NATURE 



[September 26, 1S95 



I'rol. Aytton read a paper by Mr. Mather and himself, in which 

 an^imenis were advanced against the existence of a back electro- 

 1: ' in the electric arc. The authors describe a method 

 ^ :he tnie resistance of the arc, nameh the ratio of a 

 ,M..., ^.^„>e of p0tenti.1l difference to the corresp<inding in- 

 crease in the current : this, of course, is a negative quantity. The 

 same authors descritjetl a magnetic field-tester, an apjilication of 

 the ordinary exploring coil and ballistic galvanometer method, 

 with a spiral spring to effect rapid rotation of the exploring coil, 

 and a mo<litied D'Arsonval galvanometer with shuttle-wound 

 coil capable of rotating through several turns without losing the 

 propor"' "'■■•■ f angular displacement and restoring force. 



The light in vacuum tubes conveying an electric dis- 



charge subject of a ])aper by Messrs. Edser and Star- 



ling. \ .icuum tubes were placed in the path of the two beams 

 of a Fizeau interference apparatus, and the jwsition of the bands 

 obser^•ed. No appreciable shift of the bands was obtained either 

 by setting up an induction-coil discharge, or by the discharge of 

 tcr ,:" ■ \r> through the tul>es when placed in series with a 

 I • string. The dischai^e in the latter cise lasted 



< :.- : -. of a second, and the authors show that a dis- 

 turbance 01 the bands of so long duration would have been 

 observed. 



Mr. K. fi. Baily read a pajjer on hysteresis of iron in an 

 alternating magnetic field, in which he showed that the hysteresis 

 of iron increases with the field up to a maximum value, in 

 accordance with Kwings theory. The experiments were made 

 by the isthmus method, using a small laminated armature con- 

 sisting of thin discs of charcoal iron ; the most intense magnetic 

 field used was 22,000 C.O.-S. units, and the hysteresis was 

 measured by the rise of tem|>erature of the armature. 



On \Vednc«Iay, Dr. Gladstone and Mr. W. Ilibbert made a 

 I n the change of molecular refraction in salts 



in water. The molecular refraction of a sub- 

 .^ , when the substance changes its state, and a 

 1 alteration takes place on diluting its .solution : the 



.i„ c obtained some evidence of a close connection 



bciuccn liicse changes and the variations of electric conductivity 

 of the sul<stance and its solutions. .Such a connection would have 

 an im|K)riant bearing on the theory of solution. 



The report of the Electrical Standards Committee was read. 

 The Committee hope during the year to institute a comparison 

 Iwtween ihe IJritish and (German standards of resistance, and 

 have pr<K:ure<l coils for this purpose, which have already been 

 tested at the Reichsanstalt. The Committee, recognising the j 

 need for practical units of magnetic field and magnetic potential, 

 recommend foi tentative adoption (l) aunit equal to 10' C.Ci.S. 

 lines, to be called a weber, (2) ihe C.(j.S. unit of magnetic 

 IMtential, to l>e called n gniiss. They also recommend that the 

 termination (imc be used in describing the pro]iertics of a piece 

 of matter, i.i;. the resist<r«i<: of a copper wire, and the termina- 

 tion /;■//)' or i/ily for the sjiecific properties of the material, e.g. 

 the resist/!'//)' of Copper would mean the resistance of a centi- 

 metre cul>e of it. I'rof. Oliver Lodge explained, and advoc.ited 

 the use of. the projKised units. I'rof. S. I'. Thompson, while 

 i. ' "':'■ Committee as to the desirability of having 



lield and magnetic [vitential, thought the choice 

 ulil lie left with the pr.iclical men who use 

 Lil the proposed wiher was too large, and ad- 

 r lion of the C.fi.S. " line," using the kilo- and 

 > multiples : further, he did not see any necessity 

 irit; ihe am|KTelurn in order to replace it by the 

 ' n iHiinted out a more formidable objection, 



> man Institute of Electrical Engineers have 

 ..,.,/• to a different unit, and have suggested 

 i"r the gauss. Several meniliers continued the 

 I'rof. I'erry expressed his opinion that the 

 ■I. lines ought to be settled by a general congress. 

 ~ of ap|)aratus for tracing the form of the wave of 

 ilternate current circuit were exhibited and de- 

 \ Messrs. Uarr, Hurnic and Kixigers, the other 

 ' ^'- Milhcr. 



