' 
 
 .REESE LIBRARY 
 
 _-n_ji_n, 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Deceive J &&&*< ,189(0. 
 
 No .(od I 2^5 QiUs No. 
 
m-^' 
 
 I 
 
LABORATORY MANUAL 
 
 INORGANIC PREPARATIONS 
 
 H. T. VULTE, PH. D ., F. C. S. 
 
 K01-KSSOK OF CHKMISTKY IN BAKNAKO COLLEGE, AND ASSISTANT IN CHEMISTRY AT THE 
 SCHOOL OK MINES, COLUMBIA COLLEGE, N. Y. 
 
 AND 
 
 GEORGE M. S. NEUSTADT 
 
 OF'THF- 
 
 tTNIVERSIT Y 
 
 OF 
 
 NEW YORK 
 GEO. C.OTTSBERGER PECK, PUBLISHER 
 
 II MURRAY STREET 
 
 1895 
 
^ 
 
 
 
 Entered, according to Act of Congress, in the year 1895, 
 
 BY GEO. GOTTSBERGER PECK, 
 In the Office of the Librarian of Congress, at Washington, D. C- 
 
PREFACE.- 
 
 The study of inorganic chemistry naturally precedes that of 
 organic, and in a certain way this plan is carried out in a com- 
 plete chemical course. The study of the organic branch, how- 
 ever, proceeds on a much more logical plan than that usually 
 adopted in inorganic work; one of the chief advantages being 
 the practical work, to which the student is introduced very 
 early in his course. The following work is synthetic, and shows 
 how compounds, often very complex in character, rare in occur- 
 rence or expensive in preparation, may be produced from simple 
 substances, or from those which are comparatively plenty and 
 cheap, and at the same time the bye products may be saved. 
 Such a course of study is of great value in inorganic work, but 
 should precede and lead up to, and not follow organic chem- 
 istry. However, a contrary plan seems to have been followed, 
 for while we have various works on organic preparations, there 
 are none, so far as the authors know, in the inorganic branch 
 of the subject (at least not in English), excepting the works on 
 Elementary Chemistry ; and where these treat of the subject in 
 laboratory practice, the methods are those which cannot be 
 recommended as the best and most economical. 
 
 In many laboratories the waste of material is greater than the 
 use. Students are apt to acquire the idea that after a certain re- 
 sult has been produced the rest of the material is worthless, and 
 in consequence much loss occurs from throwing away valuable 
 substances, which can be recovered or used with little trouble or 
 expense. It is not a very difficult operation to purify the various 
 commercial salts, converting them into C. P. reagents, and in the 
 operation the student cannot help acquiring facts which are 
 directly and forcibly brought to his knowledge. Too much reli- 
 ance is usually placed on the so-called C. P. chemicals in com- 
 mon use. Many are high-priced and apt to deteriorate in the 
 
11 PREFACE. 
 
 packages. There is no reason why the student should not pre- 
 pare many of these, unless it be that he does not always know 
 where to look for the necessary information. 
 
 The book is designed to meet a long felt want in the inor- 
 ganic laboratory, in training the student to prepare his own 
 reagents and to test them for the customary impurities. The 
 methods are largely those in commercial use, and should prove 
 of value to those studying Applied Chemistry. 
 
 The works of Fresenius, Erdmann and others, as well as the 
 various chemical journals for some years past, have been carefully 
 searched, and such information as \vas thought valuable has been 
 collected and arranged in order, beginning with the simplest 
 operations and gradually increasing in difficulty as the student 
 acquires skill in his work. As far as possible, references to the 
 original articles have been given. 
 
 OCTOBER, 1895. 
 
LABORATORY MANUAL 
 
 OF 
 
 INORGANIC PREPARATIONS, 
 
 WATER. 
 H 2 O. 
 
 Pure water is obtained by distilling spring water from 
 a copper still with head and condenser made of pure 
 tin. The distillation is carried to about three-fourths 
 of the quantity operated upon. If it is desired to have the 
 distilled water perfectly free Irom carbonic acid and am- 
 monium carbonate, the portions passing over first must be 
 rejected. In the larger chemical laboratories, distilled 
 water is obtained from the steam apparatus which serves 
 for drying, etc. Rain water collected in the open air may 
 in many cases be substituted for distilled water. 
 
 It must be colorless, odorless, and tasteless, and 
 should not leave the smallest residue when evaporated in a 
 platinum vessel. It should not be changed by ammonium 
 sulphide (copper, lead, iron), nor rendered turbid by baryta 
 water (carbonic acid). No cloudiness should be caused 
 even after long standing by the addition of ammonium 
 oxalate, of barium chloride and hydrochloric acid (sul- 
 
2 LABORATORY MANUAL OF 
 
 phuric acid), of silver nitrate and nitric acid (chlorides), or 
 of mercuric chloride and sodium carbonate (ammonia). 
 
 We use water principally as a simple solvent for a great 
 variety of substances. 
 
 AMMONIUM FREE WATER. 
 
 If the ordinary distilled water gives a reaction for am- 
 monia with Nessler's reagent, it should be treated with 
 sodium carbonate, about one gram to the litre and boiled 
 until one-fourth has been evaporated. 
 
 Ammonium free water may also be prepared by dis- 
 tilling water made slightly acid with sulphuric acid. 
 
 WATER FREE FROM ORGANIC MATTER AND AMMONIA.* 
 
 About 15-20 litres of ordinary distilled water, to which 
 about I gram, of potassium hydrate and 0.2 gram, of 
 potassium permanganate have been added are maintained 
 at about 100 C. for twenty-four hours under an- inverted 
 condenser, after which the condenser is reversed and the 
 water distilled off. Apply Nessler's test to the distillate 
 from time to time, until 100 c.c, show no coloration and 
 collect that which comes over subsequently, stopping 
 5OOC.C. short of dryness. 
 
 As an additional precaution the water thus obtained 
 may be acidified with sulphuric acid and re-distilled. 
 
 For preparing distilled water, the ordinary tin lined 
 copper still and block tin condenser may be used, or a 
 more economical way is to make use of the well known 
 Domestic Water Still, (Fig. i). This piece of apparatus 
 
 * Water Analysis, FRANKLAND, p. 113. 
 
INORGANIC PREPARATIONS. 3 
 
 yields a good quality of product, with a minimum ex- 
 penditure of heat and condenser water, and is moreover 
 very compact. 
 
 FIG. l. 
 
 Water free from organic matter and ammonium, which 
 is indispensable in water analysis and the preparation of 
 many standard solutions such as potassium permanganate, 
 argentic nitrate etc., is best prepared in the apparatus 
 shown in. Fig 2, which consists of a glass-stoppered flask 
 with side-neck tube. The end of the side-neck tube is turned 
 vertically downward, being thrust deeply into the tin tube 
 of the condenser, and held in place there by a short piece of 
 rubber tubing. The three-eighth inch block tin pipe forming 
 the condenser-tube is bent zigzag instead of in the conven- 
 
LABORATORY MANUAL OF 
 
 tional helix. This affords a more even flow of the distillate. 
 The cylindrical copper jacket containing the water for cool- 
 ing is about four inches in diameter, and fifteen inches long. 
 The disk closing the lower end is arched upward so that in 
 
 FIG. 2. 
 
 case the condenser " sweats " from the use of very cold 
 water, the drip from the outside can not contaminate the 
 distillate. The lower end of the tin tube is cut aslant for 
 the more certain delivery of the distillate. 
 
INORGANIC PREPARATIONS. 5 
 
 /X ^SE r UB^> 
 
 (UNIVERSITY; 
 
 Vc^?w.V 
 
 ETHYL ALCOHOL. 
 C 2 H 5 .OH. 
 
 Two sorts of alcohol are used in chemical analy- 
 sis, viz. : 1st, Commercial " 95 per cent, alcohol," 
 which really contains 93 to 94 per cent, of alcohol 
 by weight ; and 2d, absolute alcohol. The latter may be 
 prepared most conveniently by placing in a flask or tin can 
 800 grams of good quick-lime in coarse powder or small 
 lumps, adding I litre of " 95 per cent, alcohol," connecting 
 the vessel with the lower end of a Liebig condenser, and 
 keeping its contents boiling on a water bath for an hour. 
 The can is then connected to the upper end of the conden- 
 ser, and the dehydrated alcohol distilled off into a bottle 
 for use.* 
 
 Pure alcohol must completely volatilize, and ought 
 not to leave a smell of fusel-oil when rubbed between 
 the hands ; nor should it alter the color of moist blue or 
 red litmus paper. When kindled, it must burn with a faint 
 bluish, barely preceptible flame. 
 
 Commercial Alcohol invariably contains aldehyde and 
 if kept in tin cans stannic oxide as well; such alcohol can- 
 not be used for the preparation of alcoholic potash solutions, 
 argentic nitrate or for Hiibl's iodo-mercuric chloride 
 solution. For such purposes either of the two following 
 methods may be used. 
 
 A convenient amount of the alcohol to be purified is 
 shaken with pulverized potassium permanganate until it 
 a'ssumes a decided color. It is then allowed to stand for 
 
 * ERLENMEYER ; J. LAWRENCE SMITH. 
 
6 LABORATORY MANUAL OF 
 
 some hours, until the permanganate has been decomposed 
 and brown manganese oxide is deposited. A pinch of 
 pulverized calcium carbonate is then added, and the alcohol 
 distilled at the rate of about 50 c. c. in 20 minutes from 
 a flask provided with a Wurtz tube or one of the Lebel- 
 Heninger pattern. The distillate is tested frequently until 
 about 10 c. c. thereof, when boiled with I c. c. of strong 
 (syrup) solution of caustic soda or potash, gives no percept- 
 ible yellow coloration on standing for 20 minutes or half 
 an hour. What distills over after that time is preserved for 
 use. 
 
 The first distillates may be added to the small amount 
 remaining in the distilling flask (which should not be driven 
 down to the complete dryness), and a fresh portion of puri- 
 fied alcohol recovered. 
 
 The rationale of the proceeding appears to be that the 
 permanganate oxidizes and destroys chiefly the fusel-oil, 
 furfurol and other compounds of that, nature, the acids 
 resulting from the reaction are neutralized by the calcium 
 carbonate added before distillation, and by distilling 
 slowly the aldehyde at least is concentrated in the first 
 portions of the distillate. Distillation of alcohol contain- 
 ing caustic potash or soda seemed to cause a constant 
 formation of aldehyde. The alcohol thus purified is per- 
 fectly neutral, and gives most satisfactory results when 
 used as a solvent for caustic alkalies or silver nitrate, the 
 solutions remaining as colorless as distilled water, even 
 after boiling and standing indefinitely, if properly pro- 
 tected from dust and other external influences.* 
 
 * Jour. Am. Chem. Soc. E. WALLER. 
 
INORGANIC PREPARATIONS. 
 
 The second method consists in distilling the alcohol 
 with some caustic potash in the presence of a large quantity 
 of non-volatile fatty acid ; either oleic or stearic is gener- 
 ally used, the process is simple and the result good. 
 
 OXYGEN. 
 O. 
 
 The compressed gas put up in steel cylinders is 
 sufficiently pure for most purposes, but when not avail- 
 able the gas may be readily prepared by heating a mixture 
 of equal parts of potassium chlorate and manganese di- 
 oxide, in a copper retort, or better, in an apparatus similar 
 to fig. 3. 
 
 FIG. 3. 
 
 Oxygen gas made in this way is liable to contain 
 chlorine or oxides of chlorine and carbon dioxide, it is 
 purified by washing with potassium hydrate and dried by 
 passing through concentrated sulphuric acid. 
 
 Oxygen may also be prepared by treating sodium 
 dioxide NagOg with dilute acid, either hydrochloric or 
 sulphuric. 
 
8 LABORATORY MANUAL OF 
 
 Na 2 O 2 + 2H.C1 = O + 2NaCl + H 3 O, 
 
 great heat is evolved in this reaction and the operation 
 must be conducted with care; it is however an excellent way 
 to oxidize solutions, in which case the solution is made acid 
 and the sodium dioxide dropped in and well stirred until 
 the desired effect has been produced. 
 
 In the wet way oxygen is produced by treating 
 "Chloride of Lime " Ca(ClO) 2 ,CaCl 3 in disc form, in a Kipp's 
 Apparatus with a mixture of I litre of hydrogen dioxide and 
 53 c. c. nitric acid com. Sp. Gr. 1.265. The same pre- 
 cautions for purification are necessary as in the case of 
 manganese dioxide and potassium chlorate. 
 
 To prepare oxygen, cubes consisting of a mixture of 
 2 parts of barium dioxide, I part of manganese dioxide 
 and i part of pla.ster are used with hydrochloric acid (sp. 
 gr. 1.12) diluted with an equal volume of water. The oxy- 
 gen evolved contains traces of chlorine and must there- 
 fore be washed with an alkali.* 
 
 It can also be prepared by adding potassium perman- 
 ganate to hydrogen peroxide made alkaline with ammonia.t 
 
 Oxygen is a colorless gas, and without odor. It is 
 liquified with difficulty, requiring a pressure of 320 atmos- 
 pheres at 212 F. Oxygen is remarkable for the wide 
 range of its chemical attraction for other elementary bodies 
 with all of which it is capable of entering into combi- 
 nation except one, namely fluorine. 
 
 * G. NEUMANN, Ber. 20, 1584. 
 
 f C. F. GOHRING, Chem. Zeit. 12, 1659. 
 
INORGANIC PREPARATIONS. 
 
 HYDROGEN. 
 H. 
 
 Hydrogen is best prepared from granulated zinc 
 and dilute sulphuric acid (i litre acid, 5 litres water) in 
 Kipp's Apparatus ; the zinc should not be too pure or the 
 supply of gas will be slow and feeble. In any case it is well 
 to add a small amount of copper sulphate solution, just 
 sufficient to produce a thin coat of copper on the zinc, 01 
 a piece of platinum foil may be used in place of the copper 
 sulphate ; in this latter case it is better to amalgamate the 
 zinc, by first treating with dilute sulphuric acid and then 
 adding mercury and shaking, or by simply treating the 
 zinc with a strong solution of mercuric nitrate containing 
 free nitric acid. 
 
 A granulated alloy of tin and zinc, containing about 83 
 per cent, of the latter, prepared by adding zinc to molten 
 tin as long as it dissolves, is recommended for use in 
 Kipp's apparatus. The pieces retain their shape and size 
 after all the zinc is dissolved out, and therefore have no 
 tendency to fall through into the lower bulb.* 
 
 Hydrogen may also be prepared by sodium amalgam 
 with dilute acids. 
 
 Hydrogen gas prepared by the action of zinc and acid 
 is never pure, but may contain hydrocarbons, hydrogen 
 sulphide, sulphur dioxide, etc. 
 
 The very small amount of arsenic generally present, 
 as AsH 3 , may be neglected. The other impurities are re- 
 moved by first passing the gas through a solution of 
 
 * J. HABERMANN, Zeit. Anal. Chem. 28, 
 
 (tri 
 
 - 
 
ID LABORATORY MANUAL OF 
 
 potassium permanganate in order to oxidize hydrocarbons, 
 hydrogen sulphide, etc., then through the potassium 
 hydrate to absorb carbon dioxide, sulphur dioxide, etc., 
 and finally through concentrated sulphuric acid and calcium 
 chloride to remove water. 
 
 Hydrogen is a colorless, odorless and tasteless gas, is 
 highly combustible, burning with a very hot but slightly 
 luminous flame, and when mixed with air or free oxygen, 
 explodes with violence. 
 
 NITROGEN. 
 
 N. 
 
 This gas is seldom used, but when required may be 
 readily prepared by heating equal parts of concentrated 
 aqueous solutions of ammonium chloride and potassium or 
 sodium nitrite. 
 
 NH 4 Cl + KNO 2 = N 3 + KC1 + 2H 2 O. 
 
 The operation is conducted in a roomy flask, the out- 
 going gas mixed with steam, ammonium chloride, and pos- 
 sibly some oxides of nitrogen, is cooled washed with water 
 and dried over sulphuric acid. Nitrogen prepared in this 
 way contains no argon. 
 
 Nitrogen is a colorless, odorless and tasteless gas, and 
 is a non-supporter of combustion. 
 
 CHLORINE AND CHLORINE WATER. 
 
 Cl. 
 
 Chlorine is prepared by mixing 18 parts of common 
 salt in lumps with 1 5 parts of finely pulverized good man- 
 
INORGANIC PREPARATIONS. II 
 
 ganese dioxide, free from calcium carbonate ; put the mix- 
 ture in a flask, pour a completely cooled mixture of 45 parts 
 of concentrated sulphuric acid and 2 1 parts of water upon 
 it, and shake the flask : a uniform and continuous evolution 
 of chlorine gas will soon begin, which, when slackening 
 may be easily increased again by the application of a gentle 
 heat. This method of WlGGERS is excellent, and can be 
 highly recommended. Conduct the chlorine gas evolved 
 first through a flask containing a little water, then into a 
 bottle filled with cold water, and continue the process until 
 the fluid is saturated. Where it is desired to obtain 
 chlorine water quite free from bromine, the washing flask 
 is changed after about one-half of the chlorine has been 
 expelled, and the gas which now passes over is conducted 
 into a fresh bottle filled with water. If the chlorine water 
 is to be quite free from hydrochloric acid, the gas must be 
 passed through a U tube containing manganese dioxide. 
 The chlorine water must be protected from the action of 
 light ; since, if this precaution is neglected, it speedily suf- 
 fers complete decomposition, being converted into dilute 
 hydrochloric acid, with evolution of oxygen (resulting from 
 the decomposition of water). Smaller quantities, intended 
 for use in the laboratory, are best kept in a stoppered 
 bottle protected by a case of pasteboard. Chlorine water 
 which has lost its strong peculiar odor is unfit for use. 
 
 CHLORINE FROM CHLORIDE OF LIME IN KIPP'S APPA- 
 RATUS. 
 
 Dry chloride of lime is intimately mixed with plaster 
 and moistened to such a degree that it can only with diffi- 
 culty be rolled into balls between the fingers. It is made 
 
12 LABORATORY MANUAL OF 
 
 homogeneous by powdering in an iron mortar and beaten 
 into an iron frame 10-12 m.m. high by means of an iron 
 mallet. It is then covered with a piece of oilcloth and 
 submitted to great pressure. The plate of chloride of lime 
 is then cut into cubes while still in the frame and dried as 
 quickly as possible at 20 C. The cubes are then preserved 
 in well-closed vessels. It is used in a Kipp's apparatus 
 with hydrochloric acid (sp. gr. 1.124) diluted with an 
 equal volume of water. The acid must be free from sul- 
 phuric acid.* 
 
 When chlorine is generated from bleaching powder and 
 hydrochloric acid in a Kipp's apparatus, it is advisable, af- 
 ter using the apparatus, to blow in a little air, otherwise a 
 slow but continuous action takes place, owing to the ab- 
 sorption of the chlorine by the acid.t 
 
 APPARATUS FOR A CONSTANT SUPPLY OF CHLORINE. 
 
 I. The manganese dioxide is used in fragments the size of 
 peas, and is placed in a two-necked bottle, at the bottom 
 of which there is a layer of broken glass or pumice. This 
 stands in a water bath. Hydrochloric acid is supplied 
 from a reservoir at a higher level by a tube reaching to 
 the bottom of the layer of glass, a T-piece and stopcocks 
 allowing the same tube to serve for the removal of the 
 manganese solution. The corks should be soaked in par- 
 affin. Suitable drying apparatus can be attached and will 
 not require replenishing for a long time. The chlorine 
 begins to come off when the temperature of the bath 
 reaches 50 C., and by means of a stopcock on the outlet its 
 
 * C. WINKLER, Ber. 20, 184. 
 f C. WINKLER, Ber. 22, 1076. 
 
INORGANIC PREPARATIONS. 13 
 
 rate is completely under control. The evolution can 
 speedily be arrested by closing the stopcock at the outlet 
 of the drying apparatus and emptying the water bath. 
 
 The apparatus is then left full of chlorine, and is ready 
 at any moment to give supply of the gas completely free 
 from oxygen.* 
 
 II. From sodium chloride, pyrolusite, and sulphuric 
 acid. It is usually supposed that in this reaction the whole 
 of the chlorine is evolved in the free state ; detailed experi- 
 ments have, however, shown that this is not the case, but 
 that the reaction which takes place is as follows : 
 
 4NaCl+ MnO 3 + 3H 3 SO 4 = 2NaHSO 4 f Na 3 SO 4 + MnCl 3 + 
 2H 3 O + C1 2 . 
 
 The necessary proportions are, therefore, 5 parts of 
 pyrolusite, 11 parts salt, and 14 parts of sulphuric acid 
 diluted with an equal volume of water. 
 
 III. From pyrolusite, hydrochloric and sulphuric acids. 
 The instructions usually given for the preparation of 
 chlorine by this method are to take I part of pyrolusite, 2 
 of hydrochloric acid of sp. gr. 1.14, and I part of sulphuric 
 acid mixed with an equal bulk of water, the reaction being 
 supposed to take place according to the equation : 
 
 MnO 3 + 2HC1 + H 3 SO 4 = MnSO 4 + 2H 3 O + C1 3 . 
 
 As in the foregoing case this equation is quite incorrect, 
 only 65 per cent, of the chlorine being obtained in the free 
 state. 
 
 * A. VOSMAER, Zeit. Anal. Chem., 27, 638. 
 
14 LABORATORY MANUAL OF 
 
 CHLORINE FOR LABORATORY PURPOSES. 
 
 When hydrochloric acid of sp. gr. i.i, heated to about 
 80 C., is allowed to come slowly in contact with pieces of 
 potassium chlorate which have been previously fused, a 
 steady evolution of gas takes place. Under these condi- 
 tions, about 82 to 85 per cent, of the gas is chlorine, the re- 
 mainder being chlorine dioxide. Another 10 per cent, of 
 the dioxide may be decomposed by passing the evolved 
 gas through a saturated hydrochloric acid solution of man- 
 ganous chloride at 90 C. If the gas is wanted absolutely 
 pure, the gas, after passing through the manganous chlor- 
 ide, may be passed through a combustion tube filled with 
 asbestos and heated to redness. Care must be taken to 
 have the acid hot, and not to allow the action to become 
 rapid, or the proportion of chlorine dioxide may become 
 much increased and explosion occur, i gram of potas- 
 sium chlorate yields about half a litre of chlorine. 
 
 If a Kipp or some similar constant gas-generating ap- 
 paratus is employed, and the acid heated by a steam 
 jacket or by standing the generator in hot water, this 
 method forms a convenient constant chlorine apparatus for 
 laboratory use.* 
 
 Chlorine is a heavy greenish, yellowish gas, having a 
 strong and suffocating odor, and if inhaled in sufficient 
 quantities is capable of producing suffocation. Free 
 chlorine gas is readily detected by its color and odor. 
 
 * F. A. GOOCH and D. A. KREIDER, Zeit. Anorg. Chem., 7, 17. 
 
INORGANIC PREPARATIONS. 
 
 HYDROCHLORIC ACID, OR 
 
 HYDROGEN CHLORIDE. 
 
 HC1. 
 
 Pour a cooled mixture of seven parts of concen- 
 trated sulphuric acid and two parts of water over 
 four parts of sodium chloride in a retort ; expose the re- 
 tort, with slightly raised neck, to the heat of a sand-bath 
 until the evolution of gas ceases ; conduct the evolved 
 gas, by means of a bent tube, into a flask containing six 
 parts of water, and take care to keep this vessel constantly 
 cool. To prevent the gas from receding the tube ought to 
 dip but about one line into the water of the flask. When 
 the operation is terminated, try the specific gravity of the 
 acid produced, and dilute with water until it marks from 
 1. 1 1 to 1.12. If you wish to ensure the absolute purity of 
 the acid, and its perfect freedom from every trace of arsenic 
 and chlorine, you must take care to free the sulphuric acid 
 intended to be used in the process from arsenic and the 
 oxygen compounds of nitrogen, according to the directions 
 (see sulphuric acid, page 22.) A pure acid may also be 
 prepared cheaply from the crude hydrochloric acid of com- 
 merce by diluting the latter to a specific gravity of 1.12 and 
 distilling the fluid with addition of some chloride of sodium. 
 Or you may put the acid into the retort in the concentrated 
 form, placing 60 parts of water into the receiver for every 
 100 parts of concentrated acid, and not luting the receiver 
 to the retort. If the crude acid contains chlorine this 
 should be removed first by cautious addition of solution of 
 sulphur dioxide, before proceeding to the distillation; if, 
 
l6 LABORATORY MANUAL OF 
 
 on the other hand, it contains sulphur dioxide, this is re- 
 moved in the same way by cautious addition of some 
 chlorine water. Hydrochloric acid not unfrequently con- 
 tains arsenious chloride, owing to the presence of arsenic 
 in the sulphuric acid employed. To free it from this im- 
 purity, the acid is mixed with twice its volume of water, 
 hydrogen sulphide is conducted into it, the mixture allowed 
 to stand at rest for some time, the clear fluid then decanted 
 from the sulphur and arsenious sulphide, and heated, to ex- 
 pel the hydrogen sulphide. 
 
 Hydrochloric acid must be perfectly colorless and 
 leave no residue upon evaporation. If it turns yellow 
 on evaporation, ferric chloride is present. It must not im- 
 part a blue tint to a solution of potassium iodide mixed 
 with starch paste (chlorine or ferric chloride), nor discolor 
 a fluid made faintly blue with iodized starch (sulphur 
 dioxide). Barium chloride ought not to produce a pre- 
 cipitate in the highly diluted acid (sulphuric acid). Hy- 
 drogen sulphide must leave the diluted acid unaltered (ar- 
 senic). After neutralization with ammonia, ammonium 
 sulphide must produce no change in it (iron, thallium). 
 
 It can also be prepared by distilling a mixture of cone, 
 sulphuric and hydrochloric acids; this latter method is bet- 
 ter where gaseous hydrochloric acid is needed. 
 
 METHODS FOR OBTAINING CONSTANT STREAMS OF HY- 
 DROGEN CHLORIDE AMMONIA AND NITROGEN. 
 
 Hydrogen chloride can be generated in a Kipp's ap- 
 paratus by the action of ordinary sulphuric acid on carnal- 
 lite and ammonia gas by allowing a solution of ammonia 
 to react with solid potassium hydroxide. When the ma- 
 
INORGANIC PREPARATIONS. I/ 
 
 terials are exhausted, the solution of potash which is 
 formed may be used for ordinary laboratory purposes after 
 it has been boiled to expel ammonia. 
 
 To prepare nitrogen in Kipp's apparatus, it is best to 
 employ cubes containing chloride of lime made according 
 to Winkler's method (page n); these are treated with 
 a mixture of equal volumes of ammonia and water. 
 The resulting gas contains suspended ammonium chloride 
 and other impurities, which may be removed by passing 
 it through water, potash and sulphuric acid.* 
 
 FIG. 4. 
 
 NITRIC ACID. 
 
 HNO 3 OR NO 3 OH. 
 
 Prepared by slowly distilling a mixture of 5 parts of 
 sodium nitrate and 3 parts of cone, sulphuric acid, in an 
 apparatus as shown in Fig. 4 ; the product is usually not 
 
 By G. NEUMANN, (J. pr. Chem. [2] 37, 342-345). 
 
I 8 LABORATORY MANUAL OF 
 
 sufficiently concentrated, and must be redistilled with five 
 times its volume of cone, sulphuric acid in an apparatus 
 similiar to the above. If the product is colored yellow or red 
 by dissolved oxides of nitrogen, it may be rendered color- 
 less by blowinga current of dry air through the acid for some 
 minutes. Concentrated nitric acid 1.53 spcific gravity 
 has a strong affinity for water and must be kept closely stop- 
 pered. 
 
 The sudden frothing which frequently takes place when 
 nitric acid is prepared from sodium nitrate and sulphuric 
 acid is explained on the assumption that the first portions 
 pass over at 84 C, and that the heating must be commenced 
 cautiously, and the temperature only allowed to rise after 
 the first reaction abates. After the temperature has risen 
 above 109 C., no acid passes over until the temperature 
 117 C. is reached, when the last portions pass over. The 
 latter acid has a sp. gr. 1.42, and corresponds with the 
 hydrate, 2HNO 3 + H 3 O, which distills at 120 to 121 C. 
 without decomposition.* 
 
 Another method of preparation is to heat crude nitric 
 acid of commerce, as free as possible from chlorine, and of 
 a specific gravity of at least 1.31 in a glass retort to 
 boiling, with addition of some potassium nitrate ; let the 
 distillate run into a receiver kept cool, and try from time 
 to time whether after dilution it still continues to precipi- 
 tate or cloud solution of silver nitrate. As soon as this 
 ceases to be the case, change the receiver, and distill until 
 a trifling quantity only remains in the retort. Dilute the 
 distillate with water until the specific gravity is 1.2. 
 
 * By C. W. VOLNEY, J. Amer. Chem. Soc. 13, 246-251. 
 
INORGANIC PREPARATIONS. 19 
 
 Another method is to dilute crude nitric acid of com- 
 merce of about 1.38 specific gravity with two-fifths of its 
 weight of water, and add solution of silver nitrate as long 
 as a precipitate of silver chloride continues to form ; then 
 add a further slight excess of solution of silver nitrate, let 
 the precipitate subside, decant the perfectly clear super- 
 natant acid into a retort or an alembic with ground head ; 
 add some potassium nitrate free from chlorine, and distill 
 until only a small quantity remains, taking care to attend 
 to the proper cooling of the fumes distilling over. Dilute 
 the distillate, if necessary, with water until it has a specific 
 gravity of .1.2. 
 
 Pure nitric acid must be colorless and leave no 
 residue upon evaporation on platinum foil. Solution of 
 silver nitrate or of barium nitrate must not cause the 
 slightest turbidity in it. Dilute the acid with water before 
 adding these reagents, as otherwise nitrates will pre- 
 cipitate. Silver should be tested for by hydrochloric acid. 
 
 NITROUS OXIDE. 
 N 2 O. 
 
 Five parts of stannous chloride, 10 parts of hydrochloric 
 acid sp. gr. 1.21, and 0.9 part of nitric acid sp. gr. 1.38, 
 are heated to boiling, when the evolution of nitrous oxide 
 commences, and continues to be evolved quite regularly 
 and in a pure state. The above proportions of ingredients 
 should be adhered to, as otherwise the gas is evolved ir- 
 regularly, and even with violent explosions.* 
 
 G. CAMPORI, Ann. Chine. Pharm., 8, 253. 
 
20 LABORATORY MANUAL OF 
 
 It can also be prepared from a mixture of ammonium 
 sulphate and sodium nitrate, kept at 102 C. for 2 to 3 hours, 
 undergoes in great part decomposition into sodium sulphate 
 and ammonium nitrate. If, however, it is rapidly raised 
 to a higher temperature, nitrous oxide begins to be evolved 
 atiio C.,and comes off with some rapidity at 115 to 120 
 C. During the heating up a little ammonia is evolved, and 
 the longer the mixture is kept at about 104 to 1 10 C. the 
 more ammonia is lost. If, then, the two salts have been mixed 
 in molecular proportions, the deficiency in the ammonia 
 leads to the evolution of some of the higher oxides of nitro- 
 gen towards the end of the reaction. This may be remedied 
 by increasing the proportion of ammonium sulphate, the 
 mixture, with an additional 5 per cent, of that salt, affording 
 a larger yield of nitrous oxide than would be obtained from 
 the equivalent quantity of ammonium nitrate. The gas is 
 evolved with regularity, whereas ammonium nitrate, raised 
 to 115 C., decomposes with a rapidity, accelerating towards 
 explosive violence.* 
 
 NITRIC OXIDE. 
 
 NO. 
 
 A Woulff's bottle, fitted with a funnel and delivery 
 tube, is filled loosely with strips of copper, and then one- 
 third with a cold saturated solution of sodium nitrate. 
 Strong sulphuric acid is added more or less quickly, ac- 
 cording to the amount of gas required. The evolution of 
 gas is very regular, and may be kept up for hours. f 
 
 * BY W. SMITH, J. Soc. Chem. Ind., 11.867; 12, 10. 
 f By H. KAEMMERER, Ber. 18, 3064-3066. 
 
INORGANIC PREPARATIONS. 21 
 
 Nitric oxide may also be prepared from a mixture of 
 solutions of potassium ferrocyanide and potassium nitrite 
 added gradually from a stoppered funnel to a flask contain- 
 ing acetic acid ; the contents of the flask must be vigor- 
 ously shaken during the operation.* 
 
 Another method is to add a strong solution of 
 sodium nitrite to a solution of ferrous chloride or sulphate 
 in hydrochloric acid. If the sodium nitrite contains car- 
 bonate, it may be removed by precipitation with calcium 
 chloride.t 
 
 In order to obtain this gas in a very pure condition, the 
 reaction which takes place in a Lunge's nitrometer is em- 
 ployed; namely, treating mercury with a mixture of sul- 
 phuric acid and nitric acid. The purity of the gas was placed 
 beyond question by the results obtained on leading it over 
 glowing copper ; the increase in weight of the metal, giv- 
 ing the weight of oxygen, whilst the gas evolved, which 
 was collected and measured, gave the weight of nitrogen. 
 In the reaction between copper and nitric oxide, which 
 is attended by the liberation of much heat, the metal is 
 quantitatively converted into cuprous oxide.J: 
 
 NITROGEN TETRAOXIDE. 
 
 N 3 4 . 
 
 200 grams arsenious acid in pieces the size of a pea 
 are placed in a tubulated retort with bent neck, 200 grams 
 nitric acid 1.38 sp. gr. poured over it, and very moderately 
 
 * By C. M. VAN DEVENTER, Ber. 26, 589-593. 
 f By J. THIELE, Annalen 253, 146. 
 j By F. ENRICH, Monatsh, 13, 73-77. 
 
22 LABORATORY MANUAL OF 
 
 warmed. The evolved gas passes into an empty wash- 
 bottle, is then dried by a tube filled with calcium nitrate 
 and is finally conducted into a wide combustion-tube which 
 is surrounded by a freezing mixture of ice and common salt. 
 A dark-green liquid condenses in this tube. Dry oxygen 
 gas is conducted into it until the liquid has changed to 
 a pure yellow, then the tube is sealed. 
 
 The arsenic trioxide reduces the nitric acid passing 
 into arsenic acid. In drying the gases calcium chloride 
 must not be used, as they would be contaminated with 
 chlorine, nor sulphuric acid, as it absorbs the gases. 
 The condensed mixture of nitrogen trioxide and tetroxide 
 is transformed by oxygen into pure tetroxide. 
 
 The liquid should show a sp. gr. of 1.45 and boil at 
 25 to 26 C. On cooling rapidly it should stiffen to a color- 
 less crystal mass, which melts at about 12 C. 
 
 SULPHURIC ACID. 
 H 3 SO 4 OR SO 2 (OH) 2 . 
 
 a. Concentrated pure sulphuric acid. 
 
 b. Concentrated sulphuric acid of commerce. 
 
 c. Common dilute sulphuric acid. 
 
 The following method may be recommended for pre- 
 paring chemically pure sulphuric acid : 
 
 a. Put 1,000 grams of ordinary concentrated sulphuric 
 acid in a porcelain dish, and 3 grams of ammonium sul- 
 phate, and heat till copious fumes of SO 3 begin to escape, 
 in order to destroy the oxides of nitrogen which are 
 present. After cooling, add 4 or 5 grams of powdered 
 manganese dioxide, and heat to boiling with stirring, in 
 
INORGANIC PREPARATIONS. 23 
 
 order to convert any arsenious acid into arsenic acid. 
 When cool pour off the clear fluid by means of a long 
 funnel tube into a retort coated with clay. The retort 
 should not be more than half full, and is to be heated 
 directly over charcoal. To prevent bumping, rest the 
 retort on an inverted crucible cover, so that the sides may 
 be more heated than the bottom. The neck of the retort 
 must reach so far into the receiver that the acid, distilling 
 over, drops directly into the body. To cool the receiver 
 by means of water is unnecessary and even dangerous. 
 To prevent the receiver from coming into actual contact 
 with the hot neck of the retort, some asbestos in large 
 fibres is placed between them. When about 10 or 15 
 grams has been drawn over, change the receiver and slowly 
 distil off three-fourths of the contents of the retort. This 
 method depends upon the fact discovered by Bussy 
 and Buignet, that on distilling sulphuric acid, which 
 contains arsenic in the form of arsenic acid, an arsenic-free 
 distillate is obtaine'd. 
 
 b. Pour into 4 parts of water I part of concentrated 
 sulphuric acid, and conduct into the mixture for some time 
 a slow stream of hydrogen sulphide, keeping the fluid 
 heated to 70 C. Let the mixture stand at rest for several 
 days, then decant the clear supernatant fluid from the 
 precipitate, which consists of sulphur, lead sulphide, per- 
 haps also arsenic sulphide, and heat the decanted fluid in a 
 tubulated retort with upturned neck and open tubulature 
 until sulphuric acid fumes escape with the aqueous 
 vapor. The acid so purified is fit for many purposes 
 of chemical analysis ; if it is desired, however, to free 
 it also from non-volatile substances, it may be distilled 
 
4 LABORATORY MANUAL OF 
 
 from a coated retort as in a. As soon as the drops in the 
 neck of the retort become oily, the receiver is changed, 
 and the concentrated acid which then passes over is kept 
 in a separate vessel. 
 
 c. Common dilute sulphuric acid. Add to 5 parts of 
 water in a thin glass or porcelain dish gradually, and whilst 
 stirring, I part of concentrated sulphuric acid. The lead 
 sulphate which seperates is allowed to subside, and the clear 
 fluid finally decanted. 
 
