BRIDGMAX. 



THERMODYNAMIC PROPKRTIES OF WATER. 



329 



compressihility at 40° up to 2200 U^iii. The (irst set of readings at 

 five ttMiiporatures is consistent with this hitter set above 1000 kgni., 

 but at the h)wer pressures gives vahies for the compressibihty which 

 are doubtless too higli. To hnd the best vahie for the cliange of 

 volume at low pressures-we now have three sets of data, those of the 



TABLE I. 

 Volume of Water at 40° and Low Pressures by Different Methods. 



present determination, those of the previous work by the method of 

 the steel piezometers, and the results of Amagat. The most probable 

 value for the change of volume has been found by comparing these 

 three sets of values. These values are given in Table I, as also the 

 mean selected from them as the most probable value from the data 

 at present in hand. In taking this mean, the greater weight has been 

 given to the values of Amagat at the lower pressures, since his method 

 of measurement was doubtless more accurate for the low pressures 

 than the present method, which was intended only for high pressures, 

 but at the upper end of the range in the neighborhood of 2000 kgm., 

 more weight has been given to the present determinations. It is to 

 be noticed that the mean \'alue taken as final is lower than that found 

 by Amagat. This divergence is in the same direction as that found 

 by Parsons and Cook, who worked with a method like the present one. 

 The dexiation found by them from the results of Amagat is greater 

 than that adopted here. 



