113 



Professor Faraday on Gunpowder. 



The Professor observed that much had been lately said respecting 

 Schonbein's gun-cotton, and at the previous meeting this curious dis- 

 covery had formed the subject of a lecture by Mr. Brande. Under 

 these circumstances, he thought it only fair to come before them on 

 this occasion, and put in a claim for gunpowder. Gunpowder was 

 nothing more than a mechanical mixture of three substances, nitre, 

 sulphur, and charcoal, each harmless in itself, and producing no par- 

 ticular phenomena when an ignited body was applied to it. When, 

 however, these substances were reduced to a fine powder, and brought 

 into close proximity by trituration, the most extraordinary effects 

 resulted on the application of any ignited body. The black solid 

 was instantly converted into gaseous matter of enormous bulk, com- 

 pared with the mass of powder producing it, and possessing a power 

 of overthrowing and rending asunder every thing which opposed its 

 expansive force. 



Although a mechanical mixture, it was necessary to observe certain 

 proportions in mixing the materials, or the maximum effect could not 

 be obtained. One hundred parts of good gunpowder consisted of 75 

 nitre, 15 charcoal, and 10 sulphur. The materials were merely well 

 mixed by the agency of water, and a perfectly homogeneous paste was 

 obtained, from which the g\m-jpowder was afterwards procured. The 

 name given to this substance was inappropriate, since it could not be 

 considered as a powder : on the contrary, when properly prepared, 

 it consisted of distinctly rounded grains, having a polished surface, 

 and leaving, in consequence of this spherical structure, an enormous 

 interspace filled with air. This was highly important with regard to 

 its properties, as would be hereafter explained. 



Each constituent of gunpowder had its own mode of action. The 

 nitre furnished oxygen : the carbon furnished gaseous matter, and 

 served to maintain a high temperature : while the sulphur tended to 

 spread the heat with greater rapidity throughout the mass. The 

 action of nitre was illustrated by dropping a piece of ignited charcoal 

 into a flash containing this salt in a melted state : the charcoal con- 

 tinued to glow and burn at the expense of the oxygen of the nitric acid 

 for a considerable time, and volumes of gaseous matter poured from 



