146 
ON CHEMISTRY. 
their several functions, as it manifestly is indispensable to tbe very 
existence of the animal creation. But what is Air P is it, in fact,— 
as was sacredly believed at no very remote period, a simple element, 
one of “ the four,” or is it not ? 
Let us have recourse to experiment—and in the first place, let us 
pay the just tribute of respect due to the great Lavoisier, and adduce 
his important, his conclusive discovery. 
As it will be impossible to present a drawing of the apparatus em¬ 
ployed by the operator, I must be content to state the materials em¬ 
ployed, and the final results, in general terms, referring the reader to 
Vol. 1, pages 82 and 3, of the fifth edition of the “ Elements of 
Chemistry." Four ounces of quicksilver were introduced into a 
glass-matrass or retort, the beak of which passed through a body of 
the same fluid metal, into a bell-glass receiver. These two vessels 
contained about fifty cubical inches of atmospheric air. “Having 
accurately noted the height of the thermometer and barometer,” (I 
quoted the pxact words) “ I lighted a fire in the furnace” (upon this 
furnace the retort was placed, and reference is here given to an en¬ 
graving,) “ which I kept up almost continually during twelve days, 
so as to keep the quicksilver always very near its boiling point. 
Nothing remarkable took place during the first day : the mercury, 
though not boiling was continually evaporating, and covered the in¬ 
terior surface of the vessel with small drops, which gradually aug¬ 
menting to a sufficient size, fell back into the mass at the bottom of 
the vessel. On the second day, small red particles began to appear 
on the surface of the mercury; these, during the four or five follow¬ 
ing days, gradually increased in size and number, after which they 
ceased to increase in either respect. At the end of twelve days, see¬ 
ing the calcination of the mercury did not at all increase, I extin¬ 
guished the fire, and allowed the vessels to cool.” The bulk of air 
in the body and neck of the matrass, and in the bell-glass, at the 
same medium height of the barometer and thermometer as at the 
commencement of the experiment, w r as reduced from fifty cubical 
inches to something between fortv-two and forty-three cubical inches ; 
“ consequently it had lost about one-sixth of its bulk. Afterwards, 
having collected all the red particles from the running mercury in 
which they floated, I found these to amount to forty-five grains.” 
This experiment was several times repeated to attain assured ac¬ 
curacy ; this being effected, “ the air,” he adds, “ which remained 
after the calcination of the mercury in this experiment, and which 
was reduced to five-sixths of its former bulk, was no longer fit either 
for respiration or for combustion : animals being introduced into it 
