28o 



NATURE 



[July 23 1908 



narrow. The efficiency of powder extinguishers depends 

 materially on the closeness of range, the position of the 

 operator's shoulder, and on a certain knack or dexterity 

 in handling the appliance. The action of powder extin- 

 guishers would appear to be largely mechanical. 



We have received from the Deutschen Gesellschaft zur 

 Bekampfung des Strassenstaubes a pamphlet of thirty-five 

 pages, in which Colonel Layriz has compiled from the 

 scattered notes in technical journals a report on the 

 methods at present in use to obviate the dust nuisance on 

 roads. The data collected tend to show that efficacious 

 methods are now available for obviating the formation of 

 dust in densely populated cities and in the vicinity of 

 summer resorts, but that the unavoidable cost renders it 

 impossible to apply such methods, except by degrees, so 

 as to make country high-roads free from dust. 



The June number of the Journal of the Franklin Institute 

 is of special interest to metallurgists. Mr. E. A. Custer 

 has a copiously illustrated article describing the casting 

 of pipes in permanent moulds that the hottest iron attain- 

 able from the cupola does not destroy. The method is one 

 deserving careful attention, for it has long been the dream 

 of every foundryman whose trade requires a large number 

 of duplicate castings to make such castings in moulds that 

 would not merely survive the process, but would also pro- 

 duce castings that would be marketable and be easily 

 machined. Mr. G. B. Heckel reviews the methods in use 

 for protecting iron and steel against corrosion, and Mr. 

 H. P. Cochrane discusses engineering practice as applied 

 to the handling of fuel at power stations. 



Numerous attempts have been made to obtain ammonia 

 from peat, but the difficulties of dealing with a substance 

 which often contains 90 per cent, of water have hitherto 

 proved insuperable, and none of the methods has survived 

 the experimental stage. We have received an account of 

 the Woltereck process, stated by the inventor to have over- 

 come successfully all these difficulties. The, peat is slowly 

 decomposed at a regulated temperature by means of a 

 blast of air charged with , water vapour, and forms 

 " paraffin tars," acetic acid, and ammonia. These pass 

 successively through a scrubber to remove tar, an alkali 

 tower containing a hot solution of caustic soda or milk 

 of lime to absorb the acetic acid, and finally through an 

 acid tower, where the ammonia is taken up by sulphuric 

 acid. The tar on distillation yields a wax said to be 

 worth 4!. a ton ; the acetate is to be utilised for pre- 

 paring either acetic acid or acetone. The ash of the peat 

 is a saleable manure, and contains potash, lime, and 

 phosphoric acid. It is estimated that the cost of producing 

 the sulphate of ammonia will not be more than 5L 85. 

 per ton, and, as the present market price is 12!., a con- 

 siderable profit is anticipated. 



The officiating director-general of observatories (Mr. 

 J. H. Field) has issued a memorandum, dated June 9, on 

 the meteorological conditions prevailing in the Indian 

 monsoon region before the advance of the south-west 

 monsoon of 1908, with an estimate of the probable dis- 

 tribution of the monsoon rainfall. Account is taken, as 

 \j5ual, of the recent conditions over a wide area, including 

 parts of Australia, Africa, Siberia, and South America, 

 and all the available data have been analysed by the 

 method developed by Dr. Walker and described by him 

 in his forecast for last year. The result indicates, inter 

 alia, that the total rainfall for the whole of India during 

 the period from June to September will probably be 

 nearly normal or in slight defect. 



NO. 2021, VOL. 78] 



We have received part ii., vol. xx., of the Memoirs of 

 the Indian Meteorological Department, containing kite 

 observations made by Mr. J. H. Field at Belgaum (Bombay 

 Presidency) during the pre-monsoon and monsoon periods 

 in 1906, in continuation of those begun at Karachi in 1905 

 (published in part i.). One series was made in May, in 

 which month the normal weather is dry and hot ; the 

 records, which are diagrammatically shown, indicated no 

 marked increase in wind velocity up to 1300 metres, the 

 maximum height reached. Temperature gradients were 

 strong, by day always considerably above the adiabatic 

 rate for unsaturated air. Comparatively humid air ex- 

 tended on different days to a height of 600-1100 metres; 

 above it exceedingly dry air was met with. The other 

 series was made in August and September, when the 

 weather was comparatively cool, with frequent rain, 

 especially in September. The wind velocity was, on the 

 whole, nearly uniform up to the maximum height reached, 

 2500 metres. The temperature gradients were consider- 

 ably smaller than in May and, except near the surface, 

 always below the adiabatic rate. The upper limit of humid 

 air had risen by about 1000 metres since May. 



With reference to the article on recent developments 

 in electric lamps which appeared in our issue of June 25, we 

 are informed by the General Electric Co. that the state- 

 ment to the effect that tungsten lamps for high voltages, 

 200 and above, have not yet been commercially introduced 

 is not correct, as they have had these lamps on the market 

 since the commencement of April. This firm is now in a 

 position to deliver Osram and Wolfram lamps up to 260 

 volts pressure in 50 and 100 candle-power sizes and lamps 

 for 100 to 130 volts in 25, 30, 50, and 100 candle-power 

 sizes. In addition to this, 25-voIt lamps are made for 

 10, 16, and 25 candle-power, and there is a large demand 

 for this type of lamp for private plants and for alternating- 

 current circuits where advantage can be taken of the possi- 

 bility of transforming down the voltage. The company 

 sends us two very well arranged catalogues setting out 

 the advantages and possibilities of these lamps. 



Vol. v. of Contributions from the Jefferson Physical 

 Laboratory of Harvard University consists of reprints of 

 ten papers by the staff and students which appeared in 

 the Proceedings of the American Academy, the Physical 

 Review, &c., during the year 1907. Of those not already 

 noticed in these pages may be nientioned a paper by Mr. 

 G. W. Pierce on " Crystal Rectifiers for Electric Currents 

 and Electric Oscillations," part i., in which the author 

 follows up and explains the fact recently discovered by 

 General Dunwoody that a crystalline mass of carborundum 

 between two electrodes will act as a receiver for electric 

 waves when used either with or without a cell in series 

 with it. This property is shown to be due to carborundum 

 not following Ohm's law, but conducting better for high 

 than for low voltages. It thus falls into line with other 

 detectors of electric waves investigated by Profs. Braun 

 and Strientz. The author is not yet prepared to advance 

 any theory as to the cause of the phenomenon, but con- 

 siders that there is sufficient evidence to show that it 

 is not of thermoelectric origin. 



Mercuky has usually been regarded as completely in- 

 soluble in water and other solvents. It has, however, a 

 definite vapour pressure, although a very low one at 

 ordinary temperatures, and since no gas is completely 

 insoluble in water, it appeared not improbable that this 

 vapour should prove to be slightly soluble in water. This 

 question is dealt with by Mr. A. Christoff in the current 

 number of the Zcitsclirifl fiir physikalische Chc'nie (June 



