February 13, 1896] 



NATURE 



349 



occurred, accompanied by a shaking of the ground and of build- 

 ings. A red-tinted cloud was for a long time visible in the east. 

 The directors of the Observatory suppose that the phenomenon 

 was caused by an aerolite. Owing to the time that elapsed 

 between the observation of the explosion and the report, the 

 aerolite must have burst at a great distance from the earth." 

 The note adds that no traces of the meteorite have yet been 

 found. Nevertheless, it is reported that several small pieces of 

 grejnsh stone, still warm, have been picked up in Madrid. 



Great interest has been aroused in France by the discoveries 

 of Prof Rontgen, and experiments have been at once made con- 

 firming and extending the original results. Last week's number 

 of the Comptes rendits contained further work by M. Jean 

 Perrin on the properties of the kathode rays (see ante, 

 p. 298), showing that they are not identical with the Rontgen 

 rays. The current issue (February 3) contains papers on this 

 subject by MM. L. Benoist and D. Hurmuzescu, A. Nodon, 

 ^". Chabaud, and G. Moreau. The first of these gives an 

 account of a most remarkable property of the rays, that of com- 

 pletely and rapidly discharging an insulated charged electroscope, 

 the effect being produced more rapidly if the charge borne by 

 the gold leaves is a negative one. This phenomenon is not in 

 any way interfered with by an aluminium screen, although the 

 latter protects the electroscope perfectly from both light and 

 electricity. The note by M. Nodon further emphasises the 

 difference between these rays and the ultra-violet rays. An 

 ordinary dry plate wrapped in several thicknesses of blackened 

 paper was exposed at a distance of 40 cm. from a power- 

 ful arc lamp (20 amperes) for fifteen minutes ; on developing, 

 the plate was unaffected, although under the same con- 

 ditions the Rijntgen rays produced a very marked result. 

 The latter also were found to pass with equal facility 

 through differently coloured screens of the same material. 

 The transparency of metals to the X-rays is the subject 

 of the communication by M. Chabaud. Fourteen metals 

 and alloys were examined by the photographic method, the 

 results being substantially identical with those published by 

 Prof. Rontgen in his original paper ; results which were obtained 

 very simply by the use of a phosphorescent screen. M. Chabaud 

 makes no reference to these earlier experiments on the same 

 subject. The two metals most opaque to these rays are 

 those of the highest atomic weights, platinum and mercury, the 

 most transparent being that with the. lowest atomic weight, 

 aluminium. M. Moreau dispenses with the Crookes' tube 

 altogether, and uses the brush discharge of an induction coil ; the 

 curious result being obtained, that if the box containing the plate 

 be placed normally to the brush, there is no effect, whilst placed 

 parallel to the brush, strong, clear negatives are produced. No 

 explanation of these experiments is attempted. 



The same number of the Comptes rendits also contains a 

 second note by M. G. Le Bon, on photography with "dark 

 light." By placing a sensitive plate under a negative, covered 

 with a metallic plate o'5 mm. in thickness, and exposing to the 

 light of a lamp, good images are obtained on development, 

 especially if a piece of lead is bent back over the frame, so that 

 the whole printing frame is in a sort of metallic box. M. G. H. 

 Niewenglowski mentions that these results can be obtained 

 without any lamp at all, and hence suggests that they must be 

 due to luminous energy stored up in the negative. But further 

 experiments by M. Le Bon have completely eliminated this 

 source of error, as the same results are obtained with negatives 

 which have been previously submitted to blank experiments in 

 the dark. From the point of view of Maxwell's theory of light, 

 rays which can pass through 0*5 mm, of copper must differ 

 essentially from ordinary light, and M. Le Bon proposes to 

 next examine within what limits these dark rays submit to the 

 NO. 1372, VOL. 53] 



laws of refraction, and how far they are affected by a magnetic 

 field. 



It is announced that Dr. Kitasato, of Japan, has succeeded 

 in inoculating for leprosy, and that the disease is curable. 



The formal presentation of the portrait of Mr. W. Carruthers, 

 F.R.S., to the Linnean Society, was made at its meeting on 

 P'ebruary 6, by Sir W. H. Flower, on behalf of the subscribers. 



The Annual Congress of the French Association for the 

 Advancement of Science will be held this year at Tunis, 

 between the ist and nth of April. The Botanical Society of 

 France will also hold its Extraordinary Session at the same 

 place, and about the same time. 



A COURSE of six lectures to working men, on " Fermentation," 

 by Dr. W. P. Wynne, will be given in the Lecture Theatre of 

 the Museum of Practical Geology, Jermyn Street, commencing 

 on Monday, February 24. 



A Congress of Natural History and Scientific Societies of the 

 South- East of England will be held at Tunbridge Wells on 

 Saturday, April 25, under the presidency of the Rev. T. R. R. 

 Stebh)ing. 



The practical extinction of the buffalo, or American bison, is 

 very forcibly shown by an article recently published, which 

 states that 300 dols. is now refused for a good buffalo robe, such 

 as could at one time early in the seventies have been bought for 

 a dollar, or even less. 



We are requested to state that the arrangements are now com 

 plete for lighting in the evening the Southern Galleries of the 

 South Kensington Museum on the west side of Exhibition Road, 

 which contain the collections of machinery and naval models. 

 These Galleries will be open free to the public from February \^ 

 on three evenings a week — Mondays, Tuesdays, and Saturdays, 

 till 10 p.m. — in the same manner as the main building. 



Another of the wonderful potentialities of the Niagara 

 water-power is its application to the new process of Blumenberg 

 for the manufacture of chlorate of potash by the action of the 

 direct electric current upon tanks of potassium chloride. The 

 electric current is at a remarkably low voltage. Important by- 

 products are also obtained. Operations will begin next July. 

 The Alkali Union, which controls the world's output of chlorate 

 of potash, has reduced the price from 17 to ID cents a pound, in 

 anticipation of this undertaking ; but the new manufacturers 

 will probably undersell them in all the markets of the world. 



The new illuminant, acetylene, seems to be notable for its 

 efficiency and the cheapness of its production by the electrical 

 manufacture of calcic carbide, from which it is evolved by the 

 mere application of water. Calcic carbide is already made at 

 Spray, North Carolina, at a cost of 20 dols. per ton, by the 

 alternating electric current passed through a mixture of pow- 

 dered coke and lime. Works have been erected at Niagara 

 which will produce the calcic carbide at 10 dols. a ton, begin- 

 ning about the middle of this month. One ton of the carbide 

 yields 11,000 cubic feet of acetylene gas, which has many times 

 the illuminating power of common illuminating gas. The light, 

 moreover, is clear and "solid" — that is, it has not the un- 

 illuminated centre of an ordinary gas-light. Acetylene gas is 

 readily solidified, and may be conveniently distributed in 

 cylinders, like carbon dioxide and other gases. 



The Geographical Survey of the United States has issued the 

 report of a party of department geologists who recently made an 

 extended investigation and survey of the Cripple Creek region. 

 The mining district is thirty miles west of Colorado Springs, and 

 seventy-five miles south of Denver. It covers an area of six 



