128 Remarks on Priesiley's Analysis 
that vitriolic-acid-air has, according to his mode of 
expression, the power of diminishing and phlogisti- 
cating air, says: ‘ that it is owing, no dowbé, in 
part, to its imbibing the dephlogisticated part of it, 
and with it forming vitriolic acid ;* but at the same 
time part of its phlogiston may unite with another 
part of the dephlogisticated air, and with it form 
phlogisticated air.” However, when this vitriolic- 
acid-air is mixed with pure oxygenous gas in due 
proportion, the whole is absorbed and no azotic 
gas is produced. No phlogistication, therefore, takes 
place in this process. 
I shall now consider the experiments which Dr. 
Priestley has made with black bones and steel 
needles. In the former, he heated, by means of a 
burning lens, 140.5 grains of black bones in 23.75 
ounce-measures of air, which thereby were reduced 
to 20 ounce measures. In the other experiment, 
he heated 200 grains of polished steel needles in 24 
ounce measures of air, which were reduced to 19.5 
ounce measures. In these experiments the operator 
avoided to apply a great heat, and a copious pre- 
cipitation took place, or a thick crust was formed, 
when they were made over lime water. The bones 
gained no weight, but rather lost some. The needles 
and iron gained a little weight, though very incon- 
* Vitriolic acid, according to the doctrine of Phlogiston, 
is sulphur deprived of its phlogiston, 
