192 Continuation of the Experiments and Obfervations 
The fpecifk gravity of the concrete volatile alkali weighed in 
aether was 1,4076. 
The proportion of water in the different ammoniacal lalts I 
have not been able to find, on account of their volatility ; but 
believe it to be very fmall, as volatile alkali and fixed air cryftal- 
lize without the help of water, when both are in an aerial ftate. 
OF CALCAREOUS EARTH. 
, f • •'> 'Pl ' ' lUV* ■' ’ . > 
* : k J L } 
1 firft di halved this earth in the nitrous acid, and found that, 
after allowing for the lofs of fixed air and the quantity of wa- 
ter I formerly mentioned, 100 gr. of the pure earth take up 
104 of mere nitrous acid. In head of diffolving this earth im- 
mediately in the vitriolic acid, I* precipitated its folution in the 
nitrous hy the gradual addition of- the vitriolic, and found 
that to effect this 91 or 92 gr. only of mere vitriolic acid were 
• • jO , 1. jl ■ ' • 
required. . , 
100 gr. of this pure earth demand for their folution 1 1 2 of 
mere marine acid. The folution, which is at firft colofirlefs, grows 
greenilh on Handing. Natural Gypfum varies in its proportion 
of acid, earth, and water, 100 gr.'-of it containing from 32 
to 34 of acid, and alfo of earth, and from 26 to 32 of water. 
The artificial contains 32 of earth, 29,44 of acid, and 38,36 
of water; when well dried it lofes about 24 of 'Water, and 
therefore contains 42 of earth, 39 of acid, and 1 9 ot water 
per cent . 
100 gr. nitrous felenlte , carefully dried, contain 33,28 of 
acid, 32 of earth, and 34,72 of water. 
100 gr. marine felenite , well dried, io as to lofe no part of 
the acid, contain 4 2,56 of acid, 38 of earth, and 19,44 of 
water. 
OF 
