OF DILUTE SOLUTIONS OF ELECTROLYTES. HEBB. 425 



tubes fitted tightly into the cover of the protection bath, and, 

 as the outer tube was 30 cm. in length, they extended to a 

 considerable distance into this bath. A cork made of vulcanite 

 and pierced by three holes fitted into the inner tube. Through 

 the hole in the centre of the cork a thermometer passed. It was 

 fastened tightly, and in such a manner, that its bulb came 

 within 2 cm. of the bottom of the inner tube. A stirrer passed 

 through one of the other holes, while the third was kept for the 

 introduction of an ice crystal. The last two mentioned holes 

 were lined with platinum foil. 



The stirrer which was made in the usual form with a ring at 

 the bottom, was of platinum wire. This ring, which was smaller 

 than the internal diameter of the inner tube, had fastened to it 

 vanes of platinum foil. These were fastened on by platinum wire 

 and extended in towards the centre. This form of stirrer I 

 found to be much more effective in stirring than the ring 

 commonly used. 



In order to guide this stirrer, and in order to keep the 

 thermometer in the centre of the freezing-tube, another cork, of 

 rubber, was fastened on to the thermometer, some distance above 

 the highest point reached by the solution when the thermometer 

 was in position in the freezing-tube. Through this cork there 

 were two holes one for the stirrer and one for the introduction 

 of an ice crystal. These holes were linei with glass tubing. 



The above arrangement kept the stirrer from scraping against 

 the sides of the freezing-tubes. And, in order to keep it as much 

 as possible from rubbing against the sides of the holes in the 

 corks, a link was introduced in the part of the wire outside of 

 the tubes. This allowed it to hang in a perfectly vertical 

 position. 



The protection bath was 38 cm. in height and 13 cm. in 

 diameter. Its cover consisted of a brass plate through which 

 passed the freezing-tubes, a thermometer and a stirrer. This 

 stirrer consisted of a wire shaft, which had two rings fastened to 

 it one for the upper and one for the lower portions of the 

 mixture. The rings held vanes of tin. This kept the mixture 

 PROC. & TRANP. N. S. INST. Sci., VOL. X. TRANS. DD. 



