during the Combination of Acids and Bases. 



241 



— 0°.14 ; and in that of ammonia + 0°.17 and — 0°.05. These differences are 

 almost within the limits of the errors of experiment. In the other tables a 

 similar agreement will be found to exist. Indeed the sulphuric acid does not 

 exhibit in them so wide a discordance from the other acids as before. I must, 

 however, remark that the numbers for the insoluble bases are scarcely so exact 

 as those which are contained in the first four tables. 



37. Whether the base be soluble or insoluble in water, the increments of 

 temperature obtained, by combining the same base with different acids, may be 

 compared with each other ; but if we wish to discover the relations subsisting 

 between the temperatures developed by different bases, it becomes necessary to 

 take into consideration the heat absorbed by the insoluble bases, in passing from 

 the solid to the fluid state. I am not at present acquainted with any method 

 whereby the heat thus abstracted can be estimated. But the numbers for the 

 insoluble bases, from this cause, will be all too low. We may, therefore, arrange 

 the bases in the following order, in respect to their power of developing heat 

 when combining with the acids ; but this arrangement is liable to be disturbed 

 when the value of the unknown quantities shall be determined. It must also be 

 recollected that the potash, soda, barytes and lime were in the state of hydrates 

 before mixture, while the magnesia, oxide of zinc, oxide of lead, and oxide of 

 silver were anhydrous. 



Magnesia, .... 8°.24 + a: 



. 7.10 + a;' 



. 6.75 



. 6.52 



. 6.48 



. 5.52 



. 4.91 +y' 



. 3.98 + a;'" 

 . 3.23 + x"" 



Lime, 

 Barytes, 

 Potash, 

 Soda, . 

 Ammonia, 

 Oxide of Zinc, 

 Oxide of Lead, 

 Oxide of Silver, 



38. The peroxide of mercury has given results altogether at variance with 

 the preceding. It developes with the nitric and acetic acids nearly the same 

 quantity of heat, but with the hydracids the most singular anomalies occur, as 

 will appear in the next table. 



VOL. XIX. 2 1 



