264- Mr. Haycraft on the Specific Heat of the Gases. 



similar experiments upon this gas, the results of which were 

 perfectly analogous with those now detailed ; and as all the 

 experiments agree that it has by volume the same specific heat 

 as atmospheric air, namely 1000, I thought it needless to re- 

 peat them. 



Carburetted Hydrogen, 



In my former experiments on carburetted hydrogen, pro- 

 cured from the decomposition of sea-coal, I concluded that it 

 also had the same capacity as atmospheric air ; but I have since 

 found that the capacity of this gas varies extremely, according 

 to the modes in which it is procured. That produced from 

 sea-coal seems to have a capacity nearly equal to the standard ; 

 that from the decomposition by heat of animal fat, has a much 

 greater capacity. From the following experiments, however, 

 it will appear that defiant gas owes its increased capacity to 

 the empyreumatic or ethereal vapour with which it is usually 

 combined. 



No. 1. 



This experiment I conducted in the same way as No. 1. on 

 hydrogen gas. The part B was filled with defiant gas ob- 

 tained from the gas-pipes of a public Company. The calori- 

 meters at the beginning of the experiment contained water of 

 the temperature of 50°. At the end of 50 minutes the calori- 

 meter A had acquired its utmost temperature of 92°^, and of 

 B that of 93°i§ ; the surrounding medium being 66°2 8 n . 

 No. 2. 



The calorimeters were of a temperature of 52°^ at the be- 

 ginning of the experiment: after 55 minutes, the calorimeter 

 A had acquired a temperature of 92°|§, and B that of 94°2 4 n ; 

 the surrounding medium being 65°. The average result of 

 these experiments, Nos. 1. and 2., indicates the specific heat 

 of olefiant gas to be 10559. Though the results of these two 

 experiments do not quite agree with those 1 formerly made, 

 yet the difference is very trifling, and may be supposed to 

 arise from the greater freedom of the gas I formerly made use 

 of, from empyreumatic vapour. This will appear probable 

 from the following experiments. 



No. 3. 

 The part of the apparatus B was filled with carburetted 

 hydrogen, procured by the destructive distillation of mutton- 

 suet. The calorimeters were filled with water of the tempera- 

 ture of 50°!^. At the end of 40 minutes, the calorimeter 

 through which the olefiant gas passed had acquired its ex- 

 treme temperature of 95°, the other that of 88°^ ; the sur- 

 rounding medium being 65°-^ ; indicating the specific heat of 

 olefiant gas to be 12777. That 



