December 6, 1889.] 



SCIENCE 



383 



effect was observed. The leaves partially collapsed. In all exper- 

 iments that I have made by inserting dielectrics between a charged 

 body and an electroscope, less electric action has been the result. 

 If, while the charged ball be near the electroscope, the plate of it 

 be touched with the finger, the leaves collapse ; and on removing 

 the finger, and then the charged ball, they again diverge. Now let 

 a dielectric be placed between the ball and the electroscope, touch 

 the latter, and remove the finger and ball as before, and much greater 

 divergence will be produced. In both cases the electroscope is 

 charged by induction. Without putting the electroscope to earth, 

 I fail to see theoretically why any greater divergence should occur. 

 I suppose some one must have made the experiment as quoted ; 

 but, if a greater effect was produced, it must have been caused by 

 the substance used for a dielectric being charged itself. I have 

 found very great difficulty in preventing plates of ebonite. parafifine, 

 sulphur, etc., becoming electrified when placed near a charged body. 

 I should like to know if any one has experimented in this direction, 

 because either the text-books or myself must be wrong. In Guth- 

 rie's book (p. loi) there is a statement similar to Ganot's." 



Electric Lighting at Berlin. — M. Wybau.a Belgian elec- 

 trician, has recently read a paper before the Belgian Electrical So- 

 ciety on the electric lighting of Berlin, from which the following 

 particulars of this important system are taken. At Berlin the 

 electric light, as stated in Engineering, is supplied from a number 

 of central stations, the two principal of which are situated in Mark- 

 grafenstrasse and the Mauerstrasse. Of the other stations, one 

 lights the Kaiser Galerie, and the other a block of houses at the cor- 

 ner of Unter den Linden and Friedrichstrasse. A fifth station, of 

 but small importance, supplies the lighting of Leipzigerstrasse. At 

 the Markgrafenstrasse station there are eight steam-engines, each 

 of 150 horse-power, which drive sixteen Edison dynamos. To this 

 plant there have recently been added four compound inverted en- 

 gines, each capable of indicating 300 horse-power, which drive 

 direct four dynamos of 165 kilowatts each. These dynamos are of 

 the multipolar type, and are slow-moving machines, their armatures 

 making but eighty-six revolutions per minute in normal working. 

 The boiler-house contains eight De Naeyer tubulous boilers, which 

 supply the steam for the whole plant. In the switch-room is a 

 rheostat of exceptionally large size, which is used to regulate the 

 current in the distributing mains. These mains are eighty in 

 number, most of which are with their coverings about 3 inches in 

 diameter, and the greatest section of copper in any one of them is 

 800 square millimetres. At the Mauerstrasse station there are six 

 boilers, three engines of 180 horse-power each, and three of 300 

 horse-power each. At the Friedrichstrasse station there are four 

 engines of 60 horse-power each, and at the Kaiser Galerie four of 

 80 horse-power each. At the small station on the Leipzigerstrasse 

 there are two engines of So horse- power. The floor space required 

 in the above installations per 1,000 lamps for boilers and machinery 

 is from 323 to 377 square feet. At the Edison station in New 

 York about 194 square feet of floor space are required, but the 

 dynamos and engines run at much higher speeds. The total length 

 of cables laid in Berlin is about 170 kilometres, which are laid un- 

 der the footpaths. In every case Siemens cables are used. 



Electrical Sunstroke. — As a remedy against "electrical 

 sunstroke," as the affection is called that attacks men exposed to 

 the intense rays of the electric arc by means of which metals are 

 fused and welded, is a veil or mask of glazed taffeta, supported by 

 a wicker head-piece, and provided with goggles of gray glass. 



The Houstholm Electric Lighthouse. — This lighthouse, 

 the most powerful electric lighthouse in the world, was opened a 

 few weeks ago, and its working has given great satisfaction. Even 

 in rainy weather its light has been distinctly visible at Blokhus, a 

 straight distance of about thirty-five miles. The only undesirable 

 incident attending the working of the new lighthouse is the im- 

 mense number of birds which get killed, and which amount to 

 thousands, comprising starlings, snipes, larks, etc., basketfuls being 

 collected every morning in the vicinity of the lighthouse. As 

 stated in Engineering, the lighthouse is 209 feet high, and the 

 light-power in the beam is 2,000,000 candles. To guard against 

 the stoppage of the light through any accident to the machinery, 

 this is, as far as it has been possible, constructed on the twin 



principle. There are two engines, three tubular boilers, one of 

 which is a particularly quick-heating one, two electro-magnetic 

 machines with a joint capacity of 45 volts, 250 amperes, from 

 Merilens & Co., Paris, two electric lamps, with various reserve 

 lamps, etc. In connection with the lighthouse, and at a distance 

 of respectively about 2,000 and 16,000 feet, are two powerful sirens, 

 which are fed with compressed air from two air-pumps in the 

 engine-house, and which can be coupled together with the engines. 

