August 3, 191 1] 



NATURE 



i53 



charts. In July the highest temperature, 34° C, lies 

 almost wholly to the east of the Nile, the greater part of 

 iln Sahara falling between that isotherm and that of 

 32 C. ; and in Central Africa the isotherm of 26° C. 

 extends southward to about latitude 17 S. in the basin of 

 the Zambezi. 



I in meteorological chart of the North Atlantic and 

 Mediterranean for August (first issue, July 13), published 

 by the Meteorological Committee, is of special interest in 

 connection with the recent prolonged drought. The 

 weather charts for July 6-12, and the useful summary 

 which accompanies them, show that throughout that period 

 a well-developed anticyclone dominated the situation over 

 the eastern part of the ocean and western half of Europe; 

 the temperature rose at places above 90°, and even to 

 84 in Iceland. For six out of the seven days this system 

 cif high barometric pressure lay practically motionless over 

 these islands, and at the close of the period reports indi- 

 cated the continuance of anticvclonic conditions of weather 

 on the ocean. 



In an article in Symons's Meteorological Magazine for 

 July, entitled "The Disappearance of Evening Cloud at 

 Full Moon." Mr. W. Ellis, F.R.S., endeavours lowing to 

 a recent reference to the subject) to refute the opinion 

 held by Sir J. Herschel and others that the full moon 

 possesses the faculty of clearing away clouds. This 

 fallacy, like that of the artificial production of rain, is 

 difficult to eradicate from the public mind. Mr. Ellis has 

 shown from the Greenwich observations that a maximum 

 cloudiness in the forenoon and a minimum in the evening 

 represent the usual climatic variation. A change from a 

 cloudy to a clear state in the evening sky is much more 

 likely to attract attention when occurring near to full 

 moon, and this is the opinion of leading meteorologists of 

 the present day. Dr. W. N. Shaw (Quart. Journ. R. Met. 

 Soc, April, 1902) suggests a physical explanation of the 

 phenomenon, viz. that a floating cloud loses heat by 

 radiating into space more heat than it receives from the 

 earth beneath ; the water globules consequently evaporate, 

 and the cloud will vanish. " Any effect of direct radia- 

 tion of the moon may be quite properly disregarded." A 

 more recent opinion in the same sense (to which we have 

 before referred) is contained in Mr. J. R. Sutton's paper 

 on the lunar cloud period (Trans. South African Phil. 

 Soc, December, 1907). 



An article by Mr. D. Owen in The Electrician for July 7 

 places in a very clear light the importance which now 

 attaches to the " lively dance of bright spots," first 

 noticed by the English botanist Brown, in any liquid con- 

 taining minute particles in suspension when illuminated 

 from the side. Sixty years ago the observation attracted 

 little attention, but recently, through the improvements 

 which have given us the ultra-microscope, the experiments 

 ol M. Perrin and the theoretical work of Dr. Einstein, the 

 study of the Brownian movements has thrown consider- 

 able light on the properties and motions of the ultimate 

 particles of which matter is composed. 



Separate copies of several of Prof. Righi's recent papers 

 have reached us, and to one of them, which deals with 

 the effect of a magnetic field parallel to the axis of a 

 vacuum tube on the electric discharge through the tube, 

 we should like to direct special attention. If such a tube 

 with aluminium disc electrodes 15 cm. apart is covered 

 outside with tin foil and placed in a magnetising solenoid, 

 Pro/. Righi finds that a potential difference of 3000 volts 

 between the electrodes, which is insufficient to cause a 

 NO. 2 179, VOL. 8/] 



measurable discharge in the absence of a magnetic field, 

 will maintain a current through the tube with a field of 

 1250 gauss in the neighbourhood of the positive electrode, 

 or a field of above 5000 gauss in the neighbourhood of the 

 negative. He is disposed to attribute the phenomena to 

 the production of electrons at the walls of the tube by the 

 magnetic field, and is engaged in further work to test 

 this hypothesis. 



The remarkable influence of borax in raising the rota- 

 tory power of mannitol has been known for nearly forty 

 years, but the exact origin of this effect has been open 

 to question, although the combination of the mannitol 

 with the boric acid appeared the most probable explana- 

 tion. It is therefore a matter of satisfaction that the 

 compound should at last have been isolated and analysed. 

 As described by Messrs. J. J. Fox and A. J. H. Guage 

 in the June number of the Chemical Society's Journal, the 

 compound is formed, according to the equation 

 C 6 H 11 S +H 3 B0 3 = H.O+C 6 H 1S 1 ,B, 

 by dissolving mannitol and boric acid in hot alcohol, filter- 

 ing, and allowing to stand. The mannitoboric acid slowly 

 separates in compact, colourless prisms, melting at 89.5°, 

 but dissociates again when attempts are made to re- 

 crystallise it. 



The tenth volume of the Transactions of the English 

 Ceramic Society (part i.) contains as a frontispiece a por- 

 trait of the president, Mr. H. Johnson, whilst a portrait 

 of the first president, Mr. William Burton, is issued as a 

 frontispiece to vol. i. The new issue includes two 

 important technical papers on electricity for potters' 

 machinery, by Mr. Odelberg, and on liquid fuel, by Mr. 

 Kermode; these may be regarded as additions to a series 

 of papers of which those on gas-firing were noted in 

 these columns recently. Attention may also be directed 

 to a paper by Dr. J. W. Mellor on the constitution of the 

 kaolinite molecule, and to a paper on colour and its 

 measurement by Mr. J. W. Lovibond. The value of the 

 work done by this society in emphasising the importance 

 of scientific methods in one of the leading industries of 

 the country can scarcely be overestimated. 



The extension of the system of multiple evaporation in 

 the manufacture of sugar has been limited by the fact 

 that whilst the evaporation may be effected safely under 

 normal and reduced pressures of steam, the sugar begins 

 to decompose when steam under pressure is used. A report 

 on the effect of high temperatures on cane sugar in solu- 

 tion, by Noel Deerr, issued from the Experiment Station 

 of the Hawaiian Sugar Planters' Association, describes an 

 investigation of considerable technical and scientific 

 importance. It is shown that sugar inversion begins to 

 be important at no°, but may be checked by the addition 

 of alkali ; this causes 'the juice to darken, but much of 

 the colour disappears when the alkali is neutralised, and 

 the coloration in no way corresponds with loss of sugar. 

 The conclusion is drawn that the local juices may be 

 relied upon to stand half an hour's heating at 120 with- 

 out loss of sugar, whilst under careful control and observa- 

 tion a temperature of 125° (or even 130 for shorter 

 periods) is permissible. This conclusion is important, not 

 only by reason of economy in evaporation, but also because 

 a temperature of 125 is sufficient to produce almost 

 instant sterilisation, an effect that cannot be produced 

 with any certainty at 100°. A point of considerable scien- 

 tific interest, dealt with incidentally in the paper, is the 

 reciprocal interconversion of dextrose and lasvulose when 

 the solutions are heated either alone or in presence of 

 alkalis. 



