetric work the first 
 essential is to prepare accurately adjusted normal 
 solutions, and these must be kept in well-stoppered 
 bottles, and best in a cool place. From time to time 
 they need to be restandardized to see that the 
 " titre " remains unchanged, 
 
VOLUMETRIC ANALYSIS. 29 
 
 21. Normal Sulphuric Acid. 
 
 Weigli out 60 grams of concentrated H^SO,, and add 
 this to 1050 c.c. of distilled H;0; mix well, and allow 
 to cool to about 18° C, at which temperature all volu- 
 metric determinations should be made. Determine, 
 by means of barium chlorid, the amount of sulfuric 
 acid in at least three portions each of exactly 20 c.c. 
 The results must agree, or further determinations will 
 be necessary, and the average of all concordant deter- 
 minations taken as the mean. Determine from this 
 mean the amount of water necessary to add, so that 
 each 1000 c.c. shall contain exactly 49 grams of 
 HjSO^, or 40 grams of SO3, which- is the half molec- 
 ular weight. Thus if 1.078 grams H^SO^ were found 
 in 20 c.c, then in 1000 c.c. there would be 53.9 
 grams of H^SO,, in place of 49 grams, as should be for 
 a normal solution; therefore every 1000 c.c. of the 
 solution should be diluted to iioo c.c. (49 : 1000 :: 
 53.9 : ;f = 1 100 c.c). One c.c. of this solution con- 
 tains .049 gram H^SO,. From the solution by dilu- 
 tion N/5, N/io, or N/ioo solutions may be prepared 
 at any time. 
 
 22. Normal (Na^COj). 
 
 Ignite to low redness chemically pure neutral 
 sodium carbonate and from the desiccated product 
 weigh out 53 grams and dissolve to one litre. One 
 
30 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 c.c. of this should exactly neutralize i c.c. of the 
 normal H,SO,. If it does not, then one of the solu- 
 tions is wrong, and an effort should be made to deter- 
 mine the source of the error. 
 
 23. Semi-normal (NH,). 
 
 A normal solution of NH, does not keep its strength 
 well, but a half-normal solution gives good satisfac- 
 tion, and should be of such strength that each lOOO 
 c.c. shall contain 8.5 grams NH,. This is made by 
 diluting ammonia with distilled water until 20 c.c. 
 NH, will be exactly neutralized by 10 c.c. of the 
 normal H,SO, or 20 c.c. of the half normal, using 
 cochineal, litmus, or phenol-phthalein solutions as an 
 indicator. 
 
 24. Indicators. 
 
 Cochineal is prepared by digesting i^ grams pulver- 
 ized cochineal in 25 c.c. alcohol and 100 c.c. water 
 for a few days at ordinary temperature, with occasional 
 shaking. The filtered solution is used, and has the 
 advantage of not being acted upon by CO, to the 
 extent of the other indicators, but it cannot be ustd 
 in presence of iron salts. 
 
 Litmus is prepared by digesting one part of the 
 litmus in six of distilled water; filter, and divide solu- 
 tion into two parts; to one part add HNO, until of 
 reddish color, and then mix the two solutions and 
 
VOLUMETRIC ANALYSIS. 3t 
 
 add one part of strong alcohol. Litmus cannot be 
 used in presence of carbonic acid. 
 
 Phenol-phthalein is best prepared by dissolving one 
 gram of phenol-phthalein in loo c.c. of 95 per cent 
 alcohol. With the aid of the above normal solutions 
 the strength of various alkalin or acid solutions may 
 be readily determined, and the same solutions can be 
 used in food analysis, and wherever nitrogen is to be 
 determined as ammonia. 
 
 25. Iron Determination. 
 
 Standard Decinormal Potassium Permanganate is 
 made by weighing out of the dry and pure salt 3.156 
 grams and dissolving to looo c.c. The solution must 
 be kept in a cool, dark place. In titrating- perman- 
 ganate there must be present free acid, preferably 
 H,SO , to prevent the precipitation of manganous 
 oxid. Organic matter interferes and solutions cannot 
 be filtered through paper; but asbestus, glass wool, or 
 guncotton may be used. 
 
 The above solution is of such a strength that 17.35 
 c.c. will just oxidize on'e decigram of Fe. 
 
 The iron must be in the ferrous condition, and this 
 condition may be brought about by the presence of 
 magnesium or metallic zinc in H^SO, solutions, but all 
 zinc or magnesium must be dissolved or removed 
 before titration. 
 
32 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Permanganate. 
 
 I c.c. N/io solution 0056 gram Fe ; 
 
 ICC. " " 0072 " FeO; 
 
 I c.c. " " 008 " Fe,0,. 
 
 The above factors will furnish data for calculating 
 the results to the form indicated. 
 
 Determination. — Weigh out about one gram of 
 metallic iron wire, dissolve in dilute H^SO, by aid 
 of heat. Use a small fla.sk closed with cork, carrying 
 a small glass tube to act as reflex condenser. When 
 dissolved, add 50 c.c. of recently boiled distilled 
 water and titrate with permanganate, using no indi- 
 cator. 
 
 Or, weigh out of ammonium ferrous sulfate 
 (Fe(NHJj(S0Jj6H,0) .7 gram, dissolve in water, and 
 add 5 c.c. of dilute H,SO, (i to 5), and titrate with 
 the permanganate until rose-color is permanent. 
 .7 gram "of above salt equals .1 gram Fe. 
 
 Questions. — In titrating with permanganate, why 
 should free acid be present? Why is H,SO^ preferred? 
 Why cannot filter-paper be used in this work? Why 
 must the Fe be in the ferrous condition? In what way 
 is the ferric changed to the ferrous by the presence 
 of zinc? In iron determination why use a flask with 
 reflex condenser? Why use freshly boiled distilled 
 water? 
 
VOLUMETRIC ANALYSIS. 33 
 
 26. Calcium Determination. 
 
 Of calcium carbonate weigh out .5 gram, bring into 
 solution, make up to 200 c.c, and use 50 c.c. for each 
 determination. Precipitate as an oxalate, and dissolve 
 ppt. in small quantity of hot HCl; wash into flask, 
 make up to about 50 c.c. with fresh-boiled distilled 
 water, acidify with H^SO,, warm to about 75° C, and_ 
 titrate with decinormal permanganate to a faint pink 
 tinge. I c.c. permanganate = .0028 gram of CaO, or 
 .0050 gram CaCOj. 
 
 Questions. — Why is it necessary to precipitate the 
 Ca as an oxalate? Why use H,SO, to acidify with? 
 What is the reaction between the permanganate and 
 the Ca? 
 
 27. Chlorin. 
 
 For determination of CI volumetrically, a standard 
 N/io silver solution is necessary. To produce this, 
 weigh out 17 grams of AgNO, and make up to lOOO 
 c.c. with distilled water and keep in dark, i c.c. of 
 this solution is equivalent to .005837 gram NaCl or 
 to .003537 gram CI. 
 
 Determination. — Weigh out about one gram NaCl, 
 make up to 200 c.c. with distilled water, and place 
 exactly 20 c.c. in a white porcelain dish; add a few 
 drops of saturated solution of potassium chromate, 
 and titrate with N/io silver solution. Each c.c. of 
 
34 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 silver solution required in " titre " equals .003537 
 gram CI or .005837 gram NaCl. A standard solution 
 of sodium chlorid may be used for determining silver. 
 Questions. — What is the reaction between th.e silver 
 solution and the CI? What is the product formed at 
 the end reaction? What other product is formed at 
 the end reaction? 
 
CHAPTER IV. 
 THE ANALYSIS OF ASHES AND SOILS. 
 
 28. Ash Analysis. 
 
 The material for ash analysis should be burned at 
 low heat until well freed from carbon, then thoroughly 
 pulverized in an agate mortar, and preserved in well- 
 stoppered bottles until wanted. 
 
 Solutions. — Weigh out one gram of ash in a plati- 
 num evaporator, add a little water, then invert a small 
 glass funnel in evaporating-dish, and add cautiously 
 HCl until effervescence ceases; then a few drops of 
 HCl in excess, and evaporate the whole to dryness on 
 water-bath. Moisten the residue with HCl, add 
 water, and heat on water-bath for a few minutes, then 
 filter through a tared Gooch crucible. The residue is 
 sand, silica, and carbon. Dried, weighed, and ignited, 
 the loss is taken as carbon, while the residue is taken 
 as sand and silica. 
 
 Dilute the filtrate to 200 c.c, and measure out 
 50 c.c. of the filtrate, 50 c.c. for each determination, 
 or .25 grams of ash. Three portions are measured 
 out in beakers A, B, and C. 
 
 35 
 
36 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 A. Sulfuric Acid. — Dilute solution A to loo c.c. 
 or more, heat to boiling, and add barium chlorid to 
 ppt. BaSO,. Complete determination as in H,SO, 
 
 Alkalis. — Heat the filtrate from above and add 
 Ba(OH), in slight excess, then i c.c. NH.OH and 
 ammonium carbonate in slight excess, now add about 
 .5 gram of dry powdered oxalic acid; filter, and wash 
 well with hot water and evaporate filtrate to dryness, 
 adding 5 c.c. of HCl to convert alkalis into chlorid. 
 Determine Na and K as in method for separating 
 these metals. 
 
 B. Iron and Alumina. — To the 50 c.c. of orig- 
 inal solution add NH,OH to alkalinity, then a few 
 drops of sodium acetate, and acetic acid in excess. 
 The precipitate is ferric and aluminic phosphate. 
 After drying, igniting in tared crucible, and weighing 
 the desiccated product, the iron and alumina may be 
 separated as follows: Bring residue of iron and alum- 
 ina into a beaker, add 15 c.c. of dilute H,SOj (iHjSOj 
 to 4 H,0), heat on water-bath with beaker covered 
 until in solution, then determine Fe with potassium 
 permanganate by volumetric method, and from these 
 results and total iron and aluminum phosphate esti- 
 mate the amount of iron and alumina. 
 
