BEFORE PAPYRUS . . . BEYOND RAYON ESSELEN 173 



chemist, on the other hand, the reason is quite apparent, for it is only 

 a relatively short time that even the empirical composition of cel- 

 lulose has been known. For some time that was all the information 

 available, since cellulose could not be crystallized nor could its 

 molecular weight be determined. Little by little the chemistry of 

 cellulose has been unfolded and although we do not yet know the 

 whole story, it is nevertheless being recognized that in cellulose, 

 mankind has a chemical raw material available in enormous quanti- 

 ties and a substance the supply of which can be annually replenished 

 when economic conditions become such as to warrant it. 



At this point it may be of interest to digress a moment to survey 

 briefly the development of industrial organic chemistry. It started 

 with the distillation products from coal as its raw material and 

 separated from this complex mixture various substances of the 

 so-called aromatic series, from which were synthesized at first dyes, 

 and later perfumes and medicinals. In each case, however, the prod- 

 uct was a definite solid or liquid compound with well defined molec- 

 ular properties. About 10 or 12 years ago a second division of 

 applied organic chemistry appeared, which has since grown to what 

 might almost be called a heavy organic chemical industry. It 

 starts wath the simplest aliphatic hydrocarbons such as ethylene 

 and builds up from there aliphatic products which find wide use 

 in industry, many of them as solvents. The synthetic processes have 

 even been carried to a point where various polymerized molecules 

 have been produced to give solids with colloidal characteristics 

 such as the vinyl resins and the so-called synthetic rubber. At this 

 point this second division of applied organic chemistry meets the 

 third, which uses cellulose as raw material. Here we have a sub- 

 stance which occurs naturally in the form of a highly polymerized 

 molecule and the uses of it and its derivatives depend in large degree 

 upon the retention of these colloidal properties. 



In spite of the fact that industries using cellulose are centuries 

 old, it is only for a relatively short time that we have known even 

 that its empirical composition was CgHioOs. At first, it was 

 thought that there were four hydroxl groups in the CeHioOs unit, 

 and I can well remember a lively discussion at one of the meetings 

 of the American Chemical Society not more than 12 years ago as 

 to whether there were four hydroxl groups or only three. It is 

 now generally recognized, that there are only three hydroxl groups 

 in the elementary cellulose unit, but it was not until about 11 years 

 ago that their character was known. 



This question was answered very prettily by Denham and Wood- 

 house by repeated treatments of cellulose with dimethyl sulphate 



