EXCITATION OF ELECTRICITY BY STEAM AND PURE WATER. 
21 
2092. Common water in the steam-globe was powerless to excite. A little potash 
added to distilled water took away all its power ; so also did the addition of any of 
those saline or other substances which give conducting power to water. 
2093. The effect is evidently due to the water becoming so good a conductor, that 
upon its friction against the metal or other body, the electricity evolved can be im- 
mediately discharged again, just as if we tried to excite lac or sulphur by flannel 
which was damp instead of dry. It shows very clearly that the exciting effect, when 
it occurs, is due to water and not to the passing steam. 
2094. As ammonia increases the conducting power of water only in a small degree 
(554.), I concluded that it would not take away the power of excitement in the pre- 
sent case ; accordingly on introducing some to the pure water in the globe, electricity 
was still evolved though the steam of vapour and water was able to redden moist 
turmeric paper. But the addition of a very small portion of dilute sulphuric acid, by 
forming sulphate of ammonia, took away all power. 
2095. When, in any of these cases, the steam-globe contained water which could 
not excite electricity, it was beautiful to observe how, on opening the cock which was 
inserted into the steam-pipe before the steam-globe, fig. 1. (the use of which was to 
draw off the water condensed in the pipe before it entered the steam-globe), electri- 
city was instantly evolved ; yet a few inches further on the steam was quite powerless, 
because of the small change in the quality of the water over which it passed, and 
which it took with it. 
2096. When a wooden or metallic tube (2076.) was used as the exciting passage, 
the application of solution of salts to the outside and end of the tube in no way 
affected the evolution. But when a wooden cone (207/.) was used, and that cone 
moistened with the solutions, there was no excitement on first letting out the steam, 
and it was only as the solution was washed away that the power appeared ; soon 
rising, however, to its full degree. 
2097- Having ascertained these points respecting the necessity of water and its 
purity, the next for examination was the influence of the substance against which the 
stream of steam and water rubbed. For this purpose I first used cones (2077-) of 
various substances, either insulated or not, and the following, namely, brass, box- 
wood, beech-wood, ivory, linen, kerseymere, white silk, sulphur, caoutchouc, oiled 
silk, japanned leather, melted caoutchouc and resin, all became negative, causing the 
stream of steam and water to become positive. The fabrics were applied stretched 
over wooden cones. The melted caoutchouc was spread over the surface of a box- 
wood or a liuen cone, and the resin cone was a linen cone dipped in a strong solution 
of resin in alcohol, and then dried. A cone of wood dipped in oil of turpentine, an- 
other cone soaked in olive oil, and a brass cone covered with the alcoholic solution 
of resin and dried, were at first inactive, and then gradually became negative, at which 
