1 80 Abstract of recent Researches on the quantity of 



M. Hess remarks that, as these numbers are sensibly the 

 same as those obtained for potash, the rise of temperature, 

 which occurs when Na O -f S0 3 is mixed with 10HO, does 

 not take place when the solutions are mixed together ; and 

 hence infers, that the Na O is already combined with at least 

 10 Aq. 



For carrying on the experiments with lime, some additional 

 circumstances required to be observed. The lime was weighed 

 dry, and then put into a bottle with 700 grammes of water, 

 when it slaked and evolved heat. After having waited until 

 the temperature had fallen to that of the surrounding air, the 

 acid was added. In this, as in all other experiments of this 

 kind, the alkaline substance was left slightly in excess. After 

 mixture the elements are evidently differently arranged from 

 before, and consequently M. Hess always determined the spe- 

 cific heat of the mixture by a direct experiment when it was 

 liquid ; but as this could not be done in the case of lime, it was 

 necessary to determine the composition of the mixture, and 

 the specific heat of each of its ingredients. 



The numerical results obtained were, — 



Sulphuric acid 6 H O + S O a gave 481*8 units of heat. 

 2HO+SO3 ... 543-5 

 HO + S0 3 ... 628-3 

 Adding, as before, the heat evolved by the previous dilution 

 with water, we obtain with 



HO + S0 3 ... 628-3 



2H0+S0 3 ... 77-8+543-5 = 621-3 

 6 H O + S 3 ... 155-6 + 481-8 = 637'4 



These experiments were repeated in the calorimeter, and 

 the results were, — 



Sulphuric acid 6HO + SO3 gave 489-2 units of heat. 

 Second experiment, same acid ... 490*9 



Acid of 2HO + S0 3 ... 564*6 



Second experiment, same ... 556*4 



Acidof HO + S0 3 ... 6450 



Adding thereto the heat of dilution, we have, 



HO+SO3 645 + =645 



2HO + S0 3 564-6 + 77-8 = 642*4 



Ditto 556*4+ 77*8 = 634*2 



6HO + SO3 490-9 + 155*6 = 646-5 



Ditto 489*2 + 155*6 = 644*8 



The mean of these is 642*6. The mean of the former series 

 was 628-9, which, from a number of sources of loss, is neces- 

 sarily too small. But if we take the higher number, it may 



