March 21, 1895] 



NATURE 



499 



volt, 



ten 



! 



showed a negative electrification from fully 

 minutes, down to ,V volt. 



Additions of very small quantities of washing soda to water 

 greatly reduce the positive electrification obtained. 



Loch Katrine water, supersaturated with carbonic acid, and 

 placed in the insulated jar, showed, when air was bubbled 

 through it for ten minutes, a negative electrification of \ volt. 



§ 22. Ten drops of paraffin oil added to water reduced the 

 electrification to about half of that obtained from water only. 

 Thirty drops reduced it to about a tenth, which, as it amounted 

 tu only o'4 volt during the time of the experiment is negligible. 



S 23. Ten drops ol benzene reduced the electrit'ication to 

 half, and thirty drops to about a third of that taken by pure 

 water. 



§ 24. A saturated solution of granulated phenol (carbolic 

 acid) was made, and small portions of it added to the water in 

 thejar. Several experiments showed no diminution in theelectii- 

 ficationas long as the quantity of the phenol solution present in 

 the water was under lo per cent. With 25 per cent, the 

 electrification was reduced to a third. With strengths greater 

 than this up to saturation the electrification was reduced to 

 one-sixth. 



ij 25. A saturated solution of common salt was prepared. Blow- 

 ing air through 200 c.c. of water containing the quantit'ts of the 

 ^alt solution mentioned, gave us in ten minutes the following 

 electrifications : — ■ 



Volts 

 positive. 

 2-4 

 \-2 

 06 

 04 

 015 



o-o 



§ 26.' Several experiments showed that with 200 c.c. of water 

 containing not more than ten drops of absolute alcohol, 

 practically the same amount of positive electrification (4 volts in 

 ten minutes) is obtained as if pure water were used. With filty 

 drops less than 2 volis were got, and with 100 drops less than 

 I volt. 25 and 50 per cent, alcohol in the water gave very 

 small and hence negligible positive electrification. 



§ 27. One drop of saturated solution of copper sulphate in 

 :;oo c.c. of water showed one volt positive in ten minutes. 

 With \ per cent, of it in the water, the electrification was 

 reduced to a fraction of a volt positive. With greater pro- 

 portions of copper sulphate present, up to saturation, slightly 

 negative electrifications were obtained, but never amounting to 

 more than about one-tenth of a volt, and hence negligitile. 



§ 2S. On blowing carbonic acid gas from a cylinder obtained 

 from the Scotch and Irish Oxygen Company, through pure 

 water in the glass jar, the water became electrified to %\ v^olts 

 positive in ten minutes. Blowing the breath through water 

 gave an electrification of 3 volts positive in the same lime : this 

 diminished result is doubtless due chiefly to the diminished rate 

 of bubbling. 



§ 29. The blowing of oxygen from a cylinder, obtained from 

 tile Oxygen Company, through water, gave as a mean of four 

 experiments a positive electrification to the water of half a volt 

 in ten minutes. When continued for fifty-five minutes, it gave 

 the very decided result of 5 volts positive. 



S 30. Hydrogen prepared from zinc and dilute sulphuric acid 

 was passed into a large metal gas-holder ; and was parsed on 

 from this to bubble through the water in the insulated jar. In 

 two experiments this wasdone immediately after the preparation 

 of the hydrogen ; in another it was done after the hydrogen 

 had remained eighteen hours in the gas-holder. In each of the 

 three experiments the water was electrified to 2 volts positive in 

 ten minutes. 



When the hydrogen was allowed to pass direct throujh a 

 tube from the Wolffe's bottle where it was generated, to bubble 

 in the insulated jar, the magnitude of the effect obtained was 

 very much larger. In one case a mixture of muriatic acid and 

 sulphuric acid and water was used, and the reading went ofl^the 

 scale positive in thirty seconds (more than 10 volts). In 

 other two experiments with dilute sulphuric acid and zinc in the 

 Wolfle's bottle, theelectrificationsobtained were 6 volts positive 

 in seven minutes, and 7 '3 volts positive in thirteen minutes, in 

 the last of which the hydrogen was allowed to bubble through 



NO. 1325, VOL. 51"! 



caustic potash contained in a small bottle between the Wolflfe's 

 bottle and the insulated jar. 



