BRIDGMAN. — THERMODYNAMIC PROPERTIES OF LIQUIDS. 



69 



An interval of forty days separated the two sets. Both were com- 

 pleted without accident. 



The average discrepancy of the piston displacements for isothermal 

 compressibility at 40° was 0.0025 inch on a stroke of 2.05 inches. The 

 mean discrepancy in the displacements for dilatation was 0.0013 inch 

 on a mean of about 0.070 inch. 



Ij ^ 3 4 5 6 7 8 9 10 U 12 

 .Pressure, kgm. / cm.^^xllO^ 

 Ethyl Chloride' 



Figure 17. Ethyl Chloride. Volume at 20°, 40°, 60°, and 80° plotted 

 against pressure. The lower curve is for 20°. The boiling point at atmos- 

 pheric pressure is at 12°. 5, so that it was necessary to take the origin of pres- 

 sure as 500 kgm. 



The reduction factor for passing from the mathematical formula 

 was 1.032, indicating a compressibility somewhat more than normal. 



The density at 0° and atmospheric pressure was assumed to be 

 1.483. The three constants of the dilatation formula were taken as 

 a. = 0.012275, b = 0.064437, and c = 0.070258.^3 ^he boiling point 

 of ethyl bromide is 38.4°. The formula gives for the volume at 20^* 

 1.0249, and for the extrapolated value at 40°, 1.0515. Pierre also 

 gives the volumes at 20° and 40°, 1.0275 and 1.0578 respectively. 

 The discrepancies are large, 0.6% at 40°. In this case the preference 

 has been given to the values of Pierre against those of Landolt and 

 Bornstein, because Pierre actually measured the volumes at the tem- 

 peratures in question, where as the formula of Landolt and Bornstein 

 is directly applicable onl^^ at lower temperatures. Furthermore, 



53 Pierre, 1. c. (1845). 