•' il the appar.itus designed for the 



lo- ihermometers at Kew Obscrva- 



' ' ' iidar and Griffiths platinum 



■ ir |)orcelain tulie, and can be 



'liL iliLTiiiometer to l)e calibrated, in 



I "t sulphur vapour, accfirding tf> the 



■ ■■i' ■. It^ reH.stancc i.s measured by a Wheat- 



, the coils of which arc enclosed in a copper box, 



NO. 1352, VOL. 52] 



five sides of which are immersed in a water-bath of constant 

 temperature, while the top is surmounted by a case similar to that 

 of a chemical balance. The coils of the bridge are of platinum- 

 silver, wound double, and are not embedded in paratlin, the 

 object being to allow them to assume the temperature of the box 

 and surrounding water as quickly as possible. 



A vote of thanks to the Chairman and Secretaries terminated 

 the proceedings. 



CHEMISTRY AT THE BRITISH 



ASSOCIATIOX. 



\TnTH the exception of Prof. Runge's announcement of the 

 undoubtedly comixiund nature of helium, few of the 

 communications laid before Section B at Ipswich are likely to 

 awaken great interest outside chemical circles. The discussions, 

 however, which are now a recognised feature of these meetings, 

 were especially successful, and it is not too much to hope that 

 the joint meeting with the newly-formed Botanical Section may 

 be the means, if only indirectly, of bringing about results of 

 great importance to the agricultural community. 



Following the Piesident"s valuable address. Sir Henry Roscoe 

 and Dr. A. Harden communicated to the Section an interesting 

 discovery in historical chemistry. It has been generally assumed 

 that Dalton arrived at the idea of atoms with definite weights 

 from a consideration of the proportions in which certain 

 elements combined. I'rom the examination of a number of 

 manuscript volumes of Dalton's own laborator)' notes, which 

 they have recently discovered in the library of the Manchester 

 Literary and Philo.sophical Society, Sir Henry Roscoe and 

 Dr. Harden conclude that Dalton worked out his theor)' solely 

 from physical considerations as to the constitution of gases. 

 His mind being saturated with Newton's ideas concerning 

 atoms, it was from these that his own atomic theory was 

 developed. 



Later on, quoting not only his own results but those of 

 other chemists, he seems to have been led to the law of multiple 

 proportions as the only conceivable mode of combination 

 between atoms. Extracts were given from his notes showing 

 that certain numbers, usually quoted as having led him to his 

 atomic theory, e.g. the analyses of marsh gas and olefiant gas, 

 were only inserted in his tables some time after the publication 

 of his ideas. 



I'rof. .Vrnistrong said it was satisfactory to learn that Dalton 

 had really arrived at his conclusions from truly philosophical 

 considerations, without reference to the very crude numbers, 

 usually quoted as sufficient basis for the laws that he worke<l 

 out. 



The report of the Committee on the leaching of science in 

 elementary schools was read by Dr. J. II. Gladstone. During 

 |>a.st years there has been an increase in the number of subjects 

 taught, and in the number of pupils receiving instruction. The 

 alteration in the system of inspection will have an especially 

 useful effect in the teaching of science. The question of the 

 training of teachers is di.scussed in the report. A course for 

 mistresses on domestic science, tlealing as far as jiossible with 

 the nature of the processes and materials employed in tlie 

 household, has been found successful. The great obstacles to 

 good science teaching at the present time in elementary schools 

 are: (l) Large classes; (2) multitude of subjects; (3) in- 

 sufficiency of the training course for le.ichers in science subjects ; 

 ^4) effects of the old science and art system, which is clearly far 

 too formal, and pays far too little attention to ordinary re<|uirc- 

 ments. 



The courses on elementary physics and chemistry, and the 

 science of common things are found to be more attractive than 

 pure chemistry. 



( )ther subjects dealt with in the report are school visits lo 

 museums ; the right method of giving object less<ms ; and the 

 teaching of the metric system. Finally it is suggested .is a 

 question worth consideration, whether the recognised school age 

 should not l>e raised from thirteen to fourteen. 



In the discussion which followed the rciding of the re|>orl, the 

 relation of County Councils to elementary schools was debated, 

 and il was contended that these are helped indirectly by the 

 Councils providing facilities for the training of te.acher.s. 



Mr. G. J. Fowler read a [laper on the action of nitric oxide 

 on certain salts, by H. A. Auden and G. J. Fowler, in which 

 the action of nitric oxide on different salts at various tempera- 



