128 



NATURE 



[May 29, 1913 



formula in the case of the Calabrian earthquake of 

 October 23, 1897, the sea-waves of which were regis- 

 tered by the mareographs at Messina and Catania 

 (Boll. Soc. Sism. Ital., vol. xvi., 1912, pp. 166-174). 

 The actual mean velocity was 102 metres per second, 

 while the values given by Davison's, Rudski's, and 

 Lagrange's formulae were respectively 109, 114, and 

 120 metres per second. 



Vol. xiii., part 2, of the Proceedings of the Nova 

 Scotian Institute of Science contains an account, by 

 Mr. J. H. L. Johnstone, of measurements of the 

 specific resistance of ice at temperatures between o° 

 and — 19 C, made by a new method, in which the 

 effects of electrolytic polarisation were eliminated. The 

 values obtained agree fairly well with those obtained 

 by Profs. Ayrton and Perry, using a different method, 

 and show that the value of the temperature coefficient 

 is verv much higher than that of ordinary electrolytes 

 and decreases in value as the temperature de- 

 parts from 0°. The same number of the Proceedings 

 also includes an interesting account of the sacred 

 trees of India, by Capt. J. H. Barbour. 



We have received a copy of the reprint of the Car- 

 negie Institution of Washington paper on the mag- 

 netic survey work in southern and central Africa 

 carried out in 1908 and 1909 by Prof. Beattie, of the 

 South African College, Cape Town, and Prof. Morri- 

 son, of Victoria College, Stellenbosch, who for the 

 time necessary were made officials of the Carnegie 

 Institution. The cost of the work was defrayed by 

 the Carnegie Institution, 2000/., the Royal Society, 

 250Z., and Sir L. S. Jameson and Sir L. Mitchell, 

 100/. The survey covers the regions between the 

 Zambezi and the Nile, including parts of north- 

 eastern Rhodesia, the Congo, German East Africa, 

 Uganda, Nyasaland, and British East Africa, with 

 further observations in Cape Colony and German 

 South-West Africa. Throughout most of the journey 

 the only means of conveyance was by native carriers, 

 and the history of the expedition reads like a chapter 

 of Livingstone's travels. We offer our congratulations 

 to Profs. Beattie and Morrison on the successful 

 accomplishment of an important and much-needed 

 piece of magnetic survey work. 



Separate copies have reached us of a considerable 

 number of papers which have been published by the 

 staff of the Reichsanstalt during the present year. 

 Dr. F. Henning has compared the platinum resistance 

 with the hydrogen thermometer at temperatures be- 

 tween o° C. and — 193 C. He finds that Calendar's 

 formula connecting the two holds only down to 

 — 40 C, and proposes another formula, which holds 

 over the whole range. Drs. K. Scheel and W. Heuse 

 have determined by the continuous-flow method the 

 specific heats at constant pressure of helium, hydrogen, 

 nitrogen, oxygen, air, and carbonic oxide, at tem- 

 peratures down to that of liquid air. The specific 

 heats of helium and hydrogen increase with increase 

 of temperature, the others decrease. In connection 

 with these researches a thermostat suitable for low 

 temperatures has been devised by Dr. Henning. It 

 depends on the passage of a stream of liquid air 

 NO. 2274, VOL. 91] 



through a suitable liquid, as, for example, petroleum 

 ether. The air evaporates in the liquid, and the rate 

 of evaporation determines the temperature to which 

 the liquid is cooled. The former papers will be found 

 in the March and April numbers of the Annalen der 

 Physik, and the last in the February number of the 

 Zeitschrift Jiir Instrumvntenkunde. 



It has long been known that the photometry of 

 sources of light widely differing in colour is rendered 

 difficult by the peculiarities of the eye, especially at 

 low illuminations. Until recently this was not of 

 much practical importance, since most of our com- 

 mercial illuminants yielded continuous spectra and 

 light of substantially the same tint. Now, however, 

 things are changed. A recent communication by 

 Messrs. Broca, Jouast, De la Gorce, and Laporte 

 (Bull. Soc. Int. des Electriciens, February, 1913) shows 

 the perplexities likely to be met with in comparing 

 such sources as the mercury-vapour lamp and the 

 new neon tube. The former contains only yellow, blue, 

 and green light, the latter only red and orange rays 

 between 0-585 m and 0640 /*. The authors meet with 

 differences of 100 per cent, or more, according to the 

 illumination of the photometer screen. Similar dis- 

 crepancies are caused by the personal errors of dif- 

 ferent observers. To these difficulties, due to the 

 colour of the light, must be added those arising from 

 the fact that the light is not a point, but a tube of 

 considerable dimensions, so that the ordinary inverse 

 square law of photometry does not apply. Another 

 interesting observation is that objects illuminated by 

 the neon light appear more sharply defined than in 

 the case of ordinary illuminants. The reason would 

 appear to be that the monochromatic nature of the 

 light avoids the results of chromatic aberration in 

 the eye. 



Some new experiments on the preparation and pro- 

 perties of pure alcohol are described in the Chemical 

 Society's Journal by Mr. R. W. Merriman. The 

 densitv of the pure alcohol was established for about 

 forty samples as 080628 at o°/4°. It was shown that 

 freshly burnt quicklime prepared from marble is a 

 better drying agent than metallic calcium, which pro- 

 duces no improvement in alcohol dried by lime. In 

 distilling the alcohol from the lime it i-; necessary to 

 reject the first and last fractions ; the latter have a 

 high density, which is attributed to partial dehydration 

 of calcium hydroxide as the temperature of distillation 

 rises from 80° to ioo° on the water-bath. 



A "New Iron Bacterium" is described by Mr. 

 E. M. Mumford in. the Transactions of the Chemical 

 Society. It was discovered in the Bridgewater Canal 

 tunnels at Wasley, Lancashire, where the water con- 

 tains much iron derived from colliery pump water. 

 The new bacterium appears to have a twofold action, 

 an aerobic action whereby it precipitates ferric 

 hydroxide from iron solutions, and an anaerobic action 

 which transforms the ferric hydroxide into bog iron 

 ore with partial reduction of the iron to a ferrous 

 state. It is probable that the deposits of bog ore are 

 due to this organism rather than to the higher bac- 

 teria, since the latter have not the facultative power 