 Pure sulphuric acid must be colorless; when color- 
 less solution of ferrous sulphate is poured upon it in a 
 test tube, no brown tint must mark the plane of contact 
 of the two fluids (nitric acid, nitrous acid) ; when diluted 
 with twenty parts of water it must not impart a blue tint 
 to a solution of potassium iodide mixed with starch 
 paste (nitrous acid). Mixed with pure zinc and water, 
 it must yield hydrogen gas, which, on being passed 
 through a red-hot tube, must not deposit the slightest 
 trace of arsenic. It must leave no residue upon evapora- 
 tion on platinum, and must remain perfectly clear upon 
 dilution with four or five parts of alcohol (lead, iron, calcium). 
 The presence of small quantities of lead is detected most 
 easily by adding some hydrochloric acid to the sulphuric 
 acid in a test tube. If the plane of contact is marked 
 by turbidity (lead chloride), lead is present. Sulphurous 
 acid is discovered by the odor after shaking the acid in a 
 half-filled bottle. 
 
INORGANIC PREPARATIONS. 25 
 
 HYDROGEN SULPHIDE. HYDROSULPHURIC 
 ACID. SULPHURETTED HYDROGEN. 
 
 H 3 S. 
 
 Hydrogen sulphide is usually evolved from iron 
 sulphide, which is broken into small lumps and then 
 treated with dilute sulphuric or hydrochloric acid. Fused 
 iron sulphide may be purchased cheaply, or may be made 
 by heating iron turnings or I to I J^ inch iron nails, in a 
 covered Hessian crucible to a white heat, and then adding 
 
 FIG. 6. 
 
 small lumps of roll-sulphur until the entire contents of the 
 crucible are in fusion. As soon as this is the case, pour 
 the fused mass upon sand, or into an old Hessian crucible. 
 Or make a hole in the bottom of the crucible, when the 
 iron sulphide will run through as fast as it forms, and may 
 
26 LABORATORY MANUAL OF 
 
 be received in a shovel placed in the ash-pit. Or intro- 
 duce an intimate mixture of thirty parts of iron filings and 
 twenty-one parts of flowers of sulphur in small portions 
 into a red-hot crucible, awaiting always the incandescence 
 of the portion last introduced before proceeding to the 
 addition of a fresh one. When you have thus put the 
 mixture into the crucible, cover the latter closely, and 
 expose it to a more intense heat, sufficient to make the 
 iron sulphide fuse more or less, then allow the crucible to 
 cool and break the sulphide in small pieces. 
 
 The iron sulphide is then placed in a Kipp's apparatus, 
 fig. 6, and the gas is generated by the action of dilute 
 sulphuric or hydrochloric acids. 
 
 HYDROGEN SULPHIDE FREE FROM ARSENIC. 
 
 Calcium sulphide (prepared by igniting a mixture of 
 plaster of Paris and coal) yields the pure gas when treated 
 with dilute hydrochloric acid. To evolve the gas in a 
 regular stream, a mixture of calcium sulphide, with one- 
 fourth of its weight of plaster of Paris and enough water to 
 make a cream, is poured into shallow paper trays. As 
 soon as it has set, the cake is cut up into blocks, which 
 are dried at a gentle heat. They may be used in Kipp's 
 apparatus.* 
 
 Another method is to use barium sulphate (powdered 
 barytes) mixed with 25 per cent, of ground coal and 20 
 per cent, of common salt. The dampened mixture is 
 rammed into a clay crucible, which, after drying and 
 closing with a luted cover, is heated for several hours 
 
 * R. FRESENIUS, Zeit. Anal. Chem. 26, 339. 
 
(trwivr.. SITY X 
 
 INORGANIC PREPARATIONS* > 2 7 
 
 at an incipient white heat The product is in hard com- 
 pact masses which dissolve completely in dilute hydro- 
 chloric acid with a steady evolution of hydrogen sul- 
 phide.* 
 
 HYDROGEN SULPHIDE FREED FROM HYDROGEN 
 ARSENIDE. 
 
 This method is based on the fact that hydrogen arsen- 
 ide reacts violently with iodine at ordinary temperature, 
 arsenious iodide and hydrogen iodide being formed. 
 
 A narrow tube, 30 to 40 cm. long, is loosely filled with 
 coarsely powdered, air-dried iodine interspersed with glass 
 wool ; 2 or 3 grams of iodine will remove every trace of ar- 
 senic from hydrogen sulphide prepared from the ordinary 
 impure materials, passing over it for several days. In 
 purifying hydrogen, the latter is subsequently passed over 
 glass wool wetted with potassium iodide solution and then 
 through aqueous potash. t 
 
 Free hydrogen sulphide in quantity is readily detected 
 by its odor, and its blackening effect upon paper moist- 
 ened with lead acetate. 
 
 SULPHUR DIOXIDE. 
 
 S0 3 . 
 
 Prepared by gently heating in a flask scrap copper with 
 concentrated, sulphuric acid 
 
 Cu + 2H 2 SO 4 = SO 2 + 2H 3 O + CuSO 4 . 
 It can be absorbed in water and used as a solution of sul- 
 phurous acid or absorbed in caustic alkalies forming 
 
 * C. WINKLER, Zeit. Anal. Chem. 27, 26. 
 f O. JACOBSEN, Ber. 20, 1999. 
 
28 LABORATORY MANUAL OF 
 
 bisulphites which may be again used to generate sulphur 
 dioxide by the action of cone, sulphuric acid. 
 
 Prepared in this way, however, it is liable to contain 
 sulphuric acid which is not readily removed. Sulphur 
 dioxide is now obtainable in liquified condition and as 
 such is used for disinfecting and freezing purposes. 
 
 Sulphurous anhydride (SO 2 ) can be generated in 
 Kipp's apparatus by the action of ordinary concentrated 
 sulphuric acid on cubes prepared by Winkler's method 
 from a mixture of 3 parts of calcium sulphite and I part of 
 plaster. Economy in the use of cubes is effected if only 
 the number required for the generation of the amount of 
 gas needed are wetted with the acid at the commencement 
 of the operation.* 
 
 Sulphur Dioxide is recognized 
 
 1st. By its odor which is marked and well-known, re- 
 sembling that of burning matches. 
 
 2nd. Suspend in the gas a strip of paper which has 
 been dipped into a solution of starch paste and potassium 
 iodate. Iodine is liberated and the paper becomes blue. 
 
 2KIO 3 + 5SO 3 + 4H 2 O == 2HKSO 4 -f 3H 3 SO 4 + I 2 . 
 
 CARBON MONOXIDE. 
 
 CO. 
 
 Prepared by gently heating commercial oxalic acid in 
 a capacious flask with cone, sulphuric acid. The acid 
 exerts a dehydrating action and a mixture of carbon mon- 
 oxide and carbon dioxide is evolved. The mixed gases are 
 
 G. NEUMANN, Ber. 20, 1584. 
 
INORGANIC PREPARATIONS. 29 
 
 passed through potassium hydrate solution which absorbs 
 the carbon dioxide and sulphuric acid ; any water which 
 may be present being removed by passing the gases 
 through concentrated sulphuric acid. 
 
 Another and better method is as follows : 
 A mixture of finely powdered potassium ferrocyanide 
 with eight or ten times its weight of cone, sulphuric acid is 
 heated in a capacious flask ; the following reaction results: 
 K 4 Fe(CN) 6 + 6H 3 SO 4 + 6H 2 O = 
 
 6CO + 2K 2 SO 4 4- 3(NH 4 ) 2 SO 4 + FeSO 4 . 
 
 If the heat is carefully regulated the evolution of gas is 
 gentle and regular. The product, however, is liable to 
 contain carbon dioxide and cyanogen compounds, hence it 
 is better to wash with potassium hydrate. Carbon mon- 
 oxide is recognized when in sufficient quantities by the 
 bluish flame with which it burns. 
 
 CARBON DIOXIDE. 
 CO 2 . 
 
 Prepared by treating coarsely broken marble with di- 
 lute acids in Kipp's Apparatus, washed with water and dried 
 over cone, sulphuric acid. It is used to remove chlorine in 
 various operations where heat is undesireable. The gas 
 may now be obtained in the liquid form, in steel cylin- 
 ders and is used as a freezing agent. 
 
 The free gas is detected by conducting it through a 
 solution of calcium hydroxide, Ca(OH) 2 with which it 
 forms a white precipitate (calcium carbonate). 
 
 The free gas in water may be detected by adding the 
 same solution as above. 
 
30 LABORATORY MANUAL OF 
 
 SIMPLE AND RAPID PREPARATION OF PURE GASES. 
 
 Instead of using an acid for the evolution of carbonic 
 anhydride, sulphurous anhj'dride, and similar gases, it is 
 convenient to use sodium hydrogen sulphate. A mixture 
 of equivalent quantities of the respective salts in powder 
 gives, when wetted with water, a regular stream of the re- 
 quired gas, which will be free from the impurities usually 
 derived from the use of an acid.* 
 
 AMMONIA, 
 NH 3 . 
 
 AMMONIUM HYDRATE. 
 NH 4 OH. 
 
 Prepared by gently heating crude ammonium sulphate 
 with dry slaked lime 
 
 2NH 4 C1 -f Ca(OH) 2 = 2NH 3 + CaClg 4- 2H 2 O 
 
 2NH 3 + 2H 2 O = 2NH 4 OH. 
 
 If gaseous ammonia is needed it must be caught by 
 downward displacement of air, otherwise the gas is passed 
 into water until saturated. 
 
 To make ammonia for laboratory use the strongest 
 ammonia water is dropped on porous calcium chloride, 
 great heat is evolved during this operation but the gas 
 which passes over is almost pure. 
 
 * By H. BORNTRAEGER, Zeit. Anal. Chem., 29, 140. 
 
INORGANIC PREPARATIONS. 31 
 
 POTASSIUM HYDROXIDE, OR POTASSA, 
 
 KOH, 
 
 AND SODIUM HYDROXIDE, OR SODA, 
 NaOH. 
 
 The preparation of perfectly pure potassa or soda is a 
 difficult operation. It is advisable, therefore, to provide 
 besides perfectly pure caustic alkali, some which is not 
 quite pure, and some which, being free from certain im- 
 purities, may in many cases be substituted for the pure sub- 
 stance. 
 
 a. Common solution of Soda. Put into a clean cast-iron 
 pan provided with a lid, 3 parts of crystallized sodium car- 
 bonate of commerce and I 5 parts of water, heat to boiling, 
 and add, in small portions at a time, thick milk of lime pre- 
 pared by pouring 3 parts of warm water over I part of 
 fresh-burned quick-lime, and letting the mixture stand in 
 a covered vessel until the lime is reduced to a uniform 
 pulpy mass. Keep the liquid in the pan boiling while 
 adding the milk of lime, for a quarter of an hour 
 longer ; then filter off a small portion, and try whether the 
 filtrate still causes effervescence in hydrochloric acid. If 
 this is the case, the boiling must be continued, and if 
 necessary some more milk of lime must be added to the 
 fluid. When the solution is perfectly free from carbonic 
 acid, cover the pan, allow the fluid to cool a little, and 
 then draw off the nearly clear solution from the residuary 
 sediment, by means of a siphon filled with water, and 
 
32 LABORATORY MANUAL OF 
 
 transfer it to a glass flask. Boil the residue a second and 
 third time with water, and draw off the fluid in the same 
 way. Cover the flask close with a glass plate, and allow 
 the lime suspended in the fluid to subside completely. 
 Scour the iron pan clear, pour the clear solution back into 
 it, and evaporate it to 6 or 7 parts. The solution so pre- 
 pared contains from 9 to 10 per cent, of soda, and has 
 a specific gravity of from 1.13 to 1.15. If it is wished to 
 filter a solution of soda which is not quite clear, a cov- 
 ered funnel should be used, which has been charged first 
 with lumps of white marble and then with powder of the 
 same, the fine dust being rinsed out with water before the 
 filter is used (Graeger). Solution of soda must be clear, 
 colorless, and as free as possible from carbonic acid ; am- 
 monium sulphide must not impart a black color to it. 
 Traces of silicic acid, alumina, and phosphoric acid are usu- 
 ally found in a solution of soda prepared in this manner, 
 on which account it is unfit for use in accurate experi- 
 ments. Solution of soda is kept best in bottles closed with 
 ground glass caps. In default of capped bottles, common 
 ones with well-ground stoppers may be used, in which case 
 the neck must be wiped perfectly dry and clean inside and 
 the stopper coated with paraffine ; since, if this precaution 
 is neglected, it will be found impossible after a time to 
 remove the stopper, particularly if the bottle is only rarely 
 opened. 
 
 Absolutely pure soda is best prepared by dissolving 
 sodium in pure water in a silver dish and evaporating un- 
 til a drop of the liquid solidifies on cooling. 
 
 The strength of the caustic soda solution is ascertained 
 approximately by specific gravity. 
 
INORGANIC PREPARATIONS. 33 
 
 % NaOH. Sp. Gr. % NaOH. Sp. Gr. 
 
 IO 1.11$ 21 1-236 
 
 II I.I26 22 1-247 
 
 12 1.137 2 3 T - 2 5 8 
 
 13 1.148 24 1.269 
 
 i4-- --1-159 2 5 J - 2 79 
 
 15 1.170 26 1.290 
 
 16 1.181 27 1-300 
 
 17 1.192 28 1.310 
 
 1 8 i. 202 29 1-321 
 
 '9 - ...1.213 30 1.332 
 
 20 1.225 
 
 The exact strength may be determined by titrating 
 say 20 c. c. of the solution with normal acid, using phen- 
 olphthalein as indicator, if any carbonic acid is present, a 
 small quantity of barium chloride solution should be 
 added before titrating. The calculation is very simple 
 since i c. c. N/HC1 or N/2H 2 SO 4 = 0.040 gram. NaOH or 
 0.0561 KOH. 
 
 b, Potassa purified with alcohol. Dissolve some caus- 
 tic potassa of commerce in alcohol, in a stoppered bottle, 
 by digestion and shaking ; let the fluid stand, decant it, or 
 filter it if necessary, and evaporate the clear fluid in a sil- 
 ver dish over the gas or spirit lamp until no more vapors 
 escape, adding from time to time, during the evaporation, 
 some water to prevent blackening of the mass. Place the 
 silver dish in cold water until it has sufficiently cooled ; re- 
 move the cake of potassa from the dish, break in coarse 
 lumps in a hot mortar and keep in a well closed glass bot- 
 tle. When required for use, dissolve a small lump in 
 water. 
 
34 LABORATORY MANUAL OF 
 
 The potassa so prepared is sufficiently pure for most 
 purposes ; it contains a minute trace of alumina, but is 
 usually free from phosphoric, sulphuric, and silicic acids. 
 The solution must remain clear upon addition of ammonium 
 sulphide ; hydrochloric acid must only produce a barely 
 perceptible effervescence in it. The solution .acidified with 
 hydrochloric acid must, upon evaporation to dryness, leave 
 a residue which dissolves in water to a clear fluid. The 
 solution acidified with hydrochloric acid, and then mixed 
 with ammonia in the least possible excess, must not show 
 any flocks of alumina, at least until it has stood in a warm, 
 place for several hours. The solution acidified with nitric 
 acid must not give any precipitate with a nitric acid solu- 
 tion of ammonium molybdate. 
 
 Potassa prepared with baryta. Dissolve pure crystals 
 of baryta by heating with water, and add to the solution 
 pure potassium sulphate until a portion of the filtered fluid, 
 acidified with hydrochloric acid and diluted, no longer 
 gives a precipitate on addition of a further quantity of the 
 sulphate (16 parts of crystals of baryta require 9 parts of 
 potassium sulphate). Let the turbid fluid clear, decant 
 and evaporate in a silver dish. The potassa so prepared 
 is perfectly pure, except that it contains a trifling admix- 
 ture of potassium sulphate, which is left behind upon dis- 
 solving in a little water. It is but rarely required, its use 
 being in fact exclusively confined to the detection of 
 minute traces of alumina, 
 
INORGANIC PREPARATIONS. 35 
 
 BARIUM HYDROXIDE, OR BARYTA. 
 
 Ba(OH) 2 . 
 
 There are many ways of preparing baryta; but 
 as witherite (barium carbonate) is now cheaply procurable, 
 the following method is preferable: Mix intimately to- 
 gether 100 parts of finely pulverized witherite, 10 parts 
 of charcoal in powder, and 5 parts of rosin, put the mix- 
 ture in an earthenware crucible, lute on the lid with clay, 
 and expose the crucible so prepared to the heat of a brick- 
 kiln. Break and triturate the baked mass, boil repeatedly 
 with water in an iron pot, filter into bottles, stopper, and 
 let them stand in the cold, when large quantities of crystals 
 of barium hydroxide Ba(OH) 2 -f 8H 3 O will make their 
 appearance. Let the crystals drain in covered funnels, 
 dry rapidly between sheets of blotting paper, and keep 
 them in well closed bottles. For use, dissolve I part of the 
 crystals in 20 parts of water, with the aid of heat, and filter 
 the solution. The baryta water so prepared is purer than 
 the mother liquor running off from the crystals. The res- 
 idue, which is insoluble in water and consists of undecom- 
 posed witherite and charcoal, may be turned to account in 
 the preparation of barium chloride. 
 
 Baryta water must, after precipitation of the barium 
 by pure sulphuric acid, give a filtrate remaining clear when 
 mixed with alcohol, and leaving no fixed residue upon 
 evaporation in a platinum crucible. 
 
 Barium hydroxide being a strong base, precipi- 
 tates the metallic hydroxides insoluble in water from the 
 solutions of their salts. 
 
 S " OF THE A 
 
 UNIVERSITY) 
 
36 LABORATORY MANUAL OF 
 
 CALCIUM HYDROXIDE, OR LIME. 
 Ca(OH) 2 . 
 
 Calcium hydroxide is obtained by slacking lumps of 
 pure calcined lime in a porcelain dish, with half their 
 weight of water. The heat which accompanies the com- 
 bination of the lime and the water is sufficient to evapor- 
 ate the excess of water. Slacked lime must be kept in a 
 well-stoppered bottle. 
 
 To prepare lime water, digest slacked lime for some 
 time with cold distilled water, shaking the mixture occa- 
 sionally ; let the undissolved portion of lime subside, de- 
 cant, and keep the clear fluid in a well-stoppered bottle. 
 If it is wished to have the lime water quite free from all 
 traces of alkalies, baryta and strontia, which are almost 
 invariably present in slacked lime prepared from calcined 
 limestone, the liquids of the first two or three decantations 
 must be removed, and the fluid decanted afterwards alone 
 made use of. 
 
 Lime water must imp'art a strongly-marked brown 
 tint to turmeric paper, and give a not too inconsider- 
 able precipitate with sodium carbonate. It speedily loses 
 these properties upon exposure to the air. 
 
 LEAD DIOXIDE. 
 
 Pb0 2 . 
 
 a. In the dry way. 53 grams lead oxide are thor- 
 oughly mixed in a mortar with 50 grams calcium carbonate, 
 and a wide and not too deep clay crucible is filled loosely 
 
INORGANIC PREPARATIONS. 
 
 37 
 
 with the mixture and heated in Roessler's gas furnace (fig. 
 7) for half an hour to fusion, regulating the draft so that 
 there shall be an excess of air in the fusion chamber. 
 After having cooled the slightly baked frit, it is powdered 
 
 FIG. 7. 
 
 in a mortar and once more heated for half an hour at a red 
 heat. A powdered sample of the product is covered with 
 diluted HNOs; if carbonic acid is evolved, the powdered 
 mass is to be heated a short while longer to white heat* 
 
 * The oxydation goes on rapidly, if the mixture is heated in an infusi- 
 ble clay dish (iron is impracticable, as it corrodes rapidly in Roessler's gas 
 furnace at a high temperature). As soon as the mass begins to glow, stir 
 vigorously with an iron spatula. During the process the small opening in 
 the cover of the furnace is not closed. 
 
38 LABORATORY MANUAL OF 
 
 The finely powdered, flesh-colored calcium plumbate is 
 poured gradually into 200 c. c. diluted HNO 3 ; after set- 
 tling, it is decanted and ground in a mortar with fresh 
 HNO 3 (100 c. c.). Finally it is once more boiled up with 
 diluted HNO.3, filtered, rinsed with hot water and dried on 
 the waterbath. For most purposes it is more convenient 
 to merely decant the peroxide with hot water and preserve 
 it as paste. The weight of the lead peroxide obtained 
 about equals that of the lead oxide taken.* 
 
 b. In the ivet way. A solution of 190 grams lead 
 acetate in 500 c. c. water is placed into 500 c. c. of 20% 
 soda lye and the cooled milky, alkaline solution treated by 
 shaking with chlorine until no further precipitation takes 
 place. It is then decanted with water and purified, as 
 above, with nitric acid. 
 
 By the aid of atmospheric oxygen and lead oxide, 
 the carbonic acid of the calcium carbonate is expelled with 
 formation of calcium plumbate corresponding with the ortho- 
 silicates : 2CaCO 3 + PbO + O = Ca 2 PbO 4 + 2CO 2 . The 
 plumbate varying only very little in color from the original 
 mixture, is easily decomposed with HNO 3 : Ca 2 PbO4 -f 
 4HNO 3 = 2Ca(NO 3 ) 2 + PbO 2 4- 2H 3 O. 
 
 In watery solution lead peroxide is formed through 
 the action of chlorine on sodium lead oxide: Pb(ONa) 2 + 
 2C1 == PbO 2 + 2NaCl. 
 
 The dark-brown lead peroxide, after being boiled with 
 diluted HNO 3 , must not impart a violet color to the super- 
 natant solution; this color should appear immediately 
 upon adding a drop of diluted manganese sulphate solu- 
 
 * KASSNER, Chem. Ind. 13, 1890, 104-120. 
 
INORGANIC PREPARATIONS. 39 
 
 tion.* Suspended in diluted HNO 3 , it should dissolve 
 readily and entirely upon addition of sodium nitrite. To 
 determine the quantity of lead peroxide, an average sam- 
 ple of the paste or the finely powdered preparation is 
 weighed, placed into a flask with ground glass stopper, 
 covered with diluted HNO 3 and gradually add a small ex- 
 cess of normal sodium nitrite, aiding the reaction by fre- 
 quent and vigorous shaking of the closed bottle. After all 
 the peroxide has passed into solution, it is diluted with a 
 large quantity of water and the excess of nitrite titrated 
 back with potassium permanganate. 
 
 Lead dioxide, when boiled with thrice its bulk 
 of pure nitric acid for several minutes and allowed to 
 settle, must not communicate the faintest red color to the 
 acid (absence of manganese). 
 
 LEAD CARBONATE. 
 
 PbCO;{. 
 
 Lead oxide is readily converted into soluble hydroxide 
 on treatment with a moderately concentrated solution of 
 magnesium acetate. The solution thus obtained has an 
 alkaline reaction, and yields lead carbonate when treated 
 with carbonic anhydride. The white precipitate is col- 
 lected, washed and dried, and the solution of magnesium 
 acetate concentrated and used for another operation.! 
 
 * Manganese protoxide is oxydized in nitric solution by lead peroxide 
 into permanganic acid, PbO 2 + HNO 2 -f HNO a = Pb(NO 3 ) 3 -f II 2 O. 
 f W. KUBEL, Dingl. Polyt. J. 262. 143. 
 
40 LABORATORY MANUAL OF 
 
 LEAD TETRACHLORIDE. 
 Pb.Cl 4 . 
 
 When lead dichloride is suspended in hydrochloric acid 
 and gaseous chlorine passed into the liquid, a solution of 
 lead tetrachloride is obtained, from which, on addition of 
 ammonium chloride, a compound, PbCl 3 NH 4 Cl, analogous 
 to ammonium stanic chloride, separates. If this com- 
 pound is added to concentrated sulphuric acid, an en- 
 ergetic reaction ensues, and lead tetrachloride separates as 
 an oily substance ; it is purified by shaking with fresh 
 quantities of sulphuric acid. In the pure state, it is a 
 translucent, yellow, highly refractive liquid which fumes 
 in contact with moist air, with decomposition into lead 
 dichloride and chlorine ; it may be kept under cold con- 
 centrated sulphuric acid, but when heated with it, it de- 
 composes with explosion into lead dichloride and chlorine. 
 When, however, lead tetrachloride is heated in a retort 
 with concentrated sulphuric acid, and a current of chlorine 
 passes through, a certain quantity of the tetrachloride distils 
 over below 105 C., at about which temperature explosion 
 occurs. The sp. gr. of lead tetrachloride at o C. is 3.18, 
 and it solidifies to a yellowish crystalline mass at 15 C.; it 
 forms a hydrate in the presence of a little water, which, by 
 the further addition of water, decomposes into lead perox- 
 ide and hydrogen chloride ; when brought in contact with 
 a small quantity of cooled hydrochloric acid, a crystalline 
 derivative, probably PbCl 4 2HCl, is formed. 
 
 * By H. FRIEDRICH, Ber. 26, 1434-1436; compare Abetr., 1890, 699; 
 also CLASSEN AND ZAHORSKI, Zeit. anorg. Chera. 4, 100. 
 
INORGANIC PREPARATIONS. 41 
 
 BISMUTH HYDROXIDE. 
 
 BiOOH. 
 
 Dissolve bismuth, freed from arsenic by fusion with 
 hepar sulphuris, in dilute nitric acid ; dilute the solu- 
 tion until a slight permanent precipitate is produced ; 
 filter and evaporate the filtrate to crystallization. Wash 
 the crystals with water containing nitric acid, triturate 
 them with water, add ammonia in excess, and let the mix- 
 ture digest for some time ; then filter, wash and dry the 
 white precipitate. 
 
 The bismuth hydroxide is dissolved in dilute nitric 
 acid and precipitated with sulphuretted hydrogen. Part 
 of the precipitated sulphide is treated with ammonia and 
 filtered, and part treated with ammonium sulphide and 
 filtered. The filtrates are then mixed with hydrochloric 
 acid in excess ; the first should give no precipitate and the 
 second only a white precipitate of sulphur. 
 
 AMMONIUM SULPHIDE. 
 
 a. Colorless ammonium monosulphide. (NH 4 ) 2 S. 
 
 a. Transmit hydrogen sulphide through 3 parts of 
 ammonia solution until no further absorption takes 
 place ; then add 2 parts more of the same ammonia 
 solution. The action of hydrogen sulphide upon ammonia 
 gives rise to the formation, first, of (NH 4 ) 2 S, (2NH 4 OH) 
 and H 2 S = (NH 4 ) 2 S and 2(H 2 O)], then of NH 4 SH ; upon 
 addition of the same quantitv of solution of ammonia as 
 
42 LABORATORY MANUAL OF 
 
 has been saturated, the ammonia decomposes with the am- 
 monium hydrosulphide and ammonium monosulphide is 
 formed, thus: NH 4 SH + NH 4 OH = (NH 4 ) 3 S + H 3 O. 
 The rule, however, is to add only two-thirds of the quan- 
 tity of solution of ammonia, as it is better the prepara- 
 tion should contain a little ammonium hydrosulphide than 
 that free ammonia should be present. To employ am- 
 monium hydrosulphide instead of the simple monosulphide 
 is unnecessary, and tends to increase the smell of sulphur- 
 etted hydrogen in the laboratory, as the preparation al- 
 lows that gas to escape when in contact with metallic acid 
 sulphides. 
 
 Ammonium sulphide should be kept in well- corked 
 vials. It is colorless at first, and deposits no sulphur upon 
 addition of acids. Upon exposure to the air, however, it 
 acquires a yellow tint, owing to the formation of am- 
 monium disulphide, which is attended also with formation 
 of ammonia and water, thus: 2(NH 4 ) 3 S + O = (NH 4 ) 3 S 3 
 + 2NH 3 + H 3 O. Continued action of the oxygen of the 
 air upon the ammonium sulphide tends at first to the for- 
 mation of still higher sulphides ; but afterwards the fluid 
 deposits sulphur, and finally all the ammonium sulphide is 
 decomposed and the solution contains nothing but am- 
 monia and ammonium thiosulphate. The formation of 
 thiosulphate proceeds thus: (NH 4 ) 3 S 3 4- O 3 = (NH 4 ) 3 S 2 O 3 . 
 
 b. Yelloiv ammonium poly sulphide. (NH 4 ) 3 S X . 
 
 b. The ammonium sulphide which has turned yellow 
 by moderate exposure to the air may be used for all pur- 
 poses requiring the employment of yellow ammonium 
 sulphide. The yellow sulphide may also be expeditiously 
 prepared by digesting the monosulphide with some sul- 
 
INORGANIC PREPARATIONS. 4$ 
 
 phur. All kinds of yellow ammonium sulphide deposits 
 sulphur and look turbid and milky on being mixed with 
 acids. 
 
 Ammonium sulphide must strongly emit the odor 
 peculiar to it; with acids it must evolve abundance of 
 sulphuretted hydrogen ; the evolution of gas may be 
 attended by the separation of a pure white precipitate, but 
 no other precipitate must be formed. Upon evaporation 
 and exposure to a red heat in a platinum dish it must 
 leave no residue. It must not, even on heating, precipi- 
 tate or render turbid solution of magnesium sulphate or 
 solution of calcium chloride (free ammonia, ammonium 
 carbonate). 
 
 SODIUM SULPHIDE. 
 
 Na 2 S. 
 
 POTASSIUM SULPHIDE. 
 
 K 3 S. 
 
 Preparation same as for ammonium sulphide, except 
 that solutions of soda or potassa are substituted for the 
 ammonia. Filter, if necessary, and keep the fluid obtained 
 in well-stoppered bottles. If required to contain some 
 higher sulphides, digest with powdered sulphur. 
 
 AMMONIUM OXALATE. 
 
 (NH 4 ) 3 C 2 4 , 2Aq. 
 
 Dissolve commercial oxalic acid to saturation in hot 
 hydrochloric acid of 10 to 12 per cent., cool rapidly 
 
44 LABORATORY MANUAL OF 
 
 with constant agitation, wash the crystals (best with 
 help of a filter pump) with cold water to remove 
 most of the hydrochloric acid, redissolve in hot water, fil- 
 ter hot to separate dirt, cool again with stirring, and wash 
 the crystals with cold water until chlorine is mostly re- 
 moved.* 
 
 Dissolve the pure oxalic acid in 2 parts of distilled 
 water, with the aid of heat, add solution of ammonia until 
 the reaction is distinctly alkaline, and put the vessel in a 
 cold place. Let the crystals drain. The mother liquor 
 will, upon proper evaporation, give another crop of crys- 
 tals. 
 
 The solution of ammonium oxalate must not be 
 precipitated nor rendered turbid by hydrogen sulphide, nor 
 by ammonium sulphide. Ignited on platinum, the salt 
 must volatilize without leaving a residue. 
 
 SODIUM ACETATE. 
 NaC 2 H 3 O 2 3Aq. 
 
 Dissolve crystallized sodium carbonate in a little water, 
 add to the solution acetic acid to slight excess, evaporate 
 to crystallization, and purify the salt by recrystallization. 
 
 Sodium acetate must be colorless and free from empy- 
 reumatic matter and inorganic acids. 
 
 * STOLBA. 
 
INORGANIC PREPARATIONS. 45 
 
 PURE SODIUM CHLORIDE. 
 NaCl. 
 
 500 grams common salt and 1500 c. c. cold water are 
 ground together in a mortar holding 3 litres, filtered 
 through a folded filter into a porcelain dish of about 3 litres 
 capacity and heated on a gas stove. Now add milk of lime 
 prepared from 5 grams caustic lime and mix with barium 
 chloride solution in small excess. After settling, it is 
 filtered into a beaker and the clear fluid precipitated with 
 soda solution (prepared from 1 5 grams pure, dry sodium car- 
 bonate). The filtrate is neutralized at a boiling heat with 
 dilute hydrochloric acid (about 25 c. c.) and as quickly as 
 possible evaporated over a large burner to j litre. The 
 separated sodium chloride is collected on a funnel fitted with 
 a platinum cone, sucked dry with the filter pump and the 
 salt further dried by warming in a platinum or porcelain 
 dish, stirring constantly with a platinum spatula or glass rod. 
 
 The magnesium and iron contained in the common 
 salt are precipitated by the calcium hydrate as hydroxides. 
 MgClg -t- Ca(OH) 3 = Mg(OH) 3 + CaClg. 
 
 The sulphuric acid precipitated by the barium chloride. 
 CaSO 4 4- BaCl 3 = BaSO 4 4 CaCl 3 . 
 
 The alkaline earths finally separated as carbonates. 
 CaCl 3 + Na 3 CO 3 = CaCO 3 4 2NaCl. 
 
 Sodium chloride forms a snow-white crystalline powder 
 consisting of small squares. The dried salt warmed 
 in small dry tubes should not decrepitate ; and at a 
 
46 LABORATORY MANUAL OF 
 
 higher temperature it should melt to a perfect liquid. The 
 watery solution should be examined with ammonium oxa- 
 late, sodium phosphate, potassium ferrocyanide and barium 
 chloride for presence of calcium, magnesia, iron and sul- 
 phuric acid. One drop of the solution with ten drops 
 platinum chloride evaporated to a small volume on a 
 watch-glass yields upon cooling nice triclinic prisms of so- 
 dium platinic chloride, NagPtClg-l- 6Aq, which, on solution 
 in alcohol, must not leave any residue of potassium platinic 
 chloride.* 
 
 SODIUM. 
 
 Sodium, which when kept under mineral oil has be- 
 come covered with a crust, is easily purified by immersing 
 in a mixture of amyl alcohol (i part) and petroleum (3 
 parts) and rubbing with a rag soaked in the same mixture 
 until it acquires a silvery lustre. It is then laid in petro- 
 leum containing 5 per cent, of amyl alcohol, washed with 
 pure petroleum and kept in petroleum containing 0.5 to I 
 per cent, of amyl alcohol. The bright metal becomes 
 slowly covered with a film of sodium of amyloxide, which 
 is, however, easily rubbed off with filter paper. Potassium 
 and lithium can be purified in the same way and thus 
 keep their metallic lustre for a long time. 
 
 * On an average 12 g. crystallized barium chloride are used. As the 
 conclusion of the reaction is only recognized with difficulty, in the muddy 
 solution, you can take here, as in many other cases, conveniently small 
 samples from the top of the liquid by dipping in a fine capillary tube. The 
 capillary is blown out on to a watch-glass. In the present case the watch- 
 glass is placed on a black support and tested with a drop of BaCl 2 solution, 
 which will form BaSO 4 if H 2 SO 4 be present. 
 
OF THE 
 
 { UNIVER 
 INORGANIC PREPARATIONS. 47 
 
 Sodium cleaned, as above, combines at once with mer- 
 cury with evolution of light. The liquid alloy of sodium 
 and potassium is easily prepared by pressing together the 
 two clean metals under a mixture of amyl alcohol (i part), 
 and petroleum (9 parts). Sodium sulphide is also easily 
 prepared by rubbing the clean metal (i gram) and salt 3 
 grams) to a fine powder, and then mixing with sulphur 
 (0.7 gram), care being taken to avoid any pressure. When 
 the two substances are intimately mixed, combination sud- 
 denly takes place with evolution of light. If the mixture 
 of sodium powder and salt be mixed with sulphur in the 
 proportions required to form the di- or tri-sulphide, the re- 
 action takes place more quickly and violently. 
 
 Selenium and tellurium behave in the same way as sul- 
 phur when mixed with sodium powder.* 
 
 SODIUM AMALGAM. 
 
 (10%). 
 
