Pure cotton is composed of cellulose having a formula which chemists believe to be some multiple of G1-11•05. When it is acted upon by nitric acid or mixtures of nitric with sul phuric acid, under the proper conditions, cellu lose nitrates are produced through, it is be lieved, the replacement of hydrogen atoms in the molecule by NO, groups, thus forming esters or organic salts. Views differ as to the number of cellulose nitrates existing but, fol lowing Vieille, who is the most widely accepted authority on this point, taking the formula of cellulose as Csd-14000 we may have the follow ing: There are probably existing also isomers of many of the nitrates given in the table. Fol lowing their differences in composition these different cellulose nitrates have different prop erties especially as regards their solubility in organic solvents. Thus all except the endecani trate, if properly made, are soluble at ordinary temperatures in a mixture of one volume of alcohol and two volumes of ether. Such cellu lose nitrates are called pyroxylin, nitrocotton, soluble guncotton, and collodion cotton or guncotton. The decanitrate is also called pyro cellulose. All the cellulose nitrates are by some called nitrocellulose. The material produced by the Abel process described above is partly soluble, but mostly insoluble in the ether-alcohol mixture, and to this material the name gun cotton or better military guncotton is applied. In addition to guncotton, the cellulose nitrates are used in the manufacture of smokeless powder, explosive gelatine, pyroxylin plastics, pyroxylin varnishes, photographic films and collodion. For smokeless powders and ex plosive gelatine the deca- and enneanitrates are most largely used. For varnishes, collodion
and photographic films the octonitrate is gen erally employed. And the heptanitrate, which is of low nitration, is preferred for the pyroxylin plastics. This last nitrate may be made by dipping one pound of pure dry cotton or tissue paper in 100 pounds of a mixture of 66 parts of sulphuric acid, 17 parts of nitric acid and 17 Darts of water, and continuing the immersion at 30° C. for 20 to 30 minutes. The acid is then wrung nut and the nitrate washed and neutral ized. The higher nitrates are made by using stronger acids, longer exposures and higher temperatures. In making pyroxyline varnishes, which are largely used in coating metals, artifi cial leather and in waterproofing, the pyroxylin is dissolved in ethyl acetate, amyl acetate and similar organic solvents.
Coilodion, which is used in surgery, is made by placing 30 grams of pyroxylin in a suitable bottle, pouring upon it 750 cubic centimetres of ether, corking the bottle and allowing the whole to stand 15 minutes. Two hundred and fifty cubic centimetres of alcohol are then added and the bottle shaken until the pyroxylin is dissolved. On allowing to stand the solution becomes clear, and if poured upon a flesh wound the solvents evaporate and a continuous film of pyroxylin is formed which protects the wound from the air and which also, by con tracting as it dries, brings the edges of the wound together. Substances such as cantha rides, tannic acid and the like, by which to produce blistering, styptic and other effects, may be added to the collodion. See Ex