896 CO. M. Warren on Organic Elementary Analysis. 
down till the level of mercury in this tube shall be half an inch 
to an inch below the level of mercury in the receiver O; an 
from time to time during the combustion the position of this tube 
is adjusted so as to preserve about this difference between the 
levels of the mercury, or at least so as to prevent the mercury 
in the tube from ever rising above that in the receiver. 
In this manner the mercury, instead of offering resistance to 
the passage of gas from the combustion apparatus, and thus in- 
creasing the internal pressure upon the joints, which would be 
objectionable, actually operates advantageously by producing 
partial exhaustion, and thus diminishing the internal pressure 
upon the joints, and consequeutly the liability to leakage. The 
distillation of the substance is now commenced, and conducted 
as previously detailed above. So soon as condensation of mois- 
ture appears in the neck of the chlorid of calcium tube, indi- 
roses at combustion has commenced, the flow of oxygen may 
more convenient and less liable to lead to error. At the close 
of the analysis, therefore, I expel the oxygen from the apparatus 
by admitting air from the air-gasometer,* saving for further use 
the oxygen which is expelled during the first five or six m)n- 
tes. Thus far I have applied this process only in the analysis 
° The oxygen-gasometer and the air-gasometer each having a separate drying 
the ti med in changing from much 
me consul ¢ from one to the other is very 
shortened, as the necessity for displacement of the oxygen or the case may 
be— is contained in the dryimg apparatus is avoided. Each drying apparatus 
consists, 1st, of ig’s bulbs, containing sulphuric acid; 2d, o nches 
high (nearly 3 feet of tube), fill ith soda-lime for acid; and 8d, of two 
such (5 to 6 feet of tube), filled with chlorid of calcium, The object ™ 
imensions is to avoi sity of t ee 
ters stand in a pan of eopper, which is provided with 
outlet to the sink, so that they may be filled without 
o_o degree of permanence 
. 
