52 Mr. KitiW A n*s Experiments and Obfervatlons on 
would, if deprived of the whole of it. On this account I was 
obliged to ufe different methods, of which I fhall here give an 
inftance. With regard to the folution of filver in the nitrous 
acid, as it could be had extremely faturate I began with it. 
657 grs. of this folution contained, according to my calcula- 
tion, and allowing for the quantity of acid carried off in the 
nitrous air, 31,38 grs. of real acid, and 100 grs. of filver. Of 
this folution I found that 9 grs. gave a vilible red tint to as 
much of a dilute foiiltion of litmus, as a quantity of fpirit of 
nitre, which contained JLths of a grain of real acid, and 
therefore I judged thefe 9 grs. to contain an excefs of acid, 
amounting to JLths of a grain ; and if 9 grs. contain fuch an 
excefs, then the whole folution muff have contained an excefs 
amounting to 5-%-ths of a grain, deducing which from 31,38, 
we find the quantity of acid faturated by 100 grs. of filver to 
be 25,78 grs. In this manner I proceeded with mold other 
metallic folutions. The vitriolic folutjons of tin, wifmuth, 
regulus of antimony, nickel, and regulus of arfenic, contain- 
ing a large excefs of acid, I faturated part of it with cauftic 
volatile alkali before I tried them with the infufion of litmus, 
and I ufed the fame expedient with the nitrous folution of iron, 
lead, tin, and regulus of antimony, and all the marine folu- 
tions. The proportion of vitriolic and marine acid taken up by 
lead, filver, and mercury, I determined by computing the 
quantity of real acid neceflary to precipitate thefe metals from 
p 
their folutions in the nitrous acid ; and of all the determina- 
tions thefe appeared to me to be the moil exadl. However, as 
all the vitriols of thefe metals are, though in a flight degree, 
foluble in the nitrous acid, I was obliged to reftify the refult 
from other confiderations, and the fame neceffity occurred with 
regard to the marine falts of lead and mercury. 
The 
