BKIDGMAN. — THERMODYNAMIC PROPERTIES OF LIQUIDS. 55 



For Cj, we have the following values: 19.89 by Kopp^^ for the 

 temperature range 26°-44°; 24.43 by Regnault^* for the range 10°- 

 117°; 24.51 by Louguinine^s between 21° and 130°; and 22.97 be- 

 tween 20.5° and 100.1°, 23.64 between 22.2° and 111.6°, and 24.23 

 between 22.2° and 124.5° by von Reis. These values, which are 

 rather more consistent than usual, show a fairly rapid increase of Cp 

 with temperature. 



Ether. — Measurements were made on this liquid with four different 

 fillings of the apparatus. The first two, made before the method 

 had been perfected, were neither complete because of accidents, but 

 between them they give completely the compressibility and the 

 dilatation over the entire high pressure range. The third set of 

 readings was over the low pressure range; this set was repeated 

 without refilling the apparatus. The fourth set, made with the 

 perfected apparatus, was over the high pressiu-e range, and was com- 

 pleted successfully without accident. 



There were three sets of piston displacements for the compressi- 

 bility at 40°. The mean discrepancy of these was ^% on the maxi- 

 mum displacement, which is below the average in accuracy. The 

 mean discrepancy of the piston displacements for the thermal dilata- 

 tion was 0.0022 inch on about 0.070 inch, which is nearly normal. 



The reduction factor from the mathematical formula was 1.104, 

 showing that over the entire range ether remains more compressible 

 than any of the other liquids, except ethyl chloride. 



The low boiling point of ether at atmospheric pressure, 34.6°, makes 

 it impossible to tabulate the initial properties at the higher tempera- 

 tures. For this reason many of the curves start at 500 kgm. as the 

 zero instead of atmospheric pressure. 



The density of ether at atmospheric pressure and 0° was 0.7382. 

 The three constants of the dilatation formula had the values: 

 a =0.021513, h =0.05236, and c =0.07100.36 



The change of volume at 40° between 1 and 500 kgm. was taken 

 from Amagat as 0.0770. Amagat gives for the volume at 40° and 

 atmospheric pressure 1.0672 against 1.0669 of the dilatation formula 

 above. Amagat 's value for the volume at 40° and 500 kgm. was 

 corrected, therefore, in accordance with the above. The low pressure 

 measurements of this present work at 20° are in unusually good agree- 

 ment with Amagat; 0.0665 against 0.0656 for the interval 1-500 



33 Kopp, 1. c. 34 Regnault, 1. c. (1862). 



35 Louguinine, 1. c. 36 Pierre, 1. c. (1845). 



