and attractive Powers of various f aline Sub/iances . 25 
In 2 oz. French meafure ( = 945 gr. Troy) of fpirit of nitre, 
whofe fpecific gravity was 1,3160, he diflolved 2 oz. and 1 dr. 
of mercury ; the quantity of air obtained during the folution 
was 190 cubic inches French ( = 202,5 5 Englifh). This air was 
all nitrous. There remained a white mercurial fait, which, 
being diftilled, afforded 1 2 cubic inchls (= 12,785 Englifh) of 
air mixed with red vapours, and which differed little from com- 
mon air. There afterwards arofe 224 cubic inches ( = 258,56 
Englifh) of dephlogifticated air, during the production of which, 
the mercury was almoft revivified, there remaining but a few 
grains of a yellow fublimate. The 12 inches of air mixed with 
red vapours arofe, he fays, from a mixture of 36 cubic inches 
of nitrous air ( = 38,34 Englifh) and 14 of dephlogifticated air 
(14,91 Englifh); and as the mercury was almoft wholly re-, 
vived, he concludes, thefe airs arofe from the nitrous acid, ancf 
formed it ; and hence infers, that 16 oz. of this fpirit of nitre 
( = 7560 gr. Troy) contained 13 oz. 7 dr. 364 gr. (that is, 6589 
gr. Troy) of water, and confequently only 971 gr. Troy of 
real acid, and therefore 2 oz. of this fpirit of nitre contained 
hut 120 gr. Troy of real acid: but, by my calculation, 2 oz. 
of this fpirit of nitre contained 213 gr. acid ; for its ma- 
thematical fpecific gravity is 1,265. The lame weight of 
acid will alfo be found in it by computing the weight of the 
volumes of the different airs he himfelf found it confift of, or 
at leaf; to afford by its decompofition ; for 202,55 cubic inches 
of nitrous air weigh, by Mr. fontana’s experiment, 80,8174 
gr. Troy, and 238,56 inches of dephlogifticated air weigh 
100,1952 gr. Troy, and adding to thefe the weight of 38,54 
inches of nitrous air, and of 14,91 of dephlogifticated air, • 
which made the 1 2 cubic inches of air mixed with red vapours, 
we fhall find the whole weight of thefe airs to be 202,181 gr. ; 
Vol. LXXL E the 
