OF DILUTE SOLUTIONS OF ELECTROLYTES.—HEBB. 425 
tubes fitted tightly into the cover of the protection bath, and, 
as the outer tube was 30 em. 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 em. 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 lined 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 em. 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. & TRANS. N.S. INST. Scr., VOL. X. TRaNs. DD. 
