Carbonic Acid and Ammonia. 19 
nic acid, shewing it to be a,compound of the 
two elements carbone. or charcoal and oxygen, 
and ascertaining the proportion of these two 
elements which combine to produce the acid ; 
soon after, Berthollet, discovered that ammo- 
nia 1s a compound of the two elements or 
principles denominated azote and hydrogen, 
and succeeded in determining the proportion 
of these elements, which combine to form.am- 
monia. 
Sincethese discoveries various authors have 
attempted to determine the proportions.of the 
elements of the salt formed by the combina- 
tion of carbonic acid and ammonia, but not 
with equal success. Itis agreed that the salt 
contains the two elements just mentioned and 
water; but the precise quantities of each 
have not been ascertained, as the analyses 
differ materially one from another. One 
principal reason for these differences, it will 
appear from what follows, is, thatthe salt it- 
self is subject to great variations in its con- 
stitution, which the authors have not been 
sufficiently aware of. It has lately fallen in 
my way to use this salt in chemical investiga- 
tions, and I found it expedient to understand 
the proportions of its elements more accu- 
xately, and therefore instituted a course of 
experments with this express object. The 
