CONTRIBUTION TO STUDY OF HVDROXYLAMINE.— MACKAY. 335 



rod bent in a ring at tlie bottom, to pass through. A platinum 

 stirring rod could not be used owing- to its decomposing power 

 on the solution. 



In the determination of the freezing point of the solution, 

 these tubes were surrounded to their neck in a glass vessel 

 35cm. high and 11cm. in diameter, called the protection bath. 

 This stood in a large earthenware jar containing snow and 

 water. The bath was kept at 0"3 degrees below the freezing 

 point of the solution under investigation. The vessel was pro- 

 vided with a stirrer made of stout copper wire, and was covered 

 with a thick wooden cover. 



Two more glass vessels of about the same size as the pro- 

 tection bath were also used. One contained a mixture of snow 

 and salt at a temperature of about — 10 , and was used to super- 

 cool the solution whose freezing point was to be determined. 

 The other contained water at a temperature of -f 5° and was 

 used to melt the ice formed in the tube. 



The hammer of an electric bell supported over the protection 

 bath and driven by an Edison-Lalande battery was used to tap 

 the top of the thermometer before the reading. 



In determining the freezing point, the inner tube was filled 

 up to a mark on the glass with about 50cc. of the solution at 

 about 0'', and placed in the freezing bath where it was kept 

 with continuous stirring until ice formed, when it was removed 

 to the melting bath and stirred until neai'ly all the ice had 

 disappeared. It was then again removed to the freezing bath 

 and stirred until the mercury after falling commenced to rise 

 when it it was quickly transferred to the protection bath, the 

 hammer set in motion, and after two minutes of continuous 

 stirring and tapping, during which time the mercury assumed 

 its highest position, a reading of the thermometer was taken. 

 The w^hole operation was then repeated 6 times and the mean 

 of the different readings taken. 