 Lime. — Heat filtrate from last, add ammonium 
 oxalate, allow to stand a few hours, and determine 
 CaO as in calcium determination. 
 
 Magnesia. — Make filtrate from last alkalin with 
 
THE ANALYSIS OF ASHES AND SOILS. 37 
 
 NH,OH and add sodium hydrogen phosphate, and 
 allow to stand for twelve hours; filter, wash with 
 dilute ammonia, and weigh precipitate as MgjP^O, 
 by methods already given. 
 
 C. Phosphoric Acid. — To soc.c. of original solu- 
 tion add about 15 grams dry ammonium nitrate and 
 50 to 75 of molybdic solution, and continue the 
 determination as for phosphate under apatite. 
 
 Chlorin. — Weigh out one gram ash, add water and 
 a few drops HNO,, heat on water-bath for a few 
 minutes, filter and wash with hot water and determine 
 CI by means of standard AgNO, solution, using potas- 
 sium chromate as an indicator or the chlorin may be 
 precipitated with silver and weighed gravimetrically. 
 
 Carbon Dioxid. — Weigh out 3 grams of ash and 
 determine carbon dioxid same as in carbonic acid 
 determination. 
 
 Questions. — Why moisten the residue from ash with 
 HCl before dissolving and filtering? In determining 
 the alkalis why add oxalic acid ? In separating Fe and 
 Al what reactions take place? 
 
 29. Soil Analysis. 
 
 The sample of soil for analysis should be well air- 
 dried, and then passed through a sieve with circular 
 openings one-half millimeter in diameter, using if 
 necessary a rubber-tipped mortar to crush lumps, but 
 
38 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 not to grind sample. The fine portion to be used for 
 analysis should be preserved in a well-stoppered bottle. 
 
 Moisture. — Dry in water-oven on watch-glasses 
 about 3 grams of soil until weight remains nearly con- 
 stant. Loss is moisture. 
 
 Volatile Matter. — Heat the soil as dried above in a 
 platinum dish to full redness until all organic matter 
 is burned. Loss in weight represents volatile matter. 
 
 Analysis Proper. — In an Erlenmeyer flask of 200 
 c.c. capacity place 10 grams of air-dried soil and 100 
 c.c. of HCl, sp. gr. of 1. 1 1 5. Close flask with cork, 
 carrying a glass tube about 2 ft. in length to act as 
 reflux condenser. Place flask in water-bath and keep 
 at boiling temperature for ten hours with occasional 
 shaking. Transfer contents of flask to beaker, and 
 bring residue on to filter and wash with distilled 
 water; dry residue and weigh as insoluble material. 
 Make solutions and washings up to 500 c.c. with dis- 
 tilled water. 
 
 Iron and Alumina. — 100 c.c. of above solution are 
 made slightly alkalin with NH^OH, then boiled to 
 expel excess of ammonia, filtered, and well washed 
 with hot distilled water. The precipitate is iron, 
 alumina, and phosphates. These may be separated 
 as in ash analysis. 
 
 Manganese. — The filtrate above is concentrated to 
 about 100 c.c, NH^OH added to alkalinity, bromin 
 water added and the solution heated to boiling. 
 
THE ANALYSIS OF ASHES AND SOILS. 39 
 
 Allow the solution to cool and add more bromin water 
 and ammonia, and heat as before to precipitate all the 
 manganese; acidify with acetic acid, and filter. While 
 still boiling, wash with hot water and ignite as MnjO^. 
 
 Calcium. — Evaporate above filtrate to about 50 c.c, 
 add ammonia to slight alkalinity, and to the hot 
 solution add ammonia oxalate, and determine CaO as 
 by methods already given. 
 
 Magnesia. — If necessary concentrate the filtrate 
 above, make alkalin with NH^OH, and add Na^HPO^, 
 and determine Mg as under magnesia determination. 
 
 Alkalis. — To the last filtrate add NH.OH, boil to 
 expel excess of ammonia, filter, and wash. Evaporate 
 the filtrate to dryness, heat below redness to expel 
 ammonia salts, add 30 c.c. of water, then a few drops 
 of Ba(OH), solution, and heat to boiling. Filter, and 
 wash with hot water. To the filtrate add NH,OH 
 and ammonium carbonate, filter, and wash with hot 
 water. Evaporate to dryness and determine total 
 alkalis, and make separation of K and Na as in method 
 already given. 
 
 Carbon Dioxid. — In 5 grams of the air-dried soil 
 determine carbon dioxid by method already described 
 under carbonic acid determination. 
 
 Chlorin. — 20 grams of soil are placed in flask and 
 100 c.c. water added, and with frequent shakings 
 allowed to stand for two hours, then filtered, and the 
 filtrate and washings made up to 200 c.c. In 50 c.c. 
 
40 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 of solution determine CI by volumetric method, with 
 standard AgNO, solution, using potassium chromate 
 as an indicator. A porcelain dish is best for making 
 the " titre" in. 
 
 30. Nitrogen Determination. 
 
 Of the air-dried soil weigh out 3 grams, place in 
 digestion-flask, add 30 c.c. of concentrated sulfuric 
 acid (sp. gr. 1.84) containing one gram of salicylic 
 acid, and thoroughly mix by shaking. Heat over a 
 low flame until no further frothing, aftd then boil 
 briskly for five or ten minutes ; now add about 0.7 gram 
 of mercuric oxid, and continue the boiling until solu- 
 tion is colorless; then complete oxidation by adding 
 slowly fine pulverized potassium permanganate to the 
 hot solution, until after shaking the solution is green 
 or purple in color. Transfer the contents of the cool 
 flask to a distilling flask, using about 100 c.c. of 
 water, and add a few pieces of granulated zinc to pre- 
 vent bumping; now add 30 c.c. of potassium sulfid 
 solution (40 grams K,S in 1000 c.c. H,0), and after 
 shaking add 80 c.c. of caustic soda solution or enough 
 to make it alkalin (saturated solution of NaOH), 
 connect at once with the condenser, and distil over 
 about 125 c.c, receiving into a measured quantity of 
 standard acid, and then, titrate with standard alkali, 
 using cochineal as an indicator, i c.c. of the deci- 
 normal H,SO^ is equal to .0014 gram of nitrogen. 
 
THE ANALYSIS OF ASHES AND SOILS. 4 1 
 
 In absence of nitrates the salicylic acid may be 
 omitted from the H^SOj otherwise the nitrogen 
 determination is made the same as above, with vary- 
 ing amount of substance to be analyzed, according to 
 its nitrogen content. 
 
 Questions. — What is the action of the H,SO, on the 
 organic matter? Why is salicylic acid necessary in 
 the presence of nitrates? Why was HgO added? 
 Why not add the HgO first? What is the action of 
 the potassium permanganate? Before distilling, why 
 add KjS? What change takes place on adding the 
 NaOH solution? In what form did the N exist in the 
 soil? In what manner was it all transformed into 
 ammonia? Why use cochineal as the indicator? 
 
CHAPTER V. 
 
 ANALYSIS OF. ORES. 
 
 31. Iron Ores. 
 
 Moisture. — Dry the well-pulverized ore on a watch- 
 glass (2 to 3 grams) for two hours in water-bath. 
 
 Carbon Dioxid. — Introduce one gram of the pulver- 
 ized ore into the CO, apparatus, and determine by 
 usual method. 
 
 MAIN ANALYSIS. 
 
 Silica, etc. — Place 10 grams of the finely pulverized 
 
 ore in a porcelain dish, add concentrated HCl, and 
 
 heat on water-bath for thirty minutes. Evaporate 
 
 the solution to dryness. Add 10 c.c. HCl, warm 
 
 on water-bath, add water, and after settling decant 
 
 through filter into 500 c.c. flask; to the residue add 
 
 HCl, heat, and add water, decanting as before, 
 
 repeating if necessary until residue is free from iron; 
 
 then bring the residue on to filter, wash with hot 
 
 water, dry, and ignite as gangue and silica. The 
 
 filtrate is then made up to the 500 c.c. mark. 
 
 Sulfur. — Evaporate 100 c.c. of filtrate nearly to 
 
 42 
 
ANALYSIS OF ORES. 43 
 
 dryness, to expel acid; dilute with 150 c.c. of water, 
 boil, and add a few drops of BaCl, to ppt. BaSO, ; 
 allow to stand twelve hours, filter, and determine 
 SO3 in precipitated BaSO,. 
 
 Phosphoric Acid. — To lOO c.c. of the original filtrate 
 after heating add about 15 grams NH^OH, then the 
 molybdate solution, and allow to stand in a warm 
 place for twenty-four hours; filter, and wash with 
 ammonium nitrate solution. The precipitate on filter- 
 paper is then dissolved with NH,OH and hot water, 
 nearly neutralized with HCl, and ' ' magnesia mixture " 
 added to ppt. PjO^. After standing fifteen minutes 
 add 30 c.c. of NHjOH, and allow to stand for twenty- 
 four hours. Complete determination in usual manner. 
 If the ore is arsenic bearing, to this filtrate, before 
 .adding the molybdate solution, run in H^S to precipi- 
 tate the As as a sulfid. Heat the filtrate to expel 
 H,S, and proceed as above. 
 
 Iron, Alumina, and Phosphates. — 100 c.c. of the 
 original solution is boiled with a few drops of HNOj, 
 then acid ammonium carbonate added until the liquid 
 is yearly neutral; then to the red solution add ammo- 
 nium acetate in excess, boil for some time, and allow 
 to settle. Filter (filtrate A), wash with hot water, 
 dry, ignite, and weigh as FejOj.AljO, and phosphates. 
 Deduct the weight of phosphates already determined, 
 and residue is iron and alumina. 
 
 Separation of Iron and Alumina. — Place precipitate 
 
44 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 in flask, add dilute H,SO^, and heat on water-bath 
 until dissolved; make up to 200 c.c, measure out 50 
 c.c, and titrate with standard permanganate solution. 
 
