CHEMISTRY. 



107 



nating power of the gas, preservation of the 

 ammonia from waste, and avoidance of the 

 nuisance occasioned by the escape of ammonia 

 and other noxious vapors from the spent lime 

 or iron-oxide now used as purifiers. 



In certain processes, such as the destructive 

 distillation of animal matters for producing 

 boneblack, and the like, or for the produc- 

 tion of ammonia, bone-boiling, rendering, the 

 sweating of hides, etc., large quantities of am- 

 monia are given off, combined with other of- 

 fensive gases and vapors, that are a source of 

 much annoyance, and injurious to public health. 

 Such nuisances, it is claimed, may be readily 

 and effectually abated by employing suitable 

 means for carrying the emanations through 

 trays of salt-cake, when all the ammoniacal 

 compounds will be arrested and retained. 



Researches on the Coloring Principles of 

 Madder. It has been generally held that mad- 

 der contains four distinct coloring principles, 

 viz. : alizarine, purpurine, pseudo-purpurine, 

 and hydrated purpurine ; but the part which 

 each plays in producing the color has not been 

 well ascertained. Recent investigations of Ro- 

 senstiehl's, the results of which are published 

 in Annales de Chimie et de Physique, tend to 

 show that pseudo-purpurine, although itself 

 playing no direct part in dyeing, readily gives 

 rise to the formation of purpurine and hydrat- 

 ed purpurine, and is probably to be regarded 

 as the source whence these bodies are derived. 

 If this is true, then the number of distinct col 

 oring principles in madder is only two, namely, 

 alizarine and pseudo-purpurine. 



M. de Lalande, according to the Bulletin de 

 Mulhoiiise, has succeeded in artificially form- 

 ing purpurine by the oxidation of alizarine. A 

 mixture of concentrated sulphuric acid and 

 artificial alizarine, with arsenic acid, or other 

 oxidizing agent, is heated to 150 or 160 C., 

 and the product thrown into a large volume of 

 water ; the precipitate, when well washed, is 

 dissolved in a solution of alum, and on addition 

 of an acid the purpurine separates in dense 

 flakes. 



Improved Process fcr preparing Sulphate 

 of Nickel. An improved process for the prep- 

 aration of pure sulphate of nickel, for use in 

 the electro-deposition of that metal (nickel 

 plating), has been recently invented by M. Ter- 

 reil. This and other salts for the same pur- 

 pose, are prepared from commercial nickel, 

 which is an alloy of nickel, copper, and iron, 

 with traces of arsenic. The inventor's process 

 to get rid of these and obtain a pure sulphate, 

 consists of four operations : 



1. The nickel is dissolved in seven or eight times 

 its weight of nitro-muriatic acid, the solution is 

 evaporated nearly to dryness, and the residue is re- 

 dissolved in water, using about four times the weight 

 of the nickel employed. A little arseniate of iron 

 remains undissolved, and is removed by filtration. 

 2. Metallic iron in the shape of small nails, equal- 

 ing in weight the nickel present, is now put into the 

 hot solution, and by stirring from time to time the 

 copper is precipitated. When a piece of bright iron 

 placed in the liquid is no longer coated with copper, 



this part of the process is complete. The whole is 

 now placed on a filter and repeatedly washed. The 

 copper is then collected by sifting it under water in 

 a sieve coarse enough to let pass the coppery metallic 

 powder, but retain the iron. The copper is dried 

 and is then marketable. The filtrate now contains 

 only nickel and iron. 3. The iron is peroxidized 

 either by means of chlorine or nitric acid. Sulphu- 

 ric acid of 66 B. is then added, in the proportion of 

 two parts to one of nickel, and the whole is evapo- 

 rated to dryness in order to expel the nitric and hy- 

 drochloric acids. The dry residue is redissolved in 

 water, a little subsulphate of iron sometimes remain- 

 ing undissolved. 4. From this solution the iron is 

 precipitated by means of carbonate of baryta. This 

 separates the iron as sesquioxide, and forms at the 

 same time insoluble sulphate of baryta without, 

 however, acting upon the sulphate of nickel. The 

 last traces of arsenic are carried down with the ses- 

 quioxide of iron. The precipitation is effected by 

 gradually adding a small excess of carbonate of ba- 

 ryta to the liquid, slightly heated, but not to exceed 

 50 to 60. It is complete when a further addition of 

 carbonate of baryta causes no effervescence. Pure 

 sulphate of nickel then remains in solution. It is 

 separated from the precipitate by filtration, and the 

 filtrate is evaporated till a pellicle appears on the sur- 

 face, when it is set aside to crystallize 



Water-Analysis. The estimation of color 

 in water having become an important part of 

 water-analysis, Prof. J. Falconer King, in the 

 absence of any but rough and uncertain meth- 

 ods, has devised the following process for its 

 determination : 



To a known quantity of pure distilled water in a 

 glass tube an aqueous solution of caramel of certain 

 strength is added from a burette until the tint im- 

 parted to the distilled water is found to equal that of 

 the water under examination. Preparing the standard 

 solution of caramel is the only difficult part of the 

 operation. This is done by adding caramel to dis- 

 tilled water until the proper depth of tint is obtained. 

 The depth of color it should possess is ascertained 

 as follows : To eight ounces of %>ure water, perfectly 

 free from ammonia, contained in a glass tube, and 

 forming a column twelve inches long, add 10 grains 

 by volume of solution of ammonium chloride, con- 

 taining 3.17 grains of the salt in 10,000 grains of 

 water (or 0.0001 grain of ammonia in 1 grain of solu- 

 tion). To this mixture, after proper agitation, add 

 25 grains by volume of N easier' s solution, of the 

 usual strength ; allow this, after mixing, to repose 

 for ten minutes, at a temperature of 60 Fahr., when 

 the color produced will equal 30 on my scale. That 

 is, 300 grains by volume, or 30 (a degree being equal 

 to 10 grains by volume) of caramel solution, if of 

 proper strength, will produce exactly the same depth 

 of color when added to the same amount of distilled 

 water (eight ounces) in a column twelve inches long. 



The tubes employed are made of glass as free from 

 color as possible ; they should be fifteen inches long, 

 and of such diameter that when filled to within three 

 inches of the top, they will contain eight ounces of 

 water exactly. The caramel solution as thus pre- 

 pared maybe kept for a considerable time without 

 change. To use it in estimating the color of water, 

 fill two tubes of the dimensions given above to with- 

 in three inches off the top, one with distilled water, 

 and the other with the water to be tested ; and hav- 

 ing placed them side by side on a white slab, in a 

 good lightj add the caramel solution from a burette 

 to the distilled water until that is found to equal in 

 depth of color the water in the other tube. The 

 burette being graduated in grains, every ten grains 

 consumed will represent one degree of color. 



Influence on Vegetation of Arsenical Poisons 

 in the Soil. The use of Paris-green as an in- 



