1906.] The Chemistry of Globulin. 153 



of the suspension, we get equation (1) p (1 — q) = Aq (1 — p), in which A is the 

 ratio of a velocity of solution to a velocity of precipitation. Mellanby's 

 discovery of the dependence of M/C on valency and ionic velocity is applied 

 to MA/C, M being molecular mass, and it is shown that when temperature 

 varies, not only does MA/C depend upon the viscosity of the solvent water, 

 but also on a function of temperature given in equation (3) which expresses 

 the part played by globulin. It is noteworthy that this function has a 

 minimum value about 40° C, near the temperature of warm-blooded animals. 



For the precipitation of globulin by excess of (NH 4 ) 2 S0 4 , equation (5) is 

 established, namely p(l+p) = 28'8(c - 0152), p being the fraction which 

 the precipitated globulin is of the whole and c the concentration of the 

 (NH 4 ) 2 S0 4 solution in grammes per cubic centimetre. 



Then follow formulae for the remarkable precipitation of globulin by acids 

 from solution in neutral salts. From these it appears that three compounds 

 of globulin react in producing this precipitate. 



Section 4 is devoted to a theory of the colloidal state, namely, that a 

 colloid consists of molecules which are chemically united neighbour to 

 neighbour by the action of valencies which are usually latent. Cases of 

 multiple valency like that of nitrogen and oxygen are best accounted for by 

 the electron theory of valence due to Helmholtz, with the assumption that 

 a single atom can contain both negative and positive electrons. Thus the 

 nitrogen atom has four negative electrons and one positive. In trivalent 

 nitrogen the positive electron neutralises one of the negative, so that the 

 atom has only three effective negative electrons along with an ineffective 

 doublet. But if this doublet is opened out, it can link on its atom to two 

 neighbour atoms, the negative electron grasping a positive, and the positive 

 a negative. 



According to this chemical theory of the colloidal state, the term molecule 

 ceases to have a useful meaning when applied to a colloid, so the term 

 semplar is used to name that structure which is repeated like a pattern in 

 three dimensions through a colloid. By suppression of the colloid-producing 

 valencies of doublets, a mass of semplars is caused to fall into a collection 

 of separate molecules. In illustration of the usefulness of this theory, it is 

 applied to show the dependence of the coagulating power of an ion on its 

 valence. It is then applied also to explain the remarkable fact that the 

 amount of globulin dissolved by a given salt solution from a globulin 

 suspension depends on the concentration of the suspension. The action of 

 the ions of a neutral salt in dissolving globulin is treated as only another 

 manifestation of the same electrical effect which enables them to coagulate 

 arsenious sulphide. This theory of the colloidal state leads to a theory of 



N 2 



