282 ILLINOIS STATE ACADEMY OF SCIENCE 



ANALYSIS OF THE SOL 



The analysis of the 100% sol gave the following data : 



Arsenic per liter 2.9080 g. 



AsoSa per liter (calculated from As) 4.7737 g. 



US per liter 1363 g. 



METHOD 



The conductivity cells were of special design, resemb- 

 ling small flat-bottom flasks of about 30cc. capacity, 

 with the electrodes inserted in the sides. The procedures 

 of filling the cells, transferring to the thermostat, etc., 

 were conducted in the dark. The thermostat lamp was 

 painted black and enclosed in black paraffined paper. 

 The samples were exposed to the light of the 500 watt, 

 concentrated filament, nitrogen-filled lamp mentioned 

 above, placed at a fixed distance of about 60 cm. from the 

 cells. Exposures to the light were made for definite 

 intervals at constant temperature, the cells transferred 

 to the thermostat, and the conductivities measured, using 

 a special set-up consisting of a Wheatstone set built up 

 from Curtis coils and a Leeds and Northrup drum-type 

 Kohlrausch slide wire, with air condensers for obtain- 

 ing proper phase balance. The energizing current was 

 at 1200 frequency and was generated by an audion os- 

 cillating circuit, the bridge balance being accurately de- 

 termined by the use of a DeForest P-200 two-step audion 

 amplifier, using special high-resistance telephones. The 

 point of balance was one of complete silence, the slightest 

 movement of the contact of the 4.7 meter Kohlrausch 

 slide wire to right of left giving a distinctly audible 

 sound. The set-up was built along lines suggested by 

 Hall and Adams.^^ 



DATA 



The data of the determinations are given in the Table. 

 The curves were constructed from the same data. 



DISCUSSIOISr OF THE DATA 



It will be observed that the curves for the different 

 concentrations are nearly parallel, thus showing that the 



