338 Specific Heat of Mixtures of Alcohol and Water. [Apr. 30, 



calorimeter containing a known weight of distilled water. The tempera- 

 ture of the calorimeter will rise, owing to the introduction of the heated 

 liquid, and the elevations in temperature produced by different liquids 

 will, in this case, be directly proportional to their specific heats. 



The following Tables give the means of the various results obtained. 



Four series of experiments were made . In the first series the brass 

 weight was employed ; it was heated to a temperature of about 98° C. In 

 the second and third series the copper weight was used, heated to about 

 98° and 42° C. respectively. The fourth series was conducted in the ordi- 

 nary manner. 



Specific heat of 



5 per cent, spirit Series II 101*5 



1 per cent, spirit Series I. 103*55 



Series II. 103*49 

 Series III. 103-83 

 Series IV. 103*71 



Mean 103*64 



20 per cent, spirit Series I. 104*16 



Series II. 104*27 

 Series IV. 104*49 



Mean 104*30 



30 per cent, spirit Series II 102*47 



36 per cent, spirit Series II 99*90 



43 per cent, spirit Series II 97'59 



83 per cent, spirit Series II 65*88 



The authors finally draw special attention to the circumstance that the 

 specific heat of these mixtures not only rises in some cases (up to an 

 alcoholic strength of 36 per cent.) above the specific heat of water, but is 

 above the calculated mean specific heat up to an alcoholic strength of 

 about 74-80 per cent. ; beyond which it seems slightly below the calcu- 

 lated mean according to the researches of Regnault and Kopp. 



The maximum elevation above the calculated mean coincides pretty 

 closely with the point of maximum contraction. 



