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ROYAL SOCIETY OF CANADA 



brass segments and four brushes. When driven at full speed it gave 

 about 20 alternations per second. 



In making the measurements the conductivity vessel was placed 

 in a water bath, kept at a constant temperature by means of a 

 thermostat. The thermostat was regulated so as to give a tempera- 

 ture of 25°C, and the conductivities of the solutions in the following 



experiments were found for that temperature. The electrodes, also, 

 were coated with platinum black to prevent the absorption of 

 liberated gases. 



Experiment I. — To Prepare Standard Solutions of Silver Nitrate, 

 Hydrochloric Acid, and Potassium Chloride. 



The hydrochloric acid was standardised by means of sodium 

 hydrate which was prepared by placing a piece of sodium freed from 

 the petroleum and the crust of oxide, in the funnel F, made of nickel 



gauze. Fig. II. This funnel stood in a 

 basin of distilled water, and over the whole a 

 bell jar was placed as shewn in the diagram. 

 Under the apex of the funnel was placed a 

 platinum vessel D, which caught^^the sodium 

 hydrate as it trickled ^down from the funnel 

 above. The action was hastened by passing 

 a current of steam through a tube placed in 

 the water, so as to increase the evaporation. 

 The sodium hydrate thus formed was made 

 up to about the desired concentration, and 

 Fig. II. the resulting solution was standardised by 



means of succinic acid, using phenolpthalein 

 as indicator. The sodium hydrate solution was then used to stan- 

 dardise the hydrochloric acid solution, using the same indicator as 

 before. 



