1 



NA TURE 



[November 24, 1904 



study to which up to the present little systematic attention 

 has been given. The author considers that the;-" are four 

 different cycles which could be applied with advantage to 

 a gas turbine, giving efficiencies of from 0-25 to o 84, and 

 two of them admitting of several different cases. The 

 necessity of keeping the temperature of the blades of the 

 turbine down to about 700° C. to a certain extent limits 

 the efficiency, but, as the author points out, a decrease in 

 the temperature of the source in a Carnot's cycle affects 

 the efficiency less than an increase in the temper.it'jre of 

 the refrigerator of the same amount. 



We have received from the Stanley Electric Manufactur- 

 ing Co., of Pittsfield, Mass., an interesting wall map show- 

 ing the long distance power transmission lines in Cali- 

 fornia. There are six power houses situated on the western 

 slopes of Sierra Nevada from which power is transmitted 

 electrically to San Francisco and the surrounding district. 

 The longest transmission is from the De Sabla power house 

 to Sansaulito, which is to the north of San Francisco, on the 

 opposite side of the Golden Gate ; the length of this line is 

 232 miles. More than 10,000 h.p. is being supplied to San 

 Francisco itself from the electric power house which is 

 147 miles away. .\n additional power house is proposed, 

 and also several additional lines. 



-At a recent meeting of the Faraday Society, among other 

 papers was one by Miss B. Pool on a suggested new source 

 of aluminium. This consists of the vast deposits of laterite 

 which occur in several parts of India ; these laterites are 

 closely analogous to bauxite, from which aluminium is at 

 present manufactured. The paper gives analyses of several 

 of the laterites in different districts, and the author con- 

 cludes that this raw material, on account of its purity, 

 ready accessibility, and association with flowing water 

 should be almost an ideal source of aluminium. Mr. W. M. 

 Morrison, in the discussion, questioned whether it was prob- 

 able that the Indian laterites would be used in this country, 

 as the supply of bauxite near at hand was plentiful, though 

 it was not unlikely that at some future date they might be 

 worked in situ. 



We have received from Messrs. Christy and Co., of Old 

 Swan Lane, Lower Thames Street, E.C., a few samples of 

 the several varieties of Dr. Schleussner's dry plates, and have 

 found them to vindicate, practically, the commendations 

 bestowed upon them by many Continental men of science, in- 

 cluding several well known astronomers. The " ordinary " 

 plates are characterised by their great sensitiveness and the 

 evenness of their emulsion. The " special rapid " plates, 

 intended chiefly for stellar photography and general scien- 

 tific work, were found excellent, especially in stellar work, 

 even faint stars giving fairly dense trails when the plates 

 were exposed in a stationary camera. The results in this 

 direction especially are enhanced by the very smooth grain 

 of the finished negative. On testing the " orthochromatic " 

 plates in terrestrial and stellar spectroscopic work they 

 were found to be extremely sensitive, and, with relatively 

 short exposures, gave spectra extending well up into the 

 orange with only a short break on the less refrangible 

 side of the " F " line. The " Viridin " are especially 

 sensitive in the green, with reduced sensitiveness in the blue 

 and violet, and should be found very useful in landscape 

 work where the use of a screen is inconvenient or likely 

 to lengthen the exposure unduly. All the plates were easy 

 to develop with normal pyro-soda, and gave e.xcellent, fine- 

 grained negatives free from any trace of fog. Messrs. 

 Christy are the sole agents for these plates in Great Britain. 

 NO. 1830, VOL. 71] 



No. q of vol. cvi. of the Bulletin de la Societe d'Encoiirage- 

 ment contains several papers of metallurgical interest. 

 M. H. Le Chatelier describes a photographic method of 

 recording the temperature of pieces of steel at every instant 

 during the rapid cooling which accompanies hardening, and 

 investigates the law of this cooling in the case of the 

 commoner baths, such as water, oil and mercurv, which are- 

 employed in industry. Contrary to the usually accepted 

 view, the rate of cooling by means of mercury is much 

 smaller than that due to water ; the specific heat of the 

 quenching material, and not its thermal conductivity, is 

 obviously the principal factor to be considered in such cases. 

 The cooling by oil is relatively very slow\ ow-ing to its low 

 specific heat and to its viscosity, which prevents loss of 

 heat by convection. M. L. Guillet describes in the same 

 part the properties of tin and titanium steels, and M. P. 

 Mahler discusses the reversible actions occurring in the 

 blast-furnace. 



We have received a copy of the " British Standard Specifi- 

 cation and Sections for Bull Headed Railway Rails," issued 

 by the Engineering Standards Committee. It has been re- 

 solved that the steel' used in these rails shall be of the best 

 quality, the constituents conforming to the following 

 limits : — carbon from 035 to 05 per cent., manganese front 

 o 7 to lo per cent., silicon not to exceed 01 per cent., phos- 

 phorus 0075 per cent., and sulphur o oS per cent. The 

 manufacturer shall make and furnish to the purchaser a 

 carbon determination of each cast, and a complete chemical 

 analysis representing the average of the other elements 

 present shall be given for each rolling. \ table of the 

 general dimensions of the " B. S." rails is given, with illus- 

 trative sections. For straight lines, the committee recom- 

 mends the adoption of the following as the normal lengths 

 of the rails, namely, 30 feet, 36 feet, 45 feet, and 60 feet. 

 The tensile strength must not be less than 38 tons per 

 square inch nor more than 45 tons per square inch, and a 

 5-feet length of rail shall respond satisfactorily to the blows 

 of a falling weight of 2240 lb. The inspection and testing 

 of the rails by the purchaser during the course of their 

 manufacture are suitably provided for. 



An interesting paper by Mr. L. Gilchrist on the electro- 

 lysis of acid solutions of aniline appears in the November 

 number of the Journal of Physical Chemistry. On electro- 

 lysing a hydrochloric acid solution, aniline black is formed, 

 the depolarising effect amounting to about 03 volt. Sub- 

 stituted chloranilines are not formed to any appreciable ex- 

 tent. Electrolysis of a hydrobromic acid solution, which 

 has a considerably smaller decomposition voltage, leads on 

 the other hand to bromanilines, and no aniline black is 

 produced. 



The Proceedings of the Royal Dublin Society (vol. x... 

 No. 23) contain a report by Dr. E. J. McWeeney on the 

 cases of carbon mono.xide asphy.xiation w-hich have occurrecl 

 in Dublin since the addition of carburetted water gas to 

 the ordinary coal gas. It appears that from 1880 to 1900, 

 before the addition of carburetted water gas was practised, 

 there was no recorded case of death from coal gas poison- 

 ing, whilst during the four years that have elapsed since 

 the addition was made, there have been ten cases with 

 seven deaths due to that cause. 



In a paper published in the Manchester Memoirs (vol. 

 xlix., 1904) Mr. W. Thomson describes experiments which 

 show that arsenic is rapidly eliminated from the system by- 

 kidney secretion. After the administration of one-fiftieth 

 of a gram of arsenious oxide, about 16 per cent, was found 



