70 OXYGEN AND HYDROGEN GASES. 



sustained was 3 grains, and the tube containing 

 the muriate of lime, had increased in weight 

 0-163 grains. 



From the experiments related in the last sec- 

 tion, it follows, that the volume of hydrogen gas 

 given out during the solution of 100 grains of 

 zinc, supposing the barometer to stand at 30*1 

 inches, and the thermometer at 49, amounts to 

 136-88 cubic inches. 



The specific gravity of vapour at 49> under a 

 pressure of 30*1 inches. of mercury, is 0-00533 ; 

 and the weight of the vapour contained in 136-83 

 cubic inches of moist gas, is 0-00533 x 136-88 x 

 0-305 gr.=0-2225 grain ; but the moisture re- 

 tained by the muriate of lime was only 0*163 

 grain. It is obvious from this, that the hydro- 

 gen still retained 0-059 grain of moisture. 



If from the weight lost, amounting to 3 grains, 

 we subtract this 0-059 grain for moisture, the 

 remainder, amounting to 2*941 grains, gives the 

 true weight of the hydrogen gas exhaled, sup- 

 posing it perfectly dry. Now, from the experi- 

 ments related in the last section, we know that 

 the volume of this gas, under the pressure of 30 

 inches of mercury, and at the temperature of 

 60, is 138-7551 cubic inches. 



Thus it appears, that 138*7551 cubic inches of 



ust sixteen . 



times heavi- dry hydrogen gas (barometer 30 inches, thermo- 



drogen gL meter 60) weigh 2-941 grains: consequently, 



100 cubic inches must weigh 2*119 grains. But 



