414 Mr. Graham on the Heat disengaged in Combinations. 



tion, was dissolved in 988*8 grains of water, with a rise of tem- 

 perature in three experiments of 0°*77, 0°*70, and o, 70 ; of 

 which the mean is o, 72 R. 



Of the same salt, fused by heat and anhydrous, 1 equivalent, 

 91*95 grains, was dissolved in 1000 grains of water, with a rise 

 in two experiments of 3 0, 02 and 2 0, 99; of which the mean is 

 3°*00 R. The results, therefore, for this double salt, are — 



Heat on solution of MnO, SO a + 2 HO . 0°*72 

 MnO, SO a .... 3°*00 



III. Neutralization of Bichromate of Potash by Hydrate of 



Potash. 



Half an equivalent of bichromate of potash, 47*34 grains, 

 and a little move than half an equivalent of hydrate of potash 

 contained separately in different portions of the usual quantity 

 1544 grains or 100 grammes of water, were brought to the 

 same temperatures exactly, and mixed in two experiments : — 



Before mixture . . 63°*23 63°*50 

 After mixture . . . 67°*71 67°*97 

 Rise of temperature . 4°*48 4°*47 



Doubling 4°*48, the mean result, we have 8°*96 F. as the 

 heat evolved on neutralizing the second equivalent of chro- 

 mic acid in bichromate of potash, 



Of the neutral or yellow chromate of potash, which is the 

 product of this neutralization, 1 equivalent, 62*08 grains, was 

 dissolved by 1544 grains of water at 65° F., with a fall in 

 three experiments of 1°*82, 1°«81 and 1 0, 87, of which the 

 mean is 1°*83. 



IV. Neutralization of Acetic Acid by Hydrate of Potash. 



Half an equivalent of acetic acid, 16*08 grains, was neutral- 

 ized by potash in very slight excess, as in the other experi- 

 ments : — 



Before mixture . . 63°*52 63°*81 63°*94 



After mixture . . . 68°*68 68°-98 69°* 12 



Rise of temperature . 5°*16 5°*17 5°*18 



The mean result of these experiments 5°*17 being doubled, 



we have 10°*34 F. as the heat evolved on the saturation of 



acetic acid by hydrate of potash. 



Of acetate of potash fused without becoming black, 1 equi- 

 valent, 61*65 grains, was dissolved in 1544 grains of water at 

 65° F., with a rise of temperature in three experiments of 

 2°*45, 2°*47, 2°*44 ; of which the mean is 2°*45 F. 