 At the siren stations there are reservoirs of compressed air, which 

 are worked by means of electricity and clock-work, and great care 

 and forethought seem to have been bestowed upon the whole in- 

 stallation in all its details. 



Electrification due to Contact of Gases with Lhj- 

 UIDS. — At the meeting of the London Physical Society, held on 

 Nov. 15, Mr. Enright read a paper on "The Electrification due to 

 Contact of Gases with Liquids." Repeating his experiments with 

 zinc and hydrochloric acid, the author, by passing the gas into an 

 insulated metallic vessel connected with the electrometer, proved 

 that it was always charged with electricity of the opposit-i kind to 

 that of the solution. The elecirical phenomena of many other re- 

 actions have been investigated, with the result that the gas, whether 

 Hi, CO2, SO3, SHj, or CI, is always electrified positively when 

 escaping from acids, and negatively when leaving a solution of the 

 salt. In some cases, according to Engineering, distinct reversal 

 is not obtainable, but all these seem explicable by considering the 

 solubility and power of diffusion of the resulting salts. Various 

 other results given in the paper tend to confirm this hypothesis. 

 Seeking for an explanation of the observed phenomena, the author 

 could arrive at no satisfactory one excepting "contact" between 

 gases and liquids; and, if this be the true explanation, he hoped to 

 prove it directly by passing hydrogen through acid. In this, how- 

 ever, he was unsuccessful, owing, he believes, to the impossibility 

 of bringing the gas into actual contact with the liquid. True con- 

 tact only seems possible when the gas is in the nascent state. 

 Some difficulty was experienced in obtaining non-electrified gas, 

 for the charge is retained several hours after its production, even 

 if the gas be kept in metallic vessels connected to earth. Such 

 vessels, when recently filled, form condensers, in which the electri- 

 city pervades an enclosed space, and whose charge is available on 

 allowing the gas to escape. Soap-bubbles blown with newly gen- 

 erated hydrogen were also found to act as condensers, the liquid of 

 which, when broken, exhibited a negative charge. This fact, the 

 author suggested, may explain the so-called " fire-balls " sometimes 

 seen during thunder-storms ; for if, by any abnormal distribution of 

 heat, a quantity of electrified air becomes enclosed by a film of 

 moisture, its movements and behavior would closely resemble those 

 of fire-balls. A similar explanation was proposed for the phenom- 

 enon mentioned in a recent number of Nature, where part of a 

 thunder-cloud was seen to separate from the mass, descend to 

 earth, and rise again. The latter part of the paper describes 

 methods of measuring the contact potential differences between 

 gases and liquids, the most satisfactory of which is a "water-drop- 

 per ; " and by its means the potential difference between hydrogen 

 and hydrochloric acid was found to be about 42 volts. 



HEALTH MATTERS. 



Salt and Microbes. — A foreign observer has carried out 

 some instructive researches into the effect of salt on various patho- 

 genic micro-organisms. He found, says the Medical Press, that 

 the results varied a good deal, according to the particular microbe 

 experimented upon. The cholora bacillus, for example, curled up 

 and died in a few hours, while the bacillus of typhoid-fever and 

 the micrococci of pus and erysipelas resisted its influence for weeks 

 and even months. That part of his observations bearing on tuber- 

 culosis possesses -a practical importance, owing to the custom in 

 slaughter-houses of salting the flesh of animals recognized to be 

 tuberculous, and exposing it for sale in the course of a few weeks. 

 M. de Freytag has shown that the tubercle bacillus thrives in ihe 

 presence of an excess of salt, and salting the tuberculous tissues of 

 an ox in no wise prevented the infection of animals fed there- 

 on : hence it is highly desirable that a stop should be put to a 