 Manganese. — To filtrate A add a few drops of Br 
 water, heat to 50° C, tightly cork flasks, and allow to 
 stand for twelve hours. The manganese will precipi- 
 tate, and then may be filtered off, dried, ignited, and 
 weighed as Mn^O,. 
 
 Lime. — Concentrate last filtrate to about 100 c.c, 
 add NHjOH and ammonium oxalate to precipi- 
 tate Ca. 
 
 Magnesia. — Evaporate last filtrate to dryness, ignite 
 at low redness, redissolve, and add one gram oxalic 
 acid; evaporate to dryness and heat to low redness. 
 Redissolve alkalis, filter, wash, dry, ignite, and weigh 
 as vlgO. 
 
 Alkalis. — Evaporate filtrate from above to dryness, 
 after adding a few drops of HCl, ignite, and weigh as 
 total alkali. The potash and soda may then be sep- 
 arated by usual methods, if desired. 
 
 Questions. — Why was HCl added to residue before 
 redissolving for the silica? In what form was S in the 
 ore? How was it converted to the sulfate? In PjO^ 
 determination, why add NH,OH before adding the 
 molybdate solution ? Why not wash precipitate 
 with water? Why was ammonium acetate used in 
 precipitating iron? Why was HNO, added? What 
 is the action of the Br in the Mn determination? 
 
ANALYSIS OF ORES. 45 
 
 32. Zinc Blende. 
 
 Place about one gram of the finely pulverized ore in 
 a porcelain dish and add HNO3. This dish should be 
 covered and gradually heated on water-bath. When 
 all action has ceased, evaporate "to dryness, moisten 
 with HCl, add water, heat, and then filter and wash 
 precipitate with hot water. The residue is gangue. 
 To the filtrate add HjS to saturation, and then filter. 
 Boil filtrate to expel all of the H,S. Add a few drops 
 of Br water to oxidize any iron, add NH,OH in slight 
 excess, then a few drops of potassium permanganate, 
 and boil and filter to remove iron. To the filtrate 
 while hot add acetic acid to acidulate, and then HjS 
 until the zinc is all precipitated. Wash by decanta- 
 tion with hot water containing HjS, filter (filtrate B), 
 and dissolve precipitate in HCl. Add water and a 
 few crystals of KCIO,, and boil; filter off S, and to 
 filtrate add Na^COs to precipitate zinc as a carbonate, 
 filter, wash with hot water, dry, and ignite in a porce- 
 lain crucible as ZnO. 
 
 Filtrate B from the ZnS is boiled, and ammonium 
 oxalate added to precipitate CaO. 
 
 To the last filtrate add NH,OH and then sodium 
 acid phosphate to precipitate Mg, which is weighed 
 as Mg,P,0,. 
 
 Instead of dissolving zinc in HCl, nitric acid may 
 be used, the excess of HNO, evaporated off and 
 
46 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 •microcosmic salt added in excess, the solution heated 
 to boiling, NH.OH added to alkalinity, and the pre- 
 cipitate ignited and weighed as Zn^PjO,. Or, the 
 sulfid may be treated in the crucible with a few 
 drops of HNOj and H,SO„ and then gently heated on 
 a plate some distance above flame, until the sulfid is 
 transformed into a sulfate, and as such weighed. 
 
 Questions. — Why use HNOj instead of HCl for dis- 
 solving the blende? Why add H,S before precipitat- 
 ing Zn? Why use H,S in wash-water? Why ignite 
 in porcelain? 
 
 33. Galena. 
 
 Of the finely pulverized ore, weigh out about one 
 gram, add 20 c.c. of concentrated HNOj in covered 
 porcelain dish, and heat slowly on water-bath. 
 Evaporate nearly to dryness, then add 8 c.c. of water 
 and heat on water-bath; then add $ c.c. concentrated 
 HjSOj, and continue heating until SO, fumes are 
 given off; then allow to cool, and add 100 c.c. water 
 and heat to boiling, breaking up the precipitate by 
 stirring. Allow to cool and decant, then wash the 
 precipitate on to filter with a i per cent H,SO, solu- 
 tion, and finally wash with alcohol. Transfer precipi- 
 tate to porcelain dish, add a hot concentrated solution 
 of ammonium acetate, made slightly acid with acetic 
 acid, to dissolve the PbSO,. Filter into a beaker, 
 pouring the filtrate through the filter several times; 
 
ANALYSIS OF ORES. 47 
 
 then wash with hot water. To the filtrate add H,SO^, 
 allow to stand until precipitate has settled, then filter, 
 wash with i per cent H^SO^, and finally with alcohol ; 
 dry, ignite filtrate separately, oxidizing with HNO,, and 
 then add the ash to the precipitate and ignite as for lead. 
 
 To the filtrate, after adding loo c.c. water, add a 
 few drops of HCl to precipitate Ag if present; filter, 
 and determine Ag as AgCl. 
 
 To the filtrate add NH^OH to alkalinity to pre- 
 cipitate Fe, and determine as for Fe determination. 
 
 To filtrate add H^S to precipitate the Cu, Zn, etc., 
 as sulfids, which may then be separated and deter- 
 mined by the methods already given. 
 
 Questions. — Why redissolve precipitate with am- 
 monium acetate? Why reprecipitate with H,SO^? 
 Why add H,SO, to the wash- water? 
 
 34. Coal Analysis. 
 
 Moisture. — Place one to two grams of the finely 
 pulverized coal in a platinum crucible, and heat in an ' 
 air-bath at 1 10° for fifteen minutes. Cool and weigh. 
 Repeat for fifteen minutes more, cool, and weigh to 
 see if weight remains constant. Loss is moisture. 
 
 Volatile Matter. — Heat the above crucible with 
 contents for about three and one-half minutes over 
 IJunsen burner, and then for three and one-half 
 minutes over blast-lamp. The crucible should remain 
 
4^ QUANTITATIVE CHEMICAL ANALYSIS. 
 
 covered during the entire process. Cool and weigh. 
 Loss is volatile matter, and one-half of the sulfur that 
 may be contained in the coal in form of sulfid. 
 
 Fixed Carbon. — Heat the above crucible until ash 
 is white. Cool, and weigh, the loss being fixed carbon 
 and one-half of any sulfur that may have been in the 
 coal. 
 
 Sulfur. — Place 1.5 grams of the finely pulverized 
 coal in flask, and add concentrated HNO, and potas- 
 sium chlorate to oxidize all the organic matter; filter, 
 and to the hot filtrate add a little HCl, then BaCl, in 
 slight excess; allow to settle, filter, wash, dry, ignite, 
 and weigh as for sulfuric acid determination. The 
 weight of the precipitate multiplied by 16/1 16.5 gives 
 the weight of sulfur in the coal. 
 
CHAPTER VI. 
 ELECTROLYSIS. 
 
 Electrolysis is the galvanic decomposition of 
 compounds, called electrolytes. Electrolytic analysis 
 is the decomposition of a compound, and depositing of 
 the radicle or element in a form to be weighed or 
 " titred." Water acidulated with H,SO, and a gal- 
 vanic current passed through it is decomposed into its 
 elements H and O. One of the elements or groups of 
 a compound separates at the positive pple or anode 
 and is called anion, and the other separating at the 
 negative electrode is called cathion or electropositive 
 constituent or element. The metals are electroposi- 
 tive or cathions, while the non-metals are electronega- 
 tive or anions, and appear at the positive pole. 
 
 The ohm is the unit of resistance, and is equivalent 
 to the resistance offered by a column of pure mercury 
 106.2 centimeters in length and one 'square millimeter 
 in section at a temperature of 0° C. 
 
 The volt is the unit of electromotive force, and 
 produces a current of one ampere with a resistance of 
 one ohm. 
 
 49 
 
50 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Ampere is a unit of current, and is produced by an 
 electromotive force of one volt acting against a resist- 
 ance of one ohm. 
 
 Batteries. — The Bichromate, Leclanchd, Grover, 
 Daniell, Crowfoot, or Smee battery may be em- 
 ployed. I have found the Crowfoot and Smee 
 batteries to be satisfactory for student use, for such 
 work as has been undertaken. Expensive apparatus 
 is not necessary, and laboratory improvised pieces 
 have been used by the students, for the work men- 
 tioned beyond, as successfully as the most expensive 
 apparatus. Only enough work in electrolysis is 
 undertaken to give the student a. knowledge of the 
 processes, and those desiring further work along this 
 line are referred to the special works devoted to this 
 important subject. 
 
 Arrangement of Apparatus. — A clean platinum dish 
 free from dents — preferably one used for no other pur- 
 pose — is employed to hold the solution to be electro- 
 lyzed, and upon the inner surface of which the metal 
 is to be deposited. To the arm of an ordinary filter- 
 stand is attached a binding-screw, to which is attached 
 the positive pole' or wire from the battery and the 
 spiral coil of platinum wire that dips into the solu- 
 tion to be electrolyzed. On the base of the filter- 
 stand is placed a piece of copper plate, upon which 
 the platinum dish rests, and a binding-screw through 
 the copper plate or ring serves to connect the negative 
 
S.LECTROL VSIS. S I 
 
 wire or pole from the batteries. From one to three 
 batteries are used for the decomposition of copper, 
 iron, or nickel. If a voltmeter is available, the exact 
 current desired can be secured for each particular 
 determination; thus for electrolyzing Cu, a current 
 giving from 0.3 to 0.5 c.c. of electrolytic gas per 
 minute is all that is necessary from the sulfate solu- 
 tion, or 3 to 4 c.c. from ammonium oxalate solutions. 
 For nickel, a current of 5 c.c. electrolytic gas is best, 
 and for iron 8 to 10 c.c. per minute. 
 
 An ampere is equal to 10.436 c.c. of electrolytic 
 gas per minute. By electrolytic gas is meant oxy- 
 hydrogen gas decomposed from acidulated water by 
 the current employed. 
 
