and on the Nature of the Diamond. 3 1 1 



In order to see how far the weight of the precipitate of 

 carbonate of Hme would agree with the resuhs of the fore- 

 going experiments, we drew off 20" 5 cubic inches of the ga? 

 which had been thus altered by the combustion of diamond 

 in the last experiment by the register H, and received it in 

 bottles over mercury ; then admitting lime water, we ob- 

 tained a copious precipitate of carbonate of lime, which 

 being dried at the temperature of 21 2'"" Fahrenheit, weighed 

 12 grains. 



But as the 20*5 cubic inches require the same corrections 

 to bring them to the mean temperature and pressure ; we 

 say, as the actual volume of all the gas is to its correction, 

 so is the quantity drawn off to that which it would have been 

 at the mean : 



49-84 : 31-20 : : 20-50: 21-06, the volume after the correc- 

 tions were made. 



Then, to find how much carbonic acid was contained in 

 these 21-06 cubic inches, we state it thus: As the total 

 quantity of gas after the experiment is to the total weight of 

 carbonic acid gas found by calculation, so is the quantity 

 of gas experimented upon to the weight of carbonic acid 

 gas which it ought to have contained, 



51-20 : 13-91 : : 21'06 : 5-72 grains. 



Every 100 grains of precipitated carbonate of lime contain 

 44 grains of carbonic acid ; 12 grains were procured in our 

 experiment. 100 : 44 : : 12 : 5-23 



Therefore the carbonic acid conlained in our precipitate of 

 12 grains weighed 5*28; by calculation it should have 

 weighed 5*72; this is as near as we had a right to expect 

 from the difficulty of collecting the precipitate. 



Stone Coal. 

 Upon the suggestion of our mutual friend Professor Davy, 

 we next examined the results of the combustion of stone 

 coal and plumbago; thermometer 57° Fahrenheit, baro- 

 meter 29-65. 



The stone coal from Wales, employed by maltsters, is 

 well known to contain little or no maltha or mineral pitcli, 

 and to burn without flame, 



A portion 



