Dr. R. Hare on the Eocplosiveness of Nitre* 539 



exhausted receiver in a similar way. I found a retardation in 

 the activity of the combustion arising, as in the case of gun- 

 powder, from the absence of mechanical confinement, dimi- 

 nution of atmospheric pressure tending to lessen the contiguity 

 indispensable to intense chemical reaction, 



32. The deflagration of the tuft being effected, it caused an 

 evolution of gas equal to 19^ cubic inches. 



33. In order to concentrate the combustible ingredients, 

 resort was had to the apparatus employed in the case of gun- 

 powder, by which means 25 grains of the cotton could be 

 condensed into a cylinder of about half an inch in width, and 

 of a like length. 



34?. Two specimens of gun-cotton, of the manufacture of 

 Lennig, of 54 grains each, prepared and ignited as above de- 

 scribed, gave an evolution equal to 126^ cubic inches. 



35. As 75 grains of gunpowder gave only 55 cubic inches 

 of gas at most, it appears that equal weights being employed, 

 gun-cotton causes a gaseous evolution more than three times 

 as great as gunpowder. 



36. As 75 grains of gunpowder produce, taking the largest 

 amount in the above table, only 55 cubic inches of gas, it 

 follows, that to produce an effect equal to 54 grains of gun- 

 cotton, 172J grains of gunpowder would be requisite. 



37. The gunpowder evolved little more than seven-tenths 

 of a cubic inch per grain, while the gun-cotton evolved more 

 than two cubic inches per grain. 



38. The gas arising from the gun-cotton did not admit of 

 an examination so simple as that given out by gunpowder. 



39. By the introduction of 100 cubic inches of oxygen gas, 

 it appeared from the consequent red fumes, and absorption by 

 water, that about 35 cubic inches of nitric oxide had been 

 formed: by the introduction of caustic potash, about 25 cubic 

 inches of carbonic acid were indicated. One- third of the resi- 

 dual gas being exploded with oxygen, appeared to consist of 

 three volumes of hydrogen to four of carbon vapour. The 

 washings gave indications of cyanogen. 



40. The coexistence of nitric oxide, carburetted hydrogen 

 and cyanogen, in the products, justifies the idea, that were the 

 heat greater, the expansive effect would be augmented by the 

 transfer of the two atoms of oxygen in the oxide, to the hy- 

 drogen and carbon, producing augmentation of temperature, 

 carbonic acid and aqueous vapour. In order to bring the 

 explosive power of gun-cotton to its maximum, I infer that 

 immense resistance would be necessary, thus concentrating 

 and expediting the reaction. 



41. The residue of the explosion of gunpowder appears, 

 from a qualitative analysis, to consist of sulphocyanide and 



