J. M. Crafts on Ethers of Arsenic Acid. 11 
tially decomposed on distillation. After several distillations a 
small quantity of a body was isolated, which contained arseni- 
ous, but no arsenic seg and which proved to be an impure ar- 
senious ether. It is evident from these results that, at the 
the arseniate of ethyl can be easily prepared by the action of 
the iodid of ethyl on the arseniate of silver— 
8C,H, I+ Ag,AsO,=3Ag I+(C,H;),AsO,. 
When the two bodies, mixed with pure anhydrous ether are 
heated together at about 90° in a sealed tube, the reaction is 
completed in a few hours, and the point at which this takes 
place is marked by the change of color of the silver salt from 
red to light yellow. It is important that the arseniate of silver 
should be in excess and that the temperature should not exceed 
100°, as the iodid of Biel HS oe a portion of the arseniate 
e liquid of sil Ae ge Ne 
the tube and washed with a ether until it is entirely freed 
The solution in ether is distilled and finall th in a 
water-bath, while a current of dry air is peseol through it to 
carry off the last trace of ether. The arseniate of ethyl thus ob- 
can be most peed: ae ee te distillation in a 1 
sete in the air. 
ressure so 
as when it As —- aa — For instance, the pressure may 
well vary 2 illati 
a variation pease ap illimeters affects the boiling point 
much more than a wea from 200 to 202 millimeters, 
In the case of the —— of ethyl it was found that it dis- . 
tilled under a pressure of 60 millimeters at about 85° lower than 
in the air, and that this ditiureues of temperature was sufficient 
