and the Sulphurets of Kakodyl. 181 
1. Kakodylic Acid. 
The production of this curious body, which I formerly called 
Alkargen, dependsupon one of the most uncommon phzenomena 
of organic chemistry. It is formed namely by the direct oxi- 
dation of the radical or of its protoxide. If the former is gra- 
dually brought into contact with oxygen, this gas being al- 
lowed to come in contact with it so slowly that inflammation 
cannot occur, it absorbs one atom of oxygen and is converted 
into oxide of kakodyle. If the air be still allowed to act on 
this body under similar precautions, part of the oxide takes 
up 2 atoms more oxygen, forming an acid which combines 
with the excess of oxide, producing a new state of oxidation 
of the nature of a salt, and which, doubtless, corresponds to 
the hyponitric acid NO + NO, or N?O*%. This compound, 
which cannot however be completely freed from excess either 
of oxide or of acid, forms a tenacious thick fluid, which is less 
soluble in water than the acid, but more so than the oxide, and 
which when distilled is resolved into these two bodies. If 
this tenacious liquid be warmed to 50° C. and a current of 
oxygen passed through it for several days, it is finally con- 
verted into kakodylic acid, which may be purified by pressure 
between bibulous paper and repeated crystallization. 
The behaviour of this radical is therefore in exact contra- 
diction to the premises of Dumas’ theory of substitution*, and 
is perfectly similar to that of a simple metal, which when ex- 
posed to the influence of oxygen runs through all the inter- 
mediate steps of oxidation until it reaches the highest, as is 
seen in the accompanying table :— 
C*H® As? .... = Free radical. 
CH’ As?O... 1st product of the action of oxygen, 
TAS pt 2 DBO pve oes ae 
HO+C*H® As?O? 3rd ... side kaa 
The preparation of kakodylic acid by direct oxidation of the 
oxide is rendered both disagreeable and dangerous by the 
great inflammability of this substance, and by its stupifying 
odour. I have therefore endeavoured to discover a simpler 
method of preparation, and oxide of mercury is extremely well- 
suited for the purpose ; for when this substance is digested 
under water with oxide of kakodyl, it converts the whole of it 
in a few seconds into kakodylic acid, which may be purified 
by a single recrystallization from alcohol. 76 grammes of 
oxide of kakodyle which had not been freed from water, gave 
when treated in this manner 88 grs, of the hydrated acid. If 
the oxide had been anhydrous it should have given 92°7 grms., 
* See Phil. Mag. 8. 3. vol. xvi. p. 322.—Epir. 
