87 



are not typical of vital jirocesses. It is ahvaj's in a colloid medium 

 that the phenomena of life are manifested^*. Fischer's synthesis of 

 the polypeptides comes much nearer to an imitation of vital processes, 

 and there appears to be no chemical limit to the application of the 

 reactions he employed. 



A distinction should be drawTi between efforts to determine the 

 size of the cellulose molecule and experiments to determine the 

 configuration of the CgHmOs units. It may be remarked in passing 

 that there is no reason to suppose that all the CeHjoOj units have 

 the same configuration, and a quantitative conversion of cellulose to 

 any particular sugar is unlikely i'*'\ Pictet and Sarasin^' bj^ the dry 

 vacuum distillation of cellulose obtained Isevoglucosan, and Sarasin 

 has suggested that cellulose is built up from this unit^*. Owing to the 

 drastic nature of the decomposition involved, the suggestion must 

 be taken with some reserve, and Irvine has criticised it on other 

 grounds^^ It is interesting, however, to build up 1-glucosan with 

 the aid of tetrahedral carbon atom models, when it wiU be found that 

 the carbon atoms 1, 2, 3, 6 and the oxygen atom are approximately 

 in one plane, and the carbon atoms 6, 3, 4, 5 and the oxygen atoms 7 

 and 8 in another plane, approximately at right angles to the first plane 

 (see formula in bibliography). The complex would therefore grow 

 in three dimensions (an elementary detail which is sometimes over- 

 looked), and groups and atoms would be brought into proximity in 

 a way which would never be demonstrated by a diagram in two 

 dimensions. One is tempted to speculate whether the insolubility 

 of cellulose in water is due to this mechanical smothering of the 

 hydroxyl groups by the growing complex, or even whether the hydroxyl 

 groups reaUy exist as such in solid cellulose^". Certainly any reaction 

 which degrades the cellulose complex jdelds a product which will 

 take ujD more water than the original cellulose, and even long-continued 

 mechanical grinding will yield a sticky or pasty mass ; from which 

 it appears that increasing the surface of cellulose increases its 

 solubility in water. On the other hand, the vulnerability of cellulose 

 to esterification without profound hydrolysis militates against this 

 view. 



The chief contribution which the manufacture of celluloid makes 

 to colloidal theory at the present time is in its insistence on the 

 fundamental difference between emulsoids and suspensoids. There 

 is a close connection between the viscosity of dilute solutions of 

 cellulose esters, and the mechancial properties (or what is called in 

 the rubber industry the nerve) of the solid product^^. So far as 

 the writer is aware, neither suspensoid nor crystalloid solutions 

 possess any physical properties which can be correlated with the 

 properties of the solid derived from them by evaporations In 

 crystalloid and suspensoid solutions we have free particles — ions, 

 molecules, or aggregates — moving independently of each other in 

 the dispersion medium. But in emulsoid solutions, as exemplified 

 by cellulose esters, we find a manifestation, in a reduced degree, 

 of the same forces that produce " nerve " in the solid form. Therefore 

 the disperse phase cannot consist, at any rate entirely, of particles 

 having independent existence in the dispersion medium. There 



