85 



\ 



resting quietly on the hoop, with no appearance of 

 distress, and the mercury in the jar, when that in 

 the dish was brought to a level with it, had risen 

 six-tenths of an inch. In twenty-four hours more, 

 the frog was still alive : his respiration seemed now 

 to labour, and he rose often to the top of the jar as 

 if desirous of escaping, or of obtaining fresh air : 

 the mercury had now risen to 1.15 of an inch. 

 From this time, the difficulty of breathing continued 

 to increase, and, at the close of the fifty-ninth hour 

 from the commencement of the experiment, .after 

 having lain quiet for a considerable time, he gave a 

 convulsive struggle, and moved no more. The 

 mercury in the dish was now brought to a level with 

 that in the jar, and its height was 1.2 of an inch. 

 The barometer, at this period, was 29.8, and the 

 thermometer 65. 



70. In order to examine the residual air, we 

 plunged the dish under water, which, rising into the 

 jar, displaced the mercury, and the cup, with its so- 

 lution, was then withdrawn under water, The resi- 

 dual air suffered no diminution by being shaken with 

 lime-water, nor by contact with phosphorus, but it 

 lost rather more than ^ by agitation with the liquid 

 sulphuret of potassa. The jar originally held forty 

 cubic inches, but the animal, with the hoop, cup, and 

 solution, occupied a space equal to four, so that the 

 actual bulk of air employed was thirty-six cubic 

 inches. Having placed the jar on its bottom, water, 

 to the quantity of twenty-seven cubic inches, was 

 poured in, till it reached the point to which the mer- 

 cury, during the experiment, had risen ; and this, 

 therefore, indicated the volume of residual air : it 



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