Specific Heat of Mixtures of Alcohol and Water. 465 



The temperature of the liquid was taken by a small thermometer, 

 having a bulb 60 millims. long and about 2*5 millims. diameter. 

 Each degree was divided into twenty parts ; and by means of a tele- 

 scope yfo of a degree could be read off. 



The authors give experiments which prove that the high specific 

 heats observed are not due to evaporation caused by the introduc- 

 tion of the heated metals into the calorimeter. 



The second method used was that generally employed. A certain 

 weight of the liquid, the specific heat of which is to be estimated, en- 

 closed in a suitable vessel, is heated and then plunged, vessel and 

 all, into a calorimeter containing a known weight of distilled water. 

 The temperature of the calorimeter will rise, owing to the introduc- 

 tion 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 ordinary manner. 



Specific heat of 



5 per cent, spirit Series II 101*5 



10 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 calculated mean according to the researches of Reg- 

 nault and Kopp. 



The maximum elevation above the calculated mean coincides pretty 

 closely with the point of maximum contraction. 



