GUN- COTTON.— History. 127
The new compound attracted the attention ofmany chemists, who investigated its properties andchemical composition ; but, as will be seen from thefollowing table, the formulas given for the lattervaried very much :—-
P61ouze (1846),. h'liUiiN/bi — 0,^,TT ; ,02(H0,N0 5 )
Peligot,. Ci^I'I £i N a 0 2 4 — C 12 IT 9 0 9 ,3N0 5 .
Von Kirchhoff& Iieuter, C 12 II 9 N0 14 = C 12 H y 0 , ) ,N 05 .
Fehlinf?. C 12 H 10 N.,O 30 - C ]2 H 10 d 10 ,2NO 6 .
Porret&Teschemacher, C 24 H 1C N 8 0 56 = 2 (C 12 n 8 O 8 , 4 IS 05 ).
Pelonze (1847). ^ 24 ^ 17 ^ 5^42 =
Schmidt and Hecker,.. C 12 H 5 N 5 O 3 0 = C 12 Ii 505 , 5 N 0 5 .Gladstone,. C 24 H 15 N 6 O 40 = C 2 4H35O 20 ,5NO 4 .
ITT /I « IT V O _f O'ioHtOt^NOk.
W. Crum,. C 12 H 7 N 3 0 32 _ |c^h)Oio,3NU 4 .
The symbols represent the old atomic weights.The formulae are derived from different data — somefrom analyses, and others from the increase of weightwhich cotton undergoes when transformed intopyroxylin.
Thus, the formula given by Pelouze in 1846 wasfounded upon the tolerably constant increase inweight (between 68 and 70 per cent.) which celluloseunderwent when acted on by strong nitric acid, or amixture of nitric and sulphuric acids. But in 1847he fixed the increase of weight at between 74 and 76per cent., and this, together with the results of directanalyses, caused him to give the second formula.
These differences would appear to show that hewas working at different times with different pro-ducts ; and the statements made by other experi-menters with regard to the increase of weight clearlyindicate the varied nature of the substances theyobtained. Yon Kirchhoff and Reuter found anincrease of weight of 76 per cent., Poreet andTeSCHEMACHER only 54 per cent., while Teschemacherafterwards found the increase to be 69, and W.Crdm 78 per cent. The last-named chemist sug-gested the formula now given for tri-nitro-cellulose,but the discrepancies observed between the resultsof different experimenters remained unexplained.
In 1847 J. II. Gladstone published a paper, inwhich he attempted to show the cause of thesediscrepancies, and in which the behaviour of gun-cotton with various solvents was described. Hefound the increase of weight to vary from 73-7 to75-2 per cent. ; but by altering the proportions ofthe acids, and the ratio between the weights of theseand the cotton employed, he obtained productsshowing an increase of weight from 51-74 to 78Tper cent. The latter was obtained by using a largequantity of the mixed acids (2 measures of strongsulphuric acid to 1 of nitric, specific gravity 1-502),the former by using just sufficient acid to wet thecotton thoroughly. Moreover, by neutralizing theexcess of acid with ammonia, in the experimentwhich gave an increase of only 51-74 per cent., andevaporating to dryness, he was able to show that itcontained much organic matter ; in other words,that a part of the cellulose had been converted intoa substance soluble in the acids employed. As thexyloidin discovered by BraCONNOT is soluble in nitricacid, being precipitated on dilution with water,Gladstone was led to examine whether any altera-
tion could be effected upon gun-cotton by similarmeans. He found that an acid of specific gravity
1- 45 dissolved pyroxylin, and gave on dilution aprecipitate which weighed only four-fifths of theoriginal gun-cotton. This new product dissolved instrong sulphuric acid in the cold, and was charredby that acid at a temperature below 180° Fahr. -Thesame substance was obtained from pure cotton bythe action of nitric acid of the same strength, specificgravity 1-45. The analyses of this substance, andthe increase of weight sustained by cotton whentransformed into it, as well as the decrease of weightwhich gun-cotton suffered whenlikewisetransformed,led Gladstone to the formula, C 12 II 1? (NO 2 ) g O 10(old notation), as expressing its composition. Todistinguish it from gun-cotton, he proposed to giveit the name cotton-xyloidin.
In 1854 IIadow published a series of experiments,showing that when cotton was acted on by mixednitric and sulphuric acids, a number of differentsubstitution products were obtained. These may beregarded as cellulose, C 6 II 10 O 6 , in which peroxide ofnitrogen from the nitric acid replaces differentquantities of hydrogen, the action depending on thestrength of the acid used. According to IIadow, thereare three principal products :— (1.) C ls II 21 (N0 2 ) 9 0 lr) ,insoluble in a mixture of ether and alcohol, butsoluble in acetic ether, prepared with a mixture of
2 - atoms of nitric acid, IINO g , 2 atoms oil of vitriol,II,S0 4 , and 3 atoms water; (2.) C 18 II 22 (N0 2 ) g 0 16 ,soluble in ether-alcohol, and insoluble in glacialacetic acid, produced when the mixture contains half anatom more water than in (1.) ; (3.) C 18 II 2g (N0 o ) ! .0 :15 ,soluble in all these liquids, produced when the acidmixture contains 1 atom more water than in (1.).
The name pyroxylin has been given to thesevarious bodies. The most highly nitrated pro-duct, C 18 H 21 (N0 2 ) 9 0 15 , which is now writtenC 6 IIy(N 0 2 ) 3 0 6 , is called tri-nitro-cellulose or tri-nitric-cellulose.
Since the publication of these results by IIadow,another formula has been given for the most highlynitrated body by Pelouze and Maury ; but in 1866Professor Abel published an extensive series ofanalyses which very strongly confirmed the truth ofIIabow’s results.
The formula now given for tri-nitro-cellulose,C 6 H 7 (N0 2 ) 8 0 6 , implies what we have already stated,that it is cellulose in which three atoms of hydro-gen have been replaced by three molecules of nitricperoxide. That it contains nitric peroxide is shownby the action of caustic potash and one or tworeducing agents, such as sulphate of iron, or analcoholic solution of potassic sulphydrate. The firstdissolves the gun-cotton, and gives a solution con-taining amongst other things nitrate and nitrite ofpotash, just the substances formed by the action ofpotash on nitric peroxide. Sulphate of iron andsulphydrate of potash transform the gun-cotton backto cellulose, the latter reagent also yielding nitrateof potash and a little ammonia.
As tri-nitro-cellulose is the only product adaptedfor use in gunnery, it is best to reserve the name