190 DR. JAMES BOTTOMLEY ON THE ABSORPTION 



the carbon was ground up witli i o drops of gum, so as to 

 yield a smooth, thick consistence. The amount of dry gum 

 would be very small ; nevertheless it had a remarkable 

 effect in increasing the adhesion of the carbon to the water. 

 When I had shaken up carbon alone with water it had 

 sensibly subsided after the lapse of a few hours. After the 

 addition of so small a quantity of gum the tendency to 

 deposit is much diminished. The following are the details 

 of some experiments. The strength of the carbon diffusion 

 is given in terms of the number of cub. c. of the strong 

 carbon diffusion in 500 ; cub. c. of water. The external 

 white surface was a sheet of white paper. In all cases I 

 have used the right eye only. The number under A de- 

 denotes the mean of two trials got by pouring into the 

 cylinder, and therefore likely to yield too low results. B 

 denotes the mean of two trials got by pouring out of the 

 cylinder, and therefore likely to give too high results. C 

 denotes the mean of A and B. D denotes the length 

 required by theory. 



Standard-diffusion i'2 cub. c. in 500 cub. c. of water, 

 length of column 21 '2. 



Exp. I. — Comparison-diffusion contains i*8 cub. c. in 

 500 cub. c. 



A B 

 14*35 i6'35 



C 



15-35 



D 



14-13 



3ond trial gave 







A B 



12*65 ^^'^5 







13*65 



D 



14-13 



Exp. II. — Comparison-diffusion contains 2*4 cub. c. in 

 500 cub. c. 



A B C D 



io'6 11-25 io'93 ^0*6 



