182 DR. JAMES BOTTOMLEY ON COLORIMETRY. 



wliere Q, denotes the whole quantity of colouring-matter ; 

 so that we finally deduce 



As the basis of a method of colorimetry, I took the re- 

 lationship that the length of the column was inversely as 

 the quantity of colouring-matter present when the colour 

 was made constant. It may be readily shown to be a 

 consequence of the laws stated above. Suppose C to be 

 the constant colour, then 



The form of the equation shows that C is the sum of a 

 number of constants C^, C^, C^, &c.j such that 



whence we obtain 



n n n ' 



c 



log ~=Q^^og^,> 



log -' = ?^l0g^2 



log ~=qt\ogK', 



and by addition we obtain 



