26 Mr. W. G. Armstrong on the Electricity of Effluent Steam. 



Having thus discovered an instance in which the electricity 

 was so strongly affected by the contents of the water, I pro- 

 ceeded to try the effects of other ingredients, and the follow- 

 ing are the results I obtained : — 



Soda had much the same effect as potash, rendering the 

 electricity of the steam positive, but not occasioning quite so 

 strong a development. A minute quantity of nitric acid pro- 

 duced the contrary effect, causing the steam to be negatively 

 electrified. Muriatic acid had no perceptible influence ; nei- 

 ther had sulphuric acid, not even when iron filings were con- 

 tained in the boiler. Lime tended to produce positive elec- 

 tricity, but not powerfully. Common salt appeared to have 

 no effect. Nitrate of copper rendered the steam negative, in 

 nearly the same degree as nitric acid. 



Potash, soda or lime used in excess, always occasioned 

 what engineers call priming', which is the ejection of water 

 from the boiler in conjunction with the steam. Whenever 

 this took place the electricity either vanished entirely, or be- 

 came exceedingly feeble. It is therefore unintelligible to me 

 how it happens that Dr. Schafhaeutl obtains most electricity 

 when the steam is combined with water. 



From the powerful effects I obtained, when water contain- 

 ing a little potash was used, I have little doubt that a properly- 

 constructed electro-steam apparatus would answer all the 

 purposes of an electrifying machine. My own apparatus, 

 though small and imperfect, is no mean substitute for an elec- 

 trifying machine ; and if sharp edges, points, and asperities 

 had been avoided, its efficacy would undoubtedly have been 

 much greater than it is. A gallon of water is the utmost the 

 boiler will hold, so as to leave sufficient room for steam ; but 

 a boiler capable of holding ten gallons would not be at all in- 

 conveniently large ; and, with a duly proportioned extent of 

 heating surface, would afford ten times as much steam, and 

 consequently ten times as much electricity, as mine. There is 

 no occasion to adhere to the form I have adopted for my 

 boiler, which form is only eligible on account of its strength. 

 Experience has shown that there is not much to be gained by 

 increasing the pressure of the steam beyond 60 or 70 pounds 

 on the square inch ; and a boiler adapted to resist this pressure 

 would be found sufficiently strong. The coil of copper pipe 

 appended to my apparatus might be dispensed with, for I 

 have always obtained the strongest effects by discharging the 

 steam through a glass tube 6 or 8- inches long. It is import- 

 ant that the apparatus should be insulated, because it is much 

 easier to collect electricity from the boiler than from the jet. 

 The steam should not be discharged more rapidly than it is 



