VOL. XLIII.] PHILOSOPHICAL TRANSACTIONS. 157 



fast as it is dried by the heat within, or the electricity will not fire it : because 

 the flask, being an electric per se, will not snap at the application of the finger, 

 without the glass be first made non-electric by wetting. It has sometimes hap- 

 pened, if the finger has been applied before the inflammable air has found a ready 

 exit from the mouth of the flask, that the flash has filled the flask, and gone off 

 with an explosion equal to the firing of a large pistol ; and sometimes has burst 

 the flask. The same effect is produced from spirit of sea-salt, as from oil of 

 vitriol ; but as the acid of sea-salt is much lighter than that of vitriol, there is 

 no necessity to add the water in this experiment. 



Those who are not much acquainted with chemical philosophy, may think it 

 very extraordinary that, from a mixture of cold substances, which, both con- 

 junctly and separately, are uninflammable, this very inflammable vapour should 

 be produced. In order to solve this, it may not be improper to premise, that 

 iron is compounded of a sulphureous as well as a metallic part. This sulphur is 

 so fixed, that afl;er heating the iron red-hot, and even melting it ever so often 

 the sulphur will not be disengaged from it; but, on the mixture of the vitriolic 

 acid, and by the heat and ebullition which are almost instantly produced, the 

 metallic part is dissolved, and the sulphur, which before was intimately connected 

 with it, being disengaged, becomes volatile. This heat and ebullition continue, 

 till the vitriolic acid is perfectly saturated with the metallic part of the iron ; and 

 the vapour, once fired, continues to flame, till this saturation being perfected, 

 no more of the sulphur flies off. 



A dry sponge hanging by a packthread at the end of an electrified sword, or 

 from the hand of an electrified man, gives no signs of being made electrical; if 

 it be well soaked in water, wherever it is touched, you both see and feel the 

 electrical sparks. Not only so, but, if it be so full of water that it falls from 

 the sponge, those drops in a dark room, received on your hand, not only flash 

 and snap, but you perceive a pricking pain. If you hold your hand, or any 

 non-electrical substances, very near, the water, which had ceased dropping when 

 the sponge was not electrified, drops again on its being electrified, and the drops 

 fall in proportion to the received electricity, as though the sponge was gently 

 squeezed between your fingers. 



f Mr. W. considered, in what manner he could give a tenacity to the water 

 sufficient to make the drops hang a considerable time; and this he brought about 

 by making a mucilage of the seeds of fleawort. A wet sponge then, squeezed 

 hard, and filled with this cold mucilage, was held in the hand of an electrified 

 man, when the drops, forced out by the electricity, assisted by the tenacity of 

 the liquor, hung some inches fi-om the sponge; and by a drop of this he fired 

 not only the spirit of' wine, but likewise the inflammable air beforementioned,. 

 both with and without the explosion.. What an extraordinary effect is this, that 



