HOW MOLECULES MAKE MASSES 49 



of chloride of sodium or phosphate of sodium. The urate comes down 

 in a colloidal state, and affects included crystals as any other colloid 

 would. 



"(2) A crystalloid is deposited from solution in the presence of a 

 colloid. This occurs in Dr. Guthrie's experiment with sulfate of 

 copper and gelatin, in uric acid and urates mixed with albuminous 

 urine. 



"(3) Crystals are broken down and turned into spheres or spheroids 

 or molecules, by the action of colloids into which they are introduced 

 — a condition constantly seen in microscopical preparations. Crystals 

 of uric acid, carbonate or oxalate of lime, etc., when preserved in 

 gelatin or glycerine or glycerine-jelly, speedily lose their transparency, 

 lose their sharp outlines, and progress in various degrees towards 

 sphericity. I have drawn attention to this in respect of glycerine in 

 particular, in the Quarterly Journal of Microscopic Science for 1873. 

 The transformation of crystals of murexide put up in glycerine is a 

 particularly beautiful phenomenon, exquisite tufts of black-looking 

 needles growing at the expense of the brilliant purple prisms. 



"When we seek the causes of the spheroidal modification, several 

 possible influences present themselves for consideration. 



"(1) The 'Nascent' State ... a review of the behavior of the various 

 salts and matrices favors the idea that the nascent modification of sub- 

 stances is an important element in the production of changes of form. 

 This I have pointed out in earlier papers in relation to uric acid, 

 which is certainly precipitated in colloid form when freshly dis- 

 possessed of its combinations by other acids. The colloid state has 

 been called its hydrate by Prout; and, while in aqueous solutions it is 

 short-lived, in colloidal solutions or mixtures it endures for a long 

 time. An analysis of the phenomena in a great number of experi- 

 ments made with various media makes me inclined to believe that 

 hydrated colloids and very strong solutions of very soluble salts have 

 the power of prolonging the colloid state of certain crystals. In respect 

 of the present inquiry, any prolongation of the colloidal state in sub- 

 stances precipitated must favor the production of spheroidal forms. 

 Our knowledge, indeed, of the ways of higher colloids must be 

 admitted to be elementary. Of the albumens, for instance, we know 

 really little more than their rough chemical reactions; and though the 

 reports of various societies embalm fragments of what may be more 

 properly called their natural history, most of these fragments remain 

 unnoticed or useless. Whenever these fragments shall be put together 

 and supplemented by further investigation, the connection between 

 colloidality and hydration will be required to be carefully worked out. 

 With this the meaning of the 'nascent' state of substances will form a 

 congenial subject of inquiry; and at present the probability suggests 



