456 Mr. W. G. Armstrong on the Electricity of Effluent Sieam. 



electricity in a very high degree. It therefore became pretty 

 evident that the electricity was not developed until the steam 

 issued into the atmosphere, and that the upper stop-cock 

 derived its electricity from its contiguity to the jet. One cir- 

 cumstance alone seemed in some degree to militate against 

 this supposition, namely, that the electricity of the cock E 

 was greatly increased when the cock C was partially closed, 

 as if the expansion which in that case took place in the upper 

 tube rendered the steam electrical previously to its reaching 

 the cock from which the jet was discharged. No negative 

 electricity, however, could be discerned in any part of the 

 apparatus, and without a development of negative electricity, 

 I cannot see how positive electricity can possibly arise from 

 expansion. The more probable explanation of the effect ap- 

 peared to be, that the partial closing of the middle cock 

 shortened the transparent or non-conducting part of the jet, 

 and thereby caused the electricity to be more readily commu- 

 nicated from the opake part of the jet. 



In consequence, no doubt, of increased accumulation of 

 electricity which was thus occasioned in the highest cock, 

 together with the unavoidable dampness of the surrounding 

 medium, the upper glass tube, and the cock above it, became 

 illuminated in the most singular and beautiful manner. Flashes 

 of wavering light flickered round the exterior surface of the 

 glass, and darted from it to the distance of three or four 

 inches, while strong rays of electrical light streamed from the 

 angular parts of the cock, and the flashes from the glass were 

 accompanied by a snapping noise which was distinctly audible 

 amidst the hissing of the steam when the ear was advanced 

 within a short distance from the tube. 



The upper glass tube was then removed, and as an additional 

 test of the non-existence of free electricity in the interior of 

 the boiler, a pointed wire was thrust down through the cock 

 C and tube A into the steam, and effectual means were used 

 to prevent the escape which would otherwise take place at 

 the cock C, in consequence of the tap remaining open to 

 admit the wire. Now this wire being insulated by the glass 

 tube and communicating with the insulated cock C, must have 

 rendered that cock electrical, if the steam were electrical in the 

 boiler; but not the slightest indication of electricity could, 

 under these circumstances, be found in the cock. 



Having withdrawn the pointed wire from the tube, another 

 glass tube, of which the sectional area was about ten times 

 greater than that of the one inserted in the boiler, was then 

 attached to the cock C, in the same manner as the tube D 

 had been before. The comparatively large bore of this tube 



