692 THE POPULAR SCIENCE MONTHLY. 



a conductor, rubbing against iron, another conductor, will accumulate 

 electricity. But this is opposed to our experience. It requires friction 

 with a non-conductor to excite electricity. We have instances daily 

 of the passage of water through pipes, sometimes with great force and 

 velocity. Did friction between the two excite electricity, it should be 

 produced in great quantities. But no such effect has been observed. 



Mr. Patterson, who experimented with the same boiler that Arm- 

 strong used, tried the effect of blowing out water instead of steam 

 through a pipe from the boiler, and no electricity was thereby pro- 

 duced {Philosophical Magazine, vol. xvii., p. 459, 1840). 



Were it indeed true, as Faraday assumed, that the friction of water 

 against the sides of the exit-pipe produced electricity, it would be con- 

 ducted away as fast as formed by the metallic tube to the negative 

 boiler. Indeed, when he placed in the tube any saline or acid sub- 

 stance that increased the conducting power of water, no electrical 

 effects were obtained. In some cases negative electricity, like that of 

 the boiler, was manifested. 



I do not find, from an examination of Faraday's paper, that he made 

 any experiment upon steam at a distance from its exit, where its con- 

 densation to water mostly took place. His mode of experimenting he 

 describes as follows. He says (section 2082) : 



" "When the issuing steam produces electricity, there are two ways of exam- 

 ining the effect. Either the insulated boiler may be observed or the steam ex- 

 amined ; but these states are always contrary one to the other. ... To examine 

 the state of the boiler or substance against which the steam is excited, is far 

 more convenient, as Mr. Armstrong has observed, than to go for the electricity 

 to the steam itself. And in this paper I shall give the state of the former, un- 

 less it be otherwise expressed." 



I infer, therefore, that, in all the experiments hereinbefore detailed, 

 the tests for electricity were made at or near the boiler, and the very 

 important inquiry of the electrical effects at a distance, where conden- 

 sation alone was concerned, seems not to have attracted his attention. 

 This point, however, has been fully investigated by others. 



Mr. Patterson attached ten or twelve pointed wires to a copper rod. 

 These were bent downward and held in the escaping steam. He says 

 (ibid., page 458) : 



" The sparks were larger when the points of the conductor were held in tbe 

 steam about two feet above the valve ; but large sparks were obtained by hold- 

 ing the conductor entirely out of the cloud of steam and at a distance from it, 

 for the air in the wooden shed in which we operated became speedily electrical 

 throughout. The electricity was positive." 



Mr. Armstrong also states (ibid., page 453) : 



" Upon trying the steam in the first instance by the method adopted in the 

 previous cases, that is to say, by standing upon an insulated stool and holding 

 with one hand a light iron rod immediately above the safety-valve while the 



