[ 49 ] 
Ir is difficult to afcertain the precife quantity of pure cal- 
careous earth in marble or any calcareous ftone, by reafon of 
the quantity of water they are alfo faid to contain. The marble 
I examined contained 3 per cent. of a mixture of argil and. 
minute cryftals, which rendered the folution turbid when fome- 
what more than half faturate; but I colleéted this proportion 
from a folution of the fame marble in fpirit of falt. If marble 
contained no water the quantity of calcareous earth would thence 
be eafily had, as the quantity of air being 45 grs. that of the 
earth fhould be 55, and deduting 3 for foreign earths, the 
pure calcareous would be 52. Mr. Coudray is the. only perfon. 
I can recolle&@ who found water in white marble*, but his 
experiment was defective. Dr. Watfon could dete& none by 
diftillation even in fpart. I diftilled a folution of marble in 
nitrous acid to drynefs, and expelled all the acid, for the earth 
was converted into lime; I was however difappointed, for I 
could not colle& the whole of it, as part ftuck to the retort. 
But Mr. D’Arcet having calcined a piece of white marble of 
Carrara in the ftrongeft porcelain heat, in which he found it to 
lofe no more than $ of its weight, exactly the fame as by folution 
in acids, feems to me to have decidedly proved that it contains 
no water}. Then if 100 parts of this marble contain 52 of 
pure lime, 74 parts will contain 38,68, and thefe take up 100 
parts of the nitrous ftandard, then too: parts lime take 258,5 of 
this flandard. 
Vor. 2Ve H Mar.. 
* 5 Roziers, p. 280. + 2 Watfon, p. 252.. t 22 Roziers, p..23.. 
