5 88 THE POPULAR SCIENCE MONTHLY 



s t anC e — until now largely a chemical curiosity — would perhaps never 

 have been thought of for any technical purpose. Undoubtedly many 

 other industries will avail themselves of this new source of oxygen under 

 conditions similar to those on submarines, for example, for diving opera- 

 tions, in mines, for caisson work, etc. 



Militarism in the search for new explosives discovered guncotton 

 and thereby started the "nitrocellulose" industry. While guncotton 

 made by the treatment of cotton with nitric acid proved to be an almost 

 uncontrollable explosive, it was soon found that by a less energetic 

 action of nitric acid on cotton, substances could be produced which were 

 practically free from any danger of explosion. These lesser nitrated 

 cotton products became the starting material for the celluloid industry 

 in all its interesting and important branches. Besides furnishing vari- 

 ous well-known household articles, billiard balls, etc., and substitutes 

 for ivory and tortoise shell, celluloid became the base for a class of very 

 valuable varnishes. It made amateur photography possible by the sub- 

 stitution of sensitized celluloid films for the breakable and heavy glass 

 plates, and it provided humanity with its greatest agent of amusement 

 and instruction — the moving picture show. But as the lesser nitrated 

 cotton substances in celluloid, like all nitro derivatives, were not yet 

 absolutely free from explosive risk under certain conditions, persistent 

 efforts were made to find safe substitutes for them. Lately these ex- 

 periments were carried to a successful termination, and acetylcellulose 

 obtained by the action of acetic acid on cotton has replaced the dan- 

 gerous nitro products, especially in the manufacture of non-inflammable 

 films for moving pictures — a material in which the absence of danger 

 from fire is obviously of the highest importance. 



This acetylcellulose is also of distinct value in the manufacture of 

 a varnish which finds its largest application in the construction of flying 

 machines where its particular properties are of signal service. What a 

 brilliant record of achievement in the search of militarism for a new 

 ■.explosive ! 



Militarism has also solved the problem for the textile industry as 

 to which colors are most conspicuous and which least visible. Exhaus- 

 tive tests showed that uniforms of a peculiar grayish-green shade ren- 

 dered the soldier practically invisible in the field. How correct these 

 observations were, was demonstrated at the start of the war when it was 

 reported that the presence of the German troops was not noticed by the 

 enemy at distances greater than two hundred to two hundred and fifty 

 yards. 



The most conspicuous color in all kinds of light was found to be red 

 on white or white on red. This fact was made use of by the German 

 advertising men who now paint their posters, etc., mostly in red and 

 white, and also by the municipalities of German cities which are using 



