$±2 



Dr. R. W. Bovle on the 



the law to hold exactly. The agreement amongst their own 

 results, which former experimenters must have obtained, is 

 good presumptive evidence that the law is valid ; but un- 

 fortunately these experimenters differ seriously one from 

 another, and no exact information concerning any one tem- 

 perature can be taken from their results. For example, the 

 values of the coefficients at ordinary, or room, temperatures are 

 from Von Traubenberg * 0*33 to 0'36 



Machet 0-30 to 0-33 



Hofmann J 024 



Kofler§ 0-27 (at 18° C). 



It will be seen later that much depends on what is meant 

 by " ordinary temperature." There is an increase in the 

 coefficient of 25 per cent, while the temperature changes 

 from 18° to 11° C. 



By the methods afterwards described it is easy to put 

 Henry's law to simple and direct test, and to show that in 

 the present conditions it holds exactly. It is desirable that 

 a correct value of the solubility of the emanations in water 

 and a few other liquids should be known, especially over the 

 range of ordinary working temperatures. 



Methods of Experiment. 

 The solubility may be determined by very simple methods, 

 which may be described- as follows : — 



ABC and DEF are two bulbs of the same length, but not 



Fig. 1. 



necessarily of the same diameter. The first bulb is fitted 

 with an ordinary two-way stopcock B, and the second with 



* Phys. Zeit. v. p. 1 30, March 1 (1904). t Wiener Ber. cxiii. p. 1329 (1 904). 

 \ Fhys. Zeit. vi. p. 337 (1905). § PJnjs. Zeit. ix. p. (1908). 



