260 DR. JAMES BOTTOMLEY ON 



ganate of potash, using a shorter column for the standard 

 solution. Standard solution 2*4 in 214-6 cub. c. of water 

 (length of column 3*8) : — 



ABC 



36 a'2 4" I 



An experiment was also tried with a still weaker solu- 

 tion. Standard solution 1-4 in 2I4'6 cub. c. of water 

 (length of column 3'8) : — 



ABC 



24 2*6 2"I 



Some experiments were also made by looking through 

 the column of fluid at a white surface external to the 

 cylinder. Standard solution 12 in 500 cub. c. of water 

 (length of column 8*4) : — 



I prepared a fresh standard solution of the permanganate 

 and compared the last solution with it. The new standard 

 was similar to the last in composition : — 



ABC 



i6-8 57 17-6 



Thus the result was somewhat more favourable with a 

 newly prepared solution. I used the permanganate on 

 account of its great tinctorial power ; but it is a salt of 

 considerable instability, especially in contact with organic 

 matter. The water used in the experiments was obtained 

 by distilling Manchester town's water from a copper still 



