460 PKOCEEDINGS OF THE AMERICAN ACADEMY. 



a = 491 XIO^ at 198° C. and 300 atmospheres 

 a' = 395 X 10' at 193° C. and 34.5 atmospheres. 



The critical condition is about 194.4° C. and 35.6 atmospheres. There 

 is some indication of a maximum value of a for the temperature 198' C, 

 in the neighborhood of 700 atmospheres. 



From the data of Ramsay and Young values of a and of a' have 

 been found for alcohol, supplementary to those calculated by Professor 

 Hall from the data of Amagat and of Regnault. At low temperatures 

 the value of a' in alcohol is more than twice as great as the value of a. 

 At the last stage, at highest temperatures reached in the calculations, 

 the following values were found : 



a = 832 X 10"' at 220° and 67 atmospheres, 

 a' = 718 X 10' at 240° and 60 atmospheres. 



The critical condition is about 243° and 63 atmospheres. It would 

 appear, according to the data now available, that the values of a and a' 

 meet and cross in magnitude in the neighborhood of 215° C. ; but this 

 seems improbable. Data for the neighborhood of the temperatures 

 here considered are rather dubious. 



5. Partly from the data of Pagliani and partly from new data a 

 table (XIV) of the compressibility of mixtures of alcohol and water has 

 been made, ranging from per cent to 99.7 per cent of alcohol. It is . 

 found that the effect of a small amount of water is very marked. Thus 

 the compressibiHty of 99.7 per cent alcohol is about 4 per cent greater 

 than that of 99 per cent alcohol. 



6. In four successive attempts to return ether from the superheated 

 state to the unsuperheated state by cooling at constant pressure sud- 

 den vaporization occurred, after which this method of procedure was 

 abandoned. No difficulty was experienced in effecting the return by 

 increasing pressure at constant temperature. The reason for the 

 apparent upsetting effect of the cooling process is not evident. 



Grateful acknowledgment is made by the writer to Professor Hall 

 for constant advice and personal aid in the course of this work. 



