46 THE ROYAL SOCIETY OF CANADA 



as fulfilling these conditions fairly well, and it possesses the additional 

 advantage of having been studied extensively. Ether is fairly easy 

 to prepare, although there is nearly always some doubt as to the com- 

 plete removal of dissolved gases. Young^ has shown that this removal 

 may be accomplished by repeated freezing in liquid air, and remelting 

 when the gas bubbles escape as the solid ether melts. As no liquid 

 air plant was available the freedom of the ether from gaseous impurities 

 may be suspected ; but all means possible were employed to free the 

 substance from impurities. The method of preparation will be de- 

 scribed further on. 



APPARATUS. 



The first essential is a heating apparatus which can be main- 

 tained at constant temperature indefinitely and whose temperature 

 can be changed quickly from one point to another at will. The 

 heater and regulator have been described elsewhere^ and all 

 that is necessary to repeat here is that temperatures between 30° 

 and 300° may be maintained indefinitely within a few thousandths 

 of a degree when desired. Its capacity is large and the tempera- 

 ture is regulated easily, requiring a minimum amount of atten- 

 tion. The constancy of temperature is observed with a platinum 

 resistance thermometer in a Wheatstone bridge circuit, whose gal- 

 vanometer is of the reflecting type, on whose scale one division repre- 

 sents approximately -01 degrees. The heater is supplied with cali- 

 brated thermometers and with windows which may be covered. 

 It is mounted on three levelling jacks so that the position may be 

 adjusted easily. 



The oscillating system consists of a 22 carat gold cylinder care- 

 fully turned and highly polished.^ The dimensions of the cylinders 

 are given further on. The cylinders are constructed as follows : — 

 After they are turned down to approximate size, a hole 1 mm. in dia- 

 meter is bored perpendicular to the axis at a distance from the upper 

 end equal to one third of the length, and a soft iron plug, a little shorter 

 than the diameter of the cylinder, is inserted . The holes at the ends 

 of the plug are then filled with 18 carat gold solder, which is turned 

 off and then the cylinder is polished. A small platinum wire -4 mm. 

 in diameter is inserted axially in the upper end and bent into a hook 



^ Young loc. cit. 



^ Clark. Proceedings American Academy of Arts and Science, 48. No. 15, Jan. 

 1913. 



^ The cylinders were made by Mr. W. B. McKay of the firm of R. J. Rodger of 

 Kingston and are most satisfactory. 



