DERIVATIVES OF METHYL ALCOHOL. 41 



fire ; its vapor is very poisonous ; it combines directly 

 with oxygen, sulphur, and chlorine. 



Cacodyl chloride, (CH 3 ) 2 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. 



Cacodyl 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, [(CIP) 2 AspS. 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* 



