1906.] The Chemistry of Globulin. 143 



solution, shows that NaGCl must be relatively very unstable ; a large excess 

 of Na and CI ions is required to keep it in existence. Its existence depends 

 on the breaking of doublets and keeping them broken. The number of bonds 

 broken per second by the Na and CI ions will be proportional to the concen- 

 tration c of these ions and to the number of breakable bonds remaining to 

 be broken, that is to G — g. The rate of solution can be written kic(Gr—g). 

 Now the rate at which the dissolved g tends to go out of solution will be 

 proportional to g and to a function of c, which just vanishes when c = C, the 

 concentration which dissolves all the globulin. The simplest such function 

 is C — c, so we write the rate of precipitation as k 2 g{0 — c). So, for equili- 

 brium, 



%(C — c) = &ic(G— g), therefore p(l — q)= Aq (1 — p) = -^ c (1— p), 



(13) 



which is identical with (1) and (2). Now A is the ratio of k\, the velocity 

 of solution of the globulin, to k 2 , the velocity of precipitation. If instead of 

 c we use the number of gramme molecules c/M in these equations, its 

 coefficient becomes MA/C, which gives a measure of the ratio of the velocities 

 of solution and precipitation when gramme molecules of different salts are 

 compared as to their actions on globulin of a given concentration. Now the 

 velocity of solution of globulin by a molecule will be proportional to the 

 rate at which the doublets |b are broken by ionic charges, so it will be pro- 

 portional to the velocity of the ion and its charge, that is to say its valence. 

 But in the precipitation of globulin the ions have to be extracted from com- 

 bination with the globulin, so the number of doublets to be broken will be 

 proportional to the valence of the ions. It is assumed here that in salt 

 globulins an ion is loosely attached at the semplar doublet which it breaks, 

 and that as breaking power is proportional to valence, so also is the strength 

 of attachment. The velocity of precipitation will be therefore inversely as 

 the valence. Hence MA/C will be proportional to the square of the valence, 

 which is the modified form given to Mellanby's law in Section 1. As regards 

 the dependence of the velocity of precipitation on velocities, it will arise 

 mostly from motion of the combined ions in the globulin compound. We 

 find, then, that MA/C must be proportional to the velocity of the ions and 

 to a velocity depending on the globulin. Now the velocity of the ion must 

 not be confused with the quantity defined in physics as the ionic velocity, 

 which is a velocity generated under a certain unit external electric force. 

 Apparently, in reacting with globulin, the different ions move with about the 

 same speed. But as regards the effect of change of temperature on the velocity 

 of ions, we know the velocity to be inversely as the viscosity of water at 



