42 



J. P. KUENEN. 



(B), or when no changes of state occur, of équation (A). But then we 

 are at once confronted with the difhculty, that the équation (A), to which 

 we shall confine our attention, is well known to be incorrect. We hâve 

 only to remember that on no one scale of températures the spécifie heat 

 c is really a constant quantity. This is nothing but saying in a différent 

 way, that the équation does not represent the phenomena. 



We must tlierefore ask ourselves the following questions: (1) what is 

 the proper relation between the masses and the températures, (2) can 

 this relation be interprétée! so as to express the constancy of a quantity 

 which we can define as quantity of heat, (3) on what expérimental facts 

 is this relation based. The answer to the last question will show us at 

 the same time, by what experirnents the law could be tested. A test of 

 that sort would not be less interesting than the experirnents by Sïas, 

 Landolt, Heydweiller and others, by which the constancy of mass in 

 chemical processes was tested . 



In order to establish the relation between the masses and the changes 

 of température, we can inake use of the following set of expérimental laws. 



l st Expérimental law. The fiual température in a ^ 'mixmg-experiment ,, 

 of two or more substances does not dépend upon the order or the manner 

 in which the substances are mixed, but solely on the masses and the 

 original températures. 



The final température is the refore a mathematical function of th e 

 masses and températures, which contains constants depending upon the 

 nature of the substances. The most elementary observations in calori- 

 metry show that the function cannot be a pure température function, 

 but must dépend upon the nature of the materials mixed. We may 

 write this law in this manner : 



T = F(m i ,m i , t u t p ) 



2 nd Expérimental law. If ail the masses are changed in the same ratio, 

 the températures remaining the same, the final température is not 

 altered. 



The final température is thus a homogeneous function of the masses 

 of degree 0, or algebraïcally : 



T=IIom° (m u m 2 , t u t 1} ) 



Transforming this équation we may write for it : 



