ae came 
§ 2. Of the Proportion of Ingredients in Neutral Salts formed with 
common Mineral Acids. 
THIS problem involves all the difficulties of the former, befides 
fome that are peculiar to it. For fuppofing the proportion of acid 
to be given, it ftill remains to determine the ftrength of that acid, 
elfe the word prefents no definite meaning. This can be done 
only by reference to fome known ftandard. The chemifts whofe 
inquiries have preceded or accompanied mine, have confidered the 
acid retained by neutral falts in a red heat as the /fronge/t 
pofible. But unlefs all thefe falts poffefs the fame power of re- 
taining acids in a red heat, this term muft have a_ different 
fignification when applied to each, and confequently prefent no 
determinate idea. Now it is well known that different neutral 
falts poffefs this power in different degrees ; befides the term red 
heat isa term of great latitude, and comprehends degrees of heat 
very diftant from each other. 
Tue determination of- the proportion of water in thefe falts, 
on the fuppofition that they all neceffarily contain fome, is at- 
tended with nearly the fame difficulties. It has generally been 
fuppofed that the weight loft by neutral falts when expofed to a 
red heat, expreffed the quantity of water of cryftallization, but it 
is now known that fome of them lofe part of their acid as well 
as their water in that heat, to fay nothing of the difliculty of 
conftantly employing the fame exact degree in all cafes, or if it 
could be employed, of fuppofing that they all poffefs the fame 
power of retaining the aqueous part. Even the ancient opinion, 
that cryftallization neceffarily implies the prefence and retention 
of 
