of Atmospherical Air, Se. 129 
siderable. By these experiments it is intended to 
prove, not only that something was emitted from 
the bones and the needles, but also, and particularly 
that during the calcination of metals, and in com- 
bustion, no oxygen is absorbed or imbibed. 
«¢ What is most important in these experiments,” 
says Dr. Priestley, * is that, since the diminution of 
the air was effected by heating those substances, and 
they did not gazn any weight in the process, the 
phlogistication of air is not the absorption of any 
part of it bythe substance which produces that effect, 
as the antiphlogistic theory supposes.” 
Before I attempt to explain the result of these ex- 
periments, I must request the society to attend a 
little to their nature, and to the manner in which 
they were made. It is not only very objectionable 
that atmospherical air, or a mixture of different 
gases, was employed in experiments, the result of 
which was to shew the mutual action of the bones 
and needles on only one of them, namely, the oxy- 
genous gas; while it would have been easy to have 
made use of this gas in its greatest purity; but we 
are not even informed of the degree of purity of 
the air previous to the operation. This information 
should not have been withheld, because the purity 
of atmospherical air vaties in different places and 
circumstances. —T hese experiments were made over 
water: a method which always leaves some doubt of 
the exactness of the result, not only on account of 
VOL. v. ane 
