BEFORE PAPYRUS . . . BEYOND RAYON — ESSELEN 175 



dinger, for example, has found that cellulose from purified cotton 

 has a molecular weight of 190,000 and he feels that even this may be 

 on the low side. Freudenberg has calculated the molecular weight 

 to be in the neighborhood of 8,100, although he admits this is prob- 

 ably too low, Stamm, using the ultracentrifuge, has obtained a 

 molecular weight in the neighborhood of 40,000.^ In this connection 

 it is of interest to note that Staudinger and Schweitzer found that 

 rayon made by the cuprammonium process has a molecular weight 

 only about one-sixth that of purified cotton, and Stamm found that 

 the cellulose in wood pulp consisted largely of material having a 

 molecular weight about half that of cellulose from carefully purified 

 cotton. 



Although the use of cellulose as a technical raw material did not 

 wait for our present-day knowledge of the structure of the cellulose 

 molecule, nevertheless, the more we know about the inner chemistry 

 of cellulose, the more rapidly do its uses expand. 



The first chemical derivative of cellulose to assume importance 

 in our present-day civilization was the nitrate. When a properly 

 purified cellulose is treated with a mixture of nitric and sulfuric acids, 

 a series of nitric acid esters of cellulose is formed. Those which 

 contain about 11 percent of nitrogen are the basis of the pyroxylin 

 plastics such as celluloid; those with about 12 percent of nitrogen 

 are used for artificial leather and lacquer finishes; while those with 

 a higher percentage of nitrogen constitute our smokeless powders. 

 The significance of the last for present-day civilization needs no 

 comment. The modern pyroxylin finishes, as represented by quick- 

 drying lacquers, have been as effective in their way in increasing 

 man-hour output as has power machinery in other ways. Nitrocel- 

 lulose and cellulose acetate, as the basis of the moving-picture film, 

 have given us a means of recording events in action and in sound 

 as they previously had been recorded in story on cellulose in the form 

 of paper. 



One of the uses of transparent sheets of cellulose ester plastic 

 which is now receiving considerable attention in the public eye is in 

 the manufacture of laminated glass such as is finding increasing use 

 in the modern automobile. This glass is made by cementing a 

 specially prepared sheet of cellulose plastic material between two 

 pieces of glass. The product as used in windshields is of about the 

 same thickness as ordinary plate glass but it does not shatter nor do 

 the pieces fly when the glass is broken. A further application of the 

 same principle is in the manufacture of bullet-proof glass. This is 



* Since writing the above, the author has been advised privately that recent and more 

 accurate determinations have placed the molecular weight of carefully purified cotton 

 cellulose at 300,000. 



