UNITS OF THE FACTORS 87 



For instance, in the determination of the coefficient 

 of diffusion, the stain, as well as the alkali, is kept 

 in standard solution, and is added to the 5 cc. of 

 "coefficient jelly"; but it is most important to re- 

 member that no matter how many units of each 

 factor or substance may be contained in the 5 cc. of 

 solution added to the 5 cc. of "coefficient jelly," the 

 former solution must never be more nor less than 5 cc. 

 Therefore, every jelly-film on the slide is always made 

 from 10 cc. of jelly, which in its turn is composed of 5 cc. 

 of "coefficient jelly" and 5 cc. of another solution bearing 

 the units of the chemical factors. No matter how 

 many units of no matter how many factors the second 

 5 cc. of solution contains, it is always added in the 

 quantity of 5 cc. no more and no less. Hence, the 

 Solution 3, from which the film is prepared,will invari- 

 ably consist of 10 cc. Solution 2 may contain one unit 

 of one factor, or it may contain any number of units 

 of any of the factors. 



If all the units of the contained factors exactly 

 amount to 5 cc., all well and good; but if they do 

 not do so, the balance must be made up to 5 cc. with 

 water. By this means there will always be 10 cc. in 

 the tube of jelly used for an experiment, but it may 

 contain a great variety of units of the chemical factors 

 which increase or decrease diffusion. 



The standard solutions of the several factors must 

 be prepared with due regard to this rule. They must 

 not be too dilute or their total may exceed 5 cc. The 

 following list (abridged from the original paper on 

 the "Coefficient of Diffusion") gives not only the actual 



