GUN-COTTON 755 



sulphuric acid. The contact with the acid, &c., is to be insured by stirring and 

 pulling out tho cotton with two glass reds. As soon as perfect saturation is effected, 

 which, with good management, will be in about a minute, the cotton is to be thrown 

 into a largo pan of water, and well rinsed. Tho vessel is to be continued under a tap 

 until litmus-paper is no longer reddened. The cotton is to be squeezed in the folds 

 of a clean towel, and exposed (after being again well pulled out) to a gentle heat to 

 dry. It is curious that the most soluble cotton is often tho least explosive, although 

 there is reason to believe that the most soluble cotton is that which nearest approaches 

 in constitution to tri-nitro-cellulose. 



M. Schonbein recommends a mixture of one measure of nitric acid with three 

 measures of sulphuric acid as the best bath for the cotton. The liquid is to be 

 allowed to cool previous to its immersion. He also saturates the cotton with nitrate 

 of potash, by immersing it in a solution of that salt before drying. Cotton prepared 

 in this manner is not adapted for photographic purposes, but it is highly explosive, 

 and therefore well fitted for blasting rocks. 



The true constitution of gun-cotton is by no means well established. It appears 

 to be very liable to differ in composition according to the method of preparation. 

 According to M. Bechamp it is essential, in order to obtain a cotton both fulminating 

 and soluble in ether, to operate upon the mixture of nitre and sulphuric acid beforo 

 the temperature (which rises on the ingredients being mingled) has fallen. If cooling 

 has taken place previous to the immersion of the cotton, the resulting pyroxyline is 

 fulminating, but insoluble in ether. 



The analyses of MM. Domonte and Menard, and also of M. Bechamp, agree best 

 with bi-nitro-cellulose ; while those of Gladstone, Vankerchoff, and Renter, Schmidt, 

 and Hecker, and Pelouze are more in accordance with a tri-nitro-cellulose. To add to 

 the difficulty of forming a conclusion on the subject, M. Peligot's analyses agree best 



niZTTIO 1 



with the expression /^jQ 4 \2 \ O 12 , "which is that of bi-nitro-glucose. 



According to M. Bechamp xyloidine and pyroxyline are acted on by protoacetate of 

 iron, the original substance being regenerated. Thus xyloidine affords starch, and 

 pyroxyline cotton. The regenerated cotton was analysed with the following result : 



Experiment Calculation 



Carbon . . 43-35 C 12 = 72 44-44 



Hydrogen . 6'31 H 10 10 6-17 



Oxygen . . 60-34 O 10 80 49-39 



100-00 162 100-00 



Bechamp (and others) regarded gun-cotton as containing nitric acid. The former 

 supported his views with numerous experiments ; but there are several disturbing in- 

 fluences preventing the products of the decomposition of gun-cotton by alkalis, &c., 

 being regarded as sufficiently known to enable us to express a decided opinion as 

 to its true constitution, It may be mentioned in evidence of this that during the 

 action of caustic potash upon gun-cotton, M. Bechamp observed sugar to be produced. 

 The latter chemist, in common with many others, doubles the formula which we, 

 following M. Gerhardt, have provisionally adopted for cellulose ; he, moreover, formu- 

 lates the latter substance and its nitro-derivatives thus : 



C 21 H 17 17 ,5N0 5 ,2HO =pentanitric cellulose. 

 C 24 H 16 16 ,4N0 5 , H0 = tetranitric cellulose. 

 C"H 17 17 ,3N0 5 = trinitric cellulose. 

 C 24 H 20 20 = cellulose. 



Explosive substances analogous to gun-cotton may be prepared from many organic 

 bodies of the cellulose kind, by immersing them in the same bath as for gun-cotton. 

 Among these may be mentioned paper, tow, sawdust, and calico. 



When collodion is wanted for an application to cut surfaces, and the cotton is with 

 difficulty soluble in alcoholic ether, a solution may easily be obtained if the cotton be 

 first moistened with acetic ether, and the alcoholic ether be afterwards added. 



Several of the nitro-derivatives of starch and cellulose undergo spontaneous decom- 

 position when kept for some time in stoppered bottles (Gladstone). C. G-. W. 



When cotton wool is immersed in a mixture of strong nitric and sulphuric acids, 

 substitution takes place immediately, and the product has only to be freed from 

 adhering acid by washing with water, and then dried. But in order to insure the 

 uniform production of the most highly nitrated compound, Von Lenk adopts several 

 precautions, tho most important of which are : 



3c2 



