June 1, 1883.] 



SCIENCE. 



489 



PHYSICS. 



Liquefaction of oxygen and nitrogen, and con- 

 gelation of carbonic disulphide and alcohol. — 



On boiling ethylen in vacuo, Wroblewski and Ols- 

 zewski obtained a minimum temperature of —136° C. 

 With the temperatures thus obtained, which were 

 measured with a hydrogen thermometer, experiments 

 were performed on liquefaction and congelation. Un- 

 der the pressures 26.5, 24.8, and 22.5 atmospheres, 

 oxygen began to liquefy at the temperatures —1.31.6°, 

 —133.4°, and —135.8°. It formed a colorless and 

 transparent liquid with a well-defined meniscus. Car- 

 bonic disulphide congealed at —116°, and melted at 

 — 110°; alcohol became a viscous oil at — 129°, and 

 solidified at —130.5°; nitrogen formed a colorless 

 liquid with a visible meniscus. — (Comptes rendus, 

 xcvi. 1140.) c. F. M. [970 



Electricity. 



Alleged luminosity of the magnetic field. — 

 Professor W. F. Barrett says, " It Is well known 

 that the late Baron von Reichenbach claimed to have 

 discovered a peculiar luminous emanation arising 

 from the poles of a magnet, resembling a faint 

 electric discharge in rarefied air." 



Prof. Barrett and several other gentlemen, mem- 

 bers of a committee appointed by the Society for 

 psychical research, have been making experiments 

 with a view to proving or disproving the exist- 

 ence of the alleged ijhenomenon. No member of 

 the committee appears to have been able to see 

 the emanation; but the committee did discover, in 

 some way not detailed, a certain gentleman, Mr. 

 G. A. Smith, and a boy, Fred. Wells, ' an assistant 

 in a baker's shop,' who each appeared able, in a 

 room perfectly dark to other people, to see a faint 

 glow, like a waving cone of light, at either i)ole of 

 a strong electro-magnet, and to tell, by the appear- 

 ance or disappearance of this glow, when the cur- 

 rent was turned on or off by means of a commutator 

 in charge of several gentlemen in an adjoining 

 room. 



Prof. Barrett seems to have taken various pre- 

 cautions to avoid deception, conscious or uncon- 

 scious, on the part of the principal actors in the 

 affair; but it is to be hoped the committee will not 

 rest from its labors till it has found some means 

 of making the alleged luminosity visible, not merely 

 to bakers' assistants and other more or less irrespon- 

 sible persons, but to trained scientific observers. — 

 {Phil, mag., April.) E. H. H. [971 



ENGINEERING. 

 Theoretical mechanics. — Mr. George F. Swain 

 presents an article upon the application of the princi- 

 ple of virtual velocities to the determination of the 

 deflection and stresses of frames. An exact method 

 of finding the elastic deflection in any direction of any 

 point of a frame of any kind, due to Lame, is first ex- 

 plained. The determination of deflection is in itself 

 a problem of small importance. It finds its applica- 

 tion, however, in the calculation of the so-called 

 ' statically undetermined ' structures, such as the 

 continuous girder, and the arch with fewer than three 

 hinges, where the forces acting depend upon the con- 

 dition that the deflection of some point in the frame 

 in someparticular direction must be a given quantity. 

 These structures are taken up in succession, and the 

 general equations to be used in their calculation 

 are given. Trusses with superfluous bars are next 

 discussed ; and a historical account of the literature 

 of thesubject closes the article.— {Jowni. Frankl. inst., 

 Feb., March, April.) G. L. v. [972 



Naval iron vessels. — The advisory board of the 

 navy department reports in favor of fitting up the 

 League Island navy-yard to build the iron and steel 

 ships to be constructed. — {Bull, iron steel assoc, 

 April, 1883.) B. H. T. [973 



Forced draught in steamers. — Experiments on 

 the Satellite and Conqueror, reported by R. J. Butler 

 to the Royal institute of naval architects, indicate 

 that forced draught is not advisable on long runs, 

 but that it is useful on runs of less than six hours. 

 For such cases a fan draught is recommended. — 

 [Engineeriny, March.) K. H. T. [974 



Hydraulic machine-tools. — Mr. R. H. Twed- 

 dell describes to the British histitute of civil engineers 

 forms of machine-tools driven by hydraulic pressure. 

 Riveting has long been practised with hydraulic 

 riveters; hydraulic stamps and forglng-presses are 

 now made to do good work ; machine-tools have 

 been made by Armstrong ; and an hydraulic system 

 of power-transmission has been adopted at Penhouet, 

 France. Portable hydraulic machine-tools are found 

 to save greatly in floor-space, and to save power as 

 well. — (Engineering, March 23.) B. H. T. [975 



CHEMISTRY. 

 ( General, physical, and inorganic.) 



Borotungstic acids. — D. Klein prepared disodic 

 borotungstate (14 WO3 . B3O.J . 2 NajO . 4H.2O+ 

 25 H.2O) by adding the required amount of boracic 

 acid to neutral sodic tungstate. Although other 

 salts were prepared from the sodium salt, several at- 

 tempts to separate the acid in a state of purity were 

 unsuccessful. The mother liquors of the sodic boro- 

 tungstate contained a sodium salt of tungstoboric 

 acid, which was precipitated as the barium salt by 

 adding baric chloride. This acid, which is compara- 

 tively stable, was prepared by treating the barium 

 salt (9 WO3 . B2O3 . 2BaO-HS H.O) with dilute sul- 

 phuric acid. Tungstoboric acid proves to be a con- 

 venient reagent for characterizing the alkaloids and 

 peptones. With even a minute quantity of the salts 

 of quinine, cinchonine, strychnine, morphine, and 

 codeine, it gives a white precipitate. With peptones 

 it behaves like phosjihotungstic acid. The author 

 finds that cadmic tungstoborate is well adapted for 

 use in the mechanical separation of the mineralogi- 

 cal elements of rocks in petrography. In the solid 

 form, its specific gravity is 3.28, and a liquid may be 

 obtained from it of any density between 1 and 3.8. 

 At 75°-S0° it melts in its water of crystallization, 

 giving a sirupy liquid of sufiicient density (3.7) to 

 float garnet or spinel. — (Ann. chim. phys., xxviii. 

 350. ) c. F. M. [976 



Action of chlorine on certain metals. — When 

 thoroughly dried chlorine was allowed to remain in 

 contact with Dutch metal, A. Cowper found, that, 

 apparently, no chemical action had taken place at the 

 end of three months. On introducing even a trace of 

 moisture, the chlorine was rapidly absorbed. Zinc 

 and magnesium were not attacked by the gas after it 

 had stood several days in contact with fused calcic 

 chloride. Silver and bismuth were acted on slowly ; 

 while tin, antimony, arsenic, and mercury were at- 

 tacked with the same energy as in the moist gas. In 

 the dried gas, sodium remained untarnished. Potas- 

 sium, at first bright, became slowly covered with a 

 purple film, probably of the subchloride. — (Journ. 

 chein. soc, ccxliv. 153.) c. F. si. [977 



Drying gunpowder magazines. — It having 

 been officially recommended that chloride of litne 

 should be used for removing the moisture from maga- 

 zines. Prof. Munroe held that this was due to a con- 