 35. Copper. 
 
 Dissolve 4.9 grams of the pure copper sulfate in 
 water and make up to 200 c.c. Place 50 c.c. of this 
 solution in a platinum dish, the weight of which is 
 accurately known. The negative pole of the battery 
 is then connected with the dish, and the positive pole 
 is connected with a coiled spiral of platinum wire that 
 just dips into the solution, but does not touch the 
 dish. Continue the process until all of the Cu is 
 deposited and no reaction is shown with a freshly 
 prepared solution of potassium ferrocyanid. For the 
 successful precipitation of Cu a weak current is neces- 
 
52 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 sary. A strong current deposits the Cu in a spongy 
 condition. The deposited copper should then be 
 washed carefully with hot distilled water, then with 
 alcohol, dried, and weighed. (The 50 c.c. above 
 contain exactly .25 gram of Cu.) 
 
 36. Nickel. 
 
 Dissolve 3.586 grams of pure nickel sulfate in dis- 
 tilled water and make up to 200 c.c. Place 50 c.c. 
 of the solution in a platinum dish carefully weighed, 
 and add NH^OH to strong alkalinity. Place the dish 
 in connection with the negative pole, and the positive 
 pole attached to a platinum electrode is placed in the 
 solution, and the process continued until the Ni is all 
 precipitated ; then wash with hot water, followed by 
 alcohol; dry at 110°, cool, and weigh. (The 50 c.c. 
 of solution contain exactly .20 gram of Ni-.) A 
 strong current is required for depositing Ni. Two 
 and perhaps three Bunsen cells will be required to do 
 the work in twelve hours. 
 
 37. Iron. 
 
 Place 1.5 grams of pure iron sulfate in flask, add 
 water to dissolve, then a saturated solution of am- 
 monium oxalate in excess until precipitate redissolves 
 and solution is yellowish red in color; then make up 
 to 200 c.c. Place 50 c.c. of this solution in a tared 
 
ELECTROLYSIS. 53 
 
 platinum dish, add 50 c.c. of water, and electrolyze 
 as for nickel. While electrolyzing the solution, for 
 good results the solution should be kept at 65° to 
 70° C, when the iron will be deposited as a steel-gray 
 product. The electrolyzed solution should give no 
 reaction for iron when a few drops are made acid with 
 HCl and potassium sulfocyanid is added. Should 
 Fe(OH), be deposited during the process, this pre- 
 cipitate may be again redissolved by adding drop by 
 drop oxalic acid. A strong current is required for 
 depositing the iron. 
 
CHAPTER VII. 
 SUGARS, STARCHES. FOODS AND MILK. 
 
 38. Fehling's Solution. 
 
 1. 69.278 grams of crystallized- copper sulfate are 
 dissolved in water and made up to 1000 c.c. 
 
 2. 346 grams of Rochelle salts and 80 grams of 
 NaOH are dissolved in water up to one litre. These 
 two solutions are kept separate and mixed together in 
 equal volumes when wanted for use. 
 
 3. 104 grams of iron ammonium alum are weighed 
 out, dissolved in water, 40 c.c. of H,SO, added, and 
 the solution made up to 1000 c.c. 
 
 4- 3-5 grams of potassium permanganate are 
 weighed out, placed in a flask, and diluted to 1000 
 c.c. with distilled water. 
 
 Solution 4 should be standardized by using cane- 
 sugar of known purity. One c.c. of the permanganate 
 is equivalent to 6.9 mg. of copper reduced to cuprous 
 oxid. Or, for convenience in calculations, the fol- 
 lowing table is inserted showing milligrams of sucrose 
 and of invert-sugar for each c.c. of permanganate from 
 
 54 
 
SUGARS, STARCHES, AND FOODS. 
 
 55 
 
 I c.c. to 64 c.c. The other sugars and starch are 
 readily calculated from the data given, for fractions 
 of a c.c. of permanganate interpolations can easily be 
 made. 
 
 TABLE SHOWING MILLIGRAMS SUGAR PER C. C. 
 PERMANGANATE. 
 
 Permanga- 
 
 Sucrose, 
 
 Invert Sugar. 
 
 Permanga- 
 
 Sucrose, 
 
 Invert Sug:ar, 
 
 nate, C. C. 
 
 Milligrams. 
 
 Milligrams. 
 
 nate, C. C. 
 
 Milligrams. 
 
 Milligrams. 
 
 I 
 
 3-0 
 
 3.17 
 
 33 
 
 II5-0 
 
 121. 05 
 
 2 
 
 6.1 
 
 6.42 
 
 34 
 
 118. 8 
 
 125.05 
 
 3 
 
 9.2 
 
 9.67 
 
 35 
 
 122.5 
 
 128.94 
 
 4 
 
 12.3 
 
 12.93 
 
 36 
 
 126.3 
 
 132.94 
 
 5 
 
 15-5 
 
 16.31 
 
 37 
 
 130.0 
 
 136.84 
 
 6 
 
 . 18.8 
 
 19.79 
 
 38 
 
 i33-8 
 
 140.84 
 
 7 
 
 22.0 
 
 23-15 
 
 39 
 
 137-6 
 
 144-84 
 
 8 
 
 25.2 
 
 26.52 
 
 40 
 
 141 -5 
 
 148.94 
 
 9 
 
 28,5 
 
 30.00 
 
 41 
 
 145-4 
 
 153-04 
 
 10 
 
 31-8 
 
 33-47 
 
 42 
 
 149.3 
 
 157-15 
 
 ir 
 
 35.1 
 
 36-94 
 
 43 
 
 153-2 
 
 161.26 
 
 12 
 
 38.5 
 
 40.52 
 
 44 
 
 157-2 
 
 165.47 
 
 13 
 
 42.0 
 
 44.21 
 
 45 
 
 161. r 
 
 169.57 
 
 14 
 
 45-4 
 
 47-79 
 
 46 
 
 165.0 
 
 173-68 
 
 15 
 
 48.9 
 
 51-47 
 
 47 
 
 169.0 
 
 177-89 
 
 16 
 
 52.4 
 
 55-15 
 
 48 
 
 173-0 
 
 182.10 
 
 17 
 
 56.0 
 
 58.94 
 
 49 
 
 177-1 
 
 186.42 
 
 18 
 
 59-6 
 
 62.73 
 
 50 
 
 i8l-i 
 
 190.63 
 
 19 
 
 63.2 
 
 65-47 
 
 51 
 
 185.2 
 
 194 94 
 
 20 
 
 66.9 
 
 70.42 
 
 52 
 
 18.9.5 
 
 199.47 
 
 21 
 
 70.4 
 
 74.10 
 
 53 
 
 193-5 
 
 203.68 
 
 22 
 
 74-1 
 
 78.00 
 
 54 
 
 197.6 
 
 208.00 
 
 23 
 
 77-9 
 
 82.00 
 
 55 
 
 201.8 
 
 212.42 
 
 24 
 
 81.4 
 
 85.68 
 
 56 
 
 206.0 
 
 216.84 
 
 25 
 
 85.0 
 
 89-47 
 
 57 
 
 210.2 
 
 221.27 
 
 26 
 
 88. 9 
 
 93-57 
 
 58 
 
 214.6 
 
 225.89 
 
 27 
 
 92-5 
 
 97-37 
 
 59 
 
 2ig.o 
 
 230.52 
 
 28 
 
 96-3 
 
 101.37 
 
 60 
 
 223.5 
 
 235.26 
 
 29 
 
 100. 
 
 105 . 26 
 
 61 
 
 227.9 
 
 239.89 
 
 30 
 
 103.8 
 
 109.26 
 
 62 
 
 232.2 
 
 244.42 
 
 31 
 
 107.5 
 
 112. 10 
 
 63 
 
 236.6 
 
 249.05 
 
 32 
 
 III. 2 
 
 117-05 
 
 64 
 
 241.0 
 
 253-68 
 
56 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 39. Methods of Determination. 
 
 Sugar. — rThe solution to be tested should not con- 
 tain more than 2 per cent of sugar; solutions contain 
 ing more than this should be diluted to a known 
 volume and an aliquot part taken. 
 
 Invert sugar. — Place 10 c.c. of the sugar solution 
 in a flask or beaker, add 50 c.c. of Fehling's solution 
 (Nos. I and 2 in equal volume), and bring to a boil; 
 continue the heating on water-bath for ten minutes, 
 filter through an asbestus filter, wash with hot water, 
 transfer filter and contents again to flask, add 100 c.c. 
 of the iron-ammonium-alum solution, and titrate at 
 once with permanganate. 
 
 Sucrose. — A known quantity of the solution is 
 treated with concentrated HCl, then heated on water- 
 bath for 30 minutes, neutralized with NajCO, made up 
 to a known volume, and sugar determined in 10 c.c. 
 as for invert-sugar. From total amount deduct 
 amount of invert-sugar above and balance is sucrose. 
 
 40. Food Analysis. 
 
 The air-dried substance should be ground fine and 
 kept in well-stoppered bottles for use. 
 
 Moisture. — About 2.5 grams of substance may be 
 dried for eight hours in water-oven on watch-glass, or 
 better in current of hydrogen when possible. The 
 loss in weight is moisture. 
 
 Ether Extracts. — A convenient piece of apparatus 
 
SUGARS, STARCHES, AND FOODS. S7 
 
 may be made by perforating a small hole in bottom 
 of test-tube, either by grinding on stone or by heating 
 in flame and blowing out. A small wad of recently- 
 ignited asbestus is put in the- bottom and "a little 
 asbestus pulp added, the filter is then washed and 
 dried, and the food used for moisture determinations 
 transferred to this. Into the tube, upon the food, 
 drop" a small piece of glass rod, and place the whole in 
 a Caldwell extraction-tube, attach to a condenser, 
 and attach a small weighed flask to the bottom to 
 receive the extract ; ether is now added and the sub- 
 stance is allowed to extr ct continuously for eight 
 hours. The flask beneath the extractor is kept nearly 
 submerged in boiling water during the process of ex- 
 traction. The ether is then driven off, the flask dried 
 in the water-oven, and when cooled weighed, at once 
 giving the amount of ether extract, often taken as fat. 
 
