368 L. F. Wood—Arsenic as Pyroarseniate of Magnesia. 
grade, probably belonging partly to the saturated and partly to 
the non-saturated series; of this latter series, very considerable 
quantities may be condensed by combination with bromine after 
having passed through a freezing mixture. It is particularly 
interesting to observe that when chlorhydric acid is used, the 
chlorides of hydrocarbons are obtained. . 
Under the conditions of these experiments the quantity of 
hydrocarbons, which are not volatile with the vapor of water, 
is too small to allow them to be collected. 
No formation of an organic acid could be observed. 
. 
No. IV. On the Estimation of Arsenic as Pyroarseniate of 
Magnesia; by L. F. Woop. 
FRESENIUS determination of the solubility of arseniate of 
magnesia and ammonium in different saline solutions, and 
Puller’s+ very thorough investigation of the conditions under 
which arsenic acid should be precipitated with magnesic mIx- 
ture, and of the properties of the precipitate, show us the sources 
of error to which this method of analysis is liable and also the 
means of avoiding them. as 
Puller recommends using a slight excess of magnesia MX 
the lability to error from asty ignition, are grav order to 
the above 
0. 
Rose can be successfully used with some modifications. . 
i Ff was a solution of pure a 
as e 
magnesium in alcohol of strength about 85 per cen e solu 
tion contained about 100 grams MgCl, per liter. 
‘ 41. 
* Zeit. fiir Anal, Chemie, 1864, p. 206. + Zeit. fr Anal. Chemie, 1871) P 
eo Oat tee eee 
. 
