324- Dr. 1\ Andrews o?j the Heat disengaged during the 



time I have always given the results immediately obtained by 

 observation. 



In the following table, H represents the volume of the hy- 

 drogen gas in cubic centimetres as obtained by observation; 

 He, the same corrected for admixture of air, absorption by 

 water, &c. : B, the height of the barometer in English inches 

 reduced to 0° C ; T, the temperature of the hydrogen gas in 

 centigrade degrees ; E, the excess of the final temperature of 

 the water in the calorimeter above the air; I, the increment of 

 temperature found ; Ic, the same corrected ; W, the weight of 

 the water in the calorimeter expressed in grammes ; and V 

 the thermal value of the vessels, 



1. 2. 



H 229-3 c.c. 229-2 c.c. 



He 226-8 c.c. 226-7 c.c, 

 B 30-17 in. 30-16 in. 



T 19°-7 19°-8 



E 0"-9 0°-9 



I 2°-074 2--063 



Ic 2°-079 2--068 



W 27.5-7 grms. 27S-7grms. 277-9 grms, 273*4 grms. 

 V 27-7 grms. 27*7 grms. 27-7 grms. 27*7 grms. 



Hence we have for the heat evolved during the combination 

 of one litre of dry i)ydrogen gas measured at 0° C, and under 

 a pressure of 2992 in. (0-76 in.) with oxygen, — 



1. 2. 3. 4. 



3025 3043 3052 3025 



Taking the mean of these numbers, we deduce for the heat 

 produced during the combination of — 



One litre hydrogen with oxygen . . 3036 



One litre oxygen with hydrogen . . 6072 



One gramme oxygen with hydrogen 4226 



One gramme hydrogen with oxygen 33808 



The imit to which these numbers are referred is the same 

 as that adopted by Dulong, viz. the amount of heat required 

 to raise, tlirough one degree centigrade, one gramme of water 

 taken at the temperature at which the experiment is performed. 



The above results fully confirm the accuracy of Dulong's 

 experiments, the mean of which gives 3107 units for the heat 

 produced by the combustion of one litre of hydrogen gas. 



The heat obtained in the union of oxygen and hydrogen 

 arises from two distinct causes ; one the chemical combination, 

 the other the condensation of the vapour formed by the com- 

 bination. The latter is an accidental complication, which 



