582 STATE BOARD OF AGRICULTURE. 



Experiment II. 



The object ol" this experiineiit is to show the precision that can be ob- 

 tained while usin<>- vaiTing concentrations of KCl. The readings were 

 made by one person. 



A. Sol. M/10 KCl., E. Bridge, T. 18° C, Known Res. 26.6 ohms., Res. on 

 bridge circnit 1,000. Condnctivit}^ cell No. II, electrodes platinized and 

 10 mm. apart. 



No. reading Res. ohms. ' Bridge reading. 



1 26.6 506.8 



2 26.6 506.7 



3 26.6 506.8 



4 26.6 506.8 



A "perfect balance" was obtained. In onlj' one case was the reading .1 

 less than the others. 



B. Sol. M/50 KCl, E. Bridge, T. 18° C, Known Res. 61 ohms.. Resistance 

 on bridge circuit 1,000 ohms. Coudnctivity cell No. I, electrodes platin- 

 ized and 5 mm. apart. 



No. reading Res. ohms. Bridge reading. 



1 01 504.7 



2 61 504.7 



3 61 504.7 



A "perfect balance" was obtained. No deviation. 



C Sol. M/1,000 KCl, E. Bridge, T. 18° C. Known Res. 1, 191 ohms., Res. 

 on bridge circnit 400 ohms. Conductivity cell No. Ill, electrodes platin- 

 ized and 6 mm. apart. 



No. reading Res. ohms. Bridge reading. 



1 1191 502.60 



2 1191 502.60 



3 1191 502.70 

 A "perfect balance" w^as obtained. 



D. Sol. — twice distilled water, E. Bridge, T. 18° C, Known Res. 33,600 

 ohms. Resistance in bridge circuit, "out." Conductivity cup X, elec- 

 trodes platinized and 2 mm. apart. 



Bridge reading. 



No. readins: Res. in ohms. Left Middle Right 



1 33,600 502.5 503. 503.5 



2 33.600 502.5 503. 503.5 



3 33,600 502.5 503. 503.5 



Range of 1 scale division or .5 scale divisions on either side before de- 

 flection took place. 



E. Conductivity water having a specific conductance of 1.7x10-^ ohms, 

 at temperature of 18° C, E. Bridge, T. 18° C, Known Resistance 85,000 

 ohms. Res. in bridge circuit "out." Conductivity cup X. Electrodes 

 platinized and 2 mm. apart. 



Bridge reading. 

 No. reading Res. in ohms. Left Middle Right 



1 85,000 497. 498.5 500. 



