136 Dr Bischof 's Examination of Three Inflammable Gases 



this loss of weight would therefore have been 87684.4 grains. 

 If, now, we suppose the density of the dry atmospheric air at 

 32° F., and 28 inches barometer, equal to 0.00129967 the den- 

 sity of water, the weight of the atmospheric air displaced by 

 the balloon, the height of the barometer and thermometer being 

 the same, would be 113.961 grains. If, in the weighing of the 

 exhausted balloon, we indicate the height of the barometer by 

 I, the temperature of the air by t, and the tension of the wa- 

 tery vapour by e, while j3, r, and t, denote the same quantities 

 in the weight of the balloon filled with gas, then the follow- 

 ing formula expresses the quantity which must be added to 

 the ascertained weight of the gas, in order to correct the al- 

 tered aerostatic influence as existing in the case of the ex- 

 hausted balloon, and of the balloon filled with gas. 



n396l f P-§' l=ZJl \ 



' \28 (1+ 0.00375 r) 28(1+0.00375?/ 



This corrected weight was then reduced in the usual way 

 to 32° F., and 28 inches B., and at the same time the ex- 

 pansion of the balloon by heat was taken into account. 



The following are the results of my experiments. 



I. Weight of the atmospheric air in the balloon 97.4 grains. 

 After the correction of the aerostatic influence 97.18 grains. 



At the time of weighing the empty balloon, the height of 

 the barometer 27.58 inches,* 



Temperature, 53° F. 



At the time of weighing the full balloon, the height 

 of the barometer was • 27.573 



Barometer under the receiver, . . . 0.333 



Consequently the tension of the weighed air, 27.24 



Temperature 54°.5 F. 



The weight of the atmospheric air, therefore, at 32° F., and 

 at 28 inches = 104.539 gr. 



II. Weight of the pit-gas in the balloon 55.8 grains. After 

 the correction of the aerostatic influence 55.09 grains. 



At the time of weighing the empty balloon, the height of 

 the barometer was' 27.93 inches. 

 Temperature, 54°.3 F. 



* A,ll the heights of the barometer are reduced to equal temperatures. 