 Heat 3 kilos of mercury in a covered iron pot and 
 gradually add 300 grams of sodium, in pieces of about 
 5 grams each. On the addition of each piece of 
 sodium there is a violent action; toward the close of the 
 operation it is usually necessary to increase the heat and 
 stir the mass to produce this reaction. It is not advisable 
 to clean the sodium, as the oxide is reduced during the 
 operation and loss avoided. (During the operation glasses 
 should be worn to protect the eyes.) 
 
 By M. ROSENFELD, Ber. 24, 1658. 
 
48 LABORATORY MANUAL OF 
 
 When no further reaction takes place after stirring, the 
 melted mass is poured out on a clean iron plate, broken as 
 soon as solid and while still warm, packed in small tightly 
 closing glass-stoppered bottles. 
 
 Sodium Amalgam is used as a means of generating 
 small quantities of hydrogen for reducing purposes. (See 
 Hydrogen, page 9). 
 
 SOD'IUM CARBONATE. 
 
 (Na 2 CO 3 10Aq.) 
 
 It is best to provide this salt in several grades of 
 purity, as follows : 
 
 a. Free from sulphur and chlorine. Finely pulverize 
 " bicarbonate of soda " of commerce, put the powder into 
 a funnel stopped loosely with some cotton, make the sur- 
 face even, cover it with a disk of thick filter paper with 
 turned-up edges, and wash by pouring small quantities of 
 water on the paper disk until the filtrate, when acidified 
 with nitric acid, is not rendered turbid by solution of silver 
 nitrate, nor by solution of barium chloride. Let the salt 
 dry, and then convert it by gentle ignition into the simple 
 carbonate. This is effected best in a vessel of silver or 
 platinum ; but it may be done also in a perfectly clean 
 iron, or, on a small scale, in a porcelain dish. 
 
 b. Free from silica. The salt, as prepared in a, is liable 
 to contain silica as well as sand and dirt. To purify it 
 further, dissolve in twice its weight of water, or dissolve 
 "sal soda" crystals in their own weight of water, filter, and 
 pass into the cold solution washed pure carbon dioxide, 
 but not to complete saturation. 
 
INORGANIC PREPARATIONS. 49 
 
 The crystals of hydrogen sodium carbonate that sep- 
 arate are drained in a funnel, washed with cold water, 
 dried, and gently ignited, as above directed, as long as 
 water is given off. Prepared in glass vessels by this 
 method, sodium carbonate may be readily procured con- 
 taining but 5 oW of silica. 
 
 c. To a clear and cold solution of 145 grams of sal 
 soda crystals in 100 c. c. of water, add gradually with vig- 
 orous stirring a solution of 60 parts of purified oxalic acid 
 in too c. c. of warm water. When sodium oxalate ceases 
 to separate, break up the crystals, and transfer them to a 
 6-inch filter connected with the Bunsen filter pump, wash 
 with 500 c. c. of water and dry. Heat to full redness in a 
 platinum dish until the oxalate is fully decomposed, dis- 
 solve, filter, and evaporate to dryness.* 
 
 Sodium carbonate must be perfectly white. Several 
 grams of the salt must dissolve in water without turbid- 
 ity, and if the salt is to be used in a flux, without leav- 
 ing grains of sand. Its solution, after supersaturation 
 with nitric acid, must not be rendered turbid by ba- 
 rium chloride or silver nitrate; nor must addition of potas- 
 sium sulphocyanate impart a red, or warming with 
 ammonium molybdate and nitric acid a yellow tint to it, 
 or give a yellow precipitate ; the residue which remains 
 upon evaporating its solution to dryness, after previous 
 supersaturation with hydrochloric acid, must leave no resi- 
 due (silica) when redissolved in water. When fused in a 
 glass tube with potassium cyanide for a long time in a cur- 
 rent of carbon dioxide, it should give no trace of a dark 
 sublimate (arsenic). 
 
 * J. LAWRENCE SMITH. 
 
50 LABORATORY MANUAL OF 
 
 POTASSIUM CYANIDE.' 
 KCN. 
 
 Heat potassium ferrocyanide of commerce (perfectly 
 free from potassium sulphate) gently, with stirring, 
 until the crystallization water is completely expelled ; 
 triturate the anhydrous mass, and mix 8 parts of the 
 dry powder with 3 parts of perfectly dry potassium car- 
 bonate ; fuse the mixture in a covered Hessian, or, bet- 
 ter still, in a covered iron crucible, until the mass is in a 
 faint glow, appears clear, and a sample of it, taken out 
 with a heated glass or iron rod, looks perfectly white. 
 Remove the crucible now from the fire, tap it gently, and 
 let it cool a little until the evolution of gas has ceased ; 
 pour the fused potassium cyanide into a heated, tall, 
 crucible-shaped vessel of clean iron or silver, or into a 
 moderately hot Hessian crucible, with proper care, to pre- 
 vent the running-out of any of the minute particles of iron 
 which have separated in the process of fusion and have 
 subsided to the bottom of the crucible. Let the mass 
 now slowly cool in a somewhat warm place. The potas- 
 sium cyanide so prepared is exceedingly well adapted for 
 analytical purposes, although it contains potassium car- 
 bonate and cyanite, which latter is upon solution in water 
 transformed into ammonium carbonate and potassium car- 
 bonate (2CNOK + 4H 2 O = K 3 CO 3 + (NH 4 ) 2 CO 3 ). Keep 
 it in the solid form in a well-stoppered bottle. 
 
 Potassium cyanide must be of a milk-white color 
 and quite free from particles of iron or charcoal. It 
 must completely dissolve in water to a clear fluid. It 
 
INORGANIC PREPARATIONS. 51 
 
 must contain neither silica nor potassium sulphide ; the 
 precipitate which lead salts produce in its solution must 
 accordingly be of a white color, and the residue which 
 its solution leaves upon evaporation, after previous super- 
 saturation with hydrochloric acid, must completely dissolve 
 in water to a clear fluid. 
 
 POTASSIUM SULPHOCYANIDE., 
 KCNS. 
 
 Mix together 46 parts of anhydrous potassium 
 ferrocyanide, 17 parts of potassium carbonate, and 32 
 parts of sulphur; introduce the mixture into an iron 
 pan provided with a lid, and fuse over a gentle fire; 
 maintain the same temperature until the swelling of the 
 mass which ensues at first has completely subsided and 
 given place to a state of tranquil and clear fusion ; in- 
 crease the temperature now towards the end of the opera- 
 tion, to faint redness, in order to decompose the potas- 
 sium thiosulphate which has been formed in the process. 
 Remove the half- cooled and still soft mass from the 
 pan, crush it, and boil repeatedly with alcohol of from 
 80 to 90 per cent. Upon cooling, part of the potassium 
 sulphocyanide will separate in colorless crystals ; to obtain 
 the remainder, distil the alcohol from the mother liquor. 
 
 Solution of potassium sulphocyanide must remain 
 perfectly colorless when mixed with perfectly pure dilute 
 hydrochloric acid. 
 
52 LABORATORY MANUAL OF 
 
 HYDROGEN SODIUM SULPHITE. 
 HNaSO 3 . 
 
 Heat 5 parts of copper tacks or clippings with 
 20 parts of concentrated sulphuric acid in a flask, 
 and conduct the sulphur dioxide gas evolved, first 
 through a washing bottle containing some water, then 
 into a flask containing 7 parts of clean crystallized sal- 
 soda, and from 20 to 30 parts of water, and which is 
 not much more than half full ; continue the transmission 
 of the gas until the evolution of carbon dioxide ceases. 
 Keep the solution, which smells strongly of sulphurous 
 acid, in a well-stoppered bottle. 
 
 Acid sodium sulphite, when evaporated to dryness 
 with pure sulphuric acid, must leave a residue, the aque- 
 ous solution of which is not altered by hydrogen sulphide, 
 nor precipitated yellow by heating with a solution of 
 ammonium molybdate mixed with nitric acid. 
 
 POTASSIUM NITRITE, 
 
 KN0 2 . 
 
 In an iron pan fuse I part of nitre, add 2 parts 
 of lead, and keep stirred with an iron rod. Even 
 at a low red heat the lead becomes for the most 
 part oxidized and converted into a yellow powder To 
 oxidize the remainder, the heat is increased to visible 
 redness and maintained at that point for half an hour 
 Allow to cool, treat with cold water, filter and pass car- 
 
INORGANIC PREPARATIONS. 53 
 
 bon dioxide through the filtrate. This precipitates al- 
 most the whole of the lead in solution, the remainder is 
 removed with a little hydrogen sulphide. Evaporate the 
 clear fluid to dryness, finally with stirring, and fuse in 
 order to destroy any potassium thiosulphate. (Aug. 
 Stromeyer.) When required, dissolve I part in 2 parts 
 of water, neutralize cautiously with acetic acid, and filter. 
 
 Potassium nitrite must, upon addition of dilute sul- 
 phuric acid, copiously evolve nitrogen dioxide gas. 
 
 SODIUM AND POTASSIUM NITRITE. 
 
 A very sensitive surface of spongy platinum is ob- 
 tained by soaking asbestos yarn in a solution of platinum 
 oxalate, made by heating freshly prepared platinic chloride 
 at 204 C., until no more chlorine is evolved, then boiling 
 the residue with a slight excess of sodium carbonate, 
 finally dissolving it in oxalic acid, and concentrating the 
 solution. The soaked asbestos yarn, after drying and 
 igniting, is exposed to a current of ammonia and air in a 
 combustion tube, the remote end being heated by a Bun- 
 sen burner to start the reaction ; the whole platinized sur- 
 face soon becomes intensely hot, while dense clouds of 
 ammonium nitrite rapidly form, and are conducted into 
 sodium or potassium hydroxide, where the corresponding 
 nitrite is formed, the evolved ammonia being used for pro- 
 ducing a further supply of ammonium nitrite.* 
 
 By H. N. WARREN, (Chem. News, 63, 294). 
 
54 LABORATORY MANUAL OF 
 
 POTASSIUM PYROANTIMONATE. 
 
 Introduce a mixture of equal parts of pulverized 
 tartar-emetic and potassium nitrate in small portions 
 at a time into a red-hot crucible. After the mass 
 has deflagrated, keep it at a moderate red heat for a quar- 
 ter of an hour ; it froths at first, but after some time it will 
 be in a state of calm fusion. Remove the crucible from 
 the fire, let the mass get nearly cold, and extract it 
 with warm water. Transfer to a suitable vessel, by rinsing, 
 and decant the clear fluid from the heavy white powder 
 deposited. Concentrate the decanted fluid by evaporation. 
 After one or two days a doughy mass will separate. Treat 
 this mass with three times its volume of cold water, work- 
 ing it at the same time with a spatula. This operation will 
 serve to convert it into a fine granular powder, to which 
 add the powder from which the fluid was decanted, wash 
 well with boiling water, till the washings cease to be alka- 
 line, and dry on blotting paper. 100 parts of tartar-emetic 
 give about 36 parts of the pyroantimonate Brunner). 
 
 AMMONIUM MOLYBDATE. 
 
 CNH 4 ) 2 Mo0 4 , 
 DISSOLVED IN NITRIC ACID. 
 
 MOLYBDIC SOLUTION. 
 
 Triturate molybdenum sulphide with about an equal 
 bulk of coarse quartz sand washed with hydrochloric 
 acid, until it is reduced to a moderately fine pow- 
 
INORGANIC PREPARATIONS. 55 
 
 der ; heat to faint redness, with repeated stirring, until 
 the mass has acquired a lemon-yellow color (which after 
 cooling turns whitish). With small quantities this opera- 
 tion may be conducted in a flat platinum dish, with large 
 quantities in a muffle. Extract with solution of ammonia, 
 filter, evaporate the filtrate, heat the residue to faint red- 
 ness until it appears yellow or white, and then digest for 
 several days with nitric acid in the water bath, in order to 
 convert any phosphoric acid present to the tribasic state. 
 When the nitric acid is evaporated dissolve the residue in 
 4 parts of solution of ammonia, filter rapidly, and pour the 
 filtrate into 15 parts by weight of nitric acid of 1.20 specific 
 gravity. Keep the mixture standing several days in a 
 moderately warm place, which will cause the separation of 
 any remaining traces of phosphoric acid as ammonium 
 phosphomolybdate. Decant the colorless fluid from the 
 precipitate, and keep it for use. Heated to 40 C. no white 
 precipitate (molybdic acid or an acid salt of the same) will 
 separate ; but above that point precipitation will take place 
 unless more nitric acid be added (Eggertz). 
 
 AMMONIUM CHLORIDE. 
 
 NH 4 C1. 
 
 Select sublimed white sal ammoniac of commerce. 
 If it contains iron it must be purified by slowly pass- 
 ing chlorine gas into the nearly saturated solution for a 
 short time or until potassium ferricyanide gives no blue 
 color with a few drops of the liquid. Ammonia is then 
 added in slight excess, the whole is warmed, filtered from 
 the separated ferric oxide and evaporated to crystallization. 
 
56 LABORATORY MANUAL OF 
 
 Solution of Ammonium Chloride must leave no fixed 
 residue upon evaporation on platinum, and ammonium 
 sulphide must have no action upon it. Its reaction must 
 be perfectly neutral. 
 
 SODIUM NITRATE. 
 
 NaNO 3 . 
 
 Neutralize pure nitric acid with pure sodium car- 
 bonate exactly, and evaporate to crystallization. Dry the 
 crystals thoroughly, triturate and keep the powder for use. 
 A solution of sodium nitrate must not be made turbid 
 by solution of silver nitrate or barium nitrate, nor precipi- 
 tated by sodium carbonate. 
 
 MONO SODIUM PHOSPHITE. 
 
 2NaHP0 3 + 5H 3 0. 
 
 Is obtained by adding sodium hydroxide or carbonate 
 to phosphorous acid until the solution is neutral to methyl 
 orange. The liquid is then concentrated by evaporation 
 and the salt crystallizes. Not unfrequently a supersatur- 
 ated solution is obtained, which crystallizes in contact 
 with a fragment of the solid phosphite. If no crystals of 
 the phosphite are at hand, the solution is concentrated un- 
 til it has the composition of the crystals and is cooled to a 
 low temperature. The salt is recrystallized from water 
 and dried by exposure to air. It can also be obtained by 
 the action of phosphorus trichloride on sodium carbonate, 
 but the separation of the sodium chloride is difficult. 
 
INORGANIC PREPARATIONS. 57 
 
 Monosodium phosphite is very soluble in water and melts 
 at 42 C. At 100 C. the fused salt loses water and the 
 liquid deposits crystals which may be either a lower 
 hydrate or the anhydrous salt. If heated at IOO Q C. for 
 a long time, it becomes completely dehydrated ; it also 
 becomes anhydrous in a dry vacuum. When heated 
 above 130^ C. the phosphite changes into sodium pyro- 
 phosphite. 
 
 Potassium phosphite is obtained in a similar manner. 
 It forms anhydrous crystals, which are difficult to purify by 
 recrystallization. 
 
 POTASSIUM CHLORATE. 
 KC1O 3 . 
 
 100 grams potassium carbonate are dissolved in warm 
 water in a small flask heated to boiling, and chlorine is 
 conducted through the liquid until it is no longer alkaline. 
 Then dilute with hot water up to a volume of 350 c. c., fil- 
 ter and let it crystallize. 
 
 As a test a weighed sample of the dried salt put in a 
 covered platinum dish is heated first on the gas furnace, 
 then on the Bunsen burner with a small flame to incipient 
 redness; the uncovering of the hot dish must be avoided. 
 
 The potassium chloride remains in the mother liquor. On 
 heating the potassium chlorate, the perchlorate first forms, 
 then the chloride and this finally volatilizes at red heat. 
 
58 LABORATORY MANUAL OF 
 
 POTASSIUM BISULPHATE. 
 KHSO 4 . 
 
 Mix 7 parts of pure sodium sulphate (obtained by 
 recrystallization of clean Glauber's salts, and drying away 
 the water of crystallization at a gentle heat) with 5 parts 
 of pure concentrated sulphuric acid, in a platinum dish or 
 large platinum crucible, heat to low redness till the mass 
 is in a state of calm fusion, then pour out into a platinum 
 dish placed in cold water, or upon a piece of porcelain, 
 break the cake into smaller pieces and keep for use. 
 
 The sodium disulphate must dissolve in water with 
 ease to a clear fluid with a strong acid reaction. The 
 solution must not be rendered turbid or precipitated by 
 hydrogen sulphide or by ammonia and ammonium sul- 
 phide. 
 
 HYDROGEN SODIUM AMMONIUM PHOSPHATE. 
 NaHNH 4 PO 4 . 
 
 a. Heat to boiling 6 parts of hydrogen disodium 
 phosphate and I part of pure ammonium chloride with 2 
 parts of water, and let the solution cool. Free the crys- 
 tals produced, from the sodium chloride which adheres to 
 them, by recrystallization, with addition of some solution 
 of ammonia. Dry the purified crystals, pulverize and keep 
 for use. 
 
 b. Take 2 equal parts of pure tribasic phosphoric acid, 
 and add solution of soda to the one, solution of ammonia 
 
INORGANIC PREPARATIONS. 59 
 
 to the other, until both fluids have a distinct alkaline reac- 
 tion ; mix the two together, and let the mixture crystal- 
 lize. 
 
 Hydrogen sodium ammonium phosphate dissolves 
 in water to a fluid with feebly alkaline reaction. The 
 yellow precipitate produced in this fluid by silver ni- 
 trate must completely dissolve in nitric acid. Upon fusion 
 on a platinum wire, microcosmic salt must give a clear and 
 colorless bead. 
 
 POTASSIUM FERRICYANIDE. 
 
 Conduct chlorine gas slowly into a solution of I part 
 of potassium ferrocyanide in 10 parts of water, with 
 frequent stirring, until the solution exhibits a fine deep 
 red color by transmitted light (the light of a candle 
 answers best), and a portion of the fluid produces no 
 longer a blue precipitate in a solution of ferric chloride, 
 but imparts a brownish tint to it. Evaporate the fluid now 
 in a dish to y of its weight, and let crystallize. The 
 mother liquor will upon further evaporation yield a second 
 crop of crystals equally fit for use as the first. Dissolve 
 the whole of the crystals obtained in 3 parts of water, filter 
 if necessary ; evaporate the solution briskly to half its vol- 
 ume, and let crystallize again. The solution, as already 
 remarked, must produce neither a blue precipitate nor a 
 blue color in a solution of ferric chloride. As this salt de- 
 composes when long kept in solution, it is best preserved 
 and applied in the state of powder. 
 
60 LABORATORY MANUAL OF 
 
 POTASSIUM IODIDE. 
 K.I. 
 
 6 grams pure iron powder are suspended in a small flask 
 with 50 c. c. water, 25 grams iodine are gradually added, 
 keeping the mixture cold. At the end of the reaction there 
 must still be present a slight excess of iron. The solution 
 is filtered off from the residue, washed with a little water, 
 and 5 grams iodine added to the filtrate. Now 16.5 grams 
 potassium carbonate are dissolved in a porcelain dish with 
 50 c. c. hot water, and the ferrous iodide solution added to 
 this boiling mixture. Ferrous hydrate separates and car- 
 bonic acid is freely evolved ; filter and evaporate to crystall- 
 ization. 
 
 By the above process a mixture of ferrous and ferric 
 iodides is formed, and this by decomposition with alkali 
 yields ferrous oxide, which is readily removed by filtration. 
 
 The potassium iodide in sulphuric acid solution must 
 not turn starched paper blue, and must be free from 
 bromine and chlorine. 
 
 POTASSIUM CYANATE. 
 
 KCNO. 
 
 Commercial potassium ferrocyanide is broken in pieces, 
 dehydrated in an iron dish on a gas furnace and finely 
 powdered. 200 grams of the anhydrous salt are thor- 
 oughly mixed with 150 grams potassium dichromate which 
 has been freed from adhering moisture by fusing on the 
 
INORGANIC PREPARATIONS. 6 1 
 
 gas stove. The mixture is placed into a capacious iron 
 dish in portions by means of a spoon, and heated to such 
 an extent over a Bunsen burner or gas stove that every 
 portion of the powder added is converted into a black 
 mass. Stir with an iron spatula while putting the mixture 
 into the dish. The temperature must not rise high enough 
 to cause fusion of the mass. After cooling, the porous 
 mass is powdered, put into a flask with I litre of 8(D% 
 boiling alcohol, shaken and boiled for five minutes, 
 with reversed condenser. After settling, pour off the clear 
 solution into a beaker, which is set in cold water to cool, 
 whereupon the potassium cyanate, especially by stirring 
 with a glass rod, precipitates in a heavy white crystallized 
 powder. The mother liquor serves for further (3d or 4th) 
 extraction of the black product. 
 
 K 4 Fe(CN) 6 + 2K 3 Cr 2 O 7 = 6KCNO + 2Cr 3 O 3 + FeO + K 2 O. 
 
 The unaltered potassium ferrocyanide remains in- 
 soluble on recrystallization from alcohol. The hot 
 solutions must be cooled quickly, as by heating any length 
 of time, the water contained in the diluted alcohol would 
 decompose the cyanate. 
 
 KCNO f 2H 3 O = K(NH 4 )CO 3 . 
 
 Analyze the salt by evaporating a sample with cone, 
 sulphuric acid and fusing the remaining potassium sul- 
 phate with addition of a grain of ammonium carbonate.* 
 
 * C. A. BELL, Chem. News, 32, 99. 
 
62 LABORATORY MANUAL OF 
 
 POTASSIUM COBALTIC OXALATE. 
 
 Is obtained by mixing cobaltic hydroxide, potassium 
 oxalate, oxalic acid and water to a thick paste, and allow- 
 ing the mixture to stand from I4to2i days. After recrystall- 
 ization, the salt is obtained in nearly black, well-formed, 
 seemingly monosymmetric crystals, which in thin lamellae 
 show distinct dichroism (dark-blue and emerald-green).* 
 
 When treated with cold saturated sodium chloride solu- 
 tion, the sodium potassium salt is obtained, crystallizing in 
 beautiful pyramids. 
 
 POTASSIUM METANTIMONATE. 
 
 K 4 Sb 2 O 7 . 
 
 IOO grams of black sulphide of antimony, 150 grams of 
 potassium carbonate, IOO grams of slaked, lime and 20 
 grams of sulphur, are shaken with 12 liters of water and 
 after standing eight days the mixture is filtered. The fil- 
 trate, which contains potassium sulphantimonate, is boiled 
 with 1 20 grams of copper oxide and filtered. The filtrate 
 is diluted with water and treated with carbonic anhydride, 
 when potassium metantimonate is precipitated. t 
 
 * F. KEHRMANN, Ber., 19, 3101. 
 
 f DUYK, Bull. Soc. Roy. Pharm., Bruxelles, 37, 109. 
 
INORGANIC PREPARATIONS. 63 
 
 CRYSTALLINE NORMAL LITHIUM PHOS- 
 PHATE AND ARSENATE. 
 
 Fused lithium chloride dissolves the amorphous, normal 
 phosphate, and on cooling and washing the melted mass, 
 rhomboidal, tabular crystals of normal lithium phosphate, 
 which have a sp. gr. 2.41 at 15 C., and are infusible at a 
 white heat, are obtained. The normal arsenate is similarly 
 prepared ; it corresponds with the phosphate physically, 
 and is of sp. gr. 3.07 at 15 C.* 
 
 PREPARATION OF PURE CAESIUM AND 
 RUBIDIUM COMPOUNDS 
 
 The preparation of pure caesium rubidium salts from 
 their minerals is carried out as follows : They are first 
 separated in the form of the double salts with lead tetra- 
 chloride ; the latter is decomposed with water, the solu- 
 tion treated with a slight excess of ammonium sulphide to 
 free it from lead, and the filtrate evaporated to dryness ; 
 the mixed chlorides of caesium and rubidium are dissolved 
 in concentrated nitric acid, the solution evaporated to dry- 
 ness, the residue dissolved in water, excess of oxalic acid 
 added, and the mixture again evaporated to dryness, and 
 heated in a platinum crucible until the oxalates are com- 
 pletely converted into carbonates. The rubidium is then 
 separated as acid oxalate and the caesium as caesium anti- 
 mony chloride, t 
 
 * By A. DE SHULTEN, Bull. Soc. Chim. [3], i, 479. 
 t By H. L. WELLS, AMER. J. Sci., 46, 186. 
 
64 LABORATORY MANUAL OF 
 
 PREPARATION OF PURE RUBIDIUM SALTS. 
 
 Commercial " pure " rubidium salts contain small quan- 
 tities of caesium and potassium, which it is difficult to detect 
 by means of the spectroscope. To obtain a pure salt, com- 
 mercial rubidium chloride (30 grams) is dissolved in very 
 strong hydrochloric acid (250 c. c.) and antimony chloride 
 (2.5 grams) dissolved in strong hydrochloric acid is added. 
 The small precipitate (about 1.4 grams Rb, SbCl 4 and 
 CsSbCl 4 ) is filtered off on an asbestos filter, the filtrate 
 evaporated almost to dryness, the antimony still present 
 removed with hydrogen sulphide, and the resulting mix- 
 ture dissolved in strong hydrochloric acid. Rather more 
 of a hydrochloric acid solution of stannic chloride is added 
 than is necessary to form the stannic chloride, Rb 3 SnCl 6 ; 
 this substance is then precipitated, whilst potassium stannic 
 chloride, K 2 SnCl 6 , remains in solution. The precipitate is 
 allowed to settle, washed several times by decantation, col- 
 lected on an asbestos filter, dissolved in water, and the tin 
 removed with hydrogen sulphide. The rubidium chloride 
 so obtained is pure, 0.44 gram contains 29.30 instead of 
 29.34 per cent, of chlorine.* 
 
 PREPARATION OF TUNGSTATES FREE 
 FROM MOLYBDENUM. 
 
 Commercial tungstates and tungstic acid contain vary- 
 ing quantities of molybdenum. After several unsuccessful 
 attempts to get rid of this impurity, the following method 
 
 * By W. MUTHMANN, Ber. 26, 1019-1020. 
 
INORGANIC PREPARATIONS. 65 
 
 was found to give the desired result Sodium tungstate, 
 prepared in the usual way, is dissolved in cold water, and 
 to the saturated solution hydrochloric acid is added until 
 the reaction is only feebly alkaline ; the paratungstate thus 
 obtained is crystallized out and once recrystallized. One- 
 half of it is dissolved in boiling water, and hydrochloric 
 and a little nitric acid added ; hydrated tungstic acid is 
 precipitated. This is washed thoroughly with hot water 
 and added to a boiling solution of the other half of the 
 paratungstate, until a portion no longer gives a precipi- 
 tate with hydrochloric acid. The bulk of the solution is 
 then filtered, hydrochloric acid is added, and the solution 
 is boiled and repeatedly saturated with hydrogen sulphide. 
 This precipitates the molybdeum as sulphide, whilst the 
 metatungstate is not attacked. The solution is filtered, 
 concentrated, oxidized with a few drops of bromine water, 
 and neutralized with soda ; pure sodium paratungstate 
 can then be obtained from it by crystallization. To ob- 
 tain the potassium and ammonium salts, the acid should be 
 prepared by adding hydrochloric acid to the sodium salt, 
 and then neutralize with potash or ammonia. 
 
 An analysis of sodium paratungstate thus prepared 
 agreed better with the formula 5Na 2 O, 12WO 3 , 28H 2 O 
 than with 3Na 2 O. 7WO 3 , 16H 2 O.* 
 
 TITANIUM TRIOXIDE. 
 Ti0 8 . 
 
 Pure titanium chloride is added drop by drop to dilute 
 alcohol, and the clear and very dilute solution is treated 
 
 * By C. FRIEDHEIM and R. MEYER, Zeit. Anorg. Chem. i, 76-81. 
 
 5 
 
66 LABORATORY MANUAL OF 
 
 with a large excess of hydrogen peroxide. Ammonia, am- 
 monium carbonate, or aqueous potash, is added to the 
 solution with the production of a yellow, or in case of 
 ammonia, of a reddish yellow liquid, which after some time 
 yields a yellow precipitate. This is allowed to subside, 
 the clear solution siphoned off, and the precipitate repeat- 
 edly washed by decantation ; the compound, however, 
 tends to retain water and salts in considerable quantities. 
 When dried on a tile it approximates to the composition : 
 
 TiO 3 + 3H 2 O.* 
 
 PREPARATION OF VANADYL TRICHLORIDE. 
 
 EXTRACTION OF VANADIUM FROM ITS ORES. 
 
 For the extraction of vanadium from its ores advantage 
 is taken of the volatility of vanadyl trichloride. The 
 finely divided mineral is intimately mixed with about 
 one quarter of its weight of lamp black and a little oil, and 
 ignited to volatilize the arsenic and zinc. The calcined 
 product is then slowly heated to 131 C. in a stream of dry 
 chlorine, and the vanadyl trichloride collected in tubes im_ 
 mersed in a freezing mixture. When it is desired to 
 determine the quantity of vanadium in an ore, the above 
 method is employed, and the vanadyl trichloride is col- 
 lected in a series of bulbs containing distilled water ; the 
 vanadic acid is then reduced with zinc, and estimated volu- 
 metrically with the aid of potassium permanganate.! 
 
 * A. CLASSEN, Ber. 21, 370. 
 
 f By L. L'HOTE Ann. Chim. Phys. [6], 22, 407-412. 
 
INORGANIC PREPARATIONS. 67 
 
 X^C^^X 
 
 VANADYL CHLORH^iC^ 
 
 Prepared from vanadianite (14.42% V 2 O 5 ) by mixing 
 the powdered mineral with four times its weight of lamp 
 black, making into a paste with oil and calcining. The 
 calcined product is then heated in an oil bath in a current 
 of dry chlorine, care being taken to prevent the tempera- 
 ture exceeding 131 C. Pure vanadyl chloride begins to 
 distill at 98 C., and if the temperature is raised to 131 C. 
 the whole of the vanadium in the mineral is converted into 
 this compound.* 
 
 AMMONIUM BICARBONATE. 
 (NH 4 )HC0 3 . 
 
 Pour cone, aqua ammonia into a small flask and close 
 it with a stopper attached to a short glass tube, through 
 which carbonic acid is passed. The neutral ammonium car- 
 bonate which precipitates at first, redissolves, and after the 
 liquid has for a time been subjected to the carbonic acid, 
 the acid salt separates. More bicarbonate may be obtained 
 from the mother liquor by mixing it with alcohol. It is 
 preserved in glass tubes which are filled with carbonic acid 
 and sealed. 
 
 Ammonium bicarbonate crystallizes in hard, glossy, 
 rhombic prisms, very readily volatile. The aqueous solu- 
 tion must not be rendered turbid by the addition of 
 calcium chloride. 
 
 * BY L. L'HoTE, Compt. Rend. 101-1151. 
 
68 LABORATORY MANUAL OF 
 
 AMMONIUM BROMIDE. 
 NH 4 Br. 
 
 AND 
 
 POTASSIUM BROMIDE. 
 KBr. 
 
 From a dropping funnel with a finely drawn out stem 
 75 c. c. of bromine are allowed to flow, slowly and with con- 
 tinual shaking, into 220 c. c. of cone. (30%) ammonia con- 
 tained in a flask cooled with ice-water, taking care that the 
 liquid shall remain strongly ammoniacal at the end of the 
 reaction. It is then boiled until the free ammonia has 
 been driven out and evaporated to crystallization. The 
 ammonium bromide is dried by gently heating in a porce- 
 lain dish over an open fire. 196 grams ammonium bro- 
 mide are dissolved in hot water, 200 grams potassium 
 bicarbonate added, and the whole is heated to boiling; 
 when the ammonia has been driven out it is allowed 
 to crystallize : 
 
 4NH3+3Br=3NH 4 Br+N. 
 
 If the solution should become acid, or the bromine 
 flow in too rapidly, there might be a formation of nitrogen 
 bromide which would cause an explosion. 
 
 As a test a small sample of the salt is boiled in a re- 
 tort with a large excess of iron-ammonia alum in aqueous 
 solution, whereby any iodine which may be present will 
 pass over in a free state ; remove the bromine from the 
 residue by addition of potassium permanganate solution 
 and test for chlorine. This separation of the halo- 
 
INORGANIC PREPARATIONS. 69 
 
 genes depends on the fact that ferric salts will set free 
 iodine from neutral solutions of the iodides : 
 
 Fe 3 (S0 4 ) 3 + 2KI = 2FeS0 4 4- K 3 SO 4 + 21. 
 while the bromides remain unchanged. 
 
 On the other hand, these are also entirely decomposed 
 if a small quantity of a strong oxydizing agent (perman- 
 ganate) is present. The chlorides resist the simultaneous 
 influence of these two agents. 
 
 PREPARATION OF AMMONIUM PERSULPHATE. 
 
 A porous clay cell (80 to 100 c. c. capacity), containing 
 a saturated solution of ammonium sulphate in a mixture 
 of i part by volume of sulphuric acid with 8 parts by 
 volume of water is placed in a beaker and surrounded by 
 a mixture of equal volumes of sulphuric acid and water. 
 A lead cylinder, placed round the porous cell, serves as 
 the carthode and a platinum spiral, having a surface of 0.5 
 sq. cen., is suspended inside the porous cell to serve as the 
 anode. The beaker is embedded in ice. The electrolysis 
 is effected by a current of 2 to 3 amperes ; some 8 volts will 
 be necessary when the internal resistance of the decom- 
 posing cell is about I ohm. After 2 to 3 hours the contents 
 of the porous cell are filtered through glasswool and the 
 crystals of ammonium persulphate dried on a porous 
 plate ; the filtrate is shaken with ammonium sulphate and 
 once more electrolysed. 20 to 40 grains of the persulphate 
 may thus be obtained in one operation, the yield being 
 least at the outset, when the liquor is being saturated 
 
70 LABORATORY MANUAL OF 
 
 with the persulphate. The sulphuric acid in the outer 
 cell eventually becomes alkaline from the transit of the 
 ammonium, and pari passu the ammonium sulphate 
 in the inner cell becomes strongly acid ; from time to 
 time the former liquid must be renewed and the latter 
 nearly neutralized with ammonia. To recover the per- 
 sulphate left in the liquor when the preparation has been 
 completed a concentrated solution of potassium carbonate 
 or acetate is added ; potassium persulphate will thus be 
 precipitated, as 100 parts of water only dissolve 2 parts of 
 this salt, whereas they dissolve 65 parts of the ammonium 
 salt* 
 
 Ammonium persulphate thus prepared contains some 
 3 to 5 per cent, of impurities, consisting chiefly of ammo- 
 nium sulphate, but partly of ammonium alum, derived 
 from the clay of the porous cell. It may be recrystallized 
 from water. 
 
 AMMONIUM BICHROMATE, 
 (NH 4 ) 3 Cr 2 7 . 
 
 Chrome iron ore is heated with sodium or potassium 
 salts ; the resulting monochromate is dissolved in water, 
 treated with 2 equivalents of acids, and then neu- 
 trallized with ammonia or ammonium carbonate. The 
 solution containing a dichromate and sulphate, chloride, 
 or nitrate, as the case may be, is concentrated ; the latter 
 salts as they crystallize are removed, and finally on cool- 
 
 * By K. ELBS, J. pr. Chem. [2] 48, 185-189. 
 
INORGANIC PREPARATIONS. 71 
 
 ing ammonium dichromate crystallizes out. The potas- 
 sium or sodium salts are used again for heating with fresh 
 chrome iron ore.* 
 
 AMMONIUM NITRATE. 
 NH 4 NO 3 . 
 
 The mixture of nitrogen oxides evolved during the 
 action of arsenious anhydride or nitric 'acid is passed over 
 coarsely powdered ammonium carbonate kept cool by 
 ice. The half liquid mass is treated with alcohol, the un- 
 changed carbonate filtered off, and the ammonium nitrate 
 precipitated by means of ether. The nitrate so obtained 
 is of 90 to 94 per cent, purity, and may be purified by 
 resolution in 96 per cent, alcohol and reprecipitation 
 with ether. Pure ammonium nitrate forms almost color- 
 less needles, which are deliquescent and dissolve in water 
 with development of heat. It is easily but slowly soluble 
 in alcohol, and is precipitated from this solution by ether, 
 chloroform or ethylic acetate. Concentrated solutions ap- 
 pear to decompose with explosive violence at 60 to 70 C., 
 like the solid salt, and in acid solutions, such decomposi- 
 tion sometimes occurs at ordinary temperatures. The dry 
 salt may be safely kept in an atmosphere of hydrogen and 
 in presence of pieces of ammonium carbonate and of lime. 
 It is best kept and transported under absolutely dry and 
 alcohol free ether, t 
 
 * T. J. HOOD, Chem. Zeit. n, 55. 
 
 f S. P. L. SORENSEN, Zeit. anorg. Chem., 7, 33. 
 
