Series of Bodies derived from the fuming liquor o/" Cadet. 371 



compound unchanged. Dilute cold nitric acid forms with 

 alkarsin a thick fluid. Alkarsin is dissolved by digestion 

 with concentrated hydrous sulphuric acid; the liquid on cool- 

 ing forms a mass of small white acicular crystals : they may 

 be freed from the matrix by pressure between paper, deli- 

 quesce in the air and react acid. Nitrate of cacodyloxide 

 gives peculiar precipitates in metallic solutions, but their na- 

 ture is not as yet determined. With the hydracids alkarsin 

 forms water and a haloid salt. It extracts the oxygen from 

 the oxides of mercury, silver, gold, &c.: even arsenic acid 

 and indigo are reduced by it. Alkarsin may be used as a 

 test for the presence of arsenic. If the substance obtained 

 by Marsh's apparatus be boiled with water until dissolved, 

 and a little potash and acetic acid added, and this solution 

 evaporated to dryness, the mass when heated in a glass tube 

 gives the horrible smell of alkarsin, if any arsenic be present: 

 antimony has no such effect. If a drop of protochloride of 

 tin be added to the heated substance, the characteristic smell 

 of chloride of cacodyl is developed. 



Sulphuret of cacodyl, Cd S, is obtained by distilling chlo- 

 ride of cacodyl with hydrosulphuret of barium, BaS, HS; hy- 

 drosulphuric acid (sulphuretted hydrogen) is given off. The 

 distillation with the hydrosulphuret must be repeated. The 

 water and excess of HS may be removed by chloride of cal- 

 cium and carbonate of lead ; the fluid must then be carefully 

 protected from the air. The acid fluid which accompanies the 

 Cadet's fluid gives a considerable quantity of this protosul- 

 phuret when treated with the above-mentioned barium salt. 

 The aqueous solution of cacodylic acid (alkargen) when 

 treated with hydrosulphuric acid also gives it. In an alcoholic 

 solution the higher sulphuret is produced. 



Cd S is a clear agthereal liquid which does not fume in the 

 air, of a disagreeable penetrating odour, which reminds one 

 of alkarsin and mercaptan. Does not become solid at 

 — 40° C. : distils over with water, although its boiling point 

 is much higher than 100°. Easily inflammable in the air; 

 the sulphur is perfectly oxidized by strong nitric acid. It is 

 nearly insoluble in water, but communicates to it a stront^ 

 smell ; may be mixed with aether and alcohol in all propoi^ 

 tions ; combines with sulphur into a crystalline sulphuret. 

 Selenium also forms a similar compound, which crystal- 

 lizes out of aether in colourless laminae. Iodine forms a cry- 

 stalline substance. Oxygen converts it into alkargen, and an, 

 as yet, unexamined crystallized matter. Hydrochloric acid 



forms Cd CI + HS. Sulphuric acid gives Cd O, S"+ HS, 



2 B2 ~ 



