January 20, 19 10] 



NATURE 



347 



month by month. The stars are represented by gilt 

 asterisks on a dark blue background, upon which the 

 names of the constellations are printed in black, so that 

 when the charts are viewed at a suitable angle the stars 

 are seen without the names, the result being very effective. 

 With the 1910 issue (the thirteenth series), a chart of the 

 heavens in two hemispheres is included showing the track 

 of Halley's comet in 1909-10, and some notes upon the 

 comet's orbit and spectacular appearance. The usual 

 particulars of the positions of the sun, moon, and planets 

 throughout the year are also given. The publication is 

 excellently produced, and should continue its usefulness 

 in promoting an intelligent interest in the aspects of the 

 heavens and the movements of celestial bodies. 



A VALUABLE paper on the testing of impulse water- 

 wheels of the Pelton wheel type was presented by Mr. 

 William Rankine Eckart at the Institution of Mechanical 

 Engineers on January 7. This paper is of interest on 

 account of the experiments described being the first of the 

 kind on such a large scale. By means of the Pitot tube 

 and other measuring devices the author has measured the 

 nozzle discharge under different conditions, and so has 

 determined the hydraulic efficiency of the generating plant, 

 the capacity of each water-wheel amounting to about 3500 

 horse-power. The following table gives a summary of the 

 more important results of the four tests made, and shows 

 the distribution of the power as percentages of the power 

 in the jet : — 



Loss in bucket friction and eddies 

 Loss in residual velocity of discharge.. 



Other hydraulic losses 



Loss in friction and windage, genera- 

 tor and wheels 



Loss in generator, iron and armature.. 

 Delivered to switchboard 



29-2 

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64'I 



In the discussion on the hydraulic papers at the Institu- 

 tion of Mechanical Engineers on January 7, Dr. Unwin 

 referred to the difficulties which Canadian engineers have 

 to contend with in preventing stoppages from ice. Block 

 ice is easily dealt with. With frazil ice, i.e. minute 

 particles of ice suspended in and moving with the water, 

 the difficulty is serious. We learn from a recent number 

 of the Canadian Engineer that about forty water-wheels 

 at and near Ottawa are now equipped with heating devices, 

 which prevent frazil from stopping the wheels and clogging 

 the gates and gate-mechanisms. The latest 3000-horse- 

 power unit at the Ottawa and Hull Power and Manu- 

 facturing Company's Station has the chutes and gate 

 chambers cored out, and there are pipe connections to 

 the openings so that steam or hot water may be kept 

 circulating through them when frazil is anticipated. The 

 racks or screens are kept free from ice by electric motor- 

 driven rakes, and at present none of these is heated. Mr. 

 John Murphy recommends that the racks be submerged or 

 otherwise protected from the atmosphere, when only a 

 small amount of heat would be necessary to prevent ice 

 clinging to them. 



Commenting on the evidence offered at the inquiry into 

 the cause of the disastrous fire at Messrs. .^rding and 

 Hobbs, Clapham Junction, the Builder for January 8 finds 

 itself unable to agree with the architect's — Mr. Thorney- 

 croft — opinions regarding his belief in the merits of steel 

 as a structural material. Evidently he does not consider 

 N'O. 2099, VOL. 82] 



reinforced concrete to be a practical substitute for steef. 

 It is, of course, understood that there are difficulties in 

 altering and enlarging old buildings which prevent the 

 changing of the general nature of the construction. Other 

 evidence showed that, had there been concrete floors, and 

 if the steel- work had been encased in concrete, there would 

 have been little to burn except the contents of the rooms, 

 .^s it was, the girders were only protected by the matched 

 lining, and the distortion of the steel brought the building 

 down. However strongly one may disapprove such 

 methods of construction, the fact remains that the Clapham 

 Junction building conformed with the requirements of the 

 law, and represented quite an ordinary risk. Under the 

 new regulations of the County Council protected steel- 

 frame or reinforced concrete buildings ought to cost no 

 more than structures of brick and unprotected steel. The 

 extreme undesirability of the latter type is the most 

 Important lesson of this fire. 



On account of its fundamental importance in atomic- 

 weight determinations, numerous researches have been 

 published during the last four years on the atomic weight 

 of chlorine, in most of which the direct ratio H/Cl has 

 been attempted by gas volumetric or gas density methods. 

 The latest contribution to this subject is by Otto Scheuer, 

 who, in the current number of the Zeitschrift fiir 

 physikalische Chemie, finds the weight of a litre of hydro- 

 chloric acid to be 1-6394 under normal conditions. From 

 this the figure 35-466 is deduced as the atomic weight of 

 chlorine, differing from the 35-460 of Gray and Burt by 

 about I part in 6000. The paper in the Zeitschrift gives 

 full details of the experimental work, and also of the 

 methods of reduction emploj-ed. A critical examination of 

 the results of Gray and Burt is given at the end of the 

 paper. 



The place of honour in the Bulletin de la Sociiti 

 d' Encouragement pour I'Industrie nationale for November, 

 1909, is given to a study, by MM. Pipereaut and Vila, on 

 the manufacture of zinc sulphide and its use as a pig- 

 ment. From a report by M. A. Livache, which precedes 

 the memoir, it appears that a law has just been passed' 

 prohibiting entirely the use of white lead as a paint after 

 the expiry of a period of five years, and that the authors 

 have devised a satisfactory method of preparing zinc 

 sulphide, as a substitute, by dissolving the oxide in caustic 

 alkali and boiling the solution with sulphur, the first 

 portion of which throws down the impurities (lead and 

 other metals giving coloured sulphides), whilst the later 

 additions precipitate the zinc sulphide in a pure form 

 which (after drying at a red heat) is eminently suited for 

 use as a paint. 



The monographs on photo-chemistry by Prof. Bancroft, 

 which have been appearing in recent numoers of the 

 Journal of Physical Chemistry, have been followed up by 

 two experimental papers, one of which, by Mr. G. A. 

 Perley, on solarisation, appears in the November 

 number, and the other, by Mr. J. W. Wilkinson, on the 

 phosphorescence of some inorganic salts, in the December 

 number of 1909. The latter contains an interesting 

 account of some luminous effects produced during the 

 electrolytic preparation of insoluble metallic salts, and 

 during slow oxidation, chlorinatlon, &:c. In a large range 

 of cases It is shown that the colour of the light emitted 

 is identical with that which is produced when the salt is 

 made to phosphoresce by various methods, and the view 

 is advances that the phosphorescence is due to certain 

 definite types of chemical change. 



