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XIV. The Electrification of a Steam-jet. 

 By Shelford Bidwell, M.A., F.R.S* 



TIIHE boiler used in these experiments consists of a small 

 JL tin bottle capable of holding about fifteen fluid ounces, 

 which is supported upon a tripod above a Bunsen burner. 

 Its neck is fitted with a cork, through which parses 

 a glass tube -j 5 g in. in diameter, terminating in a nozzle 

 with an opening of about -^ in. At a point four inches 

 above the cork, the tube is bent to an angle of 100 or 

 1 10 degrees, and the nozzle may be formed at a distance of 

 five or six inches from the bend. In this case its direction 

 will, of course, be nearly horizontal. When it is desired to 

 have a vertical nozzle, the tube is again bent in an upright 

 direction at a distance of not less than five inches from the 

 first angle, the nozzle terminating two or three inches above 

 the second bend. The nozzle is made by simply drawing out 

 the tube to a point in a flame, and cutting off its end at the 

 proper place. 



I have given these dimensions in detail, not, of course, be- 

 cause they are absolutely the best possible, but in order that 

 anyone who wishes to repeat the experiment may be enabled 

 to obtain good results without trouble. The object aimed at 

 is to keep the tube as free as possible from water, whether 

 arising from ebullition or from condensation, so that the jet 

 of steam may be regular and uniform ; at the same time, it is 

 essential that the end of the nozzle from which the steam issues 

 should not be directly above the gas-burner, or the experiment 

 cannot succeed. 



The tin bottle is charged with four ounces of water, and 

 wdien it boils the burner is adjusted until the steam-jet is as 

 vigorous as is possible consistently with steadiness ; if the 

 ebullition is too violent, the water thrown up into the tube 

 will produce jerks, masking the effect to be looked for. 



The jet is most conveniently observed by means of its 

 shadow projected upon a white screen. For this purpose a 

 lime-light is desirable, but any good source of light may be 

 employed. The shadow of the jet will be seen to be of feeble 

 intensity and of a nfeutral tint ; the jet is, in fact, nearly trans- 

 parent, and does not appear to exercise any selective absorp- 

 tion upon the light. If now a sharp point, or, better, a small 

 bundle of points, in connexion with one of the terminals of 

 an influence-machine (such as a Voss), is brought near the 



* Communicated by the Physical Society : read December 6, 1880. 



