on Hepatic Air 9 
127 
SECTION II. 
Of the general CharaSlers of Hepatic Air • . 
I found the abfolute weight of this air by weighing it in a glaf$ 
bottle, previoufly exhaufted by Mr. Hurter’s new improved air- 
pump, whofe effect is fo confiderable as to leave in general only 
-g-i-g. and frequently but part of unexhaufted air. This 
bottle contained 1 16 cubic inches nearly ; and this quantity of 
hepatic air weighed 38,58 grains, the thermometer being then 
67°, 5, the barometer 29,94, and M. Saussure’s hygrometer 
84°, the weight of 116 cubic inches of atmofph^ric air 
being at the fame time 34,87 grains; hence a cubic foot of 
hepatic air weighs* in thefe circumftances, 574,7089 grains, 
and 100 cubic inches of it weigh about 33 grains; and its 
weight, relatively to that of common air, is as 10000 to 9038 
This hepatic air was extracted from artificial pyrites by marine . 
acid. 
The inflammability of this air has been already mentioned. 
It never detonates with common air ; nor can it be fired, in a 
narrow-mouthed veflel, unlefs mixed with a confiderabie* pro- 
portion of this air. Scheele found if to inflame when 
mixed with two- thirds of this air. According toM. Sennebxer 
* Hence the weight which I have afligned to common air in my firft paper, after 
M. Fontana, is evidently erroneous ; and, indeed, by that determination com.7 
mon air would not be even 700 times lighter than water, in the temperature of 
£5°, and the barometer 29,5, which contradicts . all barometrical and aeroflatic 
experiments : and I cannot omit mentioning the very near agreement of the weight 
of common air here found with that refulting from the calculation of Sir Georgs 
Shuckburgh, it is fo great as to differ only by 2 grains in a cubic foot. 
It r' 
