108 Journal of the Mitchell Society. [Nov. 



impossible any molecular weight determinations by the freez- 

 ing- or boiling point methods. They dissolve in a concen- 

 trated aqueous solution of zinc chloride and in cuprammonium, 

 forming colloidal solutions from which they may be precipi- 

 tated as gelatinous hydrates. The fact that they are colloids 

 presents one reason why chemists have not been more 

 attracted to their study. Colloids have been very unmanage- 

 able, but it is very noticeable that an increased amount of 

 w r ork is being done upon them. In the year 1890 only three 

 communications upon colloids appeared, while in 1900 there 

 were twenty-three. A brief statement of their properties is 

 sufficient to show their unattractiveness. They possess little 

 affinity, do not crystallize, dissolve to an indefinite degree in 

 a very limited number of solvents, are filtered by animal 

 membranes and form gelatinous precipitates. According to 

 one view which is held by many we have in the colloidal solu- 

 tion not a solution at all, but a suspension of very finely 

 divided particles which are much larger than simple mole- 

 cules. In view of their precipitation by electrolytes their 

 study is being prosecuted by electro-chemists and, although 

 more attention is being paid to the inorganic colloids, the 

 whole subject is undergoing development. As new light is 

 obtained, a deeper insight into the character of the celluloses 

 will necessarily follow. It w r ill help to make possible a scien- 

 tific classification, something which is lacking at present. 



The formation of the celluloses is one of the most interest- 

 ing problems connected with them and a very fundamental, 

 one, too. What is the antecedent of cellulose? Durin has 

 observed the formation in beet juice of a white insoluble sub- 

 stance, possessing the characteristic of cellulose. If this 

 substance is transferred to a pure cane sugar solution, more 

 of it is formed. These observations point to cane sugar as 

 the predecessor of cellulose. The more elaborate investiga- 

 tions of Brown and Morris point more clearly to the same con- 

 clusion. Their study of foliage leaves persuaded them that 

 starch is not the raw material out of which cellulose is built 