 Ask. — About 2 to 3 grams of the substance is 
 weighed into a platinum crucible and charred at 
 lowest possible heat, and then the burning continued 
 at low red heat until ash is white. 
 
 Nitrogen. — Place in digestion-flask .5 gram of the 
 air-dried substance and treat as for nitrogen in soil 
 analysis, omitting the salicylic acid from H^SO^, and 
 15 c.c. of the latter will usually be enough, instead 
 of 30 c.c. as in soil analysis. 
 
 Crude Protein. — The nitrogen multiplied by 6.25 
 will give the crude protein. 
 
58 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Albuminoid Nitrogen. Reagent. — Dissolve lOO 
 grams of pure copper sulfate in 5000 c.c. of water, 
 add 25 c.c. of glycerol, and then gradually a dilute 
 solution of NaOH until alkalin; filter, rub the ppt. up 
 with water containing 5 c.c. of glycerol per 1000 c.c, 
 filter, and wash the precipitate until the water is no 
 longer alkalin. Rub the ppt. up with a 10 per cent 
 glycerol solution until it will flow well from a pipette. 
 Determine the Cu (OH), per cubic centimeter of 
 this solution. Weigh out .7 gram of air-dry sub- 
 stance, add 100 c.c. of water, heat to boiling in a 
 beaker on water-bath and add enough of the cupric 
 hydrate solution to equal about .5 gram Cu (OH),; 
 filter, and wash with cold water, dry precipitate, 
 transfer to nitrogen flask, and determine nitrogen as in 
 above case, but use nearly double the amount of K^S. 
 The per cent of N X 6.25 == albuminoids. 
 
 Carbohydrates. — Of late much attention has been 
 given to a study of the carbohydrates, and experi- 
 mentally the method of Stone is given for this work. 
 
 Invert-sugar. — Weigh out of the material 10 
 grams, place in flask, add 100 c.c. 95 per cent alcohol, 
 and boil with a reflux condenser on water-bath for 
 two hours; filter, and determine sugar in aliquot part 
 by method already given, first evaporating off alcohol 
 and taking up sugar in water. 
 
 Sucrose. — A portion of the above solution is evap- 
 orated to dry off alcohol and the sugar taken up with 
 
SUGARS, STARCHES, AND FOODS. 59 
 
 water, the sucrose inverted by means of HCl, and 
 sugar determined by means of Fehling's solution, as 
 in last. Correcting for invert-sugar present, we have 
 sucrose or cane-sugar. 
 
 Dextrin. — The residue from the alcohol extraction 
 is returned to flask, 500 c.c. of water added, and the 
 whole allowed to stand for twenty-four hours with 
 frequent agitation. Filter through fine linen and 
 concentrate on water-bath to 200 c.c. In an aliquot 
 part of this solution invert with HCl, and determine 
 total invert-sugar by means of Fehling's solution. In 
 another portion precipitate the soluble starch by add- 
 ing barium hydroxid solution in excess, filter, and 
 invert by means of HCl, and determine invert-sugar, 
 which is taken as- the amount of dextrin. 
 
 Soluble Starch. — The total invert-sugar, above, less 
 that as dextrin, gives the soluble starch. 
 
 Starch. — The residue from the aqueous extract is 
 returned to the flask and 100 c.c. of water added, the 
 flask closed with a reflux condenser, and the contents 
 boiled for two minutes to convert the starch into a 
 soluble form. To the solution cooled to 60° 10 c.c. 
 of malt* infusion is added and allowed to act at a 
 temperature of not to exceed 65" from two to three 
 
 * To prepare malt infusion 10 grams of fine-ground fresh malt 
 are covered with 50 c.c. of water and kept at temperature of work 
 room from two to three hours with frequent shaking. The solu- 
 tion is then filtered and is ready for uss, 
 
6o QUANTITATIVE CHEMICAL ANALYSIS. 
 
 hours, or until there is no blue starch reaction with 
 iodin. The solution is then filtered, using a fine linen 
 filter, washed with hot water, and the filtrate concen- 
 trated on water-bath to lOO c.c. Transfer the filtrate 
 to a 200-C.C. flask, and add lo c.c. of concentrated 
 HCl and keep at temperature of boiling water on bath 
 for one hour to convert all the sugar into dextrose. 
 The solution is then neutralized with Na^CO^ and 
 sugar determined with Fehling's solution. A de- 
 termination must be made of the sugar contained in 
 the malt extract and a correction made for the same. 
 The starch may then be calculated from the inverted 
 sugar. 
 
 Pentosans. — Remove carefully from the linen filter 
 the residue from the starch determination, place in a 
 flask with lOO c.c. of water, add 2 c.c. of concentrated 
 HCl and keep at boiling temperature for one hour, 
 using reflux condenser to prevent evaporation. By 
 this treatment the most of the gums, pentosans, etc., 
 are converted into reducing-sugars, taken as xylose. 
 The solution is filtered, washed, made up to 200 c.c, 
 and the sugar determined by means of Fehling's 
 solution. 
 
 Crude Fiber. — The residue from the above is 
 brought into a flask and 200 c.c. of 1.25 per cent 
 NaOH solution added, boiled for 30 minutes, filtered on 
 an asbestus filter, washed with hot water, and finally 
 with ether; then dried, transferred to a platinum dish, 
 
SUCAKS, STARCHES, AND FOODS. 6l 
 
 weighed, ignited, and again weighed, the loss being 
 taken as crude fiber. 
 
 Undetermined Carbohydrates. — The sum of all prod- 
 ucts thus far determined from lOO gives the amount 
 of undetermined carbohydrates. 
 
 Questions. — Is the ether extract pure fat? What 
 else does it contain? About what proportion of the 
 ether extract is pure fat? 
 
 In what form did the nitrogen exist in the plant? 
 How is it converted into ammonia? Why multiply 
 the per cent of N by 6.25 ? 
 
 What is the active principle in the malt infusion? 
 W'hat is the nature of its action on the starches? Are 
 the starches of all foods alike? 
 
 What is the fiber of the food? 
 
 41. Milk Analysis. 
 
 Great care should be taken to procure a unifofm 
 sample of the product, and before taking each portion 
 for analysis the sample should be well mixed by pour- 
 ing several times from one beaker to another. 
 
 Ash. — A small platinum evaporating-dish contain- 
 ing a quantity of asbestus should be ignited, cooled, 
 and weighed. Place in this about 5 c.c. of the milk, 
 weigh, place in water-oven to dry, and then burn at 
 low redness. Cool, and weigh as ash. 
 
 Total Solids. — In a perforated test-tube, as used 
 
62 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 for ether extract in food analysis, place a small wad 
 of fat free cotton; fill tube loosely three-fourths full 
 of freshly ignited pure asbestus, and have a small wad 
 of cotton for top; the desiccated tubes should now be 
 weighed. Then remove the wad of cotton from top> 
 and run in upon asbestus about 3 c.c. of the well- 
 mixed sample of milk; retiirn the wad of cotton, and 
 weigh. These tubes should then be placed in a water- 
 oven and the perforated end of the tube connected 
 with a suction-pump and rapidly dried. For accurate 
 work, dry hydrogen gas instead of air should be 
 drawn through the tubes while drying. Cool the 
 tubes in a desiccator, and weigh to find total solids. 
 The loss is water. 
 
 Fat. — The tubes containing the desiccated milk 
 above may be placed in extractor and fat estimated 
 in the same manner as ether extracts are found in food. 
 
 Nitrogen. — Weigh out 4 to 5 grams of milk in a 
 flask and determine nitrogen in same manner as for 
 foods. The milk need not be evaporated before add- 
 ing the H^SO^. The percentage of nitrogen multi- 
 plied by 6.25 gives total nitrogen compounds, usually 
 stated as casein. Many use the factor 6.37 in prefer- 
 ence to 6.25. 
 
 Milk-sugar or Lactose. — 20 grams of milk are placed 
 in a porcelain dish with 30 c.c. of water, a few drops 
 of acetic acid added and heated to 50 c.c. to coagu- 
 late the casein. The solution is then filtered through' 
 
SVG A US, STARCHES, AND FOODS. 63 
 
 fine linen, washed, and made up to 150 c.c, and con- 
 taining a few drops of HCl heated on water-bath for 
 thirty minutes to invert-sugar; then neutralized with 
 Na,COj made up to 200 c.c, and the sugar deter- 
 mined in 10 c.c. by means of Fehling's solution. 
 
 Specific Gravity. — A uniform sample of the milk 
 should be brought to a temperature of 60° F., placed 
 in a specific-gravity tube, and the hydrometer-reading 
 taken directly from the scale. 
 
 Questions. — Is there any other nitrogenous con- 
 stituent besides casein present in the milk? Is the 
 reducing power of milk-sugar the same as that of cane- 
 sugar? 
 
CHAPTER VIII. 
 
 . 42. Water Analysis. 
 
 Tota! Solids. — lOO c.c. of water is placed in a tared 
 platinum dish and evaporated on water-bath, and then 
 dried in water-oven. This gives total solids. Ignite 
 at low heat, and loss is volatile matter. The results 
 should be exoressed as parts per million. 
 
 CHLORIN. 
 
 Solutions. — 4.789 grams of AgNO, are dissolved to 
 1000 c.c. with distilled water. One c.c. of this 
 standard AgNO, solution is equivalent to .001 gram 
 of chlorin. 
 
 Determination. — lOO c.c. of water are placed in a 
 porcelain dish, a few drops of saturated solution of 
 potassium chromate added, and the standard AgNO, 
 solution run in until permanent color is secured. The 
 results should be expressed in parts per million- 
 
 FREE AMMONIA. 
 
