222 Scientific Intelligence. 
the alkaloids are easily extracted thus. (7) The relation of japa- 
conitine to its derivatives and to aconitine is conveniently ex- 
method demands more than a passing notice. It is so simple 10 
its theory and manipulation, so universal in its application, and it 
avoids in such a remarkable way the main difficulties and sources 
of inaccuracy, which are inherent in all the methods hitherto 
employed for the same purpose, that it promises to become one 0! 
the most important aids in the investigation of chemical science. 
nee theory of the method may be stated thus. 
a known Pate +43 ‘gs : 
De | 1 dropped 
the weight of the air expelled. The problem is thus reduced to 
of the temperature or volume of the vesse which may 
in unknown quantities. All the uncertainties, therefore, coD- 
nected with the measurements of high te tures, or of the 
have only to collect the air over a common water pneumatic 
trough and measure its volume, at the ordinary temperature - 
pressure of the air in 
easily calculate the weight required; or, if the material undeF 
examination is liable to oxidation, the vessel may be previously 
filled with nitrogen or some other inert gas, since the volume of 
such gas will be the same as the volume of the air under the 