72 LABORATORY MANUAL OF 
 
 AMMONIUM DI HYDROGEN PHOSPHITE. 
 
 A solution of phosphorous acid mixed with ammonia 
 until neutral to methyl orange, and then concentrated 
 until the weight of the liquid is one-fourth or one-fifth 
 more than the calculated weight of the salt, yields large 
 deliquescent crystals, which can be dried over sulphuric 
 acid or at 100 C. Similar crystals are obtained if the 
 liquid is concentrated in vacuo at ordinary temperature. 
 The crystals have the composition NH^gPOs, a d seem 
 to be monoclinic prisms; they melt at 123 C. and are 
 very soluble in water. At 145 C. they lose half their 
 ammonia without evolution of hydrogen phosphide and 
 yield a gummy mass which seems to contain crystals. 
 At a higher temperature ammonia and hydrogen phos- 
 phide are given off and phosphoric acid is formed.* 
 
 AMMONIO ZINC CHLORIDES. 
 
 If a stream of ammonia is passed into a hot concen- 
 trated solution of zinc chloride until the precipitate first 
 formed is redissolved, and the whole is then allowed to 
 cool, nacreous scales of the composition ZnCl 2 , 4NH 3 + H 3 O 
 crystallize out. On concentration the mother liquor yields 
 crystals of the formula ZnCl 2 , 2NH 3 ; this compound 
 separates in colorless rhombic crystals, which do not 
 
 * L. Amat. Compt. Rend., 105, 809. 
 
INORGANIC PREPARATIONS. 73 
 
 change on exposure to air. It is insoluble in water, but 
 when boiled with it decomposes with evolution of am- 
 monia. It is easily soluble in solutions of ammonia or 
 ammonium chloride. The same compound is also formed 
 when ammonia is added to a cold dilute solution of zinc 
 chloride until the precipitate first formed is redissolved, or 
 when freshly precipitated zinc hydroxide is dissolved in 
 a concentrated solution of ammonium chloride. The same 
 compounds, in well formed crystals, has also been found 
 in Leclanche cells. The constitution is probably expressed 
 by the formula NH 8 Cl.Zn.NH 8 Cl.* 
 
 CUPROUS CHLORIDE. 
 CuoCte. 
 
 Cuprous Chloride can be conveniently prepared by 
 heating a mixture of copper sulphate (4 grams) and so- 
 dium hypophosphite (2 grams) in about 50 c. c. of 
 water to which 30 drops of fuming hydrochloric acid are 
 added. 
 
 The cuprous chloride is deposited and can be purified 
 in the ordinary way. The change can be explained thus : 
 Copper hypophosphite is at first formed, and this is con- 
 verted by the hydrochloric acid into cuprous chloride and 
 phosphoric acid. The equation is as follows : 2CuCl 2 -f 
 H 3 PO 2 + H 2 O = H 3 PO 3 + 2HC1 + Cu 3 Cl 2 . 
 
 Another method of preparation is to pour 100 c. c. 
 hot water over 42 grams copper chloride (cryst.) and 
 32 grams metallic copper (granulated or turnings) ; add 
 
 lBft^px. 
 . THOMAS, Be,, 2 o, 743. 
 
 J 
 
 W-.^^S 
 
74 LABORATORY MANUAL oP 
 
 200 c. c. crude hydrochloric acid (sp. gr. 1.175), and boil 
 gently in a flask closed by a small funnel ; finally add a 
 little fuming hydrochloric acid and boil until the solution 
 becomes colorless. This operation lasts one to two hours, 
 but can be hastened considerably if the copper powder in 
 cakes obtained in preparing blue vitriol is added to the 
 solution. The colorless solution is poured off from the 
 surplus copper into, a cylinder filled with cold distilled 
 water, the cheesy precipitated protochloride is allowed to 
 settle and decanted immediately, quickly filtered, washed 
 with ether and alcohol, and dried in vacuum over sul- 
 phuric acid. 
 
 CuCl 3 + Cu = Cu 2 Cl 2 .* 
 
 Cuprous chloride forms in heavy white masses, insolu- 
 ble in water, and oxydizes easily in the air and, with 
 chlorine water or aqua regia (nitromuriatic acid), dissolve 
 readily as copper chloride. By heating in small tubes 
 the protochloride melts without decomposition. 
 
 CUPROUS CYANIDE. 
 
 (CugCN).,. 
 
 50 grams crystallized blue vitriol are dissolved in 300 
 c. c. hot water, and to this hot solution in a flask, add, 
 by means of a dropping funnel, a solution of 26 grams 
 potassium cyanide in 50 c. c. water. The escaping cy- 
 anogen gas is passed through a glass tube bent upward, 
 tapering to a point and lighted at the end of the tube as 
 soon as the apparatus is filled with it. The gas is very 
 
 By A CAVAZZI, Gazzetta 16, 167-168). 
 
INORGANIC PREPARATIONS. 75 
 
 poisonous and burning is a ready way of getting rid of it. 
 The white cheesy sediment is separated by decanting from 
 the faintly bluish-colored solution, washed with water and 
 dried on an earthen plate. 
 
 CuSO 4 f 2KCN = Cu(CN) 3 -f K 3 SO 4 . 
 
 2Cu(CN) 3 = Cu 3 (CN) 3 + CN 3 . 
 
 Cuprous chloride is a tolerably stable white powder, 
 similar on the whole to the copper protochloride. Decom- 
 poses by heating, with a cyanogen odor. 
 
 COPPER AMMONIUM SULPHATE. 
 
 (NH 3 ) 4 CuS0 4 . 
 
 COPPER POTASSIUM SULPHATE. 
 
 CuK 3 (SO) 3 + 6H 3 O. 
 
 Ammonium double-salt. 30 grams blue vitriol are 
 dissolved in 100 c. c. ammonia-solution of 0,962 sp. gr. 
 150 c. c. alcohol are then placed into a high, narrow cy- 
 linder, and by means of a long-stemmed dropping funnel 
 20 c. c. water are carefully poured into the alcohol ; then 
 the copper solution is added in a very fine stream, so that 
 it will gather at the bottom of the cylinder, and is 
 separated from the alcohol by the water. Upon standing 
 from i to 4 weeks it forms large dark blue crystals. 
 
 Potassium double-salt. 100 grams blue vitriol in a 
 saturated solution at 70 C. are mixed with a solution of 
 69,8 grams potassium sulphate and 7 c. c. cone, sulphuric 
 acid. On cooling the whitish-blue crystals of the double- 
 salt separate. 
 
 Determine the copper value of the salts : Of the am- 
 
/6 LABORATORY MANUAL OF 
 
 monia double-salt by simply annealing and weighing the 
 remaining copper oxide; of the potassium double-salt by 
 precipitating with a piece of cadmium or zinc in a weighed 
 platinum dish from the diluted solution made faintly acid 
 with hydrochloric acid. When a sample of the discolored 
 solution no longer reacts with sulphureted hydrogen water, 
 rinse with a little hydrochloric acid, then with hot water, 
 and lastly with alcohol; dry at 100 C. and weigh. 
 
 CUPRIC SULPHATE. 
 CuSO 4 ,5H 2 O. 
 
 This reagent may be obtained in a state of great purity 
 from the residue remaining in the flask in the process of 
 preparing hydrogen sodium sulphite by treating with 
 water, applying heat, filtering, adding a few drops of nitric 
 acid, boiling for some time, allowing to crystalize, rnd 
 purifying the salt by recrystallization. 
 
 After precipitation by hydrogen sulphide, ammonia 
 and ammonium sulphide must leave the filtrate unaltered. 
 
 CUPROUS OXIDE. 
 
 CuoO. 
 
 A fairly concentrated solution of copper sulphate along 
 with excess of sodium chloride is thoroughly reduced by 
 treatment with gaseous sulphurous anhydride ; the excess 
 of the latter is then expelled by heating, and solid sodium 
 carbonate is added to the hot solution ; bright red cuprous 
 oxide is precipitated, and is readily washed by decantation.* 
 
 E. J. RUSSELL, Chem. News, 68, 308. 
 
INORGANIC PREPARATIONS*^; 77 
 
 CUPROUS AMMONIUM IODIDE. 
 4NH 3 Cu 3 I 4 . 
 
 IOO grams of an ammoniacal solution of cupric oxide 
 containing 7 to 8 per cent is mixed with an equal weight 
 of a 10 per cent solution of iodine in alcohol. A brown 
 precipitate of nitrogen iodide is formed, but this readily 
 disappears on warming, and if the liquid is heated for about 
 an hour on the water bath it becomes green and deposits 
 brilliant green needles, which must be dried as quickly as 
 possible. They have the composition 4NH 3 ,Cu 3 l4 or 
 4NH 3 Cu 3 I 2 ,CuI 2 and alter rapidly when exposed to air, 
 losing ammonia and iodine, and eventually changing to 
 cuprous iodide. The crystals are insoluble in water, but 
 are decomposed by prolonged boiling. They are only de- 
 composed by potash after prolonged boiling, but they 
 dissolve readily in ammonia, and the solution yields cu- 
 prammonium iodide when evaporated. If the green solu- 
 tion obtained as above is boiled with metallic copper until 
 it becomes colorless and is then allowed to cool, it deposits 
 cuprosoammonium iodide in brilliant white needles 5 to 6 
 mm. long. If the mixture of ammoniacal copper solution 
 and alcoholic iodine is allowed to stand with exposure to 
 air at the ordinary temperature, the nitrogen iodide slowly 
 dissolves, and after some hours the liquid deposits cupram- 
 monium iodide in octahedral crystals. If the ammoniacal 
 solution is boiled with iodine for several hours without ad- 
 dition of alcohol, and is then cooled, it deposits cupram- 
 monium iodide in tetrahedral crystals. 
 
78 LABORATORY MANUAL OF 
 
 CUPROAMMONIUM TETRA IODIDE. 
 4NH 3 CuI 2 ,I 2 . 
 
 Is obtained in brilliant black crystals, green by trans- 
 mitted light, by boiling 100 c. c. of the amnioniacal copper 
 solution with 20 grams of iodine, and allowing the liquid 
 to cool. If a further quantity of 20 grams of iodine is dis- 
 solved in the mother liquid from these crystals, the liquid on 
 cooling deposits cuproammonium hexiodide 4NH3,CuI 2 l4, 
 in rectangular tablets, which are brown by transmitted 
 light. This compound is usually obtained by mixing a 
 warm solution of cuproammonium nitrate with a solution 
 of iodine in potassium iodide. 
 
 CUPROUS PHOSPHIDE. 
 CugPg. 
 
 When red phosphorous is immersed in an ammoniacal 
 solution of copper sulphate, it becomes coated, as is well 
 known, with a greyish deposit, which is a mixture of 
 cuprous phosphide and metallic copper ; the same occurs 
 with an amnioniacal solution of copper phosphate, but the 
 transformation is never complete, even at 100 C. If, 
 however, red phosphorous is heated with a large excess of 
 copper phosphite and water in a sealed tube for four hours 
 at 130 C., its entire conversion is effected. The product 
 is washed quickly with aqueous ammonia and water in 
 succession, and dried in a vacuum. If the temperature hac 
 not exceeded that specified, it is not contaminated with 
 metallic copper.* 
 
 * By A. GRANGER, Compt. rend., 117, 231-232. 
 
INORGANIC PREPARATIONS. 79 
 
 Cuprous phosphide, Cu 2 ,Pg, is a grey powder resembling 
 plumbago in appearance. It is attacked by chlorine and 
 bromine in the cold, and is readily dissolved by dilute 
 acetic acid ; a mixture of it with potassium nitrate or 
 chlorate detonates violently when struck. When heated 
 in contact with air, it is oxydized to copper phosphate. It 
 is decomposed by heat into products identical with those 
 yielded by cupric phosphide. It is slightly soluble in 
 hydrochloric acid, yielding a solution from which cuprous 
 oxide is precipitated by potash, and which, when super- 
 saturated with ammonia, precipitates metallic silver from 
 a i\ ammoniacal solution of silver nitrate. 
 
 PURE SILVER. . 
 
 Ag. 
 
 a. Crystallized Silver. Any weighed quantity of 
 technical silver (coin or broken plate) is dissolved in 
 nitric acid, filtered and dried. The dried mass is 
 fused until it begins to turn black, dissolved in water, 
 filtered and diluted to such a degree that the solu- 
 tion contains 2 per cent, silver. It is now made 
 strongly ammoniacal in the cold and sodium bisulphite 
 solution added until a sample of the blue solution is de- 
 colorized on boiling. The greater part of the silver 
 separates in crystals as the solution cools, the remainder 
 by warming at 6o Q to /0 s C. The silver is washed with 
 water, then digested several times with concentrated am- 
 monia, again washed with water, dried on the waterbath 
 and weighed. 
 
 b. Molecular Silver from Residues. Silver residues 
 together with zinc sticks are boiled with addition of hy- 
 
80 LABORATORY MANUAL OF 
 
 drochloric acid. The reduced silver, freed mechanically 
 from the undissolved zinc, is washed well by decantation, 
 then dissolved in nitric acid and precipitated with hydro- 
 chloric acid. The decanted and washed silver chloride is 
 placed, while still moist, in soda lye, kept boiling in a porce- 
 lain dish and adding at intervals a few c. c. of cone, grape 
 sugar solution, until a filtered and washed sample of the 
 gray silver powder dissolves completely in nitric acid. 
 Wash, dry and weigh as described in a. 
 
 The black color appearing in fusing the impure nitrate 
 arises from the decomposition of the copper nitrate; 
 to avoid any loss of silver it is not heated until all the 
 copper salt has been converted into oxide ; but the separa- 
 tion of silver from the copper is so managed that the silver 
 from the ammoniacal solution is precipitated in metallic 
 form by sulphurous acid, while the copper, under these 
 circumstances, is reduced to protoxide, which remains dis- 
 solved in the ammoniacal solution. 
 
 Dissolve a sample of the silver in nitric acid free from 
 chloride, and note any sediment (gold, silver, chloride, tin 
 dioxide) ; precipitate the solution with hydrochloric acid 
 and test the filtrate for heavy metals. 
 
 PREPARATION OF PURE COLLOIDAL SILVER. 
 
 Solutions of ferrous sulphate (150 grams of the salt in 
 500 c. c. of the solution) and of sodium citrate (280 grams 
 of the salt in 700 c. c. of the solution) are mixed and 
 poured into a 10 per cent, solution of silver nitrate (500 
 
INORGANIC PREPARATIONS. 8 I 
 
 c. c.). Day-light need not be excluded, but it is ad- 
 visable to divide the mixture into five equal portions, as 
 small quantities can be dealt with more easily than large. 
 At the end of half an hour the supernatant liquid is re- 
 moved from the precipitated colloidal silver with a pipette, 
 and the silver is thrown on to a filter (Schleicher and 
 SchuH's No. 590 paper), filtered under diminished pressure, 
 and dissolved on the filter in the minimum quantity of 
 water ; solutions may thus be obtained containing 20 
 grams of silver per litre. To this solution absolute alcohol 
 is added with agitation until coagulation is perceptible, 
 and, after remaining for several days, the colloid is fil- 
 tered under a diminished pressure of 10 to 20 mm. on a 
 Pasteur filter-tube, when it forms a beautiful iridescent 
 incrustation. Colloidal silver in this state of purity is 
 soluble in alcohol, and cannot therefore be washed with 
 this liquid to remove the last traces of crystalloids. By 
 this method a product containing only .03 to .05 percent, of 
 iron is obtained.* 
 
 SILVER POTASSIUM CARBONATE. 
 
 AgKCO 3 . 
 
 150 grams of potassium carbonate are dissolved in 150 
 c. c. of water, cooled and agitated with 1 5 grams of potas- 
 sium hydrogen carbonate. When the liquid is saturated 
 with the latter salt at ordinary temperature, it is filtered 
 and mixed with a solution of one gram of silver nitrate in 
 25 c. c. of water. In order to obtain large crystals, the liquid 
 containing the precipitate is heated with continual agita- 
 
 * By E. A SCHNEIDER, Ber. 25, 1281-1284. 
 
 
82 LABORATORY MANUAL OF 
 
 tion. The precipitate dissolves, and when the liquid is 
 cooled it deposits long, transparent crystals with a brilliant 
 lustre: sp. gr. 3.769. They do not blacken when exposed 
 to light except in the presence of organic matter, and when 
 treated with water the silver carbonate which remains re- 
 tains the form of the original crystals. When heated the 
 compound loses carbonic anhydride, and at a higher tem- 
 perature the silver oxide which is formed gives off oxygen. 
 The crystals are microscopic, rectangular lamellae with 
 a terminal angle closely approaching 90. The refraction 
 is almost identical with that of apatite.* 
 
 PURE GOLD. 
 
 Au. 
 
 Technical gold (broken pieces of jewelry, a coin or crude 
 washgold) is broken into pieces as small as possible, weighed, 
 placed in a small flask and concentrated hydrochloric acid 
 poured over it. The flask is heated in a sand-bath, and 
 from time to time cone, nitric acid dropped into it. After 
 all is dissolved evaporate in a porcelain dish on the water- 
 bath, carefully avoiding all dust, until the remaining dark- 
 red solution solidifies on cooling. Then dissolve in plenty 
 of water, filter from the separated silver chloride and pre- 
 cipitate the filtrate hot with ferrous chloride solution in 
 excess. The separated gold in powder is decanted, boiled 
 several times with diluted hydrochloric acid, gathered on 
 an ashless filter, fused in a porcelain crucible and weighed. 
 In case larger quantities of gold are refined, a little platinum 
 
 * A DE SCHULTEN, Compt. Rend. 105, 811. 
 
INORGANIC PREPARATIONS. 8$ 
 
 and palladium (even thallium) can be separated from the 
 filtrate with iron or zinc. 
 
 The gold obtained in form of a reddish powder should 
 not impart a trace of yellowish color (iron) to boiling hy- 
 drochloric acid. If a weighed quantity is once more 
 subjected to the refining process described above the 
 weight should remain constant. 
 
 AURIC CHLORIDE, OR GOLD TRICHLORIDE. 
 
 AuCl 3 . 
 
 Take fine shreds of gold, which may be alloyed with 
 silver or copper, treat them in a flask with nitrohydrochloric 
 acid in excess, and apply a gentle heat until no more of 
 the metal dissolves, then dilute the solution with 10 parts 
 of water. If the gold was alloyed with copper which is 
 known by the brownish-red precipitate produced by po- 
 tassium ferrocyanide in a portion of the solution diluted 
 with water mix it with solution of ferrous sulphate in 
 excess. This will reduce the auric chloride to metallic 
 gold, which will separate in the form of a fine brownish- 
 black powder ; wash the powder in a small flask, and dis- 
 solve it in nitrohydrochloric acid ; evaporate the solution 
 on the waterbath, and dissolve the residue in 30 parts of 
 water. If the gold was alloyed with silver, the latter 
 metal remains as chloride, upon treating the alloy with 
 nitrohydrochloric acid. In that case evaporate the solu- 
 tion at once, and dissolve the residue in water for use. 
 
84 LABORATORY MANUAL OF 
 
 AUROSO- AURIC CHLORIDE. 
 
 By leading a stream of dry chlorine for 30 minutes 
 over gold, precipitated from a solution of gold chloride by 
 sulphurous acid, 50 to 70 grams of gold may be converted 
 into a homogeneous mass corresponding with the formula 
 Au 2 Cl 4 . The reaction is started by gentle heating, but the 
 necessary temperature is then maintained by the heat 
 evolved in the reaction, provided that cooling is prevented 
 by surrounding the tube with cotton or glass wool.* 
 
 ANHYDROUS MAGNESIUM CHLORIDE. 
 MgCI 2 . 
 
 500 grams crytallized magnesium chloride and 500 
 grams sal ammoniac are dissolved in a very small quantity 
 of water, filtered in a porcelain dish and dried in a silver 
 dish. The solid mass is broken while hot and dried in 
 small portions on porcelain or, better, on platinum dishes 
 (the mixture corrodes base metals, silver also, at a higher 
 temperature). The operation occupies some time and is 
 to be carried out with great care, as even very small 
 quantities of water frustrate the success of the experi- 
 ment. Dry in portions on several gas stoves and regulate 
 the heat so that an escape of ammonium chloride vapor does 
 not take place. Powder the portions from time to time in 
 a hot mortar, continue drying until the product, on heat- 
 
 J. THOMSEN, J. pr. Chem. [2] 37, 105. 
 
INORGANIC PREPARATIONS. 85 
 
 ing, no longer cakes and only consider the operation 
 completed when a sample heated in a test tube shows no 
 moisture ; after driving off the ammonium chloride there 
 remains a clear solution, forming radiant crystals upon 
 cooling. Then pour the powder* while still hot in a 
 spacious platinum crucible, close with a well-fitting cover 
 and place into the Roessler furnace which has previously 
 been heated. After the ammonium chloride is driven out, 
 again fill the crucible t with the loose powder, and con- 
 tinue heating until the entire mass is fused. The solidified 
 magnesium chloride, which is easily removed from the 
 crucible, should be placed in a well-stoppered bottle while 
 still warm. 
 
 Crystallized magnesium chloride can be rendered an- 
 hydrous and the formation of a basic salt prevented by 
 heating it in a current of hydrogen chloride.| 
 
 Crystallized magnesium chloride on heating loses the 
 largest quantity of its chlorine in the form of hydrochloric 
 acid; on the other hand, the double-salt (NHJgMgC^ 
 can, by heating carefully, be volatilized without decompo- 
 sition. On igniting this double-salt anhydrous magnesium 
 chloride remains. 
 
 (NH 4 ) 3 MgCl 4 = MgCl 2 + 2NH 4 C1. 
 
 Magnesium chloride crystallizes in large radiant g^ssy 
 crystals, not unlike fused sodium acetate, which melt readily 
 on heating and volatilize at red-heat. The vapors decom- 
 
 * If the dried substance is to be preserved, this must be done in well- 
 stoppered vessels. Before using the mass it should be dried for a short time 
 on the gas stove. 
 
 f When in a red-hot condition the crucible musi not be opened on 
 account of the volatility of the magnesium chloride. 
 \ W. HEMPEL, Ber. 21, 897. 
 
86 LABORATORY MANUAL OF 
 
 pose aqueous vapor instantly, forming hydrogen chloride. 
 The very hydroscopic salt should form a clear solution in 
 warm water. 
 
 CRYSTALLIZED NORMAL MAGNESIUM CAR- 
 BONATE. 
 MgCO 3 + 3 H 2 O. 
 
 If freshly precipitated magnesium carbonate, made by 
 mixing equivalent amounts of magnesium sulphate and so- 
 dium carbonate,is shaken with a solution of potassium hydro- 
 gen carbonate at the ordinary temperature, much of the mag- 
 nesium carbonate dissolves, crystallizes out of the filtered 
 solution after a time ; the separation is ended in 24 hours. 
 The same occurs if sodium hydrogen carbonate is used ; it 
 dissolves relatively more .of the magnesium carbonate, but 
 the crystals obtained are smaller. Solutions containing 
 respectively 67.5 grams of potassium and 12.96 grams of 
 sodium hydrogen carbonate per liter dissolved, respectively, 
 18.73 and 9.95 grams of magnesium carbonate. The crys- 
 tals have the composition 4MgCo 3 -f 15H 3 O ; after four 
 weeks in dry air, or 15 hours in a vacuum dessicator 
 over sulphuric acid, they have the composition 2MgCO 3 -f 
 6H 3 O; after heating at 170 C. the composition MgCO 3 + 
 l /3 VeHgO. The reaction is that a double sesquicarbonate 
 of magnesium and the alkali metal is formed, and that this 
 afterwards decomposes, magnesium carbonate being pre- 
 cipitated, and carbonic anhydride liberated, which latter 
 regenerates the alkali bicarbonate with the alkali sesqui- 
 carbonate now present. 
 
 Alkali bicarbonates do not dissolve calcium carbonate 
 
INORGANIC PREPARATIONS. 8/ 
 
 or ferric hydroxide, and upon this fact a technical process 
 for the preparation of pure magnesium carbonate from 
 dolomite, magnesite, bitterspar and from kanite or caen- 
 allite liquors has been based. The mineral is powdered, 
 dissolved in commercial hydrychloric acid and the iron 
 oxydized by warming gently with a little nitric acid. The 
 solution is then precipitated with sodium carbonate in slight 
 excess, the filtered precipitate shaken with a sufficiently 
 strong solution of alkali bicarbonate, and the solution fil- 
 tered after a lapse of 20 minutes and set aside to crystal- 
 lize. The mother liquor can be used repeatedly for the 
 extraction.* 
 
 MAGNESIUM BASIC CARBONATE. 
 
 Mg(OH) 2 ,MgC0 3 . 
 
 Prepare a strong solution of magnesium sulphate in 
 water, kieserite serves very well ; to the cold filtered solu- 
 tion add sodium carbonate solution in slight excess, mix 
 well in the cold, filter and wash slightly ; the filtrate may 
 be used to prepare glauber-salt ; transfer the precipitate 
 of magnesium carbonate to a suitable vessel, add water and 
 boil for 15 minutes; filter and wash on a filtering plate, 
 suck as dry as possible, remove from filter and dry at 
 
 o /^* 
 
 100 C. 
 
 POROUS CALCIUM CHLORIDE. 
 
 CaCl 2 . 
 
 One litre of the solution remaining from the evolution 
 of carbonic acid from marble and hydrochloric acid (crude) 
 
 * K. KIPPENBERGER, Zeit. anor. Chem. 6, 177. 
 
88 LABORATORY MANUAL OF 
 
 and which no longer reacts with marble is warmed and 
 then precipitated with milk of lime, made from 35 grams 
 caustic lime, in an iron pot of 2 litres capacity and filtered.* 
 After the strongly alkaline solution has been boiled, mix 
 the filtrate with hydrochloric acid to a strong acid reaction 
 and evaporate it on the gas stove, with further addition of 
 acid, in-, a porcelain dish of j litre capacity. As soon as 
 a coating of salt begins to form the heat is reduced, a little 
 fuming hydrochloric acid is added, and the whole left stand- 
 ing quietly without stirring; the mass becomes entirely dry 
 in the course of from four to five hours. Now carefully re- 
 move the calcium chloride from the dish with a knife, 
 break the large pieces while still hot in a warm mortar, 
 screen the pieces as quickly as possible in sieves from I to 5 
 mm mesh, and fill immediately into well-stopperd speci- 
 men bottles. 
 
 The caustic lime precipitates from the marble solution 
 magnesia, as well as the oxides of iron and manganese. 
 (Very often in standing, basic cakium chloride 3CaO, 
 CaClfc + 15H 2 O separates from the filtrate in long prisms). 
 In evaporating to dryness the solution must be acidified 
 with hydrochloric acid and the heating must be a gradual 
 one, otherwise the calcium chloride will lose HC1. and 
 take on a strong alkaline reaction. 
 
 Porous calcium chloride is a pure white, porous, very 
 hydroscopic mass, which dissolves clearly in water, and in 
 alcohol the water solution should show a reaction which is 
 slightly alkaline. 
 
 * In place of this you can also proceed from the residue of ammonia 
 production, consisting of a mixture of calcium chloride and surplus lime. 
 Boil the same with water until the last traces of ammonia have passed away, 
 then filter and continue as stated above. 
 
INORGANIC PREPARATIONS. 89 
 
 CALCIUM CHLORIDE. 
 CaCl 2 , crystallized +6H 2 O. 
 
 Dilute I part of crude hydrochloric acid with 6 parts ot 
 water, and add thereto marble or chalk until the last por- 
 tion added remains undissolved ; add now some slacked 
 lime, then hydrogen sulphide, until a filtered portion of the 
 mixture is no longer altered by ammonium sulphide. 
 Then let the mixture stand covered for 12 hours at a 
 gentle heat, filter, exactly neutralize the filtrate, concen- 
 trate by evaporation and crystallize. 
 
 Solution of pure calcium chloride must be perfectly 
 neutral, and neither be colored or precipitated by ammo- 
 nium sulphide ; nor ought it to evolve ammonia when 
 mixed with potassa or lime. 
 
 CALCIUM CARBONATE. 
 
 CaCo 3 . 
 
 Solution of pure calcium chloride is heated to boiling 
 and precipitated by a slight excess of solution of ammo- 
 nium carbonate with addition of some ammonia. The 
 precipitate is washed five or six times with hot water by 
 decantation, then is brought upon a filter and further edul- 
 corated until the washings give no turbidity with silver 
 nitrate. The contents of the filter are then dried and 
 bottled. 
 
 Calcium carbonate for use as a flux must be free from 
 salts of the fixed alkalies. When washed with hot water 
 the washing must yield no residue when evaporated to 
 dryness. 
 
90 LABORATORY MANUAL OF 
 
 CRYSTALLINE MONOCALCIUM PHOSPHATE. 
 
 CaH 4 (P0 4 ),. 
 
 Neither the crystalline nor the honey-like commercial 
 variety of monocalcium phosphate corresponds with the for- 
 mula CaH 4 (PO 4 ) 2 , owing to the free sulphuric acid in 
 the crude liquor acting on the phosphate during evapora- 
 tion. By leaving tricalcium phosphate in contact with a 
 solution of the honey-like commercial variety for some 
 time, a solution is obtained which, on gentle evaporation, 
 yields crystals of pure monocalcium phosphate.* 
 
 CALCIUM CHROMATE. 
 
 CaCr 2 O 4 . 
 
 The process is based on the fact that when chromium 
 oxide (CrgOs) is heated with a mixture of calcium chloride 
 and oxide, a chromite is formed (CaCr 2 O 4 ) which absorbs 
 oxygen from the air and yields calcium chromate. The 
 finely powdered mineral is mixed with paste composed of 
 lime, calcium carbonate and a concentrated solution of 
 calcium chloride, in such proportion that the lime and 
 the calcium carbonate are slightly in excess, of the amount 
 necessary to combine with the chromium oxide present, 
 while the calcium chloride is about one-third of the total 
 lime used. The mixture, on exposure to air, hardens and 
 is moulded into bricks, which are dried and subsequently 
 roasted at a temperature sufficient to convert the calcium 
 carbonate into lime. The bricks are exposed to the action 
 of air for about one month, then lixiviated with hot water 
 to remove the calcium chloride, and the residue containing 
 
 * G. POINTET, Bull. Soc. Chim. [3] 5, 254. 
 
INORGANIC PREPARATIONS. 91 
 
 the calcium chromate is treated with alkali carbonate or 
 
 sulphuric acid in the usual way, according as an alkali 
 chromate or chromic acid is required.* 
 
 ZINC FREE FROM ARSENIC. 
 
 Zn. 
 
 One kilo commercial zinc is melted in a hessian cru- 
 cible. Into the red-hot metal plunge pieces of anhydrous 
 magnesium chloride, forcing them to the bottom of the 
 crucible, and allow them to remain there until dissolved. 
 To retain the specifically light chloride below the fused 
 metal an iron wire is employed, the lower part of which 
 is twisted into a close spiral. Fasten in the small bell so 
 constructed, the magnesium chloride by means of a little 
 flower-wire, and press the wire into the metal. After 
 adding 1 5 grams of the chloride allow the crucible to cool 
 sufficiently to prevent the metal from igniting upon open- 
 ing it, and (the metal should be still liquid) pour it in 
 the finest possible stream into a pail of water. The gran- 
 ules upon removal from the water are drained and dried 
 
 by heat. 
 
 3MgCl 2 + 2As = 3Mg + 2AsCl 3 . 
 
 The arsenic chloride and undecomposed magnesium chlo- 
 ride pass off in thick clouds. 
 
 The zinc so obtained contains magnesium and, so dif- 
 ferently from c. p. zinc, dissolves very readily in diluted 
 acids. To test it for arsenic, pour over it, in a test tube, 
 dilute (i.i) hydrochloric acid and cover the tube with a 
 small filter, the tip of which is moistened with a drop of 
 
 J. MASSIGNON and E. VATSL, Bull. Soc. Chim. [3] 5, 371. 
 
92 LABORATORY MANUAL OF 
 
 cone, silver solution (i.i). Yellow silver arsenite Ag 3 AsO 3 
 forms after a time, which turns black and decomposes in 
 water. * 
 
 ZINC EISEN. 
 
 From one 10 two pounds of zinc are melted in a clay 
 crucible, 3 to 3.5 ozs. of anhydrous sodium ferrous chloride 
 are thrown in, and the crucible is immediately covered ; 
 violent reaction ensues, and the alloy is produced ; it is 
 very brittle, has a full metallic lustre, and is easily pul- 
 verized. t 
 
 STRONTIUM HYDROXIDE. 
 
 Sr(OH) 2 + 8H 2 0. 
 
 A well mixed mass of 150 grams finely powdered 
 celestine and 50 grams wood charcoal is pressed into a 
 hessian crucible and covered with a layer of powdered 
 coal. Close the crucible with an accurately fitting iron 
 cover, provided with a rim, and heat at white heat for an 
 hour in the Roessler gas furnace. The cool product should 
 dissolve in dilute hydrochloric acid with vigorous evolution 
 of sulphureted hydrogen, leaving only a slight coaly 
 residue ; test a portion in this manner : Suspend the mass 
 in a porcelain dish in a litre of hot water, and add to the 
 solution scales of copper (100 to 150 grams which have been 
 moistened with a little HNO 3 and then annealed), until a 
 filtered sample treated with lead acetate no longer pro- 
 
 * L. L'HoTE, Compound 98, 1491. 
 
 f H. N. WARREN, Chem. News, 55, 100. 
 
INORGANIC PREPARATIONS. 93 
 
 duces a brownish-black precipitate. Then filter hot into a 
 beaker, boil the residue with 100 c. c. water, cover the 
 entire filtrate, and allow it to crystallize. After the lapse 
 of 24 hours the liquid is poured off from the crystals, 
 which are very quickly dried on an earthen plate and 
 placed in a closed and paraffined vessel. The solution is 
 rapidly evaporated to 300 c. c in an iron dish, to obtain a 
 second crop of crystals. 
 
 The strontium sulphate, by ignition with charcoal and 
 exclusion of air, is transformed into strontium sulphide, 
 which by the action of copper oxide is converted into stron- 
 tium hydroxide: SrSo 4 + 4C = SrS + 4CO ; SrS + CuO + 
 H^O = Sr(OH 2 ) 4- CuS. 
 
 Strontium hydroxide crystallizes in perfectly clear, 
 easily efflorescent square tablets or needles of strong 
 alkaline taste, dissolving readily and without residue in 
 hot water. It melts easily on warming, and on further 
 heating solidifies again to a white mass with loss of its eight 
 molecules of water of crystallization ; at higher tempera- 
 tures it melts once more, and finally passes into strontium 
 oxide. An acetic acid solution should not be precipitated 
 by potassium dichromate (Bar.ium), but should, on the 
 other hand, be precipitated so completely by HgSC^ that 
 ammonium oxalate does not form a precipitate in the 
 filtrate (absence of lime). 
 
 PREPARATION OF PURE STRONTIUM SALTS. 
 
 The following process is given for obtaining a pure 
 
 strontium salt from a barytostrontianite containing iron, 
 
 aluminium, magnesium, calcium and barium as impurities: 
 
94 LABORATORY MANUAL OF 
 
 The mineral or the sulphide resulting from the reduction 
 of the sulphate is dissolved in such a quantity of hydro- 
 chloric acid (20 per cent.) as to leave a little undissolved. 
 The aluminum and iron are precipitated by ammonia, fil- 
 tered off, and excess of sulphuric acid added. The pre- 
 cipitate is washed first with dilute sulphuric acid (i to 2 per 
 cent.) and finally with water; it is thus freed from magne- 
 sium and calcium. It is now digested in the cold for 
 some days with ammonium or potassium carbonate solu- 
 tion (10 per cent.), washed well, the residue treated with 
 dilute hydrochloric acid, and the solution decanted ; 
 after remaining for 24 hours this is filtered, and 200 grams 
 of hydrochloric acid (sp. gr. 1.17) per litre are added 
 to it, together with 2 or 3 grams of precipitated strontium 
 sulphate, which may contain barium. After some hours 
 the solution is filtered, evaporated to dryness, dissolved in 
 water, filtered and crystallized. The spectrum given by 
 the salt thus obtained shows strontium to be the only metal 
 present.* 
 
 CADMIUM CARBONATE. 
 
 CdC0 3 . 
 
