POSITIVE OR NEGATIVE ELECTRICAL EXCITEMENT BY STEAM. 
25 
was formed into a ring, moistened with oil of turpentine and placed in the box ; 
as long as a trace of the fluid remained in the box the boiler was positive and the 
issuing stream negative. 
2110. Thus the positive or negative state can be given at pleasure, either to the 
substance rubbed or to the rubbing stream ; and with respect to this body, oil of tur- 
pentine, its perfect and ready dissipation by the continuance of the passage of the 
steam soon causes the new effect to cease, yet with the power of renewing it in an 
instant. 
2111. With olive oil the same general phenomena were observed, i. e. it made the 
stream of steam, &c. negative, and the substance rubbed by it positive. But from the 
comparative fixedness of oil, the state was much more permanent, and a very little 
oil introduced into the steam-globe (20 76.), or into the chamber C (20/9.), or into 
the exit tube, would make the boiler positive for a long time. It required, however, 
that this oil should be in such a place that the steam stream, after passing by it, 
should rub against other matter. Thus, on using a wooden tube (2076. 2102.) as the 
exciter, if a little oil were applied to the inner termination, or that at which the steam 
entered it, the tube was made positive and the issuing steam negative ; but if the oil 
were applied to the outer termination of the tube, the tube had its ordinary negative 
state, as with pure water, and the issuing steam was positive. 
2112. Water is essential to this excitation by fixed oil, for when the steam-globe was 
emptied of water, and yet oil left in it and in the passages, there was no excitement. 
The first effect (2089.), it is true, was one of excitement, and it rendered the boiler 
positive, but that was an effect due to the water condensed in the passage, combined 
with the action of the oil. Afterwards, when all was hot, there was no evolution of 
electricity. 
2113. I tried many other substances with the chamber C and other forms of appa- 
ratus, using the wet wooden tube (2102.) as the place and substance by which to 
excite the steam stream. Hog’s-lard, spermaceti, bees’-wax, castor-oil, resin applied 
dissolved in alcohol ; these, with olive-oil, oil of turpentine, and oil of laurel, all ren- 
dered the boiler positive, and the issuing steam negative. Of substances which 
seemed to have the reverse power, it is doubtful if there are any above water. Sul- 
phuret of carbon, naphthaline, sulphur, camphor, and melted caoutchouc, occasionally 
seemed in strong contrast to the former bodies, making the boiler very negative, but 
on trying pure water immediately after, it appeared to do so quite as powerfully. 
Some of the latter bodies with oil-gas liquid, naphtha and caoutchoucine, gave occa- 
sionally variable results, as if they were the consequence of irregular and complicated 
effects. Indeed, it is easy to comprehend, that according as a substance may adhere 
to the body rubbed, or be carried off by the passing stream, exchanging its mecha- 
nical action from rubbed to rubber, it should give rise to variable effects ; this, I 
think, was the case with the cone and resin before referred to (209/.)- 
2114. The action of salts, acids, See., when present in the water to destroy its 
MDCCCXLIII. E 