The hydrogen was next generated in the insulated jar itself, 

 the tube for ingre-s of air used in the ordinary experiments 

 being taken away. 200 c.c. of pure water, along with some 

 granulated zinc, was put into the jar. Then some pure sul- 

 phuric acid was added, and electrometer readings were taken. 

 In two experiments with no screen in the jar (i; 16) the read- 

 ing went off the scale nti;ati-je (i) in two minutes and (2) in 

 four minutes (more than 9 volts in each case). In another 

 experiment in other respects the same, hut with a cooper ^cieen 

 7 cm. above the surface of the liquid, the electrification showed 

 2 volts negative in two minutes, then came back to zero in five 

 minutes, and in the next six minutes went 4 volts positive. 

 The jar and pair of quadrants connected with it were then 

 metallically connected with the outer case of the electrometer 

 for a few seconds, and reinsulated ; in five minutes the reading 

 went up to 2 volts pasitri-e. A little more sulphuric acid was 

 added to thejar, which was disinsulated for a shirt time and 

 reinsulated ; the reading went up to 7 volts positive in four 

 minutes. The jar was again disinsulated for a few seconds and 

 reinsulated ; the reading went up in four and a half minutes to 

 6J vnUs/iositive. 



§ 31. Coal-gas, bubbled through water in the insulated jar, 

 gave I '4 volts positive in ten minutes. 



§ 32. In the ordinary experiment of bubbling air through a 

 small quantity of wa'er in the bottom of the jar it was noticed 

 that the electrification did not commence to be perceptible 

 generally till about the end of the first minute ; and that it went 

 on augmenting perceptibly for a minute or more after the bubbling 

 was stopped. The following experiment was therefore tried 

 several times. One of us stood leaning over thejar, with the head 

 about 10 inches above it, and the mouth so partly closed that 

 breathing was effected sideways ; another blew the bellows, and 

 another took the readings of the electrometer. After bubbling 

 had been going on for some minutes, and the readings were 

 rising gradually (4 volts per ten minutes, as in § 18), blowing 

 was stopped. As soon as the bubbling ceased, the first-men- 

 tioned observer, without moving his head or his body (see !i 7, 

 regarding the necessity to have the electrometer screened from 

 outside influences), blew into ihe jar to displace the negatively 

 electrified air in it. In every ca^e the electrometer reading 

 showed instantly a small rise in the positive direction. 



In the carrying out of these experiments we have received 

 much valuable help from Mr. Walter Stewart and Mr. Patrick 

 Hamilton. 



§ 33. The very interesting experiments describe! by Lenard, 

 in his paper on the Electricity of Waterfalls ( WieJemann" s 

 Ainialeii, 1892, vol. 46, pp. 5S4-636). anf by Prof. J. J. 

 Thomson, on the Electricity of Drops (Phil. ji/a^. April 1894, 

 vol. 37, pp. 341-358), show phenomena depending, no doubt, 

 on the properties of matter, to which we must look for ex- 

 planation of the electrical effects of bubbling described in our 

 present communication, and of the electrification of air by 

 drops of water falling through it, to which we have referred 

 as having been found in previous experiments which were com- 

 menced in 1890 for the investigation of the passage of electrified 

 air through tubes. ^ 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — The Isaac Newton Studentship in Astronomy 

 has been awarded to Mr. S. S. Hough, Scholar of St. John's 

 College, Third Wrangler in 1892, and Smith's Prizeman in 

 1894. 



Mr. C. T iHeycock, Lecturer in Chemistry at King's College, 

 First Class in the Natural Sciences Tripos 1889 has been 

 elected to a Fellowship. 



The discussion by the Senate of the proposals for the 

 encouragement of Advanced Study and Research, by the 

 admission under special conditions of Graduates of other 

 Universities, wns on the whole favourable to the scheme. 

 There seems little doubt that the preliminary resolutions on the 

 subject will be passed early next term. 



Mr. Arthur R. Hinks, of Trinity College, has been appointed 

 Second Assistant at the Observatory for five years, from July 

 I, 1895. 



' '_' Electrification of Air by a Water let." By M-tgnus Maclean and 

 Makita Goto, Phil .Mag. August 1890, vol.30, pp. 148-152. 



