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XLV. On the Chemical Composition of Gun-Cotton. 

 By Messrs. Robert Porrett and E. F. Tesciiemacher*. 



IN the paper from Mr. Teschemacher read before the So- 

 ciety on the 2nd of November, the composition of gun- 

 cotton, as deduced from careful synthetical experiments, was 

 as follows : — 



39*25 of cotton deprived of its constitutional water. 

 60' 75 of dry nitric acid. 

 100-00 

 We have now to show that this composition agrees very 

 closely with the following formula, which we have obtained 

 from the analytical experiments that will form an important 

 part of the present communication. 



The formula in question is as follows : — Cjg Hg 08 + 4NOr 

 = nitrated lignin; or in centesimal proportions. 

 Carbon 20-00 



Oxygen {^J:^} • • 62-22 



Hydrogen 2-22 



Nitrogen 15-56—10000 



Or it may be thus described : 



Lignin dried at 350° : Carbon . . 20 



Water . . . 20 = 40 

 Nitric acid (15-56 nitrogen, 44-44 oxygen) 60 



loo 



This, it will be seen, very nearly agrees with Mr. Tesche- 

 macher's synthetical result. We have thei-efore taken the 

 composition of nitrated lignin in all our experiments as iden- 

 tical with that of gun-cotton. 



Having by preliminary trials ascertained that with certain 

 precautions those products might be evolved without danger 

 and collected in close vessels, we proceed to state that our 

 method consisted in introducing the charge of gun-cotton 

 into a thin glass tube of about the diameter of a goose-quill, 

 7 inches in length, closed at one end, and bent at the other 

 so as to be conveniently introduced under a glass receiver 

 filled with and inverted over mercury, whilst the principal 

 part of the tube was held in a horizontal position ; the gun- 

 cotton was exploded by heat externally applied by means of 

 a spirit-lamp with a very small wick to the j)art of the charge 

 in the fore part of the tube, so that its combustion proceeded 

 backwards until the whole was consumed. The jjortion of 

 the glass tube which is introduced into the mercury should 



• Communicated by the Chemical Society; having been read Nov. IG, 

 184G. 

 Phil. Mag. S. 3. Vol. 30. No. 201. April 184:7. U 