 IOO grams of cut or granulated commercial cadmium 
 are placed in a flask with 400 c. c. cold nitric acid of 1.20 
 sp. gr. Run the nitrogen dioxide evolved into the drain; 
 after the action has completely ceased, pour the liquid 
 from the undissolved residue into a porcelain dish of 6 
 litres capacity ; dilute with 4 litres hot water and add a 
 little powdered commercial ammonium carbonate, until a 
 
 By BARTHE and FALIERES, Bull. soc. Chin. [3], 7, 104-108. 
 
INORGANIC PREPARATIONS. 95 
 
 permanent precipitate is formed ; filter and precipitate the 
 cadmium in the filtrate with about 150 grams ammonium 
 carbonate ; decant several times with hot water in tall glass 
 cylinders, and preserve the carbonate as paste, or else dry 
 on the water-bath. 
 
 3Cd + 8HNO 3 =3Cd(NO 3 ) 2 f 2NO -f 4H 3 O. 
 
 The foreign metals, with the exception of zinc and iron, do 
 not remain in solution, but are again precipitated in me- 
 tallic form by the surplus cadmium. The iron precipitates 
 with the first portion of cadmium carbonate : 
 
 3CdCO 3 4- Fe 2 (NO 3 ) 6 + 3H 2 O = 3Cd(NO 3 ) 2 + Fe 2 (OH) 6 f 
 
 3CO 2 . 
 
 The zinc is retained in solution by the surplus ammonium 
 salt. 
 
 The pure white salt passing into brown cadmium oxide 
 on igniting, and easily dissolving in diluted acids with effer- 
 vescence, is to be tested particularly for antimony, bismuth, 
 copper, lead, iron and zinc according to the usual method 
 of analysis. 
 
 BARIUM OXI DE. 
 BaO. 
 
 1 50 grams of heavy spar are reduced with 40 grams 
 wood charcoal, in the same manner as described for celes- 
 tine (on page 92), and the barium sulphide obtained is de- 
 composed in a litre, flask, with dropping funnel and gas 
 conduit tube, by means of dilute HNO 3 , filtered and 
 evaporated to crystallization. Of this, or else of commer- 
 cial barium nitrate, I y 2 kilos are gradually placed with an 
 
96 LABORATORY MANUAL OF 
 
 iron spoon in a red-hot Hessian crucible, which is kept cov- 
 ered with an earthen cover. After having added the whole 
 quantity the closed crucible is heated for another hour at 
 very high temperature. After the crucible has again partly 
 cooled, remove the upper layer of the barium manganate, 
 the green-colored layer of the crucible, and fill the barium 
 oxide into small flasks, at once sealing them hermetically. 
 
 The barium nitrate at first passes into barium nitrite 
 and then further into barium oxide, at white heat: 
 
 Ba(NO 8 ) 2 = Ba(NO 2 ) 2 + 2O, 
 Ba(NO 2 ) 2 = BaO + 2N -f 3O. 
 
 Barium oxide comes in grayish-white porous pieces, 
 which evolve heat with water and dissolve completely in 
 dilute hydrochloric acid without effervescing; this solution 
 should not discolor permanganate nor blue potassium iodide 
 starch paper (barium nitrate and barium superoxide). 
 
 BARIUM CHLORIDE. 
 
 BaCl 2 + 2H 2 O. 
 
 a. From heavy spar. Mix together 8 parts of pul- 
 verized barium sulphate, 2 parts of charcoal powder, and I 
 part of common rosin. Put the mixture in a crucible and 
 expose it in a blast furnace to a long-continued red heat. 
 Triturate the crude barium sulphide obtained, boil about A 
 of the powder with 4 times its quantity of water, and add 
 hydrochloric acid until all effervescence of hydrogen sul- 
 phide has ceased, and the fluid manifests a slight acid reac- 
 tion. Add now the remaining A part of the barium sul- 
 phide, boil some time longer, then filter, and let the alkaline 
 
INORGANIC PREPARATIONS. 97 
 
 fluid crystallize. Drain the crystals, redissolve them in 
 water, and crystallize again. 
 
 b. From witherite. Pour 10 parts of water upon i 
 part of pulverized witherite, and gradually add crude hy- 
 drochloric acid until the witherite is almost completely dis- 
 solved. Add now a little more finely pulverized witherite, 
 and heat, with frequent stirring, until the fluid has entirely 
 or very nearly lost its acid reaction ; add solution of barium 
 sulphide as long as a precipitate forms ; then filter, evap- 
 orate the filtrate to crystallization, and purify by crystal- 
 lizing again. For use, dissolve I part of the barium chlo- 
 ride in 10 parts of water. 
 
 Pure barium chloride must not alter vegetable colors ; 
 its solution must not be colored or precipated by hydrogen 
 sulphide, nor by ammonium sulphide. Pure sulphuric 
 acid must precipitate every fixed particle from it, so that 
 the fluid filtered from the precipitate formed upon the ad- 
 dition of that reagent leaves not the slightest residue when 
 evaporated on platinum foil. 
 
 BARIUM NITRATE. 
 Ba(NO 3 ) 2 . 
 
 Treat barium carbonate, no matter whether witherite 
 or that precipitated by sodium carbonate from solution of 
 barium sulphide, with dilute nitric acid free from chlorides, 
 and proceed exactly as directed in the preparation of 
 barium chloride from witherite. 
 
 Solutions of barium nitrate must not be made turbid by 
 silver nitrate solutions. The other tests are the same as 
 for barium chloride. 
 
98 LABORATORY MANUAL OF 
 
 BARIUM PEROXIDE. 
 Ba0 2 . 
 
 BARIUM PERHYDRATE. 
 Ba(OH) 4 + 6H 2 O. 
 
 A combustion tube is filled with 30 grams powdered ba- 
 rium oxide, moderately heated in a combustion furnace, and a 
 rapid current of oxygen dried with cone, sulphuric acid 
 conducted over it. The solid peroxide, after being ground 
 with a little water, is placed in 50 c. c. dil. hydrochloric acid 
 which has been cooled to o C., then the still faintly acid 
 solution is filtered and allowed to flow into 500 c. c. baryta 
 water which has been cooled to o C., and saturated cold. 
 The separated precipitate, consisting of glistening crystalline 
 scales, is sucked dry, washed with a little ice-water, and 
 preserved as paste. 
 
 With moderate heat the barium oxide adds another 
 atom of oxygen. The barium peroxide decomposes with 
 hydrochloric acid: 2BaO 3 f- 4HC1 = 2BaCl 2 + 2H 2 O ; the 
 hydrogen peroxide with baryta: H 3 O 3 -f Ba(OH) 3 = 
 Ba(OH) 4 . 
 
 The barium superoxide must not inflame by grinding 
 with water (property of barium oxide). The value of the 
 perhydrate is proven, if hydrogen peroxide is produced 
 from the preparation. 
 
 BARIUM CARBONATE. 
 
 BaCO 3 . 
 
 Dissolve crystallized barium chloride in water, heat to 
 boiling, and add a solution of ammonium carbonate mixed 
 
INORGANIC PREPARATIONS. 99 
 
 with some ammonia, or of pure sodium carbonate, as long 
 as a precipitate forms ; let the precipitate subside, decant five 
 or six times, transfer the precipitate to a filter, and wash 
 until the wash water is no longer made turbid by silver 
 nitrate solution. 
 
 Pure sulphuric acid must precipitate every fixed particle 
 from a solution of barium carbonate in hydrochloric acid. 
 
 BARIUM DITHIONATE. 
 
 DITHIONIC ACID. 
 H 3 S 3 6 +xH 2 0. 
 
 100 grams finely powered black oxide manganese is elu- 
 triated by mixing with water in a large mortar, decanted, 
 and the remaining coarse powder again mixed with water ; 
 this is repeated until the entire mineral is suspended in 
 water, then allow it to settle in tall cylinders ; the water is 
 removed by means of a syphon, and the black oxide of man- 
 ganese brought into a liter flask with y 2 litre water. A 
 current of sulphur dioxide is passed through the mixture, 
 the flask being cooled with ice. When the bulk of the 
 black oxide manganese has dissolved add to the solution 
 which has been heated in a dish cone, barium hydrate 
 solution until a filtered sample fails to yield a flesh-colored 
 precipitate with ammonium sulphide. The precipitate is 
 then filtered, boiled with hot water, and the combined fil- 
 trates treated hot with carbonic acid until neutral. The 
 barium dithionate crystallizes from the filtrate on concen- 
 tion. 
 
 Dithionic Acid. 59 grams barium dithionate are dis- 
 
100 LABORATORY MANUAL OF 
 
 solved in water ; 20 grams of a solution of sulphuric acid 
 diluted with water are added to the solution until it will no 
 longer react either with sulphuric acid or with barium chlo- 
 ride. After filtering off the barium sulphate the dithionic 
 acid is concentrated on a flat porcelain plate in vacuum 
 over sulphuric acid to a sp. gr. of 1.347. 
 
 The peroxide withdraws from 2 molecules of sulphur- 
 
 cr~\ rr 
 
 ous acid two atoms of hydrogen ; 2HSO 3 H 2H = ^Q 3 j 
 
 The manganese salt of the dithionic acid is decomposed 
 by the excess of baryta water. 
 
 MnS 3 O 6 + Ba(OH)2= BaS 3 O 6 -f Mn(OH)g. 
 
 Barium dithionate forms colorless, glossy crystals, 
 which in a powdered condition lose their water of crystal- 
 lization (10.81 %) at 100 C. 
 
 Determine the percentage of barium oxide (45.96 % 
 BaO) by igniting the purified salt and then weighing the 
 residue of barium sulphate. 
 
 DISTILLED MERCURY. 
 Hg. 
 
 In a combustion furnace, one end of which is lifted 
 15 mm. above the other, lay a tube of hard Bohemian 
 glass, both ends of which are bent downward, as shown in 
 figure 8. 
 
 The end drawn out is connected by means of a heavy 
 walled, closely fitting rubber tube with a glass tube of 
 medium thickness about 10 mm. outside diameter, and 
 of such a length that the entire vertical tube up to the 
 lower opening which turns upward is about 700 mm. The 
 
INORGANIC PREPARATIONS. 
 
 101 
 
 giass tube stands in a narrow glass cylinder. The other 
 end of the combustion tube is bent upward somewhat 
 within the furnace so that the last flame of the furnace 
 stands below the highest point * of the bend of the tube. 
 
 FIG, 8. 
 
 From there the tube leads downward 20 cm. without re- 
 duction in size ; into the end of this tube by means of a 
 rubber tubing, t a second glass tube is inserted, bent hook- 
 form at the bottom, which extends at least 5 cm. into the 
 wider tube, and is about 80 cm. in length. To set the 
 
 * At the point of the tube, place a loose plug of asbestos. 
 
 f In order to have at this point a perfectly airtight connection, add the 
 contrivance pictured in the small illustration on the right, which is intellig- 
 ible without further explanation. The small space ^surrounding the shaded 
 part) formed by a rubber stopper and a small pieci of wide glass tubing is 
 filled with mercury. 
 
102 LABORATORY MANUAL OF 
 
 apparatus in motion pour into the cylinder commercial 
 mercury or else mercury which has become impure by use 
 with other metals, and exhaust the apparatus with a filter 
 pump, adding an empty Woulff bottle. As soon as the 
 mercury has risen so high that it runs along in a thin 
 stream from one end of the combustion furnace to the 
 other, the rubber tubing leading to the pump is closed se- 
 curely with a pinch-cock. Now the furnace is heated with 
 a low flame while the mercury boils gently and distills 
 through the asbestos plug. As soon as the tube leading 
 downward is filled half way with mercury, open the pinch- 
 cock and carefully allow air to enter the exhausted tube ; 
 the mercury column now prevents air from entering this 
 side of the apparatus. The apparatus works automatically, 
 and the distilling mercury flows continually into a vessel 
 placed below ; from time to time the quantity of mercury 
 in the cylinder is replaced. 
 
 The mercury should be 13.595 S P- S r - at C. and 
 possess a pure silver gloss, fuse easily, and in pouring out, 
 form round regular drops leaving no threadlike residue. 
 5 grams heated in a porcelain crucible should not leave a 
 weighable and fusible residue. 
 
 PURIFICATION OF MERCURY. 
 
 Mercury can be completely freed from lead, zinc, tin, 
 and other impurities by placing it in a slightly inclined 
 glass tube provided with a funnel at the lower extremity, 
 and aspirating a gentle stream of air through the apparatus 
 for about 48 hours. The oxides of the metals collect at 
 the upper end. of the tube, and after about 24 hours, as a 
 
INORGANIC PREPARATIONS. IO3 
 
 rule, the surface of the mercury is quite clean and the 
 operation is finished. Large quantities can be treated in 
 this way, but mercury which has been used for amalgamat- 
 ing zinc contains such a large amount of impurity that this 
 method cannot be used. Silver is not removed by this 
 process. 
 
 Mercury is usually purified by shaking in a topped 
 separator with cone, sulphuric acid, allowing time to 
 settle and drawing off, continue until the mercury is bright 
 and no longer imparts a color to the mercury.* 
 
 MERCURIC CHLORIDE, 
 
 HgClg. (FROM RESIDUES.) 
 
 The residues, oxydized with crude hydrochloric and 
 nitric acids and then dried on the water bath are subjected 
 to slow sublimation in a porcelain dish on a sand-bath with 
 a large funnel set over it. Of the sublimate thus obtained 
 dissolve according to its purity i-io to 1-5 in hot water, 
 precipitate with soda lye, and grind the so obtained mer- 
 curic oxide after washing and drying with the main quan- 
 tity of the sublimate The acquired powder which turns 
 black through the formation of mercuric oxychloride, is 
 placed into a flask, covered loosely with a watch glass and 
 heated on the sand bath over a small flame. The subli- 
 mate gathers at the upper part of the flask in fine long 
 crystals. After final sublimation remove the flask from 
 the bath, break off the bottom by quickly passing over it 
 a damp sponge and separate the crystals from the glass on 
 a large sheet of paper with the aid of a goose quill. In 
 
 *J. M. CRAFTS, Bull. Soc. Chim. 49, 856. 
 
104 LABORATORY MANUAL OF 
 
 case there are poor crystals among them, they are to be 
 recrystallized in four parts of boiling water. 
 
 The crude sublimate is contaminated by other unstable 
 metallic chlorides, but these are all decomposed by mer- 
 curic oxide ; for instance : Fe 3 Cl e -f 3HgO = Fe 2 O 3 + 3HgCl 2 . 
 
 Pure white, rhombic prisms of mercuric chloride dis- 
 solve readily without residue (calomel, iron oxide, etc.) in 
 cold alcohol, ether and hot water ; heated in a test tube 
 volatilize without residue. 
 
 MERCURIC CYANIDE. 
 
 Hg(CN) 2 . 
 
 A diluted prussic acid solution is mixed in a flask with 
 yellow mercuric oxide until the solution reacts strongly 
 alkaline to litmus paper. Filter and add to the filtrate 
 enough prussic acid to make the odor of it noticeable and 
 so that the filtrate will react distinctly acid, then evaporate 
 to crystallization. Before the mother liquor is again evap- 
 orated to crystallization, add a little more prussic acid. 
 
 Mercuric cyanide crystallizes in square columns and 
 pyramids soluble in 1 1 parts of cold water and have a 
 neutral reaction. Heated in small tubes, the salt develops 
 cyanogen, gives a destillate of niercury drops and leaves 
 black paracyanogen. 
 
 CINNABAR. 
 
 HgS. 
 
 60 grams mercury are intimately mixed in a mortar 
 with 23 grams flowers of sulphur until the mercury has 
 
INORGANIC PREPARATIONS. 105 
 
 entirely disappeared. Pour over this a solution of 15 
 grams caustic potash in 80 c. c. water and digest several 
 days at about 45 C., stirring frequently and replacing the 
 evaporated water. After the mass has become of a nice 
 red color, it is separated from the unaltered mercury and 
 the largest part of the sulphur by elutriation, boiled with a 
 solution of sodium sulphite, and washed with hot water. 
 
 Cinnabar is a scarlet-red powder and when heated 
 strongly in small tubes volatilizes without residue. 
 
 MERCUROUS NITRATE 
 Hg 3 ( N O 3 ) 3 crystallized + 2 H 3 O . 
 
 Pour I part of pure nitric acid of 1.2 sp. gr. on I 
 part of pure mercury in a porcelain dish, and let the vessel 
 stand twenty-four hours in a cool place ; separate the 
 crystals formed from the undissolved mercury and the 
 mother liquor, and dissolve them in water mixed with one- 
 sixteenth part of nitric acid, by trituration in a mortar. 
 Filter the solution, and keep the filtrate in a bottle with 
 some metallic mercury covering the bottom of the vessel. 
 
 The solution of mercurous nitrate must give with di - 
 lute hydrochloric acid a copious white precipitate of mer- 
 curous chloride ; hydrogen sulphide must produce no pre- 
 cipitate in the fluid filtered from this, or at all events, only 
 a trifling black precipitate (mercuric sulphide). 
 
106 LABORATORY MANUAL OF 
 
 MERCUROUS IODIDE. 
 
 Hg 2 I 3 
 
 If a saturated solution of mercurous nitrate as free as 
 possible from oxide and slightly acidified with nitric acid, 
 is heated to boiling with iodine, the latter becomes covered 
 with a yellow powder, which partially dissolves, and the 
 solution, after decantation into a warm dish, deposits in the 
 dark, lustrous yellow, transparent, tetragonal scales of 
 mercurous iodide ; these must be dried in the dark at or- 
 dinary temperature. When the mercurous nitrate solution 
 is treated with an alcoholic solution of iodine in the cold, 
 small, yellow spangles of mercurous iodide are obtained, 
 but the product formed by the old methods of preparation, 
 by rubbing together molecular proportions of mercury and 
 iodine, and adding potassium iodide in solution to a solu- 
 tion of mercurous salt, have a green color, and are impure, 
 although the pure yellow compound can be obtained by 
 reversing the last process, and adding an excess of a dilute 
 solution of mercurous nitrate to potassium iodide in solu- 
 tion. The crystallized compound shows the usual color 
 change, yellow at 100 C. passing through orange to gar- 
 net-red at higher temperatures. Sublimation commences 
 at 1 10 to 120 C. and the salt fuses at 290 C. without de- 
 composition. Towards acids and solvents, the crystallized 
 compound behaves like that precipitated by potassium 
 iodide ; ammonia and caustic alkalies render it green, and 
 on heating convert it into the corresponding alkaline iodide 
 and metallic mercury. The crystallized iodide is less 
 sensitive to light than the precipitated yellow compound, 
 which rapidly becomes black even in diffused daylight.* 
 * A. STROMAN, Ber. 20, 2818. 
 
INORGANIC PREPARATIONS. 1 07 
 
 MERCUROUS BROMIDE. 
 
 Hg 2 Br 3 . 
 
 When mercurous nitrate solution is treated with bro- 
 mine under similar conditions, small, white, nacreous, 
 tetragonal scales of mercurous bromide are obtained, and 
 the same compound separates in yellow, crystalline span- 
 gles when an alcoholic or aqueous solution of bromine is 
 used. It sublimes at 171 to 176 C. in small scales, is less 
 sensitive to light than the iodide, dissolves in hot sulphuric 
 acid with the evolution of sulphurous anhydride becomes 
 black and gradually decomposes when heated with dilute 
 and concentrated hydrochloric acid, dissolves slowly in hot 
 nitric acid (sp. gr. 1.42), and decomposes with the forma- 
 tion of the corresponding bromides when treated with am- 
 monia and caustic alkalies. 
 
 BORON. 
 
 B. 
 
 100 grams fused hot finely powdered borax are well 
 mixed with 50 grams magnesium powder, the mass poured 
 in a Hessian crucible, pressed down well and covered with 
 a layer of pure borax. All these operations must be done 
 rapidly and are to be carried on in warmed vessels, as the 
 anhydrous borax is very hygroscopic. The crucible is 
 closed with a specially well-fitting cover of strong sheet-iron 
 with a rim, and heated in a Roessler's furnace for half an 
 hour up to red heat. After cooling, grind the product, 
 boil it with water, then with hydrochloric acid artd finally 
 
108 LABORATORY MANUAL OF 
 
 again with water and dry the grayish-brown powder on 
 the water-bath.* 
 
 PREPARATION OF AMORPHOUS BORON. 
 
 Another method is to pass a current of 35 amperes 
 through boric anhydride mixed with 20 per cent, of sodium 
 borate and heated at 1200, boron is liberated, but im- 
 mediately recombines with oxygen with vivid incan- 
 descence. 
 
 It is well known that when boric anhydride is heated 
 with the theoretical quantity or an excess of magnesium, 
 reduction takes place with formation of magnesium borides. 
 If the boric anhydride is in considerable excess different 
 results are obtained. There are two magnesium borides, 
 one unstable and decomposed by water with liberation of 
 hydrogen and boron hydride, the other stable and not af- 
 fected by water, hydrochloric acid, or nitric acid. 
 
 70 grams of finely powdered magnesium free from iron 
 and silicon, are intimately mixed with 210 grams of re- 
 cently fused boric anhydride. The mixture is heated to 
 bright redness in a clay crucible, and in a few minutes an 
 energetic reaction takes place. The central part of the 
 product is boiled with water and hydrochloric acid until 
 the magnesium borate is removed, then treated for a long 
 time with successive quantities of pure boiling hydro- 
 chloric acid, washed with water, treated with alcoholic 
 potash, again washed with water, boiled for several hours 
 with hydrofluoric acid, washed with water, and dried in a 
 vacuum. The product is a very light maroon powder 
 which does not alter when exposed to air ; it contains 94 to 
 
 * GATTERMANN, Ber. 22, 195. 
 
INORGANIC PREPARATIONS. 109 
 
 95 per cent, of boron, 2.3 to 3.75 per cent, of magnesium 
 and 1.2 to 1.6 per cent of insoluble matter. 
 
 If this product is fused with 50 times its weight of boric 
 anhydride, and the product treated in the same way as the 
 original product, a maroon powder is obtained containing 
 only traces of magnesium. 
 
 One product contained boron, 98.30 ; magnesium, 0.37; 
 insoluble, 1.18 = 99.85. 
 
 If the boron is required perfectly free from nitride, re- 
 duction must be affected in a crucible brasqued with a mix- 
 ture of finely powdered titanic oxide and carbon ; the 
 product contains from 92.6 to 99.2 per cent, of boron. 
 Boric anhydride may also be reduced by magnesium in 
 porcelain dishes in an atmosphere of hydrogen, and a very 
 pure product obtained, but the yield is small.* 
 
 It can also be prepared by mixing 3.5 grams of boric 
 anhydride and 1 1 grams of calcium fluoride by gently 
 heating with cone, sulphuric acid ; the boron fluoride 
 evolved is passed over heated potassium contained in a 
 series of bulbs. Potassium fluoride and boron are formed 
 and easily separated by washing with water. Amorphous 
 silicon may be prepared in a similar manner.t 
 
 BORAX. 
 
 Na 2 B 4 O 7 . 
 
 An intimate mixture of well-ground common salt and 
 boric acid is introduced into an acid-proof, tubulated clay 
 retort, and heated to slightly above a low red heat, when 
 sufficient superheated steam is admitted through the tu- 
 
 * By H. MOISSAN, Compt. rend., 114, 392-397. 
 f S. G. RAVVSON, Chem. News, 58, 283. 
 
110 LABORATORY MANUAL OF 
 
 bulature to condense the hydrochloric acid, which is evolved, 
 the acid being collected in a cooled receptacle attached to 
 the retort neck. Ultimately anhydrous borax only is left 
 in the retort, and this is thrown, while still hot, into cold 
 water and crystallized.* 
 
 BOR ACIC ACID. 
 H 3 B0 3 . 
 
 200 grams powdered borax are dissolved in one-half 
 litre of boiling water, and 300 c. c. dil. hydrochloric acid 
 added. After expiration of a day suck the separated scaly 
 crystals dry on the platinum cone, wash them with a very 
 little water, and recrystallize once from water. 
 
 The white, pearl-like crystals must dissolve in 6 parts 
 alcohol and 25 parts cold water and on heating, after 
 evaporation of the water, melt to a colorless glass which 
 when cooled remains transparent. The watery solution 
 reddens litmus paper ; if turmeric paper strips are saturated 
 with it and dried in a warm place, the yellow color will be 
 changed to an orange-brown, which with alkaloids be- 
 comes greenish-black. The impurities usually present are 
 hydrochloric and sulphuric acids. 
 
 SILICON. 
 
 Si 
 
 Amorphous silicon is readily obtained by the action of 
 magnesium on silica, provided that the materials are quite 
 dry, and that the action is moderated by the presence of 
 magnesium oxide. In absence of the oxide, the tempera- 
 
 * By H. N. WARREN, Chern. News, 67, 244-245 
 
INORGANIC PREPARATIONS. Ill 
 
 ture of the reaction is too high, and some of the silicon is 
 fused. Silica is not so satisfactory as magnesia for this 
 purpose. Powdered quartz and magnesium powder such 
 as is used for photographic purposes are mixed in the cal- 
 culated proportions, and to the mixture is added one-fourth 
 of its weight of calcined magnesia. The three substances 
 are very intimately mixed and placed in a fire clay cruci- 
 ble, which they must not more than half fill. A layer of 
 magnesia is placed on the top, and the crucible is then 
 heated at 149 to 205 p C. in order to thoroughly dry the con- 
 tents. The crucible with its cover is then heated to red- 
 ness for a few minutes, and as soon as the action ceases it 
 is allowed to cool. Reduction takes place at 282 C. If 
 the mixture is placed on a plate and covered with mag- 
 nesium powder, and the latter is ignited, reduction spreads 
 throughout the mass. 
 
 The product is heated with hydrochloric acid, then 
 with boiling sulphuric acid, then two or three times alter- 
 nately with hydrofluoric acid and sulphuric acid, and, 
 finally, with hydrochloric acid. After drying, the silicon 
 forms a maroon colored, homogeneous powder, containing 
 only i.o to 0.4 per cent, of impurities. Any small globules 
 of fused silicon can, if necessary, be removed by levigation.* 
 
 Another method is to heat 40 grams of finely pow- 
 dered sand with 10 grams of magnesium in not too 
 thin a test tube, the whole tube is heated first mod- 
 erately, and then a small portion is heated strongly, 
 beginning at the lower end and continuing up- 
 wards. The product is grayish-black. The frag- 
 ments of the tube, after the substance has been taken out, 
 
 * By VIGOURON, Compt. rend., iScjs, 120, 94. 
 
112 LABORATORY MANUAL OF 
 
 should be treated with acid, as the adherent substance will 
 decompose in moist air and evolve silicon hydride. Silicon 
 is obtained by heating the substance in a closed crucible 
 with zinc ; on dissolving out the zinc, it is obtained in steel- 
 btoe needles.* 
 
 It can also be prepared by introducing aluminium, 
 in pieces the size of a walnut, into a clay crucible 
 containing a fused mixture of 4 parts of potassium 
 silico-fluoride, I part of potassium chloride, and 2 
 parts of potassium carbonate, and when the violent 
 reaction has subsided, the mass is heated. to whiteness for 
 five minutes. When cool, the crucible is smashed ; the 
 button, carefully detached from adhering slag, is placed in 
 a plumbago crucible with 12 parts by weight of aluminium 
 and 2 of tin, and covered with a layer of sodium silicate, 
 the mixture is submitted for two hours to the strongest 
 heat obtainable. When cold, the piece of aluminium is 
 broken, when the new modification of silicon is found in 
 large, lustrous, infusible, oblique octahedra, insoluble in all 
 acids except hydrofluoric.! 
 
 Still another method is as follows : Small bars of 
 " silicon-eisen " are suspended in dilute sulphuric acid 
 from the positive pole of a battery of two ferric 
 chloride cells and are in contact with a platinum 
 plate forming the negative pole. The iron dissolves and 
 leaves a residue of graphite, silica, and amorphous silicon, 
 which is heated to redness in a stream of carbonic an- 
 hydride, and then to a full red heat in a closed iron 
 tube with some zinc ; the zinc button obtained in this 
 
 *L. GATTERMANN, Ber. 22, 186. 
 
 f By H. N. WARREN, Chem. News, 67, 136-137. 
 
INORGANIC PREPARATIONS. 113 
 
 manner is dissolved in hydrochloric acid, when crystal- 
 line silicon remains insoluble ; by heating the amor- 
 phous silicon at a full white heat with aluminium instead 
 of zinc, graphitoidal silicon is obtained. When an alloy 
 of aluminium and silver is heated to an intense white 
 heat with potassium silicofluoride, small quantities of 
 silicon are produced in the form of a bright reddish- 
 brown powder.* 
 
 CRYSTALLINE SILICIC ACID. 
 H 2 Si0 3 . 
 
 Silicious limestone is treated with crude concentrated 
 hydrochloric acid until carbonic anhydride ceases to be 
 evolved, filter and add to the filtrate 29 to 31 per cent, 
 hydrochloric acid until a cloudiness appears. After re- 
 maining 24 hours the solution is decanted, the precipi- 
 tate strained and washed, finally with distilled water and 
 then dried on porcelain. Silicic acid so obtained is 
 crystalline and corresponds to the formula H 2 SiO3 + 3H 2 O 
 or H 2 SiO 3 +2H 2 O. It is more soluble than the amor- 
 phous variety.! 
 
 SILICON CHLORIDE. 
 
 SiCl 4 . 
 
 Take a hard glass tube 2 m.m. wide, fill it half way 
 with the crude amorphous silicium as described above, 
 lay it horizontally in a combustion furnace and at mod- 
 erate heat, lead a current of dry chlorine over it. 
 
 * II. N. WARREN, Chem. News, 57, 54. 
 f H. HAGER, Pharm. Centralb. 29, 115. /' ^ 
 
 ITY '' 
 
114 LABORATORY MANUAL OF 
 
 The distilling silicon chloride is condensed in a receiver 
 which is surrounded by a freezing mixture of ice and com- 
 mon salt, while the surplus chlorine is absorbed in soda 
 lye. The greenish product is shaken with a little mercury, 
 and then distilled from the water- bath with a thermome- 
 ter and condenser attached. 
 
 Si -f 4C1 = SiCl 4 . The free chlorine dissolved in the 
 silicon chloride is removed by shaking with mercury. 
 
 The silicon chloride should boil at 58 to 60 C. and 
 appear as a colorless, mobile liquid fuming strongly when 
 exposed to the air, it is decomposed by water with separa- 
 tion of hydrated silicic acid : 
 
 SiCU + 4H 3 = Si(OH) 4 + 4HC1. 
 
 CHLORIDES OF SILICON, ALUMINIUM, ETC. 
 
 Iron alloys of silicon or aluminium are heated to red- 
 ness in a clay crucible, and a current of chlorine gas is 
 passed into the mass, suitable means being adopted to col- 
 lect the volatile products. With chlorine and silicon-iron, 
 the ferric chloride is condensed first, then the silicon 
 chloride ; if hydrogen chloride is used instead of chlorine, 
 the ferrous chloride formed remains in the crucible and 
 silicon chloroform distills off. The aluminium chloride ob- 
 tained from aluminium iron is purified by mixing with iron 
 borings and distilling, or if the aluminium iron alloy is 
 mixed with common salt previous to submitting it to the 
 action of chlorine, a sublimate of aluminium sodium 
 chloride is obtained. 
 
 *By H. N. WARREN, Chem. News, 60, 158. 
 
INORGANIC PREPARATIONS. 115 
 
 PREPARATION OF SILICON AND ALUMINIUM 
 CHLORIDE. 
 
 Silicon chloride, mixed with but little ferric chloride 
 and readily purified by redistillation, is obtained by pass- 
 ing chlorine 'into siliconeisen, containing 15 per cent, of 
 silicon, heated to redness in a tubulated clay retort, and 
 retaining the less volatile ferric chloride in the upper 
 part of a suitable adapter, while the lower part is cooled 
 in a freezing mixture to condense the silicon chloride. By 
 using hydrochloric acid gas instead of chlorine, ferrous 
 chloride, and the more volatile silicon-chloroform, SiHCl 3 , 
 are obtained. 
 
 By the action of chlorine on an alloy of iron with 10 
 per cent, of aluminium, aluminium chloride is produced, 
 which can be purified by distillations from iron borings. 
 When the pulverized alloy is previously mixed with sodium 
 chloride, the passage of chlorine gives rise to the sublima- 
 tion of aluminium sodium chloride. 
 
 ALUMINIUM HYDRATE. 
 
 Al3(OH)e,//w Cryolite. 
 
 50 grams cryolite are finely powdered, then thoroughly 
 mixed with 50 grams calcined marble and ignited for half an 
 hour in a platinum crucible placed in Roessler's furnace. 
 The powdered melt is boilecl with water, possible traces of 
 calcium removed from the filtered solution by a few drops 
 of soda solution and then precipitated hot with carbonic 
 
 * H. N. WARREN, Chem. News, 66, 113-114. 
 
Il6 LABORATORY MANUAL OF 
 
 acid. The separated aluminium hydrate is washed by de- 
 cantation with a good deal of hot water, collected, dried 
 on the water bath, and if desired, transformed into an- 
 hydrous aluminium sesquioxide by ignition. The filtrate 
 when evaporated, leaves pure sodium carbonate. 
 
 The aluminum sodium fluoride is decomposed by 
 caustic lime, forming sodium aluminate soluble in water: 
 
 Na d Al 3 Fi2 + 6CaO = Na 6 Al 3 O 6 + 6CaF 3 . 
 The sodium aluminate is decomposed by carbonic acid : 
 2Na 6 Al 2 O 6 + 6H 3 CO 3 = 2A1 3 (OH) 6 + 6Na 3 CO 3 . 
 
 REDUCTION OF ALUMINIUM OXIDE. 
 
 A1 2 O 3 . 
 
 Two parts of pure, finely powdered aluminium oxide 
 is made into a paste with one part of petroleum or some 
 other hydro-carbon, and then mixed with one part of sul- 
 phuric acid. When the mass is homogeneous with a pale 
 yellow tint, and begins to give off sulphurous anhydride, it 
 is wrapped in paper and thrown into a crucible heated to 
 above 800 C. in order to decompose the hydrocarbon. The 
 compact product thus obtained is powdered and mixed 
 with its own weight of a finely divided metal, the mix- 
 ture being then heated to a white heat in a plumbago 
 crucible. The regulus after being allowed to cool is found 
 to contain grains of an aluminium alloy in the midst of a 
 metallic powder. This method of reduction is applicable 
 to silica, calcium oxide, magnesium oxide, etc.* 
 
 G. A. FAURIE, Compt. Rend. 105, 494. 
 
INORGANIC PREPARATIONS. 
 
 ANHYDROUS ALUMINIUM CHLORIDE. 
 
 AloCl 6 . 
 
 Dry hydrogen chloride extracts the whole of the alum- 
 inium from an alloy of copper and aluminium without at- 
 tacking the copper. The reaction is most energetic a 
 little below a red heat. The alloys containing 15 to 40 
 per cent, of aluminium are best powdered, mixed with 
 powdered charcoal (to prevent the fusion of the remaining 
 copper), put into a graphite retort, and when heated just 
 below a red heat a current of hydrogen chloride is passed 
 through. The aluminium chloride distills over, and may 
 be condensed in suitable vessels, the liberated hydrogen 
 passing on. 
 
 FORMATION OF ULTRAMARINE IN THE 
 WET WAY. 
 
 The material used is washed kaolin, with the fol- 
 lowing percentage composition: Silica, 46.83; alumina, 
 40.25; water, 12.60; potash, 0.37; lime, trace; total, 
 100.05 ; and was expressed by the formula: 
 
 2SiO 3 : 1.997 A1 3 O 3 :: 1.79 H 2 O. 
 
 The ultramarine mixture is made in the proportion 
 Washed kaolin, IOO parts ; anhydrous sodium carbonate, 
 IOO parts; sulphur, 60 parts. The mixture is heated in 
 small porcelain crucibles, holding 15 to 20 grams of the 
 mixture; this is pressed in, and the top covered to a 
 
 * By C. F. MABERY, Ber. 22, 2658. 
 
Il8 LABORATORY MANUAL OF 
 
 depth of 5 to 6 mm. with powdered charcoal, and the cruci- 
 ble then heated with the lid on. The mixture, after heat- 
 ing and separation from the charcoal, gives on digestion 
 with solution of liver of sulphur, the deep blue of ultra- 
 marine. Kaolin, digested alone with liver of sulphur solu- 
 tion, is unchanged.* 
 
 HYDROGEN BROMIDE. 
 HBr. 
 
