272 



Frederick Guthrie on Salt Solutions 



Alcohol 

 per cent. 



Specific 

 heat. 



10 . . 



, . 103-58 



20 . . 



. . 10436 



30 . . 



. 10260 



40 . . 



. . 96-80 



45 . . 



, . 94-19 



50 . . 



. . 90-63 



Messrs. Dupre and 

 as follows : — " The w 



Page epitomis 

 lole of the ph 



Excess over 

 calculated, 



A. 

 + 7-53 

 12-27 

 14-47* 

 12-63 

 12-00 

 10-42 



hole of the physical characters of mixtures 

 of alcohol and water come to a maximum deviation from their 

 theoretical values somewhere between 30 and 45 per cent, of 

 alcohol by weight. The 30 per cent, nearly corresponds to the 

 formula C 2 H 6 + 6H 2 (29 ! 87 percent.); the 45 per cent, 

 has approximately the formula C 2 H 6 0-j-3H 2 (46 percent.)/' 

 The mean of these values is 



C 2 H 6 + 4 5H 2 0. 



§ 94. According to Rudberg (Pogg. Ann. vol. xiii. p. 496), 

 the contraction is greatest when 55 volumes of alcohol are mixed 

 with 45 volumes of water, or 43*6 weights of alcohol with 45 

 weights of water. This corresponds to the formula 



C 2 H 6 + 2-6H 2 0. 



§ 95. According to Bussy, alcohol not stronger than 33 

 Beaume may be frozen by the evaporation of S0 2 . This strength 

 is that of 78-29 per cent, of alcohol by weight, or 



C 2 H 6 0+ 1-406 H 2 0. 



According to Marchand (Journ. fie?- Chemie, vol. xxv. p. 253), 

 when 1 part by weight of spirit is mixed with 1 part of snow, 

 the depression of temperature depends upon the strength of the 

 spirit, according to the following Table : — 



cent, by weight. 



o 



90 





. . -22 



70 





. . -21 



60 





. . -19 



50 





. . -175 



40 





. . -16 



30 





. . -13 



20 





. . - 8 



This is, I believe, the condition of the question as left by 

 others. 



§ 96. My own experiments. — The alcohol I used was shaken 

 with dry carbonate of potassium and distilled from quicklime. 



