-3 2 Afrvx ir wan’s 'Experiment's, 8cc. cn Be- fpecific Gravities 
xafe' the excefs of weight will be very nearly finch as he deter* 
mined it: for -H 10,5 .8,3:: 472,5 . 373,3. Now, the whole 
weight of his nitre was 560,2, as I have above {hewn : then 
560,2 - 373,32= 1 1 6,p, which is only 4 gr„ more than he de- 
termined it. 
Hence he inferred, .that t oz. -(472,5 gr. Troy) of this oil 
of vitriol contains 291,7 gr. of acid. By my computation it 
■contains but .213,3 ; but it mu ft be confidered, he made no 
allowance for the water contained in tartar vitriolate, and ima- 
gined the whole of the increafe of weight proceeded from, the 
acid that is united in it to the fixed alkali. Now the aqueous 
part in 560 gr. of tartar vitriolate amounts to 37 gr. the re- 
maining difference may be attributed to the different degrees of 
defecation, &c. 
OF THE ACETOUS ACID. 
I have made no experiment on this acid ; but, by calculating 
from the experiment of Mr. homberg, I find the fpecific gra- 
vity of the pure acetous acid, free from fuperfluous water, 
fhould be 2,130. It is probable, its affinity to water is not 
ftrong enough to caufe any irregular increafe in its denfity, at 
lead that can be expreffed by three decimals ; and hence its pro- 
portion of acid -and water may always be calculated from its 
fpecific gravity and abfolute weight. 
100 parts of foliated tartar, or (as it fhould rather be called) 
acetous tartar, contain well dried 3 2 of fixed alkali, 1 9 of acid, 
and 49 parts of water. 
The fpecific gravity of the ftrongeft concentrated vinegar yet 
made is 1,069. 
it- 
