SPECIFIC GRAVITY OF OXYGEN GAS. ( 



A hundred grains of distilled zinc were put Method of 



r>ii i i detennin- 



into a small retort, nearly filled with a mixture i ng the true 

 of one part of sulphuric acid, and four parts 

 distilled water. The beak of the retort was im- 

 mediately plunged into a water trough, and the 

 hydrogen gas evolved, was received into a gra- 

 duated glass jar. After an interval of twenty 

 four hours, when the whole zinc had been long 

 dissolved, and the apparatus and its contents 

 had acquired the temperature of the room, the 

 hydrogen gas evolved was measured. The ex- 

 periment was twice repeated, and the quantity 

 of gas obtained in both cases was exactly the 

 same. The thermometer during both experi- 

 ments stood at 48. The barometer, during the 

 first experiment, was at 30 inches ; but during 

 the second, at 29*6 inches. 



The volume of gas extricated in the first ex- 

 periment was 137*08 cubic inches. In the se- 

 cond experiment, 100'18 grains of zinc were 

 dissolved, and the volume of the gas extricated 

 was 139 '284 cubic inches. Now, when we make 

 the necessary corrections for the height of the 

 barometer, and the excess of zinc dissolved, the 

 quantity of gas evolved is reduced to 137*08 

 cubic inches, as in the first experiment. 



These two experiments give us the volume of 

 hydrogen gas evolved during the solution of 

 100 grains of pure zinc in dilute sulphuric acid. 

 But the gas was saturated with moisture at the 