 Solutions. — I. A standard solution of ammonium 
 
 chlorid is prepared by dissolving 3.15 grams of am- 
 
 64 
 
Water analVsis. 65 
 
 monium chlorid in pure distilled water and making up 
 to 1000 c.c. One c.c. of this solution diluted to 
 100 c.c. will contain .00001 gram of ammonia per c.c. 
 
 2. Alkalin potassium permanganate is best made 
 by dissolving 200 grams of potassium hydroxid and 
 8 grams of crystallized dry potassium permanganate 
 in water, and making up to 1000 c.c. with ammonia- 
 free water. This solution should give no reaction for 
 ammonia. Should there be any ammonia a correction 
 should be made for each determination. 
 
 3. The Standard Nessler Reagent may be made by 
 dissolving 13 grams of pulverized mercuric chlorid 
 (corrosive sublimate) in 506 c.c. of distille'd water, 
 and 35 grams of potassium iodid in 200 c.c. of water. 
 Pour the mercuric chlorid solution into the potassium 
 iodid and add gradually, drop by drop, a saturated 
 solution of corrosive sublimate until a permanent red 
 precipitate just begins to remain undissolved. To 
 this solution add 120 grams sodium hydroxid, dis- 
 solved in 150 c.c. of water, and dilute the solution to 
 1000 c.c. Sensitize this solution by adding a little 
 more of the saturated solution of mercuric chlorid 
 until a slight permanent red precipitate forms ; allow 
 to settle, and decant. Keep the solution in a cool 
 place, away from the light. 
 
 4. Sodium carbonate is prepared by boiling an 
 excess of sodium carbonate in distilled water and 
 decanting off solution after cooling. 
 
56 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 5. Ammonia-free water is best prepared by redis- 
 tilling distilled water, to which a little H^SO, has 
 been added, rejecting the first portion and not distil- 
 ing too low. 
 
 Determination. — A glass retort or distilling appa- 
 ratus is thoroughly cleaned out and 500 c.c. of the 
 water to be tested is placed in the retort and i to 2 
 c.c. of the solution No. 4 (NajCOj) is added, and four 
 portions of 50 c.c. each are distilled over, being 
 received in Nesslerizing tubes. Into each of the 
 above tubes are run 2 c.c. of the standard Nessler 
 reagent, and the whole well mixed by oouring from 
 one tube to another. 
 
 In a second Nessler's tube, well cleaned with acid, 
 ammonia-free water is placed containing a measured 
 volume of the standard ammonia solution, No. i, and 
 then filled to the 50-c.c. mark with ammonia-free 
 water and 2 c.c. of Nessler solution added. If the 
 shade produced does not correspond in color with that 
 of the water sample under examination, test solutions 
 of known strength must be made until the desired 
 shade is secured; from the data may be calculated 
 the parts per million of free ammonia. Many chemists 
 Nesslerize the first 50 c.c. only of the distillate and 
 add one-third for the other three portions, which are 
 thrown away. If one has a calorimeter, the work of 
 Nesslerizing is much simplified. 
 
WATER ANALYSIS. 67 
 
 ALBUMINOID AMMONIA. 
 
 To the retort from which the free ammonia has been 
 distilled 50 c.c. of the alkalin potassium perman- 
 ganate (solution No. 2) are added, and the distillation 
 continued until three portions of 50 c.c. each have 
 been collected. These are to be Nesslerized as for 
 free ammonia, and expressed as parts per million for 
 albuminoid ammonia. 
 
 NITRATES. 
 
 The solutions required for this work are as follows: 
 
 1. Standard Potassium Nitrate. — Dissolve .722 
 gram of pure potassium nitrate in lOOO c.c. of water. 
 This solution is of such strength that I c.c. is equiva- 
 lent to .00044 gram of NOj. 
 
 2. Phenol Sulfuric Acid. — To 370 c.c. of sulfuric 
 acid, sp. gr. 1.84, add 80 grams of chemically pure 
 phenol and 30 c.c. of water. 
 
 Determinations. — Evaporate to dryness in porcelain 
 dish on water-bath 25 c.c. of the water to be tested. 
 Mix thoroughly with the residue i c.c. of the phenol 
 sulfuric acid. To the residue add i c.c. of distilled 
 water, three drops of H,SO,, sp. gr. 1.84, and warm 
 on water-bath; dilute with 25 c.c. of distilled water, 
 make alkalin with NH^OH, and dilute solution to 100 
 c.c. with distilled water. If nitrates are present a 
 yellow color is produced, the depth of color depend- 
 
68 QUANTITATIVE CffEMlCAL ANALYSIS. 
 
 ing upon the amount" of nitrate present, ammonium 
 picrate being formed. 
 
 The determination is made by comparison with 
 standard solution. Evaporate to dryness i c.c. of the 
 standard potassium nitrate solution No. i, and treat 
 the residue in same manner as water. If a calorime- 
 ter is available the comparison of the known and 
 the unknown solution can be made directly. If not 
 as in free and albuminoid ammonia determination, 
 other test solutions of differing strength will need to 
 be made until the approximate shade is reached. 
 
 These solutions should be examined in Nessler 
 tubes over white tile and surrounded by dark paper. 
 
 HARDNESS. 
 
 1. Standard Hard Water. — Dissolve one gram of 
 pure calcium carbonate in dilute HCl, and evaporate 
 to dryness. Dissolve in water and make up to looo 
 c.c. One c.c. of this solution is equivalent to .001 
 gram of CaCOj. 
 
 2. Standard Soap Solution. — Weigh out of pure 
 Castile soap 10 grams and dissolve in 35 per cent 
 alcohol and make up alcoholic solution to 1000 c.c. 
 One c.c. of this soap solution will just neutralize 
 .001 gram of carbonate of lime. As the soap is not 
 always of the proper strength, it is necessary to 
 standardize the solution by means of the standard 
 
WATER ANALYSIS. 69 
 
 water as follows: A measured quantity of the hard 
 water (No. i), say 10 c.c, is made up to lOb c.c. with 
 distilled water, and titrated with the soap solution. 
 This is best done in a glass-stoppered bottle of about 
 200 c.c. capacity, and to the test solution the soap 
 solution is added, i c.c. at a time, from a burette, 
 then shaken, and this continued until a permanent 
 lather- persists for fully five minutes. As i c.c. of the 
 soap solution is taken up by the distilled water the 10 
 c.c. above should require 11 c.c. of the standard soap 
 solution. After a few trials, if the strength is not 
 correct, the standard soap solution must be adjusted 
 by dilution or addition of more soap until the correct 
 strength is secured. The hardness of the water is 
 determined in exactly the same manner as for stand- 
 ardizing above, using 100 c.c. of water and expressing 
 the results in parts per million. The above determi- 
 nation gives the total hardness. It is frequently 
 desired to determine the permanent and temporary 
 hardness of the water which together constitutes the 
 total hardness. If so, a second portion of the water 
 under examination, say 250 c.c, is placed in a flask 
 and boiled for thirty minutes, replacing the loss from 
 time to time with hot distilled water. After cooling, 
 the water is made up again with distilled water to 250 
 c.c, and the hardness determined in 100 c.c. of this. 
 The result shows the permanent hardness; this, taken 
 
70 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 from amount of total hardness, will show amount due 
 to temporary hardness. 
 
 Questions. — In CI determination, why was potas- 
 sium chromate used? What was the change indicat- 
 ing the end reactions? 
 
 In ammonia determination, why add Na.,CO, before 
 distilling? What is the difference between the free 
 ammonia and albuminoid ammonia in the water-? 
 
 What do the presence of nitrates indicate? What 
 is the composition of the nitrates as- determined? 
 How were they transformed to this end pioduct? 
 What is the difference between the permanent and 
 temporary hardness of water? What reactions take 
 place between the soap and the products in the water? 
 
CHAPTER IX. 
 
 43. Urine. Analysis. 
 
 1. Note the time of day for taking sample, and if 
 convenient the total amount voided in twenty-four 
 hours should be saved for examination. 
 
 2. Color. — Normal urine from pale yellow to 
 brownish. 
 
 3. -Transparency. — Normal urine when freshly 
 voided is clear, but shows on standing a slight cloudi- 
 ness. 
 
 4. Consistency. — Normal urine is perfectly fluid. 
 
 5. Odor.. — Fresh normal urine has a peculiar aro- 
 matic odor. If concentrated it is strong, and in case 
 of ammoniacal decomposition it is strong, and may 
 be even putrid. 
 
 6. Reaction. — When freshly voided, normal urine 
 is usually slightly acid, generally increasing in acidity 
 for a time, and then becomes alkalin. 
 
 7. Specific Gravity. — This is taken by means of a 
 urinometer at a temperature of 15.5" C, and for 
 normal urine maybe expected to range from 1.015 
 to 1.025. 
 
 71 
 
72 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 NORMAL CONSTITUENTS. 
 Urea. 
 
 Volumetric Determination. — This is quite simple 
 and accurate when conducted with proper care, and 
 depends upon measuring the liberated nitrogen in a 
 properly constructed apparatus. The urinometer fur- 
 nished by Eimer & Amend, New York, is very satis- 
 factory, and is so graduated as to read the grams of 
 urea direct. 
 
 Solution I. — In 250 c.c. of distilled water, dissolve 
 100 grams of NaOH. 
 
 2. Bromin. — This is unpleasant to handle, but by 
 means of a small pipette with a rubber nipple it can 
 be done with little inconvenience and no danger to 
 the person. 
 
 Process. — Dilute solution No. i with an equal 
 volume of water when ready for use, and fill the long 
 arm and bulb of the urinometer with this solution, to 
 which has been added i c.c. of bromin (No. 2). Of 
 the well-mixed sample of urine draw up I c.c. into a 
 small pipette with a curved point by aid of the 
 rubber nipple, insert the end of the pipette well into 
 the neck of the urinometer, and gradually force out 
 the urine by compressing the nipple. Be careful not 
 to force in any air from the pipette after the urine is 
 expelled. Allow the apparatus to stand for a time 
 
URINE ANALYSIS. 73 
 
 and make the reading at a temperature of 15.5° C. or 
 60" F. 
 