 100 grams benzole and a few grams of anhydrous fer- 
 rous bromide are placed in a dry two-necked bottle and 
 135 c. c. bromine allowed to drop in from a dropping fun- 
 nel with long fine stem. The Woulff bottle is placed in 
 cold water during the first half of the operation, in order 
 to control the vigorous heating and volatilization of the 
 benzole which takes place. The gas is passed through a 
 small tube charged with anhydrous ferrou. bromidef then 
 through one charged with anthracene and now forms pure 
 hydrogen bromide. For the production of cone, aqueous 
 hydrobromic acid, the gas is led into a small bottle, by de- 
 grees small quantities of water are added with a wash-bot- 
 tle and cooled with a freezing mixture of ice and common 
 salt. The saturated solution is preserved in a well stoppered 
 bottle with cap and kept in a dark place. 
 
 C 6 H 6 +4Br = C 6 H 4 Br 2 + 2HBr. 
 The small quantity of ferrous bromide (FeBr 3 ) acts as 
 
 * By F. KNAPP, J. pr. Chem. [2] 32, 375-39O- 
 
 f Produced by mixing 25 grams ferrous FeBr, bromide with 3 c. c. bro- 
 mine in the cold. 
 
INORGANIC PREPARATIONS. IIQ 
 
 the transferrer of bromine. The hydrogen bromide, devel- 
 oped in a very regular stream, carries off benzole-vapors 
 which bromate in the ferrous bromide tube and are held 
 back. The gas is freed by the anthracene from the slight 
 traces of free bromine. 
 
 The aqueous solution should be entirely colorless, fume 
 strongly when exposed to the air, and have a sp. gr. of at 
 least 1.78 (at o C. saturated acid). 
 
 Another method : A mixture of I part of red phos- 
 phorus, 2 parts of water, and sufficient sand to form a 
 paste, is introduced into a flask, 10 parts of bromine then 
 gradually added by means of a funnel provided with 
 a stopcock, the flask gradually warmed, and the mixture 
 of hydrogen bromide and bromine vapor passed through a 
 deep glass jar filled with a mixture of red phosphorus and 
 asbestos, impregnated with concentrated hydrobromic acid. 
 Every trace of bromine vapor is thus effectually retained, 
 and the process is continuous and requires no supervision 
 beyond an occasional shaking of the flask.* 
 
 By means of the following arrangement, a large quan- 
 tity of bromine can be rapidly converted into hydrobromic 
 acid : A glass tube, 7 inches long and ^ inch in diameter, 
 is fitted at each end with a cork carrying a piece of small 
 tubing and a piece of stout wire. The ends of these pieces 
 of stout wire, within the longer tube, are joined by a spiral 
 of platinum wire I inch long, and after expelling the air 
 the spiral is heated to bright redness by an electric current ; 
 a stream of hydrogen, impregnated with bromine by bub- 
 bling through that liquid, which may be heated at 60 C., is 
 passed through the longer tube, and, as long as a slight 
 
 M. FILETI and F. CROSA, Gazetta, 21, 64. 
 
I2O LABORATORY MANUAL OF 
 
 excess of hydrogen is maintained, hydrobomic acid quite 
 free from bromine issues from the other end, and is col- 
 lected in water. There is very little danger from explo- 
 sion, but to render it impossible, the small supply tube may 
 be plugged with a little glass wool* 
 
 A convenient method of preparing hydrogen bromide 
 in quantity is to drop strong sulphuric acid from a tap 
 funnel on solid potassium bromide heated in a stoppered, 
 tubulated retort on the water-bath. The gas given off is 
 contaminated with small quantities of sulphurous anhy- 
 dride and bromine, from which it is freed by two sets of 
 wash- bottles, the first of which contains a strong solution 
 of bromine in hydrobromic acid, the second, amorphous 
 phosphorus suspended in hydrobromic acid. When all 
 the sulphuric acid has been added, and the evolution of 
 gas has slackened, the retort may be heated over a flame. 
 
 Another method is to pass sulphurous anhydride 
 through a solution of bromine (i vol.) in concentrated 
 hydrobromic acid (i vol.). The evolved hydrogen bro- 
 mide is then purified as above. t 
 
 Hydrogen bromide may also be prepared by adding 
 bromine (385 grams) to a mixture of liquid paraffin (500 
 grams) and dry phosphorus in small pieces 50 grams ; 
 water (about 100 grams) is then gradually run in and the 
 evolved gas purified by passage over moist phosphorus.^ 
 
 This method, proposed for the preparation of hydro- 
 bromic acid, is based on the fact that the action of 
 gaseous hydrogen sulphide on liquid bromine with forma- 
 
 *G. S. NEWTH, Chem. News, 64, 215. 
 fE. LEGER, Compt. rend. 115, 946-948. 
 JA. GASSMAN, Chem. Centr. 1893, i., 77 1 - 
 
INORGANIC PREPARATIONS. 121 
 
 tion of gaseous hydrogen bromide and solid sulphur de- 
 velops + 144 cal., without taking into account the heat 
 developed by the combination of the sulphur with the 
 excess of bromine. 
 
 Hydrogen sulphide is bubbled through a layer of 
 bromine contained in a tall, narrow vessel, and covered 
 by a layer of water or hydrobromic acid. The gas passes 
 into a second flask which contains a solution of potassium 
 bromide in hydrobromic acid holding a small quantity of 
 red phosphorus in suspension, and the gas which issues 
 from this flask contains neither bromine vapor nor hydro- 
 gen sulphide. The current of hydrogen bromide is con- 
 trolled by regulating the current of hydrogen sulphide. 
 The latter gas should be made in a " continuous " 
 apparatus.* 
 
 Although concentrated sulphuric acid decomposes po- 
 tassium bromide with liberation of bromine, when a more 
 dilute acid is used there is no evolution of bromine. To 
 obtain pure hydrobromic acid, 150 c. c. of sulphuric acid 
 of 1.41 sp. gr. is poured on to IOO grams of coarsely pow- 
 dered potassium bromide, and the mixture warmed gently 
 and shaken until the salt is dissolved. The liquid is then 
 submitted to distillation ; it begins to boil at about 126 C., 
 and the temperature slowly rises to 150 C., at which point 
 almost the whole of the hydrobromic acid passes over; then 
 the temperature rapidly goes up to 200 C., and traces of 
 sulphuric acid are mechanically carried over. The process is 
 now stopped, as between 200 and 250 C. only small quan- 
 tities of hydrobromic acid, mixed with a little sulphuric 
 acid, pass over. The distillate is redistilled, collecting only 
 
 A. RECOURA, Compt. rend., no, 784. 
 
122 LABORATORY MANUAL OF 
 
 what passes over at 1 26 C. ; this has a specific gravity of 
 1.49, contains 48 per cent, of HBr, is colorless, and con- 
 tains neither sulphuric acid, sulphurous acid, nor bromine. 
 150 grams of bromide yield about 200 grams of acid. If 
 the bromide contains bromate, the receiver is changed when 
 the distillate become colorless ; the acid thus obtained con- 
 taining bromine is treated with a little sodium sulphite, and 
 rectified with the rest. Gaseous hydrobromic acid may be 
 obtained by distilling the solution containing 48 per cent, 
 from anhydrous calcium bromide.* 
 
 HYDROGEN IODIDE. 
 HI. 
 
 In preparing hydrogen iodide from iodine and amorphous 
 phosphorus the iodine is placed in a flask provided with a 
 bent neck and connected with the vessel containing the phos- 
 phorus and water by means of a bent tube. By turning 
 the flask round the bent tube, fresh quantities of iodine 
 can be added when requisite without admitting air into 
 the apparatus. t 
 
 Another method of preparation is to moisten 100 parts 
 of iodine contained in a retort with about 10 parts of water. 
 The retort is then fitted with a funnel closed with a glass 
 rod, containing 5 parts of amorphous phosphorus mixed 
 with 10 parts of water. One drop of water containing phos- 
 phorus is let into the retort ; more phosphorus is slowly 
 
 *By W. FEIT and K. KUBIERSCHKY, J. Pharm. [5], 24, 159; from 
 Pharm. Zeit. Russ., 30, 298. 
 
 f A. ETARD, Bull. Soc. Chim. 49, 742. 
 
INORGANIC PREPARATIONS. 123 
 
 added, after which large amounts may be used. The mix- 
 ing is complete in 15 minutes. If more than a drop is 
 added at first the action cannot be controlled, and will 
 generally result in a violent explosion. No heating is 
 necessary. The iodine carried over by the hydrogen 
 iodide is nearly all deposited in the neck of the retort, 
 which is inclined upward. By using 100 grams of iodine, 
 5 grams of phosphorus and 25 c. c of water, 95 grams 
 of hydrogen iodide (of which 37.5 grams were obtained by 
 distillation) are obtained, instead of 100.8 grams. With 
 20 grams of water 98. 1 grams are obtained (74.4 grams 
 as gas and 23.7 grams by distillation).* 
 
 IODINE PENTOXIDE. 
 I 2 5 . 
 
 30 grams iodine are placed in a retort and 158 c. c. 
 of water and nitric acid free from nitrogen oxides (page 18) 
 poured over it. On shaking a reaction takes place which 
 is hastened by moderate heating. The red vapors are 
 driven out by a strong current of air, which is blown into 
 the tubulature of the retort through a glass tube. In spite 
 of this a part of the iodine is invariably reduced by these 
 nitrogen oxides ; it volatillizes and is condensed with the 
 distilling acid in a receiver, which is kept cool. At inter- 
 vals the heating is stopped and the distillate, after having 
 air blown into it, is put back. The white residue is dis- 
 solved in a little water and evaporated to dryness in a 
 porcelain dish, iodic acid anhydride remaining in white 
 crystals. 
 
 * H. I. L. MEYER, Ber. 20, 3381. 
 
124 LABORATORY MANUAL OF 
 
 IODINE TRICHLORIDE. 
 IC1 3 . 
 
 20 grams iodine are gently heated in a small retort, the 
 bent neck of which terminates in a weighed balloon filled 
 with chlorine and closed, but connected with a Kipp's 
 chlorine apparatus. As soon as the iodine vapors enter 
 the balloon a strong absorption of chlorine takes place, and 
 iodine chloride precipitates against the walls in reddish- 
 yellow crystals. Finally dry carbonic acid is led through 
 to drive out the surplus chlorine. Any particles which 
 cannot be removed from the balloon mechanically are dis- 
 solved in ten times their weight of water, and preserved as 
 iodine chloride solution. 
 
 Iodine trichloride is an orange-colored pungent crys- 
 talline powder, readily soluble in water to a clear yellow 
 liquid. Chloroform should not remove iodine from the 
 aqueous solution until a little stannous chloride has been 
 added. On heating, the iodine trichloride should change 
 without leaving any residue into brown vapors, which con- 
 dense again to an orange- colored sublimate. 
 
 HYDROCYANIC ACID. 
 HCN. 
 
 500 grams coarsely powdered potassium ferricyanide are 
 distilled on the gas stove in a well ventilated place, with a 
 mixture of 350 grams cone, sulphuric acid and 700 c. c. water. 
 With the condenser two WoulfT bottles are connected; these 
 
INORGANIC PREPARATIONS. 125 
 
 stand on ice ; the vapors escaping from the last bottle are 
 led into cold water. The insoluble residue* forming in the 
 retort causes a slight jolting of the contents, but by heat- 
 ing uniformly and carefully no danger need be feared. 
 The distillate is almost pure. If absolutely anhydrous 
 hydrogen cyanide is required, fill the first of the Woulfif 
 bottles before distillation half-way with porous calcium 
 chloride, and at the conclusion set it in warm water, in order 
 to distill its contents into the second bottle. The product 
 should not be preserved in an anhydrous, but in a diluted 
 condition ; the aqueous hydrocyanic acid keeps still better 
 if one drop of diluted mineral acid is added to every 100 
 c. c. 
 
 The anhydrous hydrocyanic acid is a very volatile, 
 colorless liquid, which when brought in contact with the 
 skin produces a cold feeling, like evaporated ether. It 
 boils at 27 C. and crystallizes in a freezing mixture. The 
 aqueous solution does not redden litmus paper, t 
 
 PURIFICATION OF HYDROFLUORIC ACID. 
 
 HF. 
 
 The apparatus employed for distilling commercial hy- 
 drofluoric acid consists of a heavy sheet-lead retort, 6 inches 
 high and 4 inches in diameter, with a rim at the top formed 
 by beating the lead over an iron ring i inch deep and ^ 
 inch thick ; the lid is of j inch iron plate, covered with 
 lighter sheet lead, and is fixed down by a screw working in 
 a socket in an iron bridge, which is secured to projections 
 
 * This residue may be used in the preparation of Berlin Blue, 
 f WOHLER, Annalen, 73, 219. 
 
126 LABORATORY MANUAL OF 
 
 on the opposite sides of the iron ring of the rim. A washer 
 of india-rubber is placed between the cover and the rim. 
 The leaden nose of the retort points upwards, and is con- 
 nected by india-rubber tubing to a Liebig condenser, the 
 inner tube of which is of thin india-rubber. The retort is 
 charged through a funnel with 25 per cent, hydrofluoric 
 acid, which yields a distillate of convenient strength for 
 analytical work. The first portions of the distillate con- 
 tain silicate and are discarded, whilst any sulphur is re- 
 moved by filtration.* 
 
 STANNOUS CHLORIDE. 
 
 SnCte, Crystallized + 2H 2 O. 
 
 Reduce grain tin to powder by means of a file, or by 
 fusing it in a small porcelain dish, removing from the 
 fire, and triturating with a pestle until it has passed again 
 to the solid state. Boil the powder for some time with 
 concentrated hydrochloric acid and a few drops of platinic 
 chloride in a flask (taking care always to have an excess of 
 tin in the vessel) until hydrogen gas is scarcely evolved ; 
 dilute the solution with 4 times the quantity of water 
 slightly acidulated with hydrochloric acid, and filter. Keep 
 the filtrate for use in a well-stoppered bottle containing 
 small pieces of metallic tin, or some pure tin-foil. If these 
 precautions are neglected the stannous chloride will soon 
 change to stannic chloride, with separation of white oxy- 
 chloride, which will render the reagent unfit for use. 
 
 * By R. HAMILTON, Chem. News, 60. 252. 
 
INORGANIC PREPARATIONS. I2/ 
 
 A solution of stannous chloride must, when added to 
 excess of solution of mercuric chloride, immediately pro- 
 duce a white precipitate of mercurous chloride ; when treated 
 with hydrogen sulphide it must give a dark brown pre- 
 cipitate ; it must not be precipitated nor rendered turbid 
 by sulphuric acid. 
 
 ANHYDROUS STANNOUS CHLORIDE. 
 
 SnCl 2 . 
 
 Commercial stannous chloride is heated slowly on the 
 gas stove ; the salt melts in its water of crystallization, then 
 becomes pasty, and gradually entirely solid. The dehy- 
 drated salt is fused once more, and in cooling it is 
 placed in a mounted retort of hard Bohemian glass, the 
 upper part of which is covered with a cap of wire gauze or 
 asbestos, to avoid too strong radiation, and distilled as 
 quickly as possible into a porcelain dish, which is kept 
 covered with a second dish. As the stannous chlo- 
 ride boils at about 327 C. the heat must be very 
 strong ; a small blow-pipe furnace will serve as the best 
 source of heat. The neck of the retort is heated with a 
 Bunsen burner, so it will not choke up with the solidifying 
 distillate. 
 
 Anhydrous stannous chloride is a white, crystalline 
 mass, melting at 250 C., dissolving readily in water, alcohol, 
 ether and soda lye. 
 
 ANHYDROUS STANNIC CHLORIDE. 
 
 SnCl 4 . 
 
 150 grams pure tin (granulated or in bars) are heated 
 to fusion on the gas stove in a mounted, tubulated retort, 
 
128 LABORATORY MANUAL OF 
 
 and a strong stream of dry chlorine led into it through a 
 glass tube opening near the surface of the fused metal. 
 The retort connects with a very long condenser and two 
 Woulff bottles as receivers. The receivers are placed in 
 ice-water, to hasten the condensation of the very volatile 
 chloride. The chloride collected is distilled from a frac- 
 tional distilling flask containg a little tinfoil. 
 
 Sn + 4C1 = SnCl 4 . The free chlorine combines with 
 the metallic tin during the rectification. 
 
 Anhydrous stannic chloride is a colorless solution, 
 boiling at 114 C, fuming strongly when exposed to air, 
 of 2.278 sp. gr. at o C., with a small amount of water, it 
 furnishes crystalline compounds, but dissolves completely 
 in a larger quantity of water. 
 
 PHOSPHORUS 
 
 FROM 
 
 PHOSPHATES OF THE ALKALIES AND ALKA- 
 LINE EARTHS BY MEANS 
 OF ALUMINIUM. 
 
 When sodium metaphosphate is heated with aluminium 
 in a current of hydrogen, 28 to 31 per cent, of the phos- 
 phorus distills over, and a residue is obtained consisting of 
 alumina, sodium aluminate, and aluminium phosphide. All 
 the phosphates of calcium and magnesium, when heated 
 with aluminium, yield phosphorus. 
 
 Aluminium phosphide, A1-P 5 is obtained by heating 
 aluminium in phosphorus vapor, and then heating the 
 product until phosphorus ceases to come off. It is a gray 
 crystalline powder. 
 
INORGANIC PREPARATIONS. 129 
 
 The whole of the phosphorus in the phosphates may 
 be obtained by adding silica to the mixture in the propor- 
 tions represented by the equation : 
 
 3Ca(PO 4 ) 2 + 10A1 + 3SiO 2 = 3CaSiO 3 + 5A1 3 O 3 + 3P 3 . 
 
 When a mixture of calcium metaphosphate and calcium 
 sulphate is heated with aluminium, a violent explosion 
 ensues. It has been found that this is due to the sulphate. 
 Barium sulphate or calcium sulphate, when heated with 
 aluminium, act with explosive violence and sulphur is set 
 free. The chlorides are also decomposed by aluminium at 
 a high temperature.* 
 
 PURE PHOSPHORIC ACID FROM SODIUM 
 PHOSPHITE. 
 
 H 3 P0 4 . 
 
 Crystals of hydrogen sodium phosphate are subjected 
 to the action of gaseous hydrogen chloride. In this man- 
 ner syrupy phosphoric acid in amount corresponding with 
 a yield of 75 per cent, of the theoretical quantity is 
 obtained, t 
 
 Pure phosphoric acid may also be obtained when pow- 
 dered calcium phosphate is added gradually to a slight 
 excess of commercial hydrofluoric acid diluted with an 
 equal volume of water, and contained in a leaden or plati- 
 num vessel. There is considerable development of heat, 
 and the liquid must be thoroughly agitated. When the 
 
 * A. ROSSEL and L. FRANK, Her. 27, 52. 
 |G. WATSON, J. Soc. Chem. Ind. 2, 224. 
 
 9 
 
I3O LABORATORY MANUAL OF 
 
 action moderates, the liquid is gently heated, water being 
 added to make up for loss by evaporation. When the 
 liquid becomes viscous, the excess of hydrogen fluoride 
 begins to escape, and the mixture is then heated until the 
 expulsion of the acid is complete. The syrupy liquid thus 
 obtained contains from 60 to 70 per cent, of phosphoric an- 
 hydride in the form of orthophosphoric acid. With pure 
 materials, the phosphoric acid obtained is very pure ; if 
 bones and ordinary acid have been used the product must 
 be heated to carbonize the organic matter, dissolved in 
 water, filtered, and again evaporated. Pyrophosphoric and 
 metaphosphoric acids can be obtained by evaporating at 
 higher temperatures.* 
 
 Another method is to heat 127 grams white phosphor- 
 us with 1400 c. c. nitric acid (1.20 sp. gr.) in a retort with 
 receiver. The phosphorus me.Us, and then the operation 
 quietly proceeds. At intervals the distillate must be poured 
 back. When the phosphorus has passed entirely into solu- 
 tion (after 10 to 12 hours) it is evaporated in a platinum 
 dish until a sample taken out with a glass rod together with 
 cone, sulphuric acid and ferrous sulphate solution ceases to 
 give a reaction for nitric acid. The temperature must not 
 exceed 188 C. The acid when mixed with mercuric chlor- 
 ide solution must show no trace of phosphorus acid. After 
 this, it is treated warm with sulphureted hydrogen until on 
 standing there is no further precipitate of arsenic sulphide, 
 then diluted with a little water, filtered, and again slowly 
 evaporated, until a thermometer dipped into it shows 
 1 60 C. 
 
 * M. NICOLAS, Compt. rend., in, 974. 
 
INORGANIC PREPARATIONS. 131 
 
 The acid should show a sp. gr. of 1.88, and be free 
 from arsenic and "phosphoric acid. 
 
 PHOSPHORUS TRISULPHIDE. 
 
 310 grams red phosphorus are mixed with 480 grams 
 powdered sulphur and the powder poured by spoonfuls 
 into a hessian crucible which has been heated on a Bunsen 
 burner. After adding each portion, the crucible is closed 
 with a cover whereupon the reaction should take place at 
 once. When the whole mixture has been added, the cruci- 
 ble is allowed to cool sufficiently to leave the mass soft, 
 and then the phosphorus sulphide is poured out on a piece 
 of sheet-iron. The solid product is broken in pieces while 
 warm and placed in a well-stoppered bottle. Phosphorus 
 trisulphide forms in a hard, gray, easily powdered mass, 
 which when exposed to air becomes moist and smeary, de- 
 veloping sulphureted hydrogen. 
 
 CALCIUM PHOSPHIDE. 
 CaP. 
 
 To a strong clay crucible, about 6^ cm. wide and 12 
 cm. high, fit a round cover of sheet-iron 2 mm. thick pro- 
 vided with a round opening in the center of 2.5 mm. 
 diameter and into which is fitted an iron tube 30 cm. long. 
 At the upper end of this iron tube, a thin walled glass 
 
132 LABORATORY MANUAL OF 
 
 tube of 1 5 cm. in length is fastened.* Fig. 9. After having 
 placed the iron tube perpendicularly in the crucible, the 
 latter is filled with 100 grams burnt marble or lime in 
 pieces the size of a hazel nut. Cover the cruci- 
 ble and then heat in Roessler's annealing furnace. 
 When the crucible has become red-hot, 65 grams 
 of dry phosphorus in sticks are dropped into it 
 through the glass tube, in pieces of about 5 to 10 
 grams. Immediately upon dropping each piece 
 of phosphorus the glass tube is closed with a 
 cork provided with a handle. The influence of 
 phosphorus on the lime is manifested each time 
 by the escape of a little phosphorus pentoxide 
 in form of a white cloud of smoke from the 
 chimney of the furnace. If this reaction fails 
 to take place, the iron tube is raised a little, 
 allowing the phosphorus to enter into the cruci- 
 ble. While at first only minimum quantities 
 escape reaction, the conclusion of the operation 
 is shown by the appearance of thick smoke. 
 The flame is then extinguished, the crucible taken out, and 
 the product immediately upon having cooled (still slightly 
 warm) is filled into a well-closed specimen cylinder. 
 
 7CaO + 7P = Ca 2 P 2 O 7 + 5CaP. Calcium phosphide 
 forms in dark, hard, rainbow-colored pieces, which when 
 thrown into warm water develop phosphureted hydrogen : 
 2CaP + 4H 2 O = 2Ca (OH) 2 -f- PgH*. \ 
 
 * For this purpose wind a little thin asbestos cord around the glass tube, 
 then twist it into the iron tube, after having moistened the asbestos with 
 water glass. The joints are covered with a pasty mixture of powdered 
 oxide manganese and water glass, then dried at moderate heat. The glass 
 tube must be sufficiently wide to conveniently allow the passage of the 
 phosphorus sticks. 
 
 f GATTERMANN and HAUSSKNECHT, Ber. 23, 1175. 
 
INORGANIC PREPARATIONS. 133 
 
 PHOSPHORUS OXY FLUORIDE. 
 
 Zinc carbonate is dissolved in excess of hydrofluoric 
 acid, the solution evaporated, and the zinc fluoride dried 
 at 300 and placed in a brass tube, to which a bromine 
 burette, containing slight excess of the calculated quantity 
 of phosphorus oxychloride, and a leaden delivery tube are 
 adapted by a paraffined cork. The leaden tube is connected 
 to another brass tube cooled by a freezing mixture to 20 C., 
 and this leads to another tube containing zinc fluoride, 
 which removes any traces of oxychloride escaping from 
 the oxyfluoride. The phosphorus oxychloride is dropped 
 slowly on to the zinc fluoride, the ensuing reaction being 
 assisted by warming carefully at 40 to 50 C., and the 
 evolved gas is collected over mercury in glass vessels.* 
 
 HYDROGEN PHOSPHIDE. 
 
 PH 3 . 
 
 Tin and zinc phosphides are prepared by adding the 
 equivalent quantity of amorphous phosphorus to the re- 
 spective metals in the molten state covered with ammo- 
 nium carbonate. Iron phosphide, FeP, by heating finely 
 divided iron and amorphous phosphorus together, copper 
 phosphide, by heating copper filings with amorphous phos- 
 phorus ; magnesium phosphide, by adding the equivalent 
 quantity of amorphous phosphorus to melted magnesium ; 
 sodium phosphide by carefully adding yellow phosphorus 
 
 * By H. MOISSAN, Bull. Soc. Chim. [3], 4, 260. 
 
134 LABORATORY MANUAL OF 
 
 to fused sodium under petroleum. The phosphides of tin, 
 zinc, iron, and copper are not decomposed by water ; 
 whilst those of sodium and magnesium, like that of calcium 
 are decomposed by water. From magnesium phosphide, 
 whether decomposed by water or by dilute hydrochloric 
 acid, non-spontaneously inflammable hydrogen phosphide 
 is obtained. From sodium phosphide, spontaneously in- 
 flammable hydrogen phosphide is obtained, which, in a 
 great measure, readily changes to solid phosphide. The 
 phosphides of tin and zinc are decomposed by cold dilute 
 hydrochloric or sulphuric acid, but those of iron and cop- 
 per are but slightly attacked even on boiling. 
 
 For the preparation of hydrogen phosphide from the 
 phosphides of tin, zinc or magnesium, an Erlenmeyer flask 
 of 2OO to 300 c. c. capacity is fitted with a stopper carrying 
 three tubes, one of which conducts carbonic anhydride gas to 
 the bottom of the flask to displace the air, the second ad- 
 mits the dilute acid from a tap-funnel, the third is the 
 delivery tube. To the latter is attached a tube, filled with 
 glass wool, from which the gas passes out into nitric acid 
 in a dish. In the case of tin phosphide the flask is warmed 
 gently on the water-bath at the commencement, after which 
 the reaction proceeds regularly for thirty minutes to one 
 hour, .when as the reaction becomes slower, the flask may 
 again be warmed. In the case of zinc or magnesium phos- 
 phides, no external heating is requisite. The method is 
 preferable to the preparation with potassium hydroxide and 
 phosphorus or to that with calcium phosphide, and demon- 
 strates the formation of the phosphide of hydrogen in 
 analogous manner to the other compounds of hydrogen 
 with the non-metals, ammonia excepted. The preparation 
 
INORGANIC PREPARATIONS. 135 
 
 of zinc phosphide is also especially recommended as being 
 simple. The synthesis of hydrogen phosphide may be 
 shown by putting sodium phosphite or hypophosphite into 
 a hydrogen generator, when the phosphide is readily de- 
 tected in the gas evolved.* 
 
 ARSENIC ACID. 
 H 3 AsO 4 . 
 
 The arsenic acid liquid produced in preparing nitrogen 
 tetraoxide (page 2 I ) is poured off from the unchanged pieces 
 of white arsenic, evaporated to dryness in a porcelain dish, 
 and the residue again dissolved by heating with a little 
 water. The solution must be free from arsenious acid, or 
 else must be again evaporated, adding a little H 2 SO 4 , and 
 dissolved once more. If the solution is pure it is boiled 
 down to a syrup, and left to crystallize at a low tempera- 
 ture in a closed vessel, adding, if necessary, a small crystal 
 of arsenic acid. When the concentration is perfect, very 
 nice, large, compact glossy crystals will be obtained; if the 
 crystallization has occurred too quickly, the mass is dis- 
 solved, the crystals are melted at a moderate heat, and 
 then allowed to slowly crystallize, so that larger crystals 
 may be obtained. 
 
 Arsenic acid should dissolve readily in water, and 
 with ferrous sulphate give no nitric acid reaction. The 
 well-diluted solution mixed with a drop of HC1 should 
 at first remain clear ; when mixed with an equal volume 
 
 *By R. LUEPKE, Chem. Centr., 1890, i i, 642 ; from Zeit. f. physikal. 
 und chem. Unterricht, 3, 280. 
 
136 LABORATORY MANUAL OF 
 
 of sulphureted hydrogen water should only become tur- 
 bid upon standing some time. A solution of the acid 
 in fuming HC1 should immediately give a thick yellow 
 precipitate with hydrogen sulphide. 
 
 2HNO 3 + As 3 O 3 4- 2H 3 O = N 3 O 3 + 2H 3 AsO 4 . Arsenic 
 acid is not precipitated from aqueous solution by hydrogen 
 sulphide, but from cone, hydrochloric acid solution ; it is 
 at once precipitated, when a mixture of arsenic pentasul- 
 phide, sulphur and arsenic trisulphide is thrown down. In 
 such a solution arsenic pentachloride, which is unknown in 
 a pure condition, seems to be present, and this is decom- 
 posed by hydrogen sulphide according to the equations : 
 
 2AsCl 5 4- 5H 3 S = As 3 S 5 + 10HC1; 
 
 AsCl 5 4- H 3 S = AsCl 3 + S + 2HC1; 
 
 2AsCl 3 + 3H 9 S = As 3 So + 6HC1. 
 
 HYDROGEN ARSENIDE. 
 
 H As. 
 
 The action of zinc on an acid solution of arsenious acid 
 produces a gas containing 70 per cent, by volume of hy- 
 drogen arsenide. Sodium amalgam containing not more 
 than 4 grams of sodium in 50 c. c. of mercury, by its action 
 on a concentrated solution of arsenious acid, produces a 
 gas containing 86 per cent, by volume of hydrogen arsenide. 
 A gas containing a large quantity of arsenic may be pre- 
 pared by the action of aluminium on a somewhat dilute 
 alkaline solution of potassium arsenite, while a solution of 
 arsenic disulphide in potash, when subjected to the action 
 of aluminium, evolves a gas quite free from arsenic.* 
 
 * A. KAVAZZI, Rend. Ace. Bologna, 1886-7, 85. 
 
INORGANIC PREPARATIONS. 137 
 
 ARSENIC PENTASULPHIDE. 
 
 As 2 S 5 . 
 
 When a solution of an alkaline arsenate, strongly acidi- 
 fied with hydrochloric acid and saturated with hydrogen 
 sulphide is heated in a closed vessel at 100 C. for one 
 hour the arsenate is completely converted into pentasul- 
 phide. It contains no trisulphide, and if due precau- 
 tions have been "taken to exclude air, no free sulphur. 
 Pure arsenic pentasulphide is lemon yellow in color, 
 does not yield any sulphur to carbon disulphide, and 
 dissolves in ammonia without separation of sulphur. 
 When the ammoniacal solution is agitated with silver nitrate 
 and filtered a clear filtrate is obtained, from which nitric 
 acid precipitates silver arsenate. Arsenical pyrates may 
 oe used instead of alkaline arsenate, in which case the 
 finely pulverized ore is digested for some time in aqua 
 regia until decomposed ; the chlorine is boiled out and hy- 
 drogen sulphide passed through the cold solution as long 
 as a precipitate forms ; this serves to remove heavy 
 metals, as sulphides ; filter and wash with hydrogen sul- 
 phide water, saturate with hydrogen sulphide, and pro- 
 ceed as before.* 
 
 ANTIMONY TRICHLORIDE. 
 
 SbCl 3 . 
 
 IOO grams powdered stibnite arc heated with 500 c. c. 
 crude HC1 in a flask, gradually adding about 4 grams po- 
 tassium chloride. When the ore has disappeared filter off 
 
 * L. W. McKAY, Chem. News, 54, 287. 
 
138 LABORATORY MANUAL OF 
 
 from the sulphur through glasswool, and distill out of the 
 retort ; at first aqueous hydrochloric acid comes over, then 
 a concentrated antimony chloride solution, which is fre- 
 quently of a yellow color from iron chloride, finally nice 
 white, pure antimony chloride, cooling in crystals, will pass 
 over. Each of these products are caught up separately. 
 The pure antimony chloride is refined in a test tube or 
 small flask, the antimony chloride solution decomposed by 
 a large quantity of water, whereby antimony oxychloride 
 is precipitated as a fine white powder (Algaroth). 
 
 The change Sb 2 S 3 + 6HC1 == 2SbCl 3 4 3H 2 S which at 
 first goes on energetically, but gradually becomes very 
 slow, and may be hastened to a conclusion by adding the 
 means of oxydation. 
 
 The antimony chloride should melt at 73 C., boil at 
 223 C., and crystallize from carbon disulphide in rhombic, 
 glossy crystals. 
 
 ANTIMONY OXYCHLORIDE. 
 
 Sb 4 O 5 Cl 2 . 
 
 60 grams powdered antimony sulphide are thoroughly 
 mixed in a mortar with 140 grams mercuric chloride, and 
 slowly distilled from a gas retort over the gas stove at 
 gentle heat. A flask is used as receiver, the neck of which 
 has been broken off; the neck of the retort is heated at in- 
 tervals with a Bunsen burner, to melt the antimony chlo- 
 ride that solidifies in it. The distillate is dissolved in a 
 little warm HC1, and then poured into a large quantity of 
 
INORGANIC PREPARATIONS. 139 
 
 hot water ; the precipitate is washed by decantation and 
 
 then dried. 
 
 Sb 2 S 3 4- 3HgCl 2 = 2SbCl 3 + 3HgS, 
 4SbCl 8 + 5H 3 O = Sb 4 O 5 Ci 3 + 10HC1. 
 
 The white crystalline powder should be insoluble in 
 water, alcohol and ether, but soluble in carbon disulphide 
 and chloroform. On heating it should give a sublimate 
 of antimonious chloride, leaving behind antimony mon- 
 oxide.* 
 
 ANTIMONIOUS SULPHATE. 
 
 Sb 2 (S0 4 ) 3 . 
 
 20 grams finely powdered antimony are added to 400 
 grams of boiling, distilled H 3 SO 4 and boiled in a platinum 
 dish until the metal has disappeared. A part of the sul- 
 phate crystallizes out of the hot solution, the rest upon the 
 cooling of the liquid, in the form of small white needles. It 
 is filtered through a platinum cone and dried on an earthen 
 plate. 
 
 BISMUTH NITRATE. 
 Bi(N0 3 ) 3 + 5H 3 0. 
 
 BASIC BISMUTH NITRATE. 
 BiONO 3 + BiOOH. 
 
 BISMUTH HYDROXIDE. 
 B O OH. 
 
 100 grams commercial bismuth and 50 grams sodium 
 nitrate are heated in a nickel dish at faint red-heat. After 
 
 * G. E. STAHL, Zufallige Gedanken und nutzliche Bedanken liber den 
 Streit von den sogennaten sulfure Halle, 1715, S. 346. 
 
140 LABORATORY MANUAL OF 
 
 the metal is completely oxydized boil thoroughly with 250 
 c. c. water, adding a solution of 20 grams sodium hydrate 
 in 1500. c. water. The bismuth oxide filtered on the 
 bare platinum cone is dissolved hot in a flask containing 
 a mixture of 140 c. c. cone. HNO 3 with 200 c. c. water, fil- 
 tered through an asbestos filter and evaporated to crystal- 
 lization. The mother liquid is evaporated further, and 
 poured into ^ litre boiling water, whereupon the basic bis- 
 muth nitrate separates in the form of a heavy white powder, 
 which, after decanting, is collected on the filter and dried 
 in the cold ; or else the acid solutions are precipitated 
 with ammonia, the bismuth oxyhydrate decanted and pre- 
 served as a paste. 
 
 The impurities of commercial bismuth consist chiefly 
 of arsenic and antimony, the oxides of which go into 
 solution upon boiling with soda. 
 
 The bismuth value of the crystallized nitrate should 
 be ascertained from a weighed sample by converting it 
 into bismuth oxide in a covered porcelain crucible, heat- 
 ing at first carefully, then energetically. Further, a sample 
 is dissolved in very dilute nitric acid, the solution poured 
 into an excess of hot soda, and the filtrate tested for arsenic 
 and antimony. 
 
 BISMUTH IODIDE. 
 BiI 3 . 
 
