158 I'HILOSOPHICAL TRANSACTIONS. [anND 1745. 



a drop of cold water (for the seeds contribute nothing, but add consistence to the 

 water) should be the medium of fire and flame ? 



Camphor is a vegetable resin, and of consequence an electric per se. This 

 substance, notwithstanding its great inflammability, will not take fire from the 

 finger of a man, nor any other body electrified, though made very warm, and the 

 vapours arise therefrom in great abundance; because, neither electrics per se ex- 

 cited, nor electrified bodies, exert their force by snapping on electrics per se, 

 though not excited. If you break camphor small, and warm it in a spoon, it is 

 not melted by heat like other resins; but, if that heat was continued, it would 

 all prove volatile. To camphor thus warmed, the finger of an electrified man, 

 a sword, or such like, will, in snapping, exert its force on the spoon, and the 

 circumambient vapour of the camphor will be fired by it, and light up the 

 whole quantity exposed. The same experiment succeeds by the repulsive power 

 of electricity. 



A poker, thoroughly ignited, put into spirit of wine, or into the distilled oil 

 of vegetables, produces no flame in either. It indeed occasions the vapours to 

 arise from the oil in great abundance ; but if you electrify this heated poker, the 

 electrical flashes presently kindle flame in either. The experiment is the same 

 with camphor. These experiments, as well as the following, sufficiently evince, 

 that the electrical fire is truly flame, and that extremely subtile. 



Mr. W. has made several trials in order to fire gunpowder alone, which he 

 tried both warm and cold, whole and powdered, but never could succeed ; and 

 this arises, in part, from its vapours not being inflammable, and in part from its 

 not being capable of being fired by flame; unless the sulphur in the composition 

 is nearly in the state of accension. This we see, by putting gunpowder into a 

 spoon with rectified spirit, which when lighted will not fire the powder, till, by 

 the heat of the spoon from the burning spirit, the sulphur is almost melted. 

 Likewise if you hold gunpowder, ground very fine, in a spoon over a lighted 

 candle, or any other flame, as soon as the spoon is hot enough to melt the sul- 

 phur, you see a blue flame, and instantly the powder flashes oft". The same 

 effects are observed in the pulvis fulminans, composed of nitre, sulphur, and 

 fixed alkaline salt. Besides, when the gunpowder is very dry, and ground very 

 fine, it (as you please to make the experiment) is either attracted, or repelled f 

 so that, in the first case, the end of your finger, when electrified, shall be 

 covered over with the powder, though held at some distance; and in the other, 

 if you electrify the powder, it will fly off" at the approach of any non-electrified 

 substance, and sometimes even without it. But he could at pleasure fire gun- 

 powder, and even discharge a musket, by the power of electricity, when the 

 gunpowder has been ground with a little camphor, or with a few drops of some 

 inflammable chemical oil. This oil somewhat moistens the powder, and prevents 



