476 



NATURE 



[September 5, 1907 



basis, they give the following melting points : — silicon, 

 ^452'' C. ; palladium, 1576° C. ; rhodium, 1968° C. ; 

 indium, 2388° C. ; the temperature of the glower at 

 normal brilliancy 2480° C, the melting point of the glower 

 material 2490° C. 



The atomic weight of radium was determined five 

 years ago by Mme. Curie on about 009 gram of a 

 highly purified radium chloride. Large quantifies of 

 Joachimsthal pitchblende residues have since then been 

 worked up, and from these 0-4 gram of pure radium 

 chloride has been obtained. The method of purification 

 adopted was re-crystallisation from weak hydrochloric acid 

 and fractional precipitation of the aqueous solution by 

 alcohol, the progress of the purification from barium being 

 followed by means of the spectroscope. It seemed 

 desirable to repeat the determination of the atomic weight 

 on the larger quantity now available, and Mme. Curie gives 

 an account of the method adopted in the current number of 

 the Comptes rendus (No. 8, August 19). Difficulties were 

 encountered owing to the presence of traces of impurities 

 in the reagents, leading to a gradual loss of radium during 

 the purification, and a detailed account is given of the 

 elaborate precautions found to be necessary for the pre- 

 paration and preservation of the reagents used. The 

 atomic weight deduced from the ratio radium chloride : 

 silver chloride is 22()-2 (.Ag= 107-8, Cl = 35-4), or 1-2 units 

 higher than the value found on 0-09 gram in 1902. It 

 is shown that the slight increase of purity of the 1907 

 over the 1902 preparation is not sufficient to account for 

 the rise of 12 units in the atomic weight, the difference 

 being most probably due to the loss of accuracy on the 

 determinations with the smaller quantity and the use of 

 reagents not properly purified. 



The August number of the Journal of the Institution 

 of Electrical Engineers (No. 185, vol. xxxix.) contains, 

 amongst others, a paper on the technical training of 

 electrical artisans, read by Mr. C. P. C. Cummings 

 before the Dublin local section of the institution. The 

 subject is one which is very rarely treated in papers read 

 before the Institution of Electrical Engineers or the branch 

 sections, but, at the same time, it is one which is very 

 important to the future development of electrical work. 

 The term electrical artisan, as referred to by Mr. 

 Cummings in his paper, deals almost entirely with those 

 electrical artisans who are generally classified as " wire- 

 men," and the paper treats of the possibilities of 

 improving the existing methods by which such men are 

 trained at the present day, so that more eflScient workmen 

 may be obtainable. Mr. Cummings very rightly points 

 out that there is a very large majority of the " so-called 

 wiremen " obtaining the maximum rate of wages per 

 hour which the highly trained and competent workman 

 is fully entitled to, who cannot be placed in the same 

 class with him, and can obtain this rate without any 

 trouble. This in itself is evidence of the serious defect 

 in the method by which electrical artisans are produced. 

 So long as these methods continue, they will produce a 

 considerable number of men who cannot be considered 

 fully competent, but very few first-class artisans, and from 

 this very fact the really competent men consider them- 

 selves so strong by virtue of their minority that their 

 demands upon employers and their general independence 

 greatly reduce their utility. Mr. Cummings describes the 

 present method of training electrical artisans, and points 

 out the faults of the system and propounds a scheme 

 which is well worth the consideration of educational 

 authorities and employers— especially the latter — for until 

 NO. 1975, ■^'OL. 76] 



the employers take a practical interest in this matter they 

 cannot hope to obtain the man most suited to their 

 requirements. 



Messrs. John J. Griffin and Sons, Ltd., of Kings- 

 way, have just issued a new edition of " Chemical Handi- 

 craft," giving particulars (in many cases illustrated) of 

 the chemical apparatus and reagents manufactured and 

 sold by them. Science teachers will find the volume very 

 handy for reference. 



The lectures delivered under the Silliman foundation 

 at Yale University in March, 1905, by Prof. E. Ruther- 

 ford, F.R.S., which were afterwards issued in book form 

 under the title of " Radio-active Transformations." have 

 now been translated into German by Dr. Max Levin, of 

 Giittingen, and published by F. Vieweg and Son, Bruns- 

 wick. Brief reference is made in the volume, in the form 

 of footnotes, to the more important advances in the sub- 

 ject which have taken place since the first appearance 

 of the work in English. 



OUR ASTRONOMICAL COLUMN. 



Daniel's Comet, 1907J. — The following is a continu- 

 ation of the ephemcris for comet 1907^ given in No. 4196 

 of the Astronomische Nachrichten (p. 337, August 23) : — 

 Ephemcris 12)1. (M.T. lierlin). 

 1907 o (true) { (iru'!) log r- log A Bright- 



Sept. 9... 9415 ■■+1' s'7 ■■• 97250 -0'ii39- 137 



,, II ... 9 53'3 ... + 10 260 



,, 13 ... 10 47 ... + 9 45-9 ... 97495 •■• 0-1408 ... IO-8 



,, 15 ... 10 157 .. + 9 5''; 



,, 17 ... 10 263 ... + 8 251 ... 97818 ... 0-1654 ... S-3 



,, 19 ... 10 36-5 ... -I- 7 449 



It will be noticed that the brightness of this object is 

 declining rapidly, and, as the comet rises nearer and nearer 

 to sunrise, it is becoming increasingly difficult to observe. 

 At present it rises about two hours before the sun, and 

 on .September 19 it will precede the sun by about I5 hours, 

 rising about 12° north of east. 



Comptes rendus, No. 8 (August 19), contains the results 

 of observations made by M. E. Esclangon at Bordeaux. 

 The head of the comet was extraordinarily bright and of 

 about s' diameter on August i. Seven tails were seen, 

 the extreme streamers being much shorter than the 

 median. .\ reproduction of the observer's drawing shows 

 the disposition of the tails. 



Solar Observations at Cartuja, Granada. — In an 

 extract from No. 3 (1907) of the Bulletin de la Soci^tc 

 hclge d'Astronomie, M. J. Mier y TerAn, S.J., publishes 

 an account of the solar observations and reductions now 

 carried on at the Observatory of Cartuja-Granada (Spain). 



Solar observations \vere commenced at the beginning of 

 1905 for obtaining statistics relating to sun-spots and 

 faculje. In January, 1906, photography was substituted 

 for eye observations for the purpose of obtaining more 

 precise measures, and photographs have since been secured 

 on each clear day. A more suitable photoheliograph has 

 recentlv been erected having an objective of 94 mm. 

 (37 inches) aperture and 150 m. focal length, and fitted 

 with a direct enlarger giving a solar image of about 

 10 cm. (4 inches) diameter. The areas and positions of 

 the spots, &c., are measured with a Hilger micrometer, 

 the positions afterwards being reduced to heliocentric 

 coordinates in the usual manner, and it is hoped that the 

 results will be found sufficiently precise to supplement the 

 Greenwich measures. As it is proposed to publish these 

 results in the tri-monthly numbers of the observatory 

 bulletin, it may be expected that solar workers will find 

 them available without having to wait for the Greenwich 

 annual publications. Spectroscopic observations of the 

 sun and the stars are also being carried on at Cartuja, 

 and it is hoped that ere long the apparatus for spectro- 

 photography with a large dispersion will be installed. 