 20 grams iodine are mixed with 35 grams finely pow- 
 dered bismuth in a mortar, quickly poured into a retort, 
 and slowly heated on the gas stove. When the reaction 
 is finished the small quantity of surplus iodine is driven out 
 
INORGANIC PREPARATIONS. 14! 
 
 by a current of dry carbonic acid gas, and the temperature 
 raised until the bismuth iodide sublimes in form of very 
 large crystals, similar in appearance to iodine. 
 
 Boiling water should convert the powdered bismuth 
 iodide into red oxyiodide. 
 
 .S^$&& UBRxi/?p\ 
 
 tTHIVEHSITY; 
 c* 
 
 BISMUTH OXYI O^^Ertt^ 
 BiOI. 
 
 95.4 grams powdered crystallized bismuth nitrate 
 (page 139) are dissolved in 120 to 160 c. c. glacial acetic 
 acid by warming gently. At the same time 33.2 grams 
 potassium iodide and 50 grams crystallized sodium acetate 
 are dissolved in 2 litres cold water. The second solution 
 is placed in a dish and the first added to it in a very thin 
 stream from a dropping funnel, with frequent stirring. At 
 the point where the liquid strikes a greenish-black pre- 
 cipitate forms at first ; upon stirring this immediately 
 changes to a lemon color. On further addition of the 
 bismuth solution the product assumes a dark, brick-red 
 color. The precipitate settles very readily. It is decanted, 
 filtered and dried at IOO C. 
 
 Bi(NO 3 ) 3 + SKI = BiI 3 + 3KNO 3 ; 
 Bi I 3 + H 2 O = BiOI f 2HI. 
 
 The hydriodic acid reacts with the sodium acetate, 
 and the potassium iodide formed again takes part in the 
 reaction. 
 
 Heated in a dry test-tube the compound should yield 
 violet iodine-vapors, and leave behind bismuth oxide ; on 
 shaking with water no halogen acid should be set free, 
 
142 LABORATORY MANUAL OF 
 
 and it should be free from arsenic and bismuth subnitrate : 
 O.2 gram shaken with 2 grams dilute sulphuric acid 
 should give a filtrate which, when mixed with twice its 
 volume of cone. H 2 SO 4 , should be permanently colored blue 
 by a drop of indigo solution (discoloration nitric acid).* 
 
 BISMUTHIC ACID. 
 HBiO 3 . 
 
 20 grams of bismuth bromide and 40 grams of potas- 
 sium bromide are dissolved in 60 grams of water and 
 mixed with excess of bromine. The solution is then 
 poured drop by drop into an almost boiling solution of 100 
 grams of potassium hydroxide in 150 grams of water, the 
 alkali remaining in excess at the end of the reaction. A 
 very dense red-brown precipitate forms immediately. This 
 is washed repeatedly with boiling water by decantation, 
 and, after a long time, part of the product forms a brown 
 emulsion with the water, whilst a red-brown compound 
 remains at the bottom of the vessel. The emulsion is de- 
 canted off, and can be precipitated by addition of a few 
 drops of nitric acid. The non-emulsified product is 
 washed with hot water until no longer alkaline, and one 
 portion is washed for several days longer. Both portions, 
 when dried at 100 C., have the composition 4KBiO3, 
 3HBiO 3 . The same product is obtained from bismuth 
 chloride ; k dissolves easily in hydrochloric acid, with 
 evolution of chlorine, but is soluble only with difficulty in 
 warm nitric acid. When heated it becomes pale-yellow, 
 
 * B. FISCHER, Die neueren Arzeneimittel, III. AufL, s. 20. 
 
INORGANIC PREPARATIONS. 143 
 
 loses oxygen, then becomes brown, melts, and on cooling 
 is pale-yellow. 
 
 Prolonged washing with boiling water yields a product 
 which, after being dried at 100 C, has the composition 
 KBiO 3 ,HBiO 3 . 
 
 All these products when treated with warm, dilute 
 nitric acid lose the whole of their potassium, and yield 
 brick -red bismuthic acid, HBiO 3 . Very often the residue 
 dried at 100 C. has the composition 
 
 ANTIMONY AND BISMUTH SULPHATES. 
 
 Anhydrous antimony sulphate, Sb 2 (SO 4 ) 3 , is best pre- 
 pared by dissolving the trisulphide in concentrated sul- 
 phuric acid heated to the temperature at which it com- 
 mences to vaporize ; the salt is deposited as a fine, very 
 deliquescent, white crystallized powder. Its products of 
 decomposition with water vary with the conditions, such 
 as mass and temperature; with boiling water the salt is 
 completely decomposed into antimonious oxide (contain- 
 ing less than I per cent, of water) and sulphuric acid, whilst 
 with water at ordinary temperatures a basic sulphate, 
 5SB 3 O 3 2SO 3 7H 3 O, is produced. The sulphate is almost 
 completely converted into antimonious chloride by a cur- 
 rent of hydrogen chloride. Anhydrous bismuth sul- 
 phate, Bi 2 (SO 4 ) 3 , prepared in a manner similar to the 
 antimony salt, crystallizes in very hygroscopic, glis- 
 tening needles ; when evaporated with water it yields a 
 
 * G. ANDRE, Compt. Rend., 113, 860-862. 
 
144 LABORATORY MANUAL OF 
 
 slightly coherent powder of the composition 
 3H 2 O, but on heating it with water at the ordinary tem- 
 perature, and evaporating the solution, a powder of the 
 composition 2Bi 2 (SO 4 ) 3 + 7H 2 O is obtained ; lastly, if the 
 salt be frequently treated with water, the final product is 
 a hydrate, Bi 2 ,O3,SO3,H 2 O. It is probable that under 
 favorable conditions the sulphate is converted by hydro- 
 chloric acid into bismuth trichloride.* 
 
 COBALT NITRATE. 
 
 Co(NO 3 ) 2 , Crystallized + 5H 2 O. 
 
 Fuse in a Hessian crucible 3 parts of potassium disul- 
 phate, and add to the fused mass, in small portions at a 
 time, I part of well-roasted cobalt ore (the purest zaffre 
 you can procure) reduced to fine powder. The mass 
 thickens and acquires a pasty consistency. Heat now 
 more strongly until it has become more fluid again, and 
 continue to apply heat until the excess of sulphuric acid is 
 completely expelled, and the mass accordingly no longer 
 emits white furties. Remove the fused mass from the 
 crucible with an iron spoon or spatula ; let it cool and 
 reduce it to powder; boil this with water until the undis- 
 solved portion presents a soft mass ; then filter the rose- 
 red solution, which is free from arsenic and nickel and 
 mostly also from iron. Add to the filtrate a small quantity 
 of sodium carbonate, so as to throw down a little cobalt 
 carbonate ; boil and filter. Precipitate the solution, which 
 is now free from iron, boiling with sodium carbonate; wash 
 the precipitate well, and treat it still moist with oxalic 
 
 * C. HENSGEN, Rec. Trav. Chim., 4, 401-413. 
 
INORGANIC PREPARATIONS. 145 
 
 acid in excess. Wash the rose-red cobalt oxalate thor- 
 oughly, dry and heat to redness in a glass tube, in a cur- 
 rent of hydrogen gas. This decomposes the oxalate into 
 carbonic acid gas, which escapes, and metallic cobalt, which 
 is left behind. Wash the metal first with water containing 
 acetic acid, then with pure water; dissolve in dilute nitric 
 acid, treat, if necessary, with hydrogen sulphide, filter the 
 fluid from the copper sulphide, etc., which may precipitate, 
 evaporate the solution in the water-bath to dryness. 
 
 Solution of cobalt nitrate must be free from other 
 metals, and especially from salts of the alkali metals ; 
 when precipitated with ammonium sulphide and filtered, 
 the filtrate must, upon evaporation on platinum, leave no 
 fixed residue. 
 
 HYDROGEN PEROXIDE. 
 
 H 3 O 3 . 
 
 One-half litre commercial hydrogen peroxide is cooled 
 in a flask to o C. and mixed with a cold, saturated barium 
 hydrate solution until a permanent precipitate forms, and the 
 solution has become alkaline. The filtered solution, cooled 
 and shaken, is allowed to flow into 2 litres of ice-cold 
 barium hydrate solution. When the crystalline precipitate 
 no longer forms, the peroxide is filtered and rinsed with a 
 little ice- water. Now 20 c. c. cone. H 3 SO4are mixed with 200 
 c. c, water, the solution carefully cooled in a freezing mix- 
 ture of ice and common salt, and enough of the still moist 
 barium peroxide added, shaking, until the solution reacts 
 only faintly acid. Then it is allowed to settle ; the ice- 
 cold solution is filtered and neutralized with a few tlrops 
 
146 LABORATORY MANUAL OF 
 
 of dilute barium hydrate, until neither H 2 SO4 nor barium 
 remains in the solution. Then the turbid solution is fil- 
 tered, and a part of the thus obtained pure hydrogen per- 
 oxide solution evaporated on a porcelain plate in vacuum 
 over H 2 SO 4 . 
 
 The reactions: H 2 O 2 + Ba(OH) 3 = Ba(OH) 4 and 
 Ba(OH) 4 + H 3 SO 4 = BaSO 4 + H 2 O 2 will only take place in 
 the cold and in not too high concentration. If these con- 
 ditions are not fulfilled, oxygen developes richly, and the 
 gain will prove a minimum. 
 
 The anhydrous peroxide should be a syrupy, bitter- 
 tasting solution of 1.46 sp. gr., which on warming decom- 
 poses readily. The watery solution should also have the 
 peculiar characteristic taste ; and yield, when mixed with 
 dil. sulphuric acid, ether and a drop of dilute potassium 
 dichromate solution, an intense blue, ether-soluble color ; 
 be free from HC1,H 2 SO 4 and barium. One per cent, of 
 alcohol is added for preservation. 
 
 The value is determined by decomposing I c. c. hydro- 
 gen peroxide solution with excess of permanganate of potas- 
 sium and dil. H 2 SO 4 in a nitrometer, or else by titration 
 of 5 c. c. with Y normal permanganate in sulphuric acid 
 solution.* 
 
 Another method for the preparation of pure hydrogen 
 peroxide is to take the solution of hydrogen peroxide 
 which results from the action of hydrochloric acid (sp. gr. 
 i.i) on barium dioxide, and is extracted by shaking with 
 ether; the ethereal solution is agitated with distilled water, to 
 which it yields the dissolved hydrogen peroxide. By repe- 
 titions of this process, a pure, neutral solution correspond- 
 
 * J. THOMSEN, Ber. 7-74. 
 
INORGANIC PREPARATIONS. 147 
 
 ing with O.8 to 0.9 per cent of hydrogen peroxide is obtain- 
 able, from which' the dissolved ether may be eliminated by 
 distillation under reduced pressure.* 
 
 It can also be prepared by adding sodium carbonate 
 to the commercial 3 per cent, aqueous solution of hydro- 
 gen peroxide, until the reaction is distinctly alkaline. The 
 solution is then filtered, and shaken up for 3 to 5 minutes 
 with 10 to 12 times its volume of ether, which extracts 
 about half of the hydrogen peroxide originally present, 
 and leaves behind most of the impurities. The ethereal 
 layer is separated and reduced to o.Oi to 0.0025 of its 
 original volume on the water-bath. The remainder of 
 ether is removed in a bell jar by solid paraffin. The loss 
 of hydrogen peroxide during the evaporation of the ether 
 is only 7 to 10 per cent. 
 
 Operating in this way two solutions are obtained : (a) 
 a colorless solution with distinctly acid reaction, and sp. gr. 
 1.1756, which contains 54 grams of anhydrous hydro- 
 gen peroxide in 100 c. c.; (b] a thick transparent 
 slightly yellow, acid liquid, of sp. gr. 1.2475, which con- 
 tains 79.6 grams of hydrogen peroxide in 100 c. c.f 
 
 Hydrogen peroxide chemically pure can be prepared 
 by mixing hydrogen peroxide of commerce with 0.25 per 
 cent, of phosphoric acid and then while vigorously stirring, 
 barium hydroxide is added until the solution is neutral to 
 litmus. The clear solution is poured into a cold saturated 
 solution of barium hydroxide and the precipitate of barium 
 dioxide is well washed and may be kept for the prepara- 
 tion of pure hydrogen dioxide. For this purpose it is 
 
 * L. CRISMER. Bull. Soc., Chim. [3], 6, 24-25. 
 \ P. SHILOFF, J. Russ. Chem. Soc., 25, 293. 
 
148 LABORATORY MANUAL OF 
 
 made into a thin magma and carefully decomposed by 
 dropping steadily into dilute sulphuric acid containing 12 
 per cent, of concentrated acid ; and excess of sulphuric 
 acid being removed by hydroxide and vice versa. Excess 
 of barium dioxide must be avoided, as it decomposes hy- 
 drogen dioxide.* 
 
 POTASSIUM AND SODIUM PEROXIDES. 
 
 When potassium is dropped into molten potassium ni- 
 trate the metal burns with a bright light, with the forma- 
 tion of yellowish potassium peroxide which dissolves in the 
 fused mass, imparting to it a deep, rich red color. In a 
 similar manner sodium and sodium nitrate give rise to a 
 yellowish-red solution, whilst potassium and potassium 
 nitrate give a brown-red solution. In all cases the color 
 disappears on cooling, but on heating again reappears. The 
 aqueous solutions from the colorless masses give a greenish 
 precipitate with copper sulphate. The action of sodium 
 on fused potassium chlorate is attended with dangerously 
 explosive violence. t 
 
 SULPHUR MONOCHLORIDE, 
 
 AND 
 
 SULPHUR DICHLORIDE, 
 SClg. 
 
 300 grams sulphur are heated to its melting point in a 
 tubulated retort over a low flame, and as in the case of tinte- 
 
 * Mann. Chem. Zeit., 12, 857. 
 
 f H. C. BOLTON Chem. News, 53, 289-290. 
 
INORGANIC PREPARATIONS. 149 
 
 trachloride a rapid stream of dry chlorine gas is passed 
 close to the surface of the melted sulphur. The vola- 
 tile chloride is redistilled in a side neck flask, and a 
 little dissolved sulphur remains as a residue. 67.5 grams 
 of the sulphur monochloride are cooled to o C. and 
 saturated with dry chlorine gas. The sulphur dichloride 
 so produced must weigh 103 grams. It is preserved in 
 well-stoppered bottles. 
 
 In the redistillation of the chloride of sulphur the 
 higher chlorides change into sulphur monochloride; on the 
 other hand at o C. sulphur monochloride combines with 
 another molecule of chlorine : SgClg + Clg = 2SC1 2 . 
 
 The sulphur monochloride should form a yellowish-red, 
 strong-smelling solution of 1.7 sp. gr., and the sulphur 
 dichloride a dark red solution, which should develop 
 chlorine at ordinary temperature the quantity increasing 
 with the temperature. 
 
 PREPARATION OF CHROMIUM FROM POTAS- 
 SIUM CHROMIUM CHLORIDE AND 
 MAGNESIUM. 
 
 Chromium can be quickly prepared in an almost chem- 
 ically pure condition in the following manner : Potassium 
 dichromate (100 grams) is dissolved in the least possible 
 quantity of water, the solution mixed with hydrochloric 
 acid of sp. gr. 1.124 (4 c - c -)> an d then 80 per cent, al- 
 cohol (100 c. c.) gradually added. The solution of potas- 
 sium chromium chloride obtained in this way is treated with 
 potassium chloride (160 grams), the filtered solution evap- 
 
150 LABORATORY MANUAL OF 
 
 orated to dryness, the residue heated until anhydrous, freed 
 from the green portions, which are produced by the de- 
 composition of the double salt, then powdered, and mixed 
 with magnesium filings (50 grams). This mixture is heated, 
 for about half an hour, to a bright red heat, in a closed 
 Hessian crucible in a blast-furnace, care being taken that 
 the potassium chloride does not volatilize completely, 
 otherwise the chromium is partially oxidized. The melt is 
 separated from the superficial layer of chromium oxide, 
 treated with water, and the finely divided metal freed from 
 salts and unchanged magnesium by washing it with water ; 
 then boiling it with dilute nitric acid, and again washing 
 with water, all the washing being done by decantation. 
 The yield of the metal, dried at IOO Q C, is about 27 grams. 
 Chromium, prepared in this way, is a light-gray, crys 
 talline, non-magnetic powder of sp. gr. 6.7284 at 16 C. 
 it can be melted in a Deville's furnace, but only with great 
 difficulty, and after being melted it shows a silvery fracture. 
 Two analyses of the powder showed that it contained 
 99-53 to 99. 5 7 per cent of chromium, and that it was free 
 from silver and magnesium.* 
 
 CHROMYL CHLORIDE. 
 CrO 2 Cl 3 . 
 
 200 grams neutral potassium chromate and 122 grams 
 common salt are melted in a Hessian crucible at a moder- 
 ate temperature, the fusion is poured on a piece of sheet- 
 
 * E. GLATZEL, Ber. 23, 3127-3130. 
 
INORGANIC PREPARATIONS. 151 
 
 iron and broken in coarse pieces, these are digested with a 
 mixture of 66 c. c. fuming H 3 SO 4 (1.096 sp. gr.) and 134 
 c. c. ordinary cone, HgSC^ in a roomy retort with con- 
 denser. The reaction is very violent at first ; when it mod- 
 erates, the retort is heated until no more brown drops 
 pass over, and the distillate is rectified in a fractional dis- 
 tilling flask. The chromyl chloride is preserved in sealed 
 tubes. 
 
 CrO 3 + 2HC1 H 2 O = 
 
 The dark red oxychloride which fumes when exposed 
 to the air should boil at I i6 Q C. 
 
 ANHYDROUS CHROMIUM CHLORIDE. 
 CrCl 3 . 
 
 The chromium oxide obtained as per directions on 
 page 151, while still moist, is kneaded to a paste with 50 
 grams powdered coal and thick starch paste. Of this, bars 
 are formed which are cut in pieces of 2 to 3 cm. long. The 
 pieces, dried at a moderate heat, are packed with coal 
 powder in a Hessian crucible, covered with a layer of coal 
 powder, closed with an iron cover and ignited for 15 
 minutes in Roessler's furnace. Now a porcelain tube is 
 set upright in a Hessian crucible, the crucible filled with 
 the pieces of chromium oxide mixture which have been 
 cooled and separated from the surplus coal-powder, a sec- 
 ond crucible of the same size with perforated bottom is 
 placed upon it bottom up. A short glass tube passes 
 through a small hole bored in the side of the upper cruci- 
 
152 
 
 LABORATORY MANUAL OF 
 
 ble. The tubes are wound with a little asbestos cord and 
 fit tight in the openings ; in order to make both crucibles 
 tight, a narrow, thin strip of soft asbestos board is wrapped 
 
 around the joint and carefully wound with k 
 
 asbestos cord, finally the asbestos cord is 
 saturated with water glass and dried at 
 moderate heat. (See fig. 10.) Then the 
 crucibles are placed in a Roessler's anneal- 
 ing furnace and this covered with two 
 semicircular pieces of thick sheet-iron 
 which have an opening in the center 
 through which the upper crucible appears. 
 It is first heated in a current of carbonic 
 acid until no trace of moisture is shown 
 on the glass tube. Then the strongest 
 heat is applied and it is ignited in a cur- 
 rent of chlorine, the uncombined chlorine 
 passes out through the glass tube and is 
 absorbed in soda. 
 
 Upon cooling the chromium chloride is found sublimed 
 in the upper crucible in violet-red very glossy scales which 
 are insoluble in water. 
 
 Cr 3 O 3 + 3C + 6C1 = 2CrCl 8 + SCO. 
 
 FIG. 10. 
 
 CHROMIUM OXIDE. 
 Cr 3 O 3 . 
 
 250 grams potassium dichromate are thoroughly mixed 
 with 50 grams of sulphur placed in a clay crucible covered and 
 
INORGANIC PREPARATIONS. 153 
 
 ignited for one hour in Roessler's annealing furnace. The 
 green contents of the crucible are ground, boiled several 
 times with water, filtered and dried. 
 
 K 3 Cr 2 Or + S = K 3 SO 4 + Cr 3 O 3 . 
 
 Only traces of the green powder should go into solu- 
 tion on boiling it with dilute hydrochloric acid. 
 
 CHROMIUM ACETATE. 
 (CH 3 COO) 2 Cr. 
 
 500 grams fuming HC1 are poured over 100 grams po- 
 tassium dichromate in a flask, and the chlorine gas, which 
 develops, upon warming, after being washed with water, is 
 used in the preparation of chlorine water or of hypo- 
 chlorite of sodium. The remaining solution is evaporated 
 to a very small volume, poured off from the separated po- 
 tassium chloride into a flask with 300 grams of granulated 
 zinc and rinsed with 400 c. c. fuming HC1. The flask, in 
 which a violent evolution of hydrogen should take place, 
 is closed with a double-bored rubber stopper similar to 
 that of a wash bottle. As soon as the solution has as- 
 sumed a light blue color similar to copper sulphate solution, 
 the glass tube permitting the free passage of the gas is 
 closed, so that the hydrogen which continues to develop 
 vigorously presses the solution out of the flask through 
 the second tube which reaches to the bottom. It is filtered 
 through a small bulb-tube with asbestos and then enters 
 
154 LABORATORY MANUAL OF 
 
 directly, without coming in contact with air, into a solu- 
 tion of 500 grams crystallized sodium acetate in 2 litres of 
 water. The red precipitate is washed by decantation sev- 
 eral times with water saturated with carbonic acid and pre- 
 served as a paste.* 
 
 K 2 Cr 2 O 7 + 14HC1 =2KC1 + 2CrCl 3 + 6CI + 7H 2 O; 
 2CrCl 3 -f Zn = 2CrCl 2 -f ZnCl 2 ; 
 
 CrClg -f 2CH 3 COONa = 2NaCl + CR 8 COO > Cr ' 
 
 The reduction of the chromium chloride only takes place 
 rapidly and completely in concentrated hydrochloric acid 
 solution with large excess of zinc. Chromium monochloride 
 absorbs the oxygen of the air with great rapidity, while the 
 insoluble chromium acetate is fairly stable in air. 
 
 The red paste should form a blue solution with diluted 
 HC1, and by energetic absorption of oxygen this quickly 
 turns dark green. 
 
 POTASSIUM CHLOROCHROMATE. 
 
 IOO grams potassium dichromate ?re powdered and 
 gently heated in a flask with a mixture of 100 c. c. of 
 water and 130 grams pure fuming HC1. As soon as dis- 
 solved, it is filtered and allowed to settle. Next day the 
 
 * Pfordten Annalen, 228, 113. 
 
INORGANIC PREPARATIONS. 155 
 
 crystals are separated from the mother liquor by decanta- 
 tion and dried on an earthen plate. 
 
 KO-C.O, 
 
 , 
 KG Cr0 2 - KO CrO,,Cl 
 
 The large, red prisms or plates develop chlorine gas on 
 heating to iooC. 
 
 Of TW 
 
 SELENIUM. 
 
 Se. 
 
 Seleniferous material or residues are melted in a Hes- 
 sian crucible with a mixture of equal parts soda and salt- 
 petre. The cooled fusion is boiled up with water, the ex- 
 tract condensed to small volume, and the solution, which 
 has been made strongly acid with cone, hydrochloric acid, 
 is boiled with a reversed condenser until no more chlo- 
 rine gas escapes. Now it is diluted in a large flask with 
 plenty of hot water, and commercial sodium disulphite 
 dropped into the boiling liquid as long as a red, very vol- 
 uminous precipitate, which quickly clots to blackish, ugly 
 masses, is formed. The separated selenium is settled, col- 
 lected on a filter and dried. 
 
 In fusing with soda and saltpetre seleniferous mate- 
 rials produce selenates ; selemc acid is quickly reduced 
 in cone, solution by muriatic acid : 
 
 H 2 SeO 4 -f 2HC1 = H 2 SeO 3 + 2C1 + H 2 O. 
 Selenious acid is decomposed by sulphurous acid : 
 H 2 SeO 3 + 2H 2 SO 3 = Se + 2H 2 SO 4 + H 2 O. 
 
 The selenium should melt at 217 G., and when cooled 
 slowly crystallize in dark-gray, metallic-shining masses ; 
 
156 LABORATORY MANUAL OF 
 
 it should dissolve in cone, sulphuric acid, with a green 
 color, and be reprecipitated out of this solution by water 
 as a very voluminous red armorphous deposit. Heated 
 in the air it should burn to selenium dioxide without re- 
 sidue, leaving an odor of radishes. 
 
 HYDROFLUOSILICIC ACID. 
 
 H 3 SiF 6 . 
 
 IOO grams calcium fluoride powder are mixed with 
 100 grams dry quartz-sand (sea-sand), and carefully heated 
 with 350 c. c. cone, sulphuric acid. The escaping gas is 
 led through an empty bottle containing a safety-tube 
 closed with a little cone, sulphuric acid, and then into a 
 porcelain dish, at the bottom of which a small vessel with 
 mercury has been placed. The gas tube is fastened so 
 that it dips into the mercury, and then 400 c. c. distilled 
 water are poured over it. After the gas evolution has 
 ceased, the silicic acid, which has separated in the water, 
 is filtered, washed with a little water, until the combined 
 filtrates amount to 400 c. c., and the still cloudy acid is 
 filtered through a folded filter. 
 
 By the water-absorbing action of the sulphuric acid 
 there is a formation of silicon fluoride : SiO 2 -f 4HF 2H 2 O 
 = SiF 4 ; this gas is decomposed by water: 3SiF 4 -j-4H 2 O 
 = 2H 2 SiF 6 + Si(OH) 4 . 
 
 The acid should yield a precipitate (Ba 2 SiO 4 ) with 
 barium chloride, but not with strontium chloride, in hydro- 
 chloric acid solution. To determine its value, the acid 
 is titrated with soda solution to alkaline reaction. The 
 
INORGANIC PREPARATIONS. 157 
 
 neutralization of the acid on titration with soda corresponds 
 with the equation :. H 2 SiF 6 + GNaOH = 6NaF +- Si(OH) 4 f 
 2H 2 O. 
 
 PERCHLORIC ACID. 
 HC10 4 . 
 
 50 grams potassium perchlorate are distilled out of a 
 good-sized retort with a mixture of 100 grams cone. 
 H a SO 4 and 20 c. c. water. The distillate is freed from chlo- 
 rine gas by gently warming, a few centigrammes of silver 
 sulphate and barium carbonate added, the trifling precipi- 
 tates of each filtered separately, and the filtrate redis- 
 tilled. 
 
 KC1O 4 + H 2 SO 4 =, HC1O 4 + HKSO 4 . 
 
 The crude acid still contains traces of HC1 and H 3 SO 4 , 
 which are removed in the manner described. 
 
 In a solution of potassium chlorate a drop of the acid 
 produces a thick crystalline precipitate. 
 
 MANGANESE. 
 Mn. 
 
 300 grams crystallized manganous chloride are grad- 
 ually dried in a porcelain dish on the gas stove, 
 and the pieces which have formed, powdered in a hot 
 mortar and dried until the pale pink-colored powder fails 
 to clot and a sample heated in a test-tube shows no mois- 
 ture. 75 grams of the anhydrous manganous chloride are 
 
158 LABORATORY MANUAL OF 
 
 thoroughly mixed in a warm condition with 150 grams 
 dry potassium chloride (the latter must first be heated 
 in a nickel or iron dish until it no longer decrepitates), and 
 the mixture packed tight in a clay crucible, 12 cm. high 
 and 7 cm. wide. The crucible is covered and heated in 
 the furnace. When the crucible has become red-hot and 
 the contents are soft, 18 grams magnesium in sticks are 
 thrown in, in pieces of from 3 to 4 grams each, closing the 
 crucible immediately after adding each piece and waiting 
 for the faint reaction. The real difficulty is in rapidly 
 producing the exceedingly high temperature in the fur- 
 nace required to fuse the manganese that has formed. 
 This can be accomplished in Roessler's furnace by pro- 
 viding a very good gas supply and by introducing a 
 strong oxygen current through the air-openings on the side 
 of the furnace. (The oxygen is generated directly from a 
 large retort, with potassium chlorate and a little black 
 oxide manganese, which is heated a few minutes before 
 adding the magnesium. The air-openings of the furnace 
 are closed loosely with strips of asbestos board, through 
 which the gas-tubes conveying the oxygen pass.) But a 
 well-built brick, air or blast furnace, with coke fire, is 
 preferable. The severe heat must last no longer than 
 half an hour. Upon cooling, if the operation has proved 
 successful, the manganese will be found as a regulus. If, in 
 place of this, only a fine black metallic powder be 
 found which, on exposure to air, changes very readily 
 into manganese dioxide, then the heat was too low. If, 
 on the other hand, the metal has solidified in crusts and 
 granules, which have not combined to a regulus, then the 
 crucible contents are ground, the light particles quickly 
 
INORGANIC PREPARATIONS. 159 
 
 elutriated with a large quantity of water, then filtered, 
 quickly washed with alcohol and ether, dried between fil- 
 tered paper, and the metallic powder so obtained is pre- 
 served in well-closed bottles. 
 
 MnCl 2 + Mg = MgCl 3 + Mn. 
 
 The magnesium chloride volatilizes and reacts with the 
 water-vapor of the gases of combustion to form hydrogen 
 chloride and magnesium oxide. During the operation 
 there is a considerable evolution of hydrochloric acid gas. 
 
 Manganese is a brittle, glossy metal, when exposed to 
 the air, especially in a finely divided and moist condition, is 
 very easily oxidizable and when excess of diluted HC1 is 
 poured over a sample, the metal should dissolve clearly 
 with a vigorous evolution of hydrogen. The solution 
 prepared hot should show no turbidity with excess of 
 ammonia, or at most a hardly noticeable one. When am- 
 monium sulphide is added to this ammoniacal solution, a 
 precipitate of flesh-colored manganese sulphide forms, 
 which gradually turns green on boiling. The filtrate from 
 the manganese sulphide mixed with sodium phosphate 
 gives a precipitate of magnesium phosphate which is never 
 entirely absent, but in successful working should be very 
 slight. 
 
 MANGANESE CHLORIDE. 
 
 MnCl 2 + 4H 3 O. 
 
 Residues of chlorine produced from black oxide of man- 
 ganese and HC1 are evaporated to dryness in a porcelain 
 dish, and the residue heated for a time on the gas stove 
 with low flame. It is then boiled up with water and iVth 
 
160 LABORATORY MANUAL OF 
 
 of the filtrate precipitated with excess of soda solution. 
 The precipitate is washed with water decanting several 
 times, then the main quantity is added to the solution and 
 digested with it, warming until a filtered sample, mixed 
 with ammonium sulphide, shows a pure flesh-colored pre- 
 cipitate, which on dissolving in dil. acetic acid leaves no 
 residue. It is then filtered and evaporated to crystalliza- 
 tion. 
 
 On heating the dry chlorides and boiling with water, 
 the compounds of the trivalent metals (iron, aluminium) 
 decompose with formation of insoluble basic salts. Pos- 
 sibly the rest of the compound is precipitated by the 
 manganese carbonate 
 3MnCO 3 + Fe 2 Cl 6 + 3H 2 O = 3MnCl 2 + Fe 2 (OH) 6 + 3CO 2 . 
 
 The magnanese chloride is tested for the absence of 
 iron, barium, calcium and magnesium salts. 
 
 SOLUBLE MANGANESE OXIDE. 
 4(MnO 2 H 2 O),Mn 3 O 4 . 
 
 Obtained by acting on potassium permanganate with 
 sodium thiosulphate, and thoroughly washing the precipi- 
 tate with water. As soon as all the potassium has been 
 removed, a brown solution is obtained, from which the oxide 
 is precipitated on the addition of any salt. The manga- 
 nese solution can be kept for a long time in sealed tubes, 
 but if filtered through paper the manganese is completely 
 precipitated.* 
 
 * W. SPRING and G. DE BOECK, Bull. Soc. Chim., 48, 170. 
 
INORGANIC PREPARATIONS. l6l 
 
 MANGANOUS SULPHIDE. 
 
 MnS. 
 
 Manganous sulphide is thrown down from ammoniacal 
 manganous solutions by ammonium sulphide as a pink 
 precipitate, which the older workers supposed to be a hy- 
 drated sulphide ; however, it is shown that if i'_ is collected, 
 washed in an atmosphere of hydrogen sulphide, and dried 
 at 70 C. in a current of carbonic anhydride it has the 
 composition MnS. The sulphide thus obtained consists 
 of tiny, reddish, transparent crystals, and is contaminated 
 with a little sulphur, which may be extracted by treat- 
 ment with carbon bisulphide; its sp. gr. at 17 C. is 3.55. 
 
 If the red precipitate be well washed, and left in a 
 solution of ammonium sulphide for a few days, it turns 
 green ; the same change is also brought about by heating 
 the red powder at 300 to 320 C. The green modifica- 
 tion is crystalline, and has the same composition as the 
 red, but a somewhat higher sp. gr., namely, 3.63, re- 
 ferred to water at 17 C. Neither modification loses sul- 
 phur on heating.* 
 
 MANGANESE SULPHATE. 
 MnSO 4 ,5H 2 O. 
 
 A concentrated solution of MnSO 4 is treated with 95 
 per cent alcohol, when almost all of the sulphate sepa- 
 rates out as a syrupy liquid, which after a short time 
 
 * By U. ANTONY and P. DOMNINI. Gazzetta, 23, i., 560-567. 
 
162 LABORATORY MANUAL OF 
 
 begins to form crystals. If, at this point, the liquid and 
 alcohol be repeatedly and strongly shaken, a crystalline 
 meal results, but if allowed to remain at rest, well-formed, 
 reddish white, prismatic crystals are deposited.* 
 
 POTASSIUM MANGANATE. 
 
 K 2 MnO 4 . 
 
 Potassium hydroxide (2 mols) is placed in a crucible, 
 some water is added, and finely divided potassium per- 
 manganate (2 mols) is added, with constant stirring and 
 heating. After two hours at a faint red heat the crucible 
 is cooled, and the manganate placed in a well-stoppered 
 flask, to prevent access of air and contact with organic 
 matter, t 
 
 BARIUM MANGANATE. 
 
 BaMnO 4 . 
 
 This green pigment is prepared by heating manganese 
 carbonate with 2 to 2. 5 times its weight of commercial barium 
 dioxide in a porcelain crucible. A better green is ob- 
 tained when well-pulverized manganese dioxide (contain- 
 ing 91 per cent of MnO 2 ) is heated with three times its 
 weight of barium dioxide.^ 
 
 PREPARATION OF BARIUM PERMANGANATE. 
 
 BaMn 3 O 8 . 
 
 Potassium permanganate (100 grams) and barium ni- 
 trate (140 grams) are disolved in water (i^ litres), and 
 
 * B. CLASSEN, Arch. Pharm. [3] 25, 310. 
 
 f A. JOLLER, Rep. Anal. Chem. 1887, No. 33. 
 
 \ E. DONATH, Dingl. Polyt. Jr. 263, 246. 
 
INORGANIC PREPARATIONS. 163 
 
 to the boiling solution barium hydroxide is added in por- 
 tions of 20 grams, until no further evolution of oxygen 
 takes place. The whole is then wanned until the solu- 
 tion has become colorless, the precipitate of barium man- 
 ganate (containing also some peroxide and carbonate) is 
 collected, washed 5 times by decantation with 5 litres of 
 boiling water, collected on the filter-pump, washed 10 
 times more with boiling water, suspended in water (i litre) 
 and carbonic anhydride, and superheated steam passed into 
 the mixture for 10 hours. The solution is then filtered 
 twice through an asbestos filter ; it contains 65 to 80 grams 
 of barium permanganate.* 
 
 FERRIC CHLORIDE. 
 
 Fe 3 Cl 6 . 
 
 Heat small iron nails in a flask with a mixture of 10 
 parts of water and one part of pure hydrochloric acid until no 
 further evolution of hydrogen is observed, even after add- 
 ing the nails in excess; filter the solution into another flask, 
 and conduct into it chlorine gas, with frequent shaking un- 
 til the fluid no longer produces a blue precipitate in a solu- 
 tion of potassium ferricyanide. Heat until the excess of 
 chlorine is expelled. 
 
 Solutions of ferric chloride must not contain an excess of 
 acid ; this may be readily ascertained by stirring a diluted 
 sample with a glass rod dipped in ammonia, when the 
 absence of any excess of acid will be proved by the forma- 
 tion of a precipitate which shaking the vessel or agitating 
 the fluid fails to redissolve. Potassium ferricyanide must 
 not impart a blue color to it. 
 
