Soda. 



Ammonia 



3°-353 



2°-976 



3°-040 



?°-648 



2°-982 



2°-623 



2°-929 



2°-566 



2°-832 



2°-492 



2°710 



2°-376 



92 DR ANDEEWS ON THE HEAT DEVELOPED IN THE 



In the following table I have collected the foregoing results, arranging the 

 acids in the order of their thermal action. 



Acid. Potash. 



Sulphuric Acid, . . 3° - 378 



Oxalic Acid, . . . 3°-058 



Hydrochloric Acid, . . 3°-021 



Nitric Acid, . . . 2°-993 



Acetic Acid, . . . 2°-852 



Tartaric Acid, . . . 2°'732 



It is interesting to observe how closely the results in the three vertical 

 columns agree relatively with one another. The acids follow in the same order 

 under each base, and even the differences in the amount of heat disengaged by 

 the several acids in combining with the different bases approximate in many 

 cases closely to one another. Thus the heat given out when the sulphuric acid 

 combines with potash exceeds that given out when the oxalic acid combines 

 with the same base by o- 320, the corresponding differences in the case of 

 soda and ammonia being 0°313 and o, 328. If, in like manner, we compare the 

 differences between the heat disengaged by the acetic and tartaric acids, we fall 

 upon the numbers o, 120, 0°122, and o, 116. Even in the case of the oxalic, 

 hydrochloric, and nitric acids, which disengage so nearly the same amount of 

 heat, the same order is observed with the three bases. It must be particularly 

 remarked that the oxalic acid disengages from 0°022 to o, 058 more heat in 

 combining with these bases than the hydrochloric acid, and from o, 065 to 

 0°111 more than the nitric acid. The conclusion of MM. Favee and Silbee- 

 mann, that the organic acids (oxalic, formic, acetic, &c.) disengage sensibly less 

 heat than the mineral acids, is thus entirely disproved ; and the original results 

 recorded in my work of 1841, according to which the oxalic acid disengages at 

 least as much heat as the nitric, phosphoric, arsenic, hydrochloric, hydriodic, 

 boracic, and other mineral acids (with the exception of the sulphuric acid) are 

 fully confirmed. The tartaric, citric, and succinic acids, it is true (as was also 

 shown in the same work), give out about j^th less heat than the average of the 

 other acids ; but the acetic and formic acids fall scarcely ^th below the mean, 

 and the oxalic acid is always above it. These results, in all their main features, 

 are fully corroborated by the experiments recorded in this paper, which were 

 performed with a more perfect apparatus and a more exact thermometer 

 than I had at my command in my earlier investigations. A reference to the 

 same paper will show that, while acids, differing so widely from one another as 

 the oxalic, phosphoric, arsenic, nitric, hydrochloric, and boracic acids, scarcely 

 present any sensible difference in the quantities of heat which they disengage in 

 combining with the bases ; and while of the other acids examined the sulphuric 

 acid (and probably also the sulphurous acid) presents an extreme deviation of 



