68 DR. JAMES BOTTOMLEY ON COLORIMETRY. 



10 cub. c. of caramel in 500 cub. c, of water^ length of 

 column 21*2 cm.): — 



A B C 



80 274 77-4 



The above result was obtained by using tbe rigbt eye 

 alone. I made another series of determinations, using the 

 left eye alone. For the greater limit the mean of four 

 trials was 2*85; and for the smaller limit the mean of four 

 trials gave 2*58. Hence the result will be as follows 

 (standard solution same as last): — 



A BO 



80 271 78*2 



I next made some experiments with stronger solutions. 

 For the greater limit the mean of four trials gave 2*78, and 

 the mean of four trials for the smaller Hmit 2*68. Hence 

 the results were as follows (standard solution 40 cub. c. 

 of caramel solution in 500 cub. c. of water; length of 

 column 2i"2 ; observations made with right eye only): — 



A B 



320 273 3io'6 



I also compared a solution containing 320 cub. c. with 

 another solution containing 10 cub. c: the theoretical 

 length was 0*65 cm.; a column between 0"6 and 07 would 

 satisfy; but the meniscus rendered the exact determination 

 difficult. I also made a farther experiment with the 

 solution containing 40 cub. c. ; one determination for the 

 greater limit gave 5*7, and one determination for the 

 smaller gave 5. Hence the results are as follows 

 (standard solution 10 cub. c. in 500 cubic c. of water, 

 length of column 2r2 cm., observations made with right 

 eye) :— 



ABC 



40 5*35 39'6 