 * By F. MUTHMANN, Ber. 26, 1016-1018. 
 
164 LABORATORY MANUAL OF 
 
 ANHYDROUS FERROUS CHLORIDE. 
 
 FeCl 2 . 
 
 Into a retort, which has been warmed and fitted up for 
 the production of ferric chloride, about 20 grams 
 anhydrous ferric chloride are poured as quickly as 
 possible. A strong current of carefully dried hydrogen 
 gas, developed from a Kipp's apparatus, is passed over it. 
 The retort is placed on a gas stove which may be lighted, 
 when it is certain that the air has been entirely removed from 
 the apparatus; the heat should be moderate. A strong evo- 
 lution of hydrogen chloride takes place at once ; the gas 
 is collected in water. When the chloride in the retort has 
 changed to a white crystalline mass and the evolution of 
 HC1 ceases, the operation is concluded. It is then allowed 
 to cool in a slow current of hydrogen ; the retort is broken 
 while still warm and the collected chloride preserved in the 
 same manner as the ferric chloride. 
 
 Fe 3 Cl 6 + 2H = 2FeCl 2 + 2HC1. 
 
 Anhydrous ferrous chloride forms in white scales, fairly 
 stable when exposed to air, melting when heated vigorous- 
 ly and subliming at a very high temperature. 
 
 ANHYDROUS FERRIC CHLORIDE. 
 
 Fe 2 Cl 6 . 
 
 50 grams bright iron wire I mm. thick in pieces 6 to 8 
 mm. long are placed in a tubulated glass retort of ^ litre 
 capacity and strongly heated on the gas stove, a chlorine cur- 
 
INORGANIC PREPARATIONS. 165 
 
 rent, dried by two wash bottles with sulphuric acid, is led 
 into it through a glass tube, which passes through a cork in 
 the tubulature of the retort ending just above the iron. 
 The neck of the retort is closed with a bored cork ; the es- 
 caping chlorine gas is either led out through a rub- 
 ber tube or else absorbed in flasks by soda or alcohol. 
 After the operation has lasted I to 2 hours, the gas current 
 and heat are interrupted, the chlorine which fills the re- 
 tort is removed by dry carbonic acid, the retort broken 
 while still hot over a large sheet of smooth paper, and 
 the ferric chloride separated from the broken glass and un- 
 changed iron, from which it is very easily removed ; it is 
 then rapidly placed in dry and warm test tubes prepared in 
 readiness, tared and fitted with suitable stoppers which are 
 immediately closed by heating before the blowpipe, taking 
 care that the aqueous products of combustion do not enter 
 the tubes. 
 
 The ferric chloride formed according to the reaction: 
 2Fe 3 -r6Cl = Fe 3 Cl6 escapes the reducing influence of the iron 
 on account of its volatility and collects in beautiful crystals 
 in the upper part of the retort.* The process is only suc- 
 cessful with complete exclusion of moisture. 
 
 Anhydrous ferric chloride forms dark greenish, compact 
 scaly masses, with a beautiful metallic gloss, dissolving 
 quickly in brown drops when exposed to the air. 
 Readily dissolved when vigorously warmed in water, 
 alcohol and ether; with more difficulty in benzol. The 
 solutions are colored brown and react acid. 
 
 * When the chlorine current is too sluggish there may be a forma- 
 tion of ferrous chloride, which then remains with the iron as a fused 
 white mass. 
 
1 66 LABORATORY MANUAL OF 
 
 FERROUS SULPHATE. 
 FeSO 4 ,7H 2 O. 
 
 Heat an excess of iron nails free from rust, or of clean 
 iron wire, with dilute sulphuric acid until the evolution of 
 hydrogen ceases ; filter the sufficiently concentrated solu- 
 tion, add a few drops of dilute sulphuric acid to the filtrate 
 and allow it to cool. Wash the crystals with water very 
 slightly acidulated with sulphuric acid, dry, and keep for 
 use. 
 
 The crystals of ferrous sulphate must have a fine pale 
 green color. Crystals that have been more or less oxidized 
 by the action of the air and give a brownish-yellow solution 
 when mixed with water, leaving undissolved ferric sulphate 
 behind, may be treated as above, with sulphuric acid and 
 excess of clean iron wire or nails, until the residue dissolves 
 and the solution is clear pale green. Hydrogen sulphide 
 must not precipitate solution of ferrous sulphate after ad- 
 dition of some hydrochloric acid, nor even impart a black- 
 ish tint to it. 
 
 ANHYDROUS FERROUS BROMIDE. 
 FeBr 3 . 
 
 IOO grams of bright iron wire are vigorously heated in a 
 round bottom flask on the gas stove, and 100 c. c. bromine 
 distilled slowly from a water-bath into the flask. The glass 
 tube conducting the bromine-vapors should reach close 
 to the bottom of the flask, but the hot glass must -be 
 protected from fracture by the dropping bromine, 
 
INORGANIC PREPARATIONS. l6/ 
 
 either with iron filings or a little asbestos. When the reac- 
 tion begins the temperature may be somewhat moderated. 
 Finally dry air or carbonic acid is passed through the 
 apparatus ; upon breaking the flask the preparation is 
 gathered and preserved in the same manner as described 
 for ferric chloride. 
 
 IRON AMMONIUM ALUM. 
 
 Fe(NH 4 )(S0 4 ) 2 -f-12Aq. 
 
 400 grams ferrous sulphate are dissolved in 400 c. c. water 
 70 grams cone, sulphuric acid and about 120 grams of cone, 
 nitric acid added to the boiling solution until a diluted 
 sample mixed with ammonia shows a pure rust-colored pre- 
 cipitate. Now it is evaporated until the mass is resinous 
 then again diluted with water to sp. gr. 1.3 17 to 1.319. To 
 300 grams of this ferric sulphate solution a solution of 28 
 grams ammonium sulphate in 100 c. c. water is added and al- 
 lowed to cool slowly and quietly. The crystals are washed 
 with a little cold water and dried without warming. 
 
 The last traces of nitric acid are removed from the fer- 
 ric sulphate solution by evaporation. 
 
 Iron alum crystals are amethyst-colored octahedra 
 which must be entirely free from chlorine. Determine the 
 iron value by weighing the ferric oxide which remains after 
 ignition with a little ammonium nitrate. 
 
 BERLIN BLUE. 
 
 Hydrocyanic acid residues (page 124) are washed with 
 water by decantation and rinsed in a porcelain dish with 
 
1 68 LABORATORY MANUAL OF 
 
 crude hydrochloric acid. A chloride of lime emulsion 
 is prepared by suspending chloride of lime in water, allow 
 it to flow in, stirring well, through a funnel, the stem of 
 which rests on the bottom of the dish in the hydrochloric 
 acid, until the mass has turned to a nice blue color and the 
 solution begins to smell of chlorine. The precipitate is 
 washed with a dilute solution of common salt, as it does 
 not settle in water. 
 
 The hydrocyanic acid residues consist of the ferro-salt 
 of hydrogen ferrocyanide, which is converted into ferric 
 salt by the oxidizing influence of the chloride of lime. 
 
 PURE PLATINUM. 
 
 Pt. 
 
 The following method of Finkener's for obtaining plati- 
 num free from impurities, especially iridium, is here describ- 
 ed; it depends on recrystallization of sodium platinochloride. 
 Commercially purified platinum is dissolved in aqua regia, to 
 the solution of the chloride, freed from oxides of nitrogen, 
 the calculated amount of pure sodium chloride is added, the 
 solution is concentrated to a small bulk, and allowed to cool 
 whilst being continuously stirred. The crystals which sep- 
 arate are freed from mother liquor by suction, washed with 
 a concentrated solution of sodium chloride, and dissolved 
 in a one per cent, solution of sodium carbonate. The solution 
 is allowed to cool, when the salt again separates. It is 
 then dried at 120 C., reduced in a current of hydrogen at a 
 low temperature, and the platinum sponge thus obtained is 
 washed for a long time with water, and finally dried and 
 ignited. The metal thus obtained is extremely pure ; no 
 
INORGANIC PREPARATIONS. 169 
 
 impurities could be detected in it by the methods mentioned 
 above and it is calculated that it contains at least 99.99 per 
 cent, of platinum.* 
 
 It may be of interest to mention that pure platinum is 
 now prepared in Germany. The method of purification is 
 simpler than the English one, not involving the use of lead, 
 and it yields a very pure product. In a sample of 40 grams, 
 no palladium or rhodium could be detected, and only a 
 trace of iridium; a trace of iron, at most o.OOi per cent., 
 was, however, present. 
 
 PLATINIC CHLORIDE. 
 
 PtCl 4 , Crystallized j-10H 2 O. 
 
 Heat in a clay crucible 5 parts of zinc to fusion, with 
 sufficient common salt to cover the surface and prevent its 
 oxidation, then introduce I part of platinum scraps in small 
 quantities at a time into the fused metal. An alloy is 
 formed from which the zinc is to be removed by digesting 
 in somewhat dilute common hydrochloric acid, until all 
 effervescence ceases, and subsequent boiling for a time with 
 fresh hydrochloric acid. The residual platinum is com- 
 pletely washed with water and boiled with nitric acid. It 
 is again washed, and finally dissolved by warming with con- 
 centrated hydrochloric acid and some nitric acid. Evapo- 
 rate the solution on the water bath, with addition of hydro-. 
 chloric acid, and dissolve the semifluid residue in 10 parts 
 of water for use. 
 
 * F. MYLIERS & FOERSTER, Ber. 25, 660 J^T 1 T 
 
I/O LABORATORY MANUAL OF 
 
 Platinic chloride must, upon evaporation to dryness in 
 the water-bath, leave a residue which dissolves completely 
 in alcohol. 
 
 PLATINIC CHLORIDE. 
 
 From Residues, 
 
 If the platinum residues contain alkalies and organic 
 substances they are roasted in a porcelain dish on the gas 
 .stove, then mixed with a little diluted crude hydrochloric 
 acid and reduced by zinc. The undissolved zinc is removed, 
 washed and the impure metal boiled up several times with 
 water and hydrochloric acid. The residue is then dissolved 
 in aqua regia, evaporated to a small volume and precipita- 
 ted with cone, salammoniac solution. The filtered platinum 
 ammonium chloride is ignited in a porcelain crucible, the 
 residue of spongy platinum boiled with HC1, dissolved in 
 aqua regia, and evaporated to dryness on the water-bath in 
 a weighed dish occasionally adding a few drops of HC1. 
 The residue of pure platinum chloride is dissolved in 10 
 parts of water. 
 
 Ten drops of the solution with one drop of sodium chlor- 
 ide solution evaporated on a watch-glass to a very small 
 volume, should on cooling yield a crystalline mass, in 
 which, under the microscope, only well formed, reddish-yel- 
 low prisms of sodium platinum chloride are to be seen, and 
 which must not be contaminated with amorphous, brown 
 masses (iron ; nitrogen oxide compounds of the platinum 
 chloride). 
 
INORGANIC PREPARATIONS. 171 
 
 PLATINOSOCHLORIDES. 
 
 When potassium platinocbloride (12 grams) is heated in 
 a covered vessel, on a water-bath, with hydrogen potassium 
 sulphite (9 grams) and water (160 c. c.) for 10 to 12 hours, 
 the reduction is complete, and the red salt crystallizes out 
 on evaporation. Similar results are obtained by heating 
 the platinochloride (9 grams) with potassium hypophosphite 
 (i gram) and water (300 c. c.), at 80 to 90 C., for 1 8 to 20 
 hours. The completion of the action is shown by the pure 
 ruby color of the solution, the least shade of orange indica- 
 ting the presence of platinochloride. The first method is 
 the safest, as the reduction cannot go beyond the platino- 
 sochloride, but in the second method the red salt separates 
 more easily and completely, and with care, very good re- 
 sults are obtained. If, when reducing with potassium hy- 
 pophosphite, the action is continued after complete 
 conversion into the red salt, the solution rapidly changes to 
 dark brown. Hydrochloric acid has no effect on this so- 
 lution, nitric acid discolorizes it, potash causes a brown pre- 
 cipitate soluble in excess of the precipitant, and ammonia a 
 brown precipitate insoluble in excess.* 
 
 SPECIALLY ACTIVE PLATINUM-BLACK. 
 
 Very active platinum-black can be conveniently pre- 
 pared as follows: An aqueous solution (50 to 60 c. c.) of 
 platinic chloride (50 grams) is mixed with 40 to 45 per 
 cent, of formaldehyde solution (70 c. c.), the mixture cooled 
 
 * M. CARY LEA, Amer. Jr. Sci., 1894 [3], 48,397. 
 
LABORATORY MANUAL OF 
 
 well, and then sodium hydroxide (50 grams) dissolved in 
 water (50 grams) gradually added; after standing for 12 
 hours the solution is filtered. A yellow liquid, from which 
 a small quantity of platinum is deposited on boiling, first 
 passes through the filter, but as soon as most of the salts 
 have been washed out of the residue, the filtrate assumes a 
 deep black color. The process is interrupted at this stage 
 for several hours because the residue soon absorbs oxygen, 
 the temperature rising to 36 to 40 C, and the washings then 
 pass through colorless. As soon as oxidation is complete, 
 the residue is washed until completely free from sodium 
 chloride, pressed, and dried over sulphuric acid. 
 
 If the deep black filtrate referred to above is submitted 
 to dialysis in absence of air, a black, transparent liquid is 
 obtained which is stable in absence of air ; on exposure to 
 the air, however, this liquid gradually becomes colorless, 
 and a small quantity of a black powder is deposited. The 
 black solution decomposes hydrogen peroxide very energet- 
 ically, and when mixed with alcohol or shaken with air, the 
 odor of aldehyde is immediately perceptible. These and 
 other experiments seem to show that this black liquid is 
 a solution of atomic platinum containing small quantities of 
 organic platinum compounds.* , 
 
 PENTATHIONIC ACID. 
 
 When 10 c. c. of decinonnal sodium thiosulphate solu- 
 tion are treated with a drop of a solution of potassium 
 arsenite containing I per cent, of arsenic trioxide, and 
 
 A. LOEW, Ber., 23, 289. 
 
OF THC. 
 
 UNIVERSITY; 
 
 r. OF ' 
 
 INORGANIC PREPARATIONS. ' 173 
 
 with an excess of hydrochloric acid, the solution becomes 
 turbid and has a slight odor of hydrogen sulphide ; after a 
 long time arsenic sulphide and a little sulphur are precipi- 
 tated. When filtered, the solution gives reactions for pen- 
 tathionic acid.* 
 
 PREPARATION OF CRYSTALLIZED HYDROXY- 
 
 LAMINE. 
 
 A mixture of dry hydroxylamine zinc chloride (10 
 grams) and anhydrous aniline (20 c. c.) is distilled under 
 a pressure of 20 m.m. on a water-bath. The distillate of 
 hydroxylamine, which crystallizes on cooling, is washed 
 with ether, care being taken to prevent access of moist air; 
 or dry ammonia gas is passed through absolute ether, hold- 
 ing the zinc salt in suspension, and the decanted etherial 
 solution of hydroxylamine is subsequently distilled under 
 reduced pressure, when crystals are obtained. t 
 
 HYDROXYLAMINE HYDROCHLORIDE. 
 
 A saturated solution of sodium nitrite (i mol.) is 
 added to a solution of hydrogen sodium sulphite (2 
 mols.) in a cooled vessel, and then a cold saturated solution 
 of potassium chloride is added. In 24 hours hydroxyla- 
 mine potassium disulphonate separates. This salt is boiled 
 in water during several hours, and, on cooling, potassium 
 sulphate is first deposited, and subsequently hydroxyla- 
 
 * T. SALZER, Ber. 19, 1696 
 
 f 1.. CRISNER, Bull. Soc. Chim. [3], 6, 
 
174 LABORATORY MANUAL OF 
 
 mine sulphate. A solution of this salt, treated with the 
 necessary amount of barium chloride, yields the hydro- 
 chloride, which can be obtained in colorless crystals, very 
 hygroscopic, easily soluble in water and alcohol. It melts 
 at 151 C, and decomposes at a higher temperature, 
 yielding nitrogen, hydrogen chloride, ammonium chloride, 
 and water.* 
 
 HYDRAZINE. 
 
 Hydrazine sulphate is best obtained when triazoacetic 
 acid (250 grams in 2 litres of water) is warmed with sul- 
 phuric acid (300 grams) until all effervescence ceases; the 
 sulphate crystallizes out on cooling. More may be ex- 
 tracted from the mother liquor by shaking with small 
 quantities of benzaldehyde, thus converting the hydrazine 
 into benzalazine, which separates out; after recrystalliza- 
 tion this is decomposed by sulphuric acid, whereby hydra- 
 zine sulphate and benzaldehyde are formed ; the latter is 
 then distilled off.t 
 
 CHYDRAZAINE OR PROTOXIDE OF 
 AMMONIA. 
 
 Chydrazaine is evolved when a solution of potassium 
 permanganate (158 grams) and sulphuric acid (40 grams SO 3 ) 
 is added to dried, crystallized ammonium oxalate (141.2 
 grams) thewhole well mixed and gently heated until it begins 
 
 * EICHKOFF, Arch. Pharm. [3], 27, 713. 
 
 f T. CURTIUS and R. JAY, Jr. pr. Chem. [2], 39,27. 
 
INORGANIC PREPARATIONS. 175 
 
 to boil. The gaseous product is absorbed in hydrochloric 
 acid, and a neutral solution of the salt can thus be obtained. 
 The hydrochloride is crystalline, and very readily soluble 
 in water, but only sparingly in alcohol. The sublimed 
 salt has the composition N 3 H 6 O 2 2HC1, but the crystals 
 dried by means of the anhydrous salt contain one-fifteenth 
 of their weight of water. When a solution of the hydro- 
 chloride i.s mixed with platinic chloride, a platinochloride 
 is obtained, the composition of which varies with the con- 
 ditions of the experiment ; with excess of the hydro- 
 chloride a yellow salt is formed, the composition of which is 
 approximately N 3 H 6 O,H 3 PtCl 6 ,but if excess of platinic chlo- 
 ride is added the proportion of platinum is sensibly increased. 
 The sulphate is crystalline and soluble in water, but only 
 sparingly so in absolute alcohol ; it forms a double-salt 
 with aluminium sulphate. The nitrate is crystalline When 
 a solution of the nitrate is evaporated, nitric acid, nitric 
 peroxide, nitrogen, and a compound having the composi- 
 tion N 2 H 2 are evolved.* 
 
 CARBON OXYSULPHIDE. 
 
 COS. 
 
 Is prepared by adding 50 c. c. of a concentrated aque- 
 ous solution of potassium or ammonium thiocyanate to a 
 cooled mixture of 290 c. c. (520 grams) of strong sul- 
 phuric acid and 400 c. c. of water. The whole is heated 
 at 25 C. in a water bath. The gas thus prepared con- 
 tains only about 2.5 per cent, of carbonic anhydride and 
 0.05 per cent, of carbon disulphide. The latter is absorbed 
 
 * E. J. MAUMENE, Bull. Soc. Chim. 49, 850. 
 
LABORATORY MANUAL OF 
 
 by passing the gas through triethylphosphine and this in 
 turn is removed by pure sulphuric acid. Carbon oxysul- 
 phide is only absorbed very slowly by a 33 percent, solu- 
 tion of potash. If the gas obtained as above is passed 
 slowly through about 20 c. c. of such a solution, the whole 
 of the carbonic anhydride is absorbed with a loss of only 
 about 7 per cent, of the oxysulphide. A 33 per cent, 
 aqueous solution of potash mixed with its own volume of 
 alcohol absorbs carbon oxysulphide completely and rapidly, 
 and is the best reagent for use in estimating it. 
 
 Pure carbon oxysulphide is odorless and tasteless. Its 
 physiological effects are very similar to those of nitrous 
 oxide. When passed through a saturated solution of 
 baryta, no opalescence is produced for at least half a min- 
 ute, while if any carbonic anhydride is present, the solu- 
 tion becomes milky at once. With lead acetate solution, 
 the precipitate is a quarter of an hour in forming.* 
 
 NEW METHOD OF PREPARING CARBON OXYSULPHIDE. 
 
 Carbon oxysulphide is obtained when carbonyl chloride 
 is passed through concentrated sulphuric acid to dry it, 
 and then through a tube 50 cm. long, filled with ignited 
 asbestos well mixed with finely pulverized cadmium sul- 
 phide, the tube being placed in a combustion furnace and 
 heated. Even when no external heat is applied a small 
 quantity of carbonyl sulphide is formed, but the most 
 favorable temperature for its formation appears to be 260 to 
 280 C. The gas thus produced is found on analysis to 
 contain COS, 94.87 per cent ; CO, 3.98 per cent.; air 1.15 
 per cent. A quantity of crystals, which are identified a;. 
 
 * P. KLASON, Jr. pr. Chem. [2], 36, 64. 
 
INORGANIC PREPARATIONS. I 77 
 
 cadmium chloride, are observed in a tube previously 
 charged with a layer of cadmium sulphide and heated in a 
 flame during the passage of a current of carbonyl chloride; 
 the reaction, therefore, appears to be a double decompo- 
 sition.* 
 
 PURIFICATION OF CARBON BISULPHIDE. 
 
 To one litre of carbon disulphide 0.5 c. c. bromine is 
 added and allowed to remain for 3 to 4 hours. The bromine 
 is then separated again by shaking the carbon disulphide 
 with a slight excess of potash or by means of copper turn- 
 ings. The carbon disulphide may now be opalescent, but 
 this is readily removed by agitating it with a little potas- 
 sium chloride, when the filtered disulphide will be obtained 
 clear, colorless and of agreeable odor. It leaves no resi- 
 due on evaporation.! 
 
 * By J. NURICSAX, Her. 24, 2967-2974. 
 f A. CHENEVIER, L'Union pharm., 33, 204 
 
1/8 LABORATORY MANUAL OF 
 
 PREPARATION OF NORMAL SOLUTIONS OF 
 ACIDS AND ALKALI. 
 
 A normal solution contains in one litre the same num- 
 ber of grams of the substance as there are units in the 
 molecular weight. Example : 
 
 Normal HC1 36.5 gms. per litre. 
 
 HNO 3 63.0 " 
 
 KOH 56.1 " 
 
 NaOH 40.0 " 
 
 N/HC1, N/NHO 3 , etc., are the expressions usually used. 
 These solutions are equivalent as shown by the reaction, 
 
 HC1 + KOH = KC1 f H 2 O 
 
 36.5 + 56.1 = 74.6 + "18 
 
 The same is true of NaOH and HNO 3 ; in fact all compounds 
 with single hydrogen replacing power belong to this class. 
 Half Normal or N/2 solutions, as of H 2 SO 4 Na 2 CO 3 , etc., 
 contain one-half of the molecular weight in the same vol- 
 ume; these are equivalent to the first class, as will be seen 
 by the reaction, 
 
 H 2 SO 4 + 2KOH = K 2 SO 4 + H 2 O 
 
 98 112 2 174-2 36 
 
 or 49 56.1 
 
 so also with Na 2 CO 3 . 
 
 It is impossible to weigh out any exact amount of a 
 volatile liquid like HC1 or any hygroscopic solid as KOH, 
 hence we must prepare these solutions indirectly. The 
 following will be found to be good methods : Take pure 
 dry Na 2 CO 3 , weigh oft" 53 grams, one-half the molecular 
 weight, and dissolve in 300 to 500 c. c. of distilled water, cool 
 to 15 C. and dilute to exactly one litre; now make up a 
 solution of H 2 SO 4 a little more than half normal strength, 
 
INORGANIC PREPARATIONS. 179 
 
 using the hydrometer, place it in a burette, draw 10 c. c. of 
 the soda solution from another burette, dilute largely with 
 water, add a few drops of methyl orange (do not use 
 phenolphthalein, it is acid to CO 2 ) and run in the sulphuric 
 acid slowly, stirring vigorously until neutral. Example : 
 IDC. c. NagCOs require 9.8 c.c. H 2 SO4 
 
 Evidently if the soda solution is correct the acid is too 
 strong by 0.2 c.c., therefore add 0.2 c. c. of water to every 
 10 c. c. of the solution or 20 c. c. to the litre. The strength 
 of the sulphuric acid may also be determined by taking any 
 exact quantity, say 10 c. c., adding a drop or two of HC1 
 and a slight excess of BaCl 3 , weigh the BaSO 4 and calculate 
 the SO4 present ; there should be 48 grams per litre. In 
 the same way make up N/HC1; the strength of this may be 
 determined by AgNO 3 , either volumetric or gravimetric. In 
 the first case the solution must be neutralized exactly with 
 KOH or NaOH before titration; in the latter made slightly 
 acid with HNO 3 . The normal hydrochloric acid has cer- 
 tain advantages over sulphuric, especially in organic anal- 
 ysis, as the sulphates formed during the reaction are more 
 insoluble in organic liquids, alcohol, etc., than the chlor- 
 ides. 
 
 An acid solution may also be prepared by using oxalic 
 acid H 3 C 3 O 4 , 2H 3 O, which it is possible to obtain in a state 
 of great purity. In this case the water of crystallization 
 must be counted in, and since the solution is N/2 or half 
 normal we need 63 grams. The strength may be exactly 
 determined by titration with K 2 Mn 3 O 8 solution, such as is 
 used for iron determinations ; the solution should be warm 
 and acid with sulphuric acid and the permanganate added 
 until a faint pink shade is obtained 5H 3 C 3 O 4 +K 3 Mn 2 O 8 
 
i8o 
 
 LABORATORY MANUAL OF 
 
 4- 3H 2 SO 4 = 10CO 3 + K 2 SO 4 + 2MnSO 4 + 8H 3 O. Five 
 parts of oxalic acid are equal to 10 parts of ferrous iron. 
 
 The alkali solutions of KOH and NaOH are made up 
 by the hydrometer stronger than necessary, cleared of 
 COg by the addition of a small amount of BaCl 2 and 
 titrated with the standard acid (if it be H 2 SO 4 , no BaCl 2 
 must be used) ; the dilution is carried out the same as 
 described for H 2 SO 4 . 
 
 In all cases the acid solutions will retain their strength 
 much longer than the alkalies, they need only be protected 
 from evaporation ; with the alkali the case is different. 
 CO 2 , SO 2 , H 2 S, etc., are absorbed, glass is attacked, hence 
 the strength should be redetermined from time to time. 
 
 Phenolphthalein, acid colorless, alkaline pink, is the 
 best indicator. It cannot be used in presence of ammo- 
 nium salts and is acid to CO 2 . Methyl orange acid pink, 
 alkaline yellow, is neutral to CO 2 and organic acids, and 
 acts in the presence of ammonium salts. 
 
 Table of equivalents in c. c. 
 
 HC1 0.0365 
 
 HNO 3 0.063 
 
 H 2 SO 4 0.049 
 
 H 2 C 2 O 4 , 2H 2 O 0.063 
 
 H 3 P0 4 
 
 KOH 
 
 NaOH 
 
 NH 4 OH 
 
 Na 2 CO 3 
 
 BaOH 
 
 gram. 
 
INDEX. 
 
 PAGE. 
 
 id, Arsenic. . . . '. 135 
 ' Bismuthic 142 
 Boracic no ' 
 
 i' 
 Antimony Tritachloride 
 Antimonious 
 Arsenic Pentasulphide 
 " Trioxide 
 
 \GE. 
 
 137 
 139 
 137 
 
 22 
 
 83 
 8 4 
 98 
 96 
 
 99 
 35 
 162 
 
 97 
 95 
 98 
 162 
 98 
 35 
 167 
 
 139 
 140 
 
 139 
 139 
 141 
 
 143 
 142 
 no 
 109 
 107 
 94 
 
 63 
 89 
 89 
 87 
 9 
 36 
 90 
 
 131 
 
 26 
 
 29 
 177 
 
 28 
 
 175 
 10 
 
 12 
 
 H 
 II 
 
 ' Dithionic . 99 
 
 Hydriodic 122 j 
 Hydrobromic 118 \ 
 ' Hydrochloric 15, 16 ! 
 
 Auric Chloride 
 
 Auroso Auric Chloride 
 
 Barium Carbonate 
 
 Properties of, 16 
 Hydrocyanic 124 I 
 
 " Chloride 
 Dithionate 
 Hydroxide 
 
 1 Hydrofluoric 125 ! 
 ' Hydrofluosilicic 156 ! 
 Hydrosulphuric 25 
 ' Nitric 17 
 
 ' ' Manganate 
 
 " Nitrate 
 Oxide 
 
 Properties of ig 
 ' Perchloric . . . 157 
 
 " Perhydrate 
 " Permanganate 
 " Peroxide 
 Baryta Water 
 Berlin Blue 
 Bismuth Hydroxide 41, 
 Iodide 
 " Nitrate 
 
 ' Pentathionic . . 172 
 
 Phosphoric . . . . 129 
 
 ' Silicic, Crystalline 113 
 Sulphuric 22 
 " Properties of . . 24 
 Icohol, Commercial 5 
 
 Ethyl 5 
 
 " " Basic 
 " Oxyiodide 
 
 luminium Chloride 114, 115 
 Anhydrous, 1 17 
 Hydrate n 1 ", 
 Oxide, reduction of,n6 
 [urn, Iron Ammonium 167 
 mmonia . 16, 30 
 
 " Sulphate 
 Bismuthic Acid 
 
 Borasic Acid 
 Borax, manufacture of 
 Boron 
 Cadmium Carbonate 
 Caesium Compounds, Prepara- 
 tion of 
 
 " Hydrate 30 
 mmonium P>icarbonate 67 
 Bromide 68 
 
 Chloride 55 
 ' ' Properties 
 of 56 
 Dichromate 70 
 
 Calcium Carbonate 
 " Chloride 
 
 " porous 
 " Chromate 
 
 Di Hydrogen Phos- 
 phite .. 72 
 
 " Hydroxide 
 Phosphate, crystalline. 
 Phosphide 
 
 Molybdate 54 
 Nitrate 71 
 
 " Sulphide 
 
 Oxalate 43 
 
 Carbon Dioxide 
 
 Properties of, 44 
 " Persulphate . . .69 
 
 " Bisulphide 
 " Monoxide 
 " Oxysulphide 
 Chlorine 
 
 Protoxide . 1 74 
 
 Sulphide 41 
 ' ' Properties 
 of 43 
 mmonio Zinc Chlorides 72 
 ntimony Oxychloride 138 
 " Sulphate . . 143 
 
 " Apparatus for a con- 
 stant supply of .... 
 for Laboratory pur- 
 poses 
 
 " from Chloride of Lime. 
 
INDEX. 
 
 Chlorine Properties of 14 
 
 " Water 10 
 
 Chromium 149 
 
 Acetate 153 
 
 Chloride, Anhydrous, 151 
 
 Oxide 152 
 
 Chromyl Chloride 150 
 
 Chydrazaine 1 74 
 
 Cinnabar 104 
 
 Cobalt Nitrate 144 
 
 Copper Ammonium Sulphate . . 75 
 Potassium . . 75 
 
 Cupric Sulphate 76 
 
 Cuprous Ammonium Iodide ... 77 
 
 " Chloride 73 
 
 " Properties of, 74 
 
 " Cyanide 74 
 
 Oxide 76 
 
 Phosphide 78 
 
 Cuproammonium Tetraiodide. . 78 
 
 Ferric Chloride 163 
 
 Anhydrous. . . . 164 
 
 Ferrous Bromide, Anhydrous.. 166 
 
 Chloride . . i 64 
 
 Sulphate 166 
 
 Furnace, Roessler's 37 
 
 Cold 82 
 
 " Trichloride 83 
 
 Hydrazaine 174 
 
 Hydrofluosilicic Acid 156 
 
 Hydrogen g 
 
 Arsenide 136 
 
 Bromide 118 
 
 Iodide 122 
 
 Peroxide 145 
 
 Phosphide 133 
 
 Properties of 10 
 
 Sodium Ammonium 
 
 Phosphate . 58 
 " Sulphite ... 52 
 
 Sulphide 25 
 
 " Arsenic 
 
 fiee from . . 26 
 Propert i e s 
 
 of 27 
 
 " Hydrogen 
 Arsenide, free 
 
 from 27 
 
 Hydroxylamine 173 
 
 Hydroxylamine Hydrochloride. 173 
 
 Iodine Pentoxide 123 
 
 " Trichloride r24 
 
 Iron Ammonium Alum 167 
 
 Lead Carbonate 39 
 
 Dioxide 36 
 
 " " Properties of ... 48 
 
 " Tetrachloride 40 
 
 Lime 36 
 
 Lithium Normal Arsenate 63 
 
 " " Phosphate ... 63 
 
 Magnesium, Basic Carbonate. . 87 
 Carbonate, crystal- 
 lized, normal . . 86 
 Chloride Anhydrous, 84 
 
 Manganese 157 
 
 Chloride 159 
 
 " Oxide TOO 
 
 Sulphate 161 
 
 Manganous Sulphide 161 
 
 Mercury 100 
 
 Mercurous Bromide 107 
 
 Mercuric Chloride 103 
 
 " Cyanide 104 
 
 Mercurous Iodide 106 
 
 " Nitrate 105 
 
 Mercury, Purification of 102 
 
 Mono Calcium Phosphate Crys- 
 talline go 
 
 " Sodium Phosphite 56 
 
 Nitrogen. . 10, 16 
 
 Properties of 10 
 
 Tetraoxide 21 
 
 Nitric Oxide 20 
 
 Nitrous " 19 
 
 Normal Solutions 178 
 
 Oxygen 7 
 
 r ' Cubes 8 
 
 " Properties of 8 
 
 Phosphoric Acid 129 
 
 Phosphorus 128 
 
 Phosphorus Oxyfluoride 133 
 
 Trisulphide 131 
 
 Platinoso Chlorides 171 
 
 Platinum 1 68 
 
 Black 171 
 
 " Platinic Chloride. ... 169 
 Potassa, Prepared with Baryta. 34 
 Potassa, Purified with Alcohol . 33 
 
INDEX. 
 
 Ill 
 
 PAGE. ! 
 
 Potassium Bisulphate 58 : 
 
 Bromide 68 
 
 Chlorate 57 
 
 Chlorochromate 154 
 
 Cobaltic Oxalate. . . 62 
 
 Cyanate 60 
 
 Cyanide 50 
 
 Ferricyanide 59 
 
 Hydroxide 31 
 
 Iodide 60 
 
 Manganate 162 
 
 Metantimonate 62 
 
 Nitrite 52, 53 
 
 Properties of, 53 I 
 
 Peroxide 148 
 
 Pyroantimonate 54 
 
 Sulphide 43 
 
 Sulphocyanide 51 
 
 Koessler's Furnace 37 
 
 Rubidium Compounds, Prepar- 
 ation of 63 
 
 Salts, Preparation of, 64 
 
 Selenium 155 
 
 Silicon 1 10 
 
 " Chloride 113, 114, 115 ! 
 
 Silver 79 i 
 
 " Potassium Carbonate 81 
 
 Sodium 46 
 
 Acetate 44 : 
 
 Amalgam 9, 47 
 
 Ammonium Hydrogen 
 
 Phosphate 58 
 
 Carbonate 48 
 
 Free from Sul- 
 phur and 
 Chlorine . . 48 
 Free from Sil- 
 ica 48 
 
 Properties of, 49 
 
 Sodium Chloride 45 
 
 Dioxide 7 
 
 Hydrogen Sulphite 52 
 
 " " " Prop- 
 erties of 5 2 
 
 " Hydroxide 31 
 
 Specific Grav- 
 ity of Solutions of 33 
 
 Nitrate 56 
 
 " Nitrite 53 
 
 " Peroxide 148 
 
 Sulphide 43 
 
 Stannic Chloride, Anhydrous.. 127 
 
 Stannous " 126 
 
 " , Anhydrous . 127 
 
 Strontium Hydroxide 92 
 
 Salts, Preparation of, 93 
 
 Sulphur Dichloride 148 
 
 Dioxide 27 
 
 Properties of, 28 
 
 Monochloride 148 
 
 Titanium Trioxide 65 
 
 Tungstates, Free from Molybde- 
 num 64 
 
 Ultramarine 117 
 
 Vanadyl Chloride 67 
 
 " Trichloride 66 
 
 Volumetric Analysis 178 
 
 Water i 
 
 " Ammonia free 2 
 
 Fiee from Organic Mat- 
 ter and Ammonia. . . 2 
 Apparatus for Preparing 
 free from Organic Mat- 
 ter and Ammonia. ... 3, 4 
 
 , Chlorine . 10 
 
 Zinc free from Arsenic 91 
 
 " Fisen 92 
 
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