and attractive Powers of different f aline Subjlances . 1 7 
m the form of air, as Dr, Priestley has fhewn ; for when it 
is deprived of water and phlogifton, and furnifhed with a due 
proportion of elementary fire, it ceafes to have the properties of 
an acid, and becomes dephlogifticated air ; I could not, there- 
fore, determine its proportion in fpirit of nitre as I had done 
that of the marine acid, but was obliged to ufe another 
method. 
ift.To 1 963.25 gr. of this fpirit of nitre, whofe fpecific 
gravity was 1,419, I gradually added 179,5 gr. of diftilled wa- 
ter, and when it cooled I found the fpecific gravity of this mix- 
ture 1,389. 
2dly. To 1984,5 gr. of this I again added 178,75 gr. of wa- 
ter.; its fpecific gravity was then 1,362. 
I then took 100 gr. of a folution of fixed vegetable alkali, 
whofe fpecific gravity was 1,097, the fame I had before ufed in 
the trials with fpirit of fait, and found this quantity of alkali 
to be faturated by 1 1 gr. of the fpirit of nitre, whofe fpecific 
gravity was 1,419 ; and by 12 gr. of the fpirit, whofe fpecific 
gravity was 1,389 ; and by 13,08 of that, whofe fpecific gra- 
vity was 1,362. The quantities here mentioned were the me- 
dium of five experiments. I found it neceffary to dilute the 
nitrous acid with a fmall proportion of water, of which I kept 
an account. When I neglected this precaution, I found that 
part of the acid was phlogiftiqated, and went off with the fixed 
air. Note alfo, that after each affufion of acid ten minutes 
were allowed to the matters tQ unite, a precaution which I alfo 
found abfolutely neceffary. 
Hence (upon the fuppofition that a given quantity of fixed 
vegetable alkali is faturated by the fame weight of both acids) 
we fee that 11 gr. of fpirit of nitre, whofe fpecific gravity is 
1,419, contain the fame quantity of acid as 27 gr. of fpirit of 
Vol. LXXI. D 7 fait. 
