of a Jet of Steam issuing from a Boiler. 373 



the other, was fully an inch. A Florence flask, coated with 

 brass filings on both surfaces, was charged to such a degree 

 with the sparks from the knob, as to cause a spontaneous 

 discharge through the glass ; and several robust men received 

 a severe shock from a small Leyden jar charged by the same 

 process. The strength of the sparks was quite as great 

 when the knob was presented to any conductor communica- 

 ting with the ground, as when it was held to the boiler. It 

 appeared to make very little difference in what part of the 

 jet the plate attached to the conducting wire was held ; but 

 when a thick iron wire was substituted for the plate, the effect 

 was greatest when the wire was held very near to the orifice. 

 The valve was loaded at the rate of thirty-five pounds per 

 square inch ; but the pressure of the steam fluctuated consi- 

 derably, which gave me an opportunity of observing that the 

 quantity of electricity derived from the jet increased and di- 

 minished with the pressure. The electricity of the steam was 

 positive ; for when the pith balls of the electrometer diverged 

 upon an instrument connected with the steam, they were at- 

 tracted by a piece of sealing-wax rubbed on woollen cloth ; 

 and when a pointed wire was held by the person on the stool, 

 under the shade of a hat, a pencil, and not a slar, of electrical 

 light became visible. 



Besides the principal jet of steam which I operated upon, 

 there were several small streams issuing from different parts 

 of the boiler, and in each of these the electrometer indicated 

 the presence of electricity. From the peculiar manner in 

 which the steam blew off from the safety-valve when the weight 

 on the lever was lifted, it was quite impossible to try any satis- 

 factory experiment upon the steam which was allowed to escape 

 by that means. I applied the gold-leaf electrometer to vari- 

 ous parts of the boiler, which, I ought to observe, is in direct 

 communication with the ground by means of the steam-pipes, 

 but could scarcely detect a trace of electricity in any part 

 of it. 



The engine has another boiler besides the one in question, 

 and the two boilers lie immediately adjacent to each other. 

 Having been informed that similar phenomena had been dis- 

 covered in this second boiler, I proceeded to apply the elec- 

 trometer to some small pencils of steam which were escaping 

 in different parts, and found the same indications which I had 

 observed under similar circumstances in the first boiler. I 

 then raised the safety-valve, and the column of steam which 

 escaped from it proved as highly charged with electricity as 

 the horizontal jet which issued from the other boiler, and in 

 which the phenomenon had first been observed. 



