March i. 1900] 



NATURE 



42 



IS a substitute for red lead for junctions of pipes, also for a 

 bicycle brake ; to Demetrio Prada and Co., for extracts used in 

 tanning and for the manufacture of oxygenated water ; and to 

 I. Loffler, for introducing into Milan the manufacture of artifi- 

 cial flowers in porcelain. A gold medal and 300 lire is awarded 

 to the Italian Colour Manufactory under Max Meyer and Co., 

 and a bonus of 300 lire to E. Tuffanelli, of Milan,«for an inven- 

 tion connected with water and gas pipes. 



The present position of chemical industry in Japan is referred 

 to in the Board of Trade Joiirttai. Near Osaka, the Yuso 

 Kwaisha alkali works and the Nippon Vuso Kwaisha sulphuric 

 acid plant are both in steady operation. It is stated that the 

 Yuso Kwaisha plant was started in 1893 by English engineers, 

 who fitted it up on the most approved principles, but is now 

 entirely under Japanese management. At the works of the 

 Nippon Yuso Kwaisha sulphuric acid is concentrated in Kioto 

 porcelain vessels in terraced succession. Wakayama and 

 Okayama pyrites, containing from 47 to 50 per cent, of sulphur, 

 are used. The sulphuric acid, packed in earthenware carboys, 

 has been exported in small quantities as far as Bombay. Iodine 

 is also manufactured from seaweed, but in a very small way. 



Among the new instruments brought out by Messrs. Isenthal, 

 Potzler and Co., for use in connection with radiography and 

 wireless telegraphy, is a mercury jet interrupter, which is 

 one of the most perfect forms of break yet designed, and is 

 more serviceable than Wehnelt's electrolytic interrupter. It 

 consists essentially of a fine jet of mercury forming one contact 

 piece, and a series of teeth cut in a cylindrical surface forming 

 the other contact piece. The cylindrical surface surrounds the 

 jet. Its axis is vertical, and the teeth taper downwards. 

 Hence, when the cylinder is made to revolve, by means of a 

 small motor to which it is connected, contact is made when the 

 jet impinges upon a tooth, and broken when it comes upon an 

 interspace. By raising or lowering the jet the ratio of contact 

 to interruption may be varied from zero to infinity, and thus the 

 mean current strength may be adjusted to any required value 

 without interposing resistances. The number of interruptions 

 may be varied through a wide range, and with twenty-four 

 contacts and the motor geared up to three thousand revolutions, 

 it reaches 72,000 per second, which suffices for practically every 

 purpose. 



The magnetic qualities of building brick, to which so much 

 attention has been directed of late by the work of Folgheraiter 

 and others, have been tested quantitatively by Messrs. G. A. 

 Gage and 11. E. Lawrence, who, writing in the Physical 

 Review, describe experiments, -the original object of which 

 appears to have been connected with the choice of bricks used 

 in building physical laboratories so as to cause the least possible 

 magnetic disturbance to the instruments. From the diagrams 

 and tables it appears that certain bricks, described as " brown " 

 and "pressed red," exhibited the most marked magnetic 

 properties, and some of those described as white were among 

 the least magnetic ; and the authors infer that the effects are 



lue to the presence of magnetic iron oxide either a constituent 



if the clay or formed by heat. 



Reference was recently made in Nature to Signor G. 

 Guglielmo's observations on certain modifications of hydrometers. 

 In a still more recent number of the Atti dei Lincei (ix. 2), the 

 same writer describes certain still different forms of total im- 

 mersion hydrometers, in which the inclination of the instrument 

 to the horizon determines the density of the liquid. The 

 principle is, to all intents and purposes, the same as that of the 

 bent lever balance commonly used for weighing letters. The 

 hydrometer is an un.symmetrical body capable of turning about 

 a horizontal axis at one extremity, and having its centres of 



NO. 1583, VOL. 61] 



gravity and buoyancy not in a straight line through this axis. 

 On pouring any fluid into the vessel containing the hydrometer, 

 the latter will rotate into a position in which the moments 

 about the axis of support of the weight of the hydrometer 

 and the upward reaction of the liquid balance each other, 

 and as the position of equilibrium depends on the density of 

 the liquid, the latter is determined by reading off the inclination 

 of the instrument to the horizon. The object of this device is 

 to obviate the disturbances due to capillarity which are in- 

 separable from all forms of total-immersion hydrometers. 

 Finally, by the use of a mirror method for reading the inclina- 

 tion (the effects of refraction being practically avoided by at- 

 taching the scale to the face of the containing vessel), great 

 sensitiveness is obtained. It is easy to obtain hydrometers in 

 which two or three degrees variation in temperature changes 

 the deflection by 40°, but these are necessarily available only for 

 a very limited range of density. 



The quarterly formerly entitled Terrestrial Magnetism, \>\\\. 

 which has now adopted the more comprehensive title of Terres- 

 trial Magnetism and Atmospheric Electricity, bids fair to be- 

 come a cosmopolitan medium of publication for papers bearing 

 on this department of geophysics. In the last number (iv. 4) 

 Profs. Elster and Geitel discuss, in a paper in German, the 

 question of the existence of free electrical ions in the atmosphere, 

 and the possibility of explaining the phenomena of atmospheric 

 electricity by the properties of ionised air (see p. 422). This 

 theory, while still open to objection, would appear to overcome 

 some of the difficulties attaching to Exner's and Arrhenius's 

 theories. In the same language. Dr. Ludeling describes certain 

 researches on the diurnal variation and on magnetic dis- 

 turbances in polar regions. Dr. Ludeling investigates 

 graphically the phenomenon of the diurnal variation of the 

 earth's magnetism for eleven stations with the aid of Von 

 Bezold's vector diagrams. It would appear that when the 

 magnetic disturbances are excluded, the direction of the curve is 

 clockwise, but that the direction of the disturbance vector dia- 

 gram is anti-clockwise ; and Schuster's assumption, that the part 

 of the diurnal variation freed from disturbance can be referred 

 to an invariable revolving system, is not far from the truth. 

 An article by the late General de Tillo deals with the rela- 

 tion between the magnetic elements and the distribution of 

 land and sea, and the mean temperature of the earth's surface. 

 The other papers include notes on the magnetic anomaly near 

 Kursk, Russia, by G. W. Littlehales ; on new magnetic inten- 

 sity variometers, by A. Heydweiller ; and a biographical sketch 

 of Prof. Wild, illustrated by a portrait and view of the Con- 

 stantine Observatory at Paulowsk. 



A report on the commercial value of the metric system, 

 with special reference to the classification of German iron 

 manufactures, was recently forwarded to the Wolverhampton 

 Chamber of Commerce by the British Consul at Amsterdam, 

 and is referred to in the Board of Trade Journal. The Consul 

 states that the iron and steel manufacturers' unions of Germany 

 have adopted a uniform system of dimensions for articles of 

 universal consumption at home and abroad. Angle iron of all 

 descriptions, flanged boiler ends or fronts for Cornish or 

 Lancashire boilers, the boilers them'selves, and iron and steel 

 tubes and all fittings connected with them, such as valves, 

 cocks, T pieces, are made, so far as flange, diameter, and 

 working lengths are concerned, in normal standard sizes, in 

 order that every part of one work may be procured at once to 

 fit every corresponding part of another construction. These 

 normal standards are all fixed by the free co-operation of the 

 combined German engineers' associations, and are unanimously 

 adopted h\ the various manufacturers all over Germany. At 

 present a committee of the engineers' associations is occupied 