 Uric Acid. 
 
 On standing, crystals of uric acid may form on sides 
 and bottom of beaker. Urine containing large quan- 
 tities of urates, on the addition of concentrated HNO3, 
 form a ring resembling albumen. On standing or by 
 heating the ring disappears. 
 
 The Murexid Test. — On evaporating to dryness, 
 with a few drops of HNOg, urine supposed to contain 
 urates, and then adding to the residue a few drops of 
 ammonia water, there will be formed a beautiful purple 
 or violet-red color. 
 
 ■ Approximate Estimation. — To 300 c.c. of urine add 
 10 c.c. of HCl, and allow to stand in a cool place 
 for twenty-four hours and the crystals of uric acid will 
 form. Filter and wash; remove from the filter, dry, 
 and weigh. By this method an approximate idea may 
 be secuied of the amount of urates present. 
 
 Indican. 
 
 Jaffe's Test. — Place in test-tube 10 c.c. of clear 
 urine, add 10 c.c. of concentrated hydrochloric acid, 
 and mix well. To this is added, drop by drop, a 
 freshly prepared concentrated solution of calcium 
 hypophosphite until a blue color is produced, provid- 
 
74 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 ingindican be present. Now add 3 c.c. of chloroform 
 and shake well, and the color is wholly taken up by 
 the chloroform. In place of the hypophosphite a 
 concentrated solution of chlorid of lime will answer. 
 An excess of the reagent should be avoided. 
 
 Chlorids. 
 
 1. Dissolve 7.269 grams of pure AgNO, in distilled 
 water and make up to 250 c.c. One c.c. of this solu- 
 tion is equivalent to .01 gram NaCi. 
 
 2. Prepare a small quantity of a saturated solution 
 of potassium chromate. 
 
 Method. — Place 10 c.c. of the urine in a flask and 
 make up to lOO c.c. with distilled water. Place in a 
 porcelain dish, add a few drops of HNO, to prevent 
 precipitation of phosphates, put in a few drops of 
 potassium chromate solution (No. 2), and add with 
 constant stirring the AgNO, solution until the begin- 
 ning of a permanent orange tint indicates the end 
 reaction. 
 
 Phosphates. 
 
 The phosphates are of two classes, alkalin and the 
 earthy phosphates. Phosphates may be precipitated 
 by heat, which precipitate must not be mistaken for 
 albumen. The addition of a little acid to the urine 
 will redissolve the phosphates or prevent their being 
 formed. 
 
URINE ANALYSIS. 75 
 
 Alkalin Phosphates. — To the urine add a few drops 
 of acetic acid, and heat to precipitate any albumen; 
 then filter, and add NH.OH or KOH. Precipitate 
 is alkalin phosphates. 
 
 Earthy Phosphates. — To the filtrate above add 
 " magnesia mixture," and the precipitate is due to 
 earthy phosphates. In normal urine the alkalin phos- 
 phates constitute about two-thirds and the earthy 
 phosphates one-third of the total amount. 
 
 ABNORMAL CONSTITUENTS. 
 
 Albumen. — Fill a test-tube two-thirds full of urine 
 and add a few drops of acetic acid to prevent phos- 
 phates from being precipitated. Hold the tube 
 obliquely over the flame so as to heat the upper por- 
 tion to boiling. If precipitate is formed, add slowly, 
 drop by drop, lo to 20 drops of concentrated HNO,; 
 if a cloudiness appears or is not redissolved by the 
 nitric acid, then albumen is present. 
 
 Another test is to place in a test-tube about two 
 inches of the urine to be examined, and then by means 
 of a pipette, held in the urine, to allow concentrated 
 HNO3 to flow down the side of the tube below the 
 urine so as not to mix with it. If albumen be present 
 at the juncture of the two liquids, there will be a 
 cloudy ring. A similar ring higher up due to the 
 presence of urea or uric acid must' not be mistaken for 
 albumen. 
 
76 QUANTITATIVE CHEMICAL ANALYSIS. 
 
 Sugar. — Heat the urine to be examined and filter, 
 and then to lo c.c. of the urine add 50 c.c. of Fehl- 
 ing's solution, and treat as for sugar in food. 
 
 Blood. — Pour about two inches of urine in a test- 
 tube, and add KOH solution. The precipitated 
 phosphates, which in normal urine are white, are col- 
 ored red or a rosv tint if blood is present. 
 
 Bile. — A urine that retains its foam for a long time 
 after shaking indicates the presence of bile. Such- 
 urines are usually yellow in color. 
 
 If fuming, nitric acid is added to urine in a test- 
 tube in such a way that it shall flow down through 
 the urine, the formation of a green ring at the junc- 
 tion of the two fluids indicates bile, and below this 
 ring may appear blue, violet, and yellow rings. 
 
 Questions. — What reaction takes place in determin- 
 ing the urea? What is the gas measured in the 
 urinometer? In what form is the uric acid in the 
 urine? Why is HCl added before standing aside to 
 crystallize? What is indi'can? What reaction takes 
 place on adding the calcium hypophosphite? In what 
 way does the chloroform act? Why avoid an excess 
 of the hypophosphite? What is the difference be- 
 tween the alkalin and the earthy phosphates? Why, 
 on the addition of the alkali, are not the earthy phos- 
 phates precipitated? 
 
APPENDIX. 
 
 TABLE OF ELEMENTS. 
 
 ATOMIC WEIGHTS BASED ON CLARKE'S RECALCULATION, 1897. 
 
 Elements. 
 
 
 
 t 
 
 71 
 
 Valence. 
 
 Atomic 
 
 Weight. 
 
 Xi E* 
 
 s 
 
 By Whom 
 
 H=i 
 
 = 16 
 
 Discovered. 
 
 Aluminum 
 
 Antimony 
 
 Argon 
 
 Arsenic 
 
 Al 
 
 Sb 
 
 A 
 
 As 
 
 Ba 
 
 Bi 
 
 B 
 
 Br 
 
 Cd 
 
 Ca 
 
 C 
 
 Ce 
 
 Cs 
 
 CI 
 
 Cr 
 
 Co 
 
 Cb 
 
 Cu 
 
 E 
 
 p. 
 
 Gd 
 
 Ga 
 
 Ge 
 
 Gl 
 
 Au 
 
 He 
 
 H 
 
 In 
 
 I 
 
 Ir 
 
 Fe 
 
 La 
 
 Pb 
 
 Li 
 
 Mg 
 
 Mn 
 
 Hg 
 
 Mo 
 
 Ill 
 III-V 
 
 lii-v 
 
 II 
 III-V 
 III-V 
 I-VII 
 
 II 
 
 II 
 IV-II 
 
 IV 
 
 I 
 
 I-VII 
 
 II-III-VI 
 
 II-VI 
 
 III-V 
 
 II , 
 
 III 
 
 I 
 
 ii-iv 
 
 IV 
 
 'ill 
 
 I 
 III 
 
 I-VII 
 
 II-IV-VI 
 
 II-III-VI 
 
 IV 
 
 II-IV 
 
 I 
 n 
 
 II-VII 
 
 II 
 
 VI 
 
 z6.QZ 
 
 119.52 
 
 74-44 
 136.39 
 
 79-34 
 
 IH.IO 
 
 39.76 
 
 IT. 91 
 138.30 
 131.89 
 
 35- 18 
 5; -74 
 58.5s 
 93.02 
 
 63. J2 
 
 165.06 
 
 18.91 
 
 %■% 
 
 7 '-93 
 
 9.01 
 
 195-74 
 
 1. 00 
 112.99 
 125.89 
 19.. 66 
 
 55.60 
 
 137-59 
 
 205.36 
 
 6.97 
 
 24.10 
 
 54.57 
 198.49 
 
 95.26 
 
 27.11 
 120.43 
 
 75-01 
 137-43 
 208.11 
 
 10.95 
 
 79-95 
 
 III -95 
 
 40.07 
 
 12.00 
 
 ■39.35 
 
 132.89 
 
 35-45 
 
 52.14 
 
 58.99 
 
 93-73 
 
 63.60 
 
 166.32 
 
 19.06 
 
 156.76 
 
 69.91 
 
 72.48 
 
 9.08 
 
 197^.23 
 
 1.008 
 
 113-85 
 
 126.8s 
 
 193.12 
 
 56.02 
 
 138.64 
 
 206.92 
 
 7 03 
 
 24.28 
 
 54-99 
 
 200.00 
 
 95-99 
 
 1827 
 
 1894 
 1694 
 1808 
 
 1808 
 1826 
 1817 
 1808 
 
 1826 
 i860 
 
 1774 
 1797 
 1735 
 1801 
 
 1886 
 
 1875 
 1886 
 1828 
 
 1895 
 1766 
 1863 
 I81I 
 1804 
 
 1839 
 
 1817 
 1808 
 1774 
 
 1782 
 
 Wohler 
 
 Rayleigh & Ramsey 
 
 Schroder 
 
 Davy 
 
 Lussac & ThSnard 
 Balard 
 
 Bismuth 
 
 Boron 
 
 Bromin 
 
 Cadmium 
 
 Stromeyer 
 Davy 
 
 
 
 
 
 
 
 Chlorin ..,.^.... 
 
 Chromium 
 
 Cobalt 
 
 Scheele 
 
 Vauquelin 
 
 Brandt 
 
 Columbium.. 
 
 Hatchett 
 
 
 
 Fluorin 
 
 Moissan 
 
 Gadolinium 
 
 Gallium 
 
 Germanium 
 
 Glucinum 
 
 Gold 
 
 Boisbaudran 
 
 Winkler 
 
 Wohler 
 
 
 Ramsey 
 
 Hydrogen 
 
 Cavendish 
 Reich & Richter 
 
 lodin 
 
 Courtois 
 
 
 Tennant 
 
 
 
 Lanthanum 
 
 Lead 
 
 Mosander 
 
 
 Arfvedson 
 
 Magnesium 
 
 Manganese 
 
 Davy 
 Gahn 
 
 Molybdenum .... 
 
