108 CONTRIBUTION TO THE STUDY OF 



vaiying from 5 cc. to 25 cc. of a fit'th-normal solution, 3'et no effect 

 was pi-oduced on the titration, showing that the presence of sodium 

 salts does not effect the estimation of hj^'droxylamine in a non- 

 acid solution of di-sodium phosphate. 



Electrical Co nductu 'i ty . 



The method used in determining the electrical conductivities 

 of solutions of hydroxylamine and its salts, was that of 

 Kohlrauscli with alternating current and telephone. 



The Wheatstone bridge consisted of four resistance coils 

 which were certified by Queen & Co. of Philadelphia to be 

 correct to one-fiftieth of one per cent., and a platinoid bridge 

 wire wound on a marble dram. The small induction coil used 

 had a very rapid vibrator, and was kept in an adjoining room 

 that its noise might not interfere with the sound minimum in 

 the telephone. The cell in which the solutions were placed for 

 the determination of the resistance was of the form suggested by 

 Arrhenius. Before using, the electrodes were polished to a bright 

 surface and then coated with platinum black. This was done 

 by pa.ssing a current from three Edison-Lalande cells backwards 

 and forwards between the electrodes through a solution of 

 platinic chloride. This solution was prepared bj" dissolving 1 

 part of platinic chloride and 0.008 part of lead acetate in 30 

 parts of water. The current was reversed every ten minutes 

 and continued until the electrodes were covered with a good 

 coating of the platinum black. To dissolve out any platinic 

 chloride which miglit be adhering to them, they were suspended 

 in boiling water for a couple of hours. 



The water used in making up solutions was purified bj^ boil- 

 ing ordinary distilled water with a few grammes of barium 

 hydroxide. The water was condensed in a block tin worm. Tlie 

 first portion of about 200 cc. that came off was always thrown 

 away. The water thus purified had at 18° a mean conductivity 

 of about 1.1 X 10®, expressed in terms of mercury. Water 



