MR HAYCRAFT on the Specific Heat of the Gases. 207 



The air appeared, after the experiments, to contain 88 per 

 cent, of Hydrogen Gas, as indicated by explosion with Oxygen 

 Gas*. 



In these two experiments it may be observed, that the wa- 

 tery vapour which may be presumed to be in the Hydrogen Gas, 

 before it had been sufficiently exposed to the drying influence of 

 the muriate of lime, seemed to decrease in specific heat, exactly 

 contrary to what might be expected. In the first experiment, at 

 the expiration of the first five minutes, it had a capacity of 9222, 

 pretty nearly the same as indicated in the experiments of Messrs 

 DE LA ROCHE and BERARD ; but in proportion as the experiment 

 had advanced, and the hydrogen had been exposed longer to the 

 muriate of lime, its specific heat approached to that of atmo- 

 spheric air, till, at the end of the experiment, they were quite 

 equal. 



No. 2. was performed upon the same hydrogen, in its driest 

 state ; and throughout the whole experiment it indicated also a 

 capacity equal to the standard. In this experiment I know of 

 no source of fallacy, as the Gases, while entering into the calo- 

 rimeters, were of exactly the same temperature, and care \vas ta- 

 ken to ensure accuracy. 



* The apparatus which I found most convenient for exploding gases, is a modi- 

 fication of Dr UHE'S syphon eudiometer. It consists of a hole bored in the solid bot- 

 tom of a mercurial trough, representing an inverted syphon ; one end of which opens 

 into the part" containing mercury, and the other through the edge of the trough to 

 the open air. To the latter opening is cemented an open glass tube ; and to the for- 

 mer a common graduated eudiometer is made to fit accurately. When this appara- 

 tus is used, the graduated tube is filled in the usual way, and applied to the opening 

 communicating with the trough. Mercury is poured into the other tube, to the same 

 height as that contained in the graduated one. The finger is then applied to the open 

 tube, and the electric spark passed. After the explosion, more mercury is poured into 

 the open tube, to the same height that it had risen in the eudiometer, after which the 

 degrees are read off. 



