1821.] Causes of Calorijic Capacity, Latent Heat, &>c. 443 



Mathematical Laws of the Phenomena of Corpuscular Aggrega- 

 tion and Decomposition, or of the Phenomena adduced in 

 Support of the Hypothesis of Latent Heat, &;c. 



Prop. XVI. Prob. III. 



It is required to determine from experiment and the principles 

 already delivered, the ratio of the baromerins of a given body in 

 the solid and fluid state. 



The bodies of which I now intend to treat are those which 

 change their state at a fixed temperature ; and as I have not 

 time before me to enter minutely into the peculiarities of each 

 one of this class, I shall confine myself to the consideration of 

 the phsenomena of water, which will serve for an example of the 

 way in which like inquiries with other bodies are to be conducted. 



Ice below 1000 true temperature brought into a room, or into 

 an air, of a much higher temperature, will gradually become 

 warmer, until it has attained the temperature of its liquefaction 

 1000. No sooner has its temperature ascended to (this point 

 than it continues stationary until the whole ice is melted, how- 

 ever much higher the temperature of the surrounding air may be. 

 But when all the ice is once melted, the temperature will again 

 progressively ascend to within a trifle of the temperature of the 

 air. During the time the liquefaction is proceeding, the con- 

 stant communication of temperature goes, as I have already 

 shown, to supply the defects in the individual temperatures 

 occasioned by the decompositions. Thus then distributing a 

 certain additional quantity of motion among the particles of a 

 given quantity of ice may raise it from a certain temperature to 

 the point of liquefaction without melting any of it. Increasing 

 the quantity of that distributed excess will only tend to melt a 

 part of the ice, but have no effect on the temperature, provided 

 it be not more than sufficient to melt the whole of the ice. 

 Hence as it is immaterial in what way the addition of tempera- 

 ture comes, we may conceive it to be communicated from water 

 of a higher temperature mixed with the ice. It is, therefore, 

 evidently possible to find two such quantities of water at a given 

 temperature above 1000, or to find two such temperatures above 

 1000 for a given quantity of water, that if the two quantities be 

 mixed with two given but equal portions of ice at a given tem- 

 perature, in one mixture the temperature shall be just 1000 with- 

 out any of the ice being melted, and in the other the temperature 

 shall be the same, and all of it melted. In the former instance, 

 the baromerin of the ice remains unchanged ; in the latter, it is 

 equal to that of water. And the same change in the baromerin 

 of the ice and no more would take place, if the whole of it, 

 instead of being just melted, had been raised to a considerably 

 higher temperature. From these premises we have to determine 

 the ratio of the baromerins. 



