M. J. Thorn sen's Thermo- chemical Researches. 



413 



of sulphate of soda we obtained — 



with J equivalent of nitric acid 



Thermal units. 



- 452 



- 808 

 -1292 

 -1752 

 -2026 

 -2050 



It may be concluded from this that the decomposition in- 

 creases with the proportion of nitric acid. The complete trans- 

 formation of sulphate of soda into nitrate would give rise to an 

 absorption of 2072 thermal units. 



In a second series of experiments, the action of two equiva- 

 lents of nitric acid on one equivalent of acid sulphate of soda of 

 various degrees of acidity, NaO, (1 +y) SO 3 , was examined ; we 

 have for 



Thermal units, 



7 = .... -2026 



= 1 .... - 978 



= 2 .... - 664 



= 3 .... - 520 



In order to appreciate the influence which the presence of pre- 

 existing nitrate of soda could have on the reaction, nitric acid 

 was made to act on a mixture of sulphate and nitrate of soda in 

 equal quantities, 



/3N0 5 on iNaO, S0 3 + iNaO, NO 5 ; 



Thermal units. 

 we have for /3= £ . . . —546 

 = i . . . -761 



= 1 



-968 



Decomposition of sulphate of soda by hydrochloric acid. — 

 We have only examined the action of various proportions of 

 hydrochloric acid on an equivalent of neutral sulphate of soda. 

 The results are : — 





Fori 



1 



' 2 



4 



equivalent of acid . 

 >> 



>> 



Thermal units. 

 . -1247 

 . -1682 

 . -1878 

 . -1896 



Thus 



with hydrochloric acid, 



and likewise with nitric acid, the 



lution may occasion in the thermic effects accompanying the double decom- 

 positions. We shall return to this subject in the following article (Bibl. 

 Univ. p. 319).— C. M.] 



