266 Di\ Thomas Thomsons Experiments, Sfc, 



When an integrant particle of (1 acid + 3 water) is 

 mixed with an integrant particle of water the heat evolved 

 is 46°. In this the multiple of 0'375, which represents the 

 specific heat, is less than the number of atoms present by 3. 

 Therefore, 3 atoms of the constituents are destitute of heat. 

 But two of these atoms are accounted for by the two pre- 

 ceding combinations. Hence, the diminution by mixing 

 (1 acid -f 3 water) with 1 water should be only -^ih. ; or 

 in other words, -^th. of the heat should be evolved. But 

 16 X 46 = 736. TJie reason of this great diminution is, 

 probably, the greater quantity of matter to be heated, while 

 the absolute quantity of heat evolved is nearly the same. 

 In the first experiment 1000 grains of oil of vitriol and 

 183-6 grains of water were mixed ; in the second 1550*9 

 grains of acid of (1 acid -f 3 water) were mixed with 183*6 

 grains of water. It is impossible that the sensible heat 

 evolved can be the same when the quantity of matter to be 

 heated is constantly increasing. It is not worth while 

 to investigate the table farther. 



The preceding experiments appear to me to show, in the 

 clearest manner, that the whole theory of Dr. Irvine re- 

 specting the cause of the evolution of heat, when two liquids 

 combine, is inconsistent with fact, and, therefore, erroneous. 

 The quantity of heat evolved appears in all cases to be pro- 

 portional to the energy and rapidity of the combination. 

 The method which I have indicated in this paper, and a 

 preceding one seems to lead to a pretty obvious way of de- 

 termining what portion of the whole heat in a body is 

 evolved when two liquids combine. But it would be 

 requisite to vary and extend the experiments a good deal 

 farther before we draw definite conclusions. Nitric acid 

 and alcohol might be employed with advantage. As the 

 avidity of these bodies for water is not so great as that of 

 sulphuric acid, the experiments could be made with greater 

 ease and accuracy ; while the diminished increase of tem- 

 perature would enable us to determine the heat evolved 

 with greater certainty than can be done when the thermo- 

 meter suddenly rises from 60° to 286°, as it did in one of 

 my experiments. 



