BUNSEN ON THE CACODYL SERIES. 303 
6. Hydrous Chloride of Cacodyl. 
If muriatic acid gas, well dried by sulphuric acid and chloride 
of calcium, be conducted into pure oxide of cacodyl, so as to 
allow no air to enter at the same time, it will be absorbed with 
great violence and the evolution of much heat. The liquid di- 
vides into two layers, and a small quantity of a brick-red pow- 
der is deposited, which will be described in another place. A 
homogeneous liquid is obtained by placing the oxide in a cool- 
ing mixture, and continuing the absorption of the gas till no 
more takes place. A quantity of gas escapes from this liquid 
by simply stirring it with an angular substance. It also divides 
itself into the two layers by heating it in an atmosphere of 
carbonic acid so long as any gas makes its escape. The upper 
layer is very limpid, and presents all the characters of the chlo- 
ride of cacodyl. The under layer is so viscous that it cannot be 
drawn up into a fine glass tube. It is clear that this under 
layer can be nothing else than hydrous chloride of cacodyl, as 
no other product is formed in this process. We know, from 
former observations, that chloride of cacodyl and water are 
formed by the action of the gas, and this latter body is not de- 
posited, as it can be dissolved by the new substance formed, 
and therefore immediately unites with the chloride in the mo- 
ment of its formation. This water is partially separated by di- 
stillation, and hence the formation of the two layers, which con- 
sist respectively of anhydrous and hydrous chloride of caco- 
dyl, as they are only very slightly soluble in each other. This 
view is also supported by the fact, that chloride of calcium deli- 
quesces in the viscous fluid and leaves pure chloride of cacodyl. 
I could not make an analysis of this interesting compound, in 
consequence of its being decomposed by distillation, without 
which it would contain traces of muriatic acid. 
7. Iodide of Cacodyl. 
If concentrated hydriodic acid be distilled with oxide of caco- 
dyl, a yellow oily liquid collects in the receiver under the water, 
which on cooling deposits a yellow crust on the surface; and 
if this be allowed to proceed slowly, very fine, well-formed, and 
_ transparent rhombohedral plates make their appearance. The 
fluid portion is the iodide of cacodyl, and in order to separate 
this completely, the whole must be cooled down as low as pos- 
sible in a freezing mixture. The fluid which remains must be 
