HYDHOXYLAMIXE AXD ITS SALTS.— ROSS. Ill 



tions were prepared by adding to a half-liter flask 50 cc. of the 

 one-tenth normal solution, and then filling up to the mark with 

 water. Those of one-twentieth and one-fiftieth normal wer& 

 obtained by adding to the cell directly about 25 cc. of the one- 

 tenth normal solution and water in the proper proportions. 

 Solutions of greater dilution were made up in a corresponding 

 way. 



Before determining the resistance of a solution, the cell was 

 first rinsed out twice with a solution of the same strength. It 

 was then placed in the bath for ten minutes, in order to be 

 brought to the same temperature, with the electrodes joined in 

 the circuit and suspended just above the ^.urface of the solution 

 in the cell. The current was then turned on, the electrode-s 

 dropped into the solution, and the reading taken as quicKly as 

 possible. In this way determinations could be made accurately 

 with coated electrodes up to one-hundredth normal. The plates- 

 were then heated very gently until they had assumed a grayish; 

 appearance. With the platinum black thus reduced the con- 

 ductivities of solutions were determined up to one-thousandtb 

 normal. For solutions of greater dilution a third cell was fitted- 

 up having the electrodes nearer together. They were heated to 

 bright redness, and then rubbed gently with a smooth cloth 

 until almost bright. 



All solutions were made up at 18°, and the conductivities- 

 determined at the same temperature within one-fiftieth of a 

 degree. The conductivity of the water used in making up eacb 

 solution was determined, and subtracted from the observed con- 

 ductivity of the solution. 



The constants of the cells were determined by means of 

 standard potassium chloride solutions, the specific electrical 

 conductivities in reciprocal ohms of -^, ^^ and i^ solutioni?, as 

 given by Arrhenius,-^ being as follows : 



k, at 18*, for j^ normal K CI = 0.011203. 

 " ^V " " =0.0057875. 



" -^V " " =0.0023992. 



* Electro-Chemistry, p. 13o. 



