$60 On thé Gaseous Combinations of 
portion of water, the remainder of the 100 must be fluoric 
acid. Hence fluate of lime is composed of, 
Lie Ao ret 
‘Fluoric acid ........ 32°66 ; 
ee 
100°00. 
This result differs very materially from the analysis al- 
Juded to in the beginning of this’ paper, which makes the 
amount of the acid in the same weight of spar only 16 
grains, and the lime 57 grains; the remaining 27 grains 
being considered as water. But, from the care with which, 
my experiment was conducted, I flatter myself that the re- 
sult which it exhibits is very near the truth*. 
XLVI. On the Gaseous Combinations of Hydrogen and 
Carbon. By THomas THomson, M.D. F.R.S.E.F 
Tas gases formerly distinguished by the name of heavy 
inflammable airs, which are evolved during the distillation 
of most animal and vegetable substances, differ so much 
from each other in their properties, that it has been hitherto 
impossible to reduce them under a small number of species. - 
When burnt, they all yield carbonic acid and water, and of 
course contain carbon and hydrogen; but the proportion 
of these bodies formed, and of oxygen consumed, during 
the combustion, varies very much at different times. Many 
of these gases have been examined with much address by 
Cruickshanks, Dalton, and Henry.  Berthollet also has 
examined them at different times, and published very in- 
genious dissertations on their composition. 
From a great many experiments on these gases, at dif- 
ferent times, and in different states, I have convinced my- 
self that they usually hold an empyreumatic oil in solution, 
and that the differences in their specific gravity, and other 
properties, depend very much upon the proportion of oil 
present. Hence no pure gases, fit for examination, and 
comparable with each other, can be obtained from those 
vegetable or animal substances which yield an oil when 
subjected to heat, as is the case with most of them, To 
this oil is to be ascribed the great variation in the specific 
* Since the preceding paper was read, I have seen an analysis of fluor 
apar by Klaproth, in the 4th volume of his Beitrige, conducted in a very dif- 
- ferent manner ftom mine, but leading to almost the very same result. He 
found fluate of lime composed of 672 lime, and 32} acid,—quantities which 
goincide with mine within less than 1 per cent——Nov., 1809. 
+ From the Wernerian Transactions, 
gravity 
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