DERIVATIVES OF METHYL ALCOHOL. 41 



fire ; its vapor is very poisonous ; it combines directly 

 with oxygen, sulphur, and chlorine. 



Cacodyl chloride, (CH 3 )'AsCl. Liquid, boiling at 

 100 ; heavier than water ; unites with metallic chlo- 

 rides. The iodide and bromide are similar to the chlo- 

 ride. The cyanide forms large prisms, fusing at 30, 

 boiling at 140. Exceedingly poisonous. 



Cac9dyl oxide, [(CH 3 ) 2 As] 2 0. Is formed by slow 

 oxidation of cacodyl, simultaneously with cacodylic 

 acid, and can be separated from the latter by distilla- 

 tion. Liquid, boiling at 150, of disagreeable odor. 

 It does not give off fumes in contact with the air, and 

 does not take fire ; is oxidized slowly, however, forming 

 cacodylic acid. It combines with 2HgCl 2 , yielding a 

 crystalline compound. 



Cacodyl sulphide, [(CH 3 ) 2 As] 2 S. By distilling 

 cacodyl chloride with potassium or barium sulphhy- 

 drate. Colorless liquid, of a disagreeable odor; insolu- 

 ble in water, easily soluble in alcohol and ether. 

 Yields cacodyl chloride and hydrosulphuric acid when 

 treated with hydrochloric acid. 



Cacodyl disulphide, (CH 3 ) 4 As 2 S 2 , is formed by dis- 

 solving sulphur in cacodyl or cacodyl sulphide. Large 

 colorless crystals, fusing at 50 ; not volatile without 

 decomposition. 



Cacodylic acid, (CH 3 ) 2 As.OH. Is produced by 

 slow oxidation of cacodyl, and by the action of mer- 

 cury oxide on cacodyl under water (or on the crude 

 liquid alkarsin). Large, colorless, deliquescent prisms, 

 which fuse at 200 ; are inodorous and -not poisonous. 

 Phosphorous acid reduces it, forming cacodyl. 



Cacodyl trichloride, (CH 3 ) 2 AsCl 3 . Is formed by 

 the action of phosphorus pentachloride (under ether) 

 on cacodylic acid, or when chlorine is conducted upon 

 the surface of a solution of cacodyl in carbon bisul- 



4* 