 Hjehu 
 
 77 
 
78 
 
 APPENDIX. 
 
 Elements. 
 
 
 
 Valence. 
 
 Atomic Weight. 
 
 ■d 
 
 By Whom 
 
 H = i 
 
 0= 16 
 
 Discovered. 
 
 Neodymium 
 
 Nickel 
 
 N 
 
 Os 
 
 O 
 
 Pd 
 
 P 
 
 Pt 
 
 K 
 
 Pr 
 
 Rh 
 
 Rb 
 
 Ru 
 
 Sm 
 
 Sc 
 
 Se 
 
 Si 
 
 Ag 
 
 Na 
 
 Sr 
 
 S 
 
 'Fa 
 
 Te 
 
 Tr 
 
 Tl 
 
 Th 
 
 Tm 
 
 Sn 
 
 Ti 
 
 W 
 
 U 
 
 V 
 
 Yb 
 
 Y 
 
 Zn 
 
 Zr 
 
 'ii' 
 
 Ill-V 
 
 IV-VI 
 
 II 
 
 II-IV-VI 
 
 III-V 
 
 II-IV-VI 
 
 I 
 
 ii-iv-vi 
 I 
 
 IV-VIII 
 
 IV 
 
 II-IV-VI 
 
 IV 
 
 I 
 1 
 II 
 
 II-IV-VI 
 
 V 
 II-IV-VI 
 
 I-III 
 
 IV 
 
 lY 
 IV 
 
 I^ 
 
 III 
 II 
 
 IV 
 
 139.70 
 58.24 
 13-93 
 
 189.55 
 15-88 
 
 105.56 
 30.79 
 
 193-41 
 38.8= 
 
 142.50 
 
 102.23 
 84.78 
 
 100.91 
 
 149.13 
 43-78 
 78.42 
 23.18 
 
 107.11 
 22.88 
 86.95 
 
 31-83 
 181.45 
 126.52 
 158.80 
 202. fit 
 230.87 
 169.40 
 118.15 
 
 47-79 
 183-43 
 237-77 
 
 50.99 
 
 '88:35 
 64.91 
 89. 72 
 
 140.80 
 
 58.69 
 
 14.04 
 190.99 
 
 16.00 
 106.36 
 31.02 
 
 194.89 
 39.11 
 143.60 
 103.01 
 
 85-43 
 
 101.68 
 150.26 
 
 44.12 
 79.02 
 28.40 
 107.92 
 23-05 
 87.61 
 32.07 
 
 182.84 
 
 127.49 
 
 160.00 
 
 204.15 
 232.63 
 170.70 
 119.05 
 
 184.83 
 239-59 
 51-38 
 173.19 
 89.02 
 65.41 
 
 go. 40 
 
 1751 
 1772 
 1804 
 
 1803 
 1669 
 1750 
 1807 
 
 1803 
 i860 
 '84s 
 
 1S79 
 1817 
 1822 
 
 1807 
 1808 
 
 1802 
 1798 
 
 1861 
 1828 
 
 1824 
 
 1785 
 
 1867 
 1825 
 
 Welsbach 
 Cronstedt 
 
 
 
 
 
 
 Priestley 
 
 Palladium 
 
 Phosphorus 
 
 Platinum 
 
 Potassium 
 
 Praseodyniium... 
 
 Rhodium 
 
 Rubidium 
 
 Ruthenium 
 
 Smarium 
 
 WoUastoD 
 
 Brandt 
 
 Watson 
 
 Davy 
 
 Welsbach (f) 
 
 WoUaston 
 
 Bunsen 
 
 Claus 
 
 Scandium 
 
 Nilson 
 
 Silicon 
 
 
 Silver 
 
 
 Sodium 
 
 Strontium 
 
 Davy 
 
 Tantalum 
 
 Tellurium 
 
 Terbium 
 
 Thallium 
 
 Eckeburg 
 Klaproth 
 
 Crookes 
 Berzelius 
 
 Thulium '. . 
 
 Tin 
 
 
 Titanium 
 
 Tungsten 
 
 Uranium 
 
 Vanadium 
 
 Ytterbium 
 
 Yttrium 
 
 Zinc 
 
 Zirconium 
 
 Berzelius 
 d'Elhujar 
 Peligot 
 Roscoe 
 
 Berzelius 
 Valentine 
 Berzelius 
 
INDEX. 
 
 PAGE 
 
 Acid solutions, normal 28, 29 
 
 Alkali solutions, normal 28, 29 
 
 Alkalin phosphates in urine 75 
 
 Albumen in urine 75 
 
 Albuminoid ammonia in water 67 
 
 Albuminoid nitrogen 58 
 
 Aluminum, determination of 11, 36 
 
 Ammonia, semi-normal 30 
 
 Ammonia in water 64 
 
 Ampere, defined 50 
 
 Apatite, analysis of 26 
 
 Appendix 77 
 
 Ash analysis 35 
 
 Atomic weights, table of 77 
 
 Balances , care of 5 
 
 Barium, determination of 12 
 
 Batteries for electrolysis 50 
 
 Bile in urine 76 
 
 Blood in urine 76 
 
 Calcium, gravimetric analysis ir 
 
 Calcium, volumetric analysis 33 
 
 Carbohydrates, determination of 58 
 
 Carbon dioxid, to determine 22, 39 
 
 Casein in milk 62 
 
 Chlorids in urine 74 
 
 Chlorin, gravimetric analysis 14 
 
 Chlorin, volumetric analysis 33 
 
 Chlorin in water, determination of 64 
 
 Cleanliness and neatness .,......,,', 2 
 
 Coal analysis 47 
 
 79 
 
80 INDEX. 
 
 t>AGB 
 
 Cochineal indicator, to prepare 30 
 
 Copper analysis, electrolytic 51 
 
 Copper analysis, gravimetric 15 
 
 Crucibles , care of 6 
 
 Desiccators 3 
 
 Directions, general 2 
 
 Dolomite, analysis of 23 
 
 Drying precipitates 4 
 
 Earthy phosphates in urine 75 
 
 Electrolysis 49 
 
 Electrolytic apparatus 50 
 
 Electrolytic gas .' 51 
 
 Elements, when discovered 77 
 
 Fat in foods, to determine 57 
 
 Fat in milk, to determine 62 
 
 Feldspar, analysis of 24 
 
 Fehling's solutions 54 
 
 Ferrous ammonium sulfate, analysis of 32 
 
 Filtration 3 
 
 Foods, analysis of 56 
 
 Formula for calculating results 9 
 
 Galena, analysis of 46 
 
 Gravimetric analysis 1-9 
 
 Gypsum, analysis of ". 25 
 
 Hardness of water, to determine 68 
 
 Ignition of precipitates 5 
 
 Indican in urine 73 
 
 Indicators 30 
 
 Iron analysis by electrolysis 52 
 
 Iron and alumina, to separate 36 
 
 Iron, gravimetric methods for 9-42 
 
 Iron ores, analysis of 42 
 
 Iron, volumetric methods for 31 
 
 Jaffe's test for indican 73 
 
 Lactose in milk 62 
 
 Lead, analysis of 16 
 
 Lead ores, analysis of 46 
 
 Litmus as an indicator 30 
 
 Magnesia, determination of 10, 44 
 
 Magnesia mixture 8 
 
 Malt, solution for starch 59 
 
INDEX. 8 1 
 
 PAGE 
 
 Manganese, determination of 17, 38 
 
 Milk analysis 61 
 
 Molybdic solution 7 
 
 Murexid test in urine 72 
 
 Neatness and cleanliness 2 
 
 Nessler's reagent 65 
 
 Nesslerizing 66 
 
 Nickel, analysis by electrolysis 52 
 
 Nitrates in water, to determine 67 
 
 Nitric acid test for albumen 74 
 
 Nitrogen, determination of 40, 57 
 
 Nitrogen, albuminoid 58 
 
 Notes, accuracy of ,. 2 
 
 Normal solutions 28 
 
 Ohm, defined 49 
 
 Orthoclase, analysis of 24 
 
 Pentosans, determination in foods 60 
 
 Permanganate process for iron 32 
 
 Permanganate solution normal 31 
 
 Permanganate solution for iron 31 
 
 Permanganate solution for sugar 54 
 
 Permanganate solution for water 65 
 
 Phenolphthalein as an indicator 31 
 
 Phosphates in urine 74 
 
 Phosphates, mineral, analysis of 26 
 
 Phosphoric anhydrid, analysis for 18-43 
 
 Potassium, determination of 13 
 
 Potassium, separation from sodium 20 
 
 Platinum crucibles, care of 6 
 
 Precipitates, how ignited 5 
 
 Recording weights 6 
 
 Silver determination , 47 
 
 Silver solution for chlorin 64 
 
 Soap solution for water analysis 68 
 
 Sodium carbonate, normal solution of 29 
 
 Sodium chlorid 20 
 
 Specific gravity of milk 63 
 
 Standardizing solutions 29 
 
 Standard solutions 7i 27 
 
 Sucrose determination 59 
 
 Sugar determinations • • • 56 
 
82 INDEX. 
 
 PAGE 
 
 Sugar in urine 7^ 
 
 Sulfur in coal 4^ 
 
 Sulfuric acid, analysis for 13 
 
 Sulfuric acid, normal 29 
 
 Urea, determination of 72 
 
 Uric acid determination . .'. 73 
 
 Urine analysis ' 71 
 
 Valency of the elements 77 
 
 Volt, defined. .". 49 
 
 Volumetric analysis 2, 27 
 
 Washing precipitates 4 
 
 Water analysis 64 
 
 Weighing 5 
 
 Weights, how recorded 6 
 
 Zinc, determination of 17 
 
 Zinc blende, analysis of 45 
 
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 16