36 Mr. kirwan’s Experiments , &c. on the fpecific Gravities 
cubic inch of fixed air (the barometer being at 29°!) would 
weigh 0,57 of a grain; therefore the weight of the whole 
quantity of fixed air amounted to 58,368 gr. which is nearly 
one third of the weight of the marble. At this rate, 100 gr. 
of the marble contained 32,42 of fixed air. 
To determine the proportion of water and calcareous earth, 
andalfo the fpecific gravity of this latter, I put 3009,25 gr. of 
the fame marble finely powdered into a crucible, loofely covered ; 
the crucible audits contents, before calcination, weighed 8394 
gr. and after remaining fourteen hours in a white heat I found 
it to weigh 7067,5 gr. The weight of the crucible alone was 
c 3^4>75 g r * 5 therefore the weight of the lime fingly was- 
1682,75 gr. The marble then loft by calcination 1326,5 gr. ; 
180 gr. of the marble fhould then lole 79,343 gr. and 100 gr. 
lhould lofe 44,08 ; but of thefe 44,08, 32,42 were fixed air, as 
is already feen, therefore the remainder, that is, 11,66 gr. 
were water, and the quantity of pure calcareous earth in 100 
gr. of the marble was 55,92 gr. 
I next proceeded to difeover the fpecific gravity of the lime. 
Into a brafs box, which weighed 607,65 gr. and in the bot- 
tom of which a fmall hole was drilled, I fluffed- as much as 
poflible of the finely powdered lime, and then ferewed the cover 
on, and weighed it both in air and water. When immerfed in 
this latter, a confiderable quantity of common air was expelled'; 
when this ceafed, I weighed it. Therefultof this experiment 
was as follows : 
Weight 
