December 27, 1917] 



NATURE 



ly 



A" PAMPHLET by the late Prof. Henrik Mohn, " Der 

 Luftdruck zu Framheim und seine Tagliche 

 Periode" (Christiania : Jacob Dybwad), deals with 

 the pressure at Framheim, lat. 78° 38' S., 

 long. 163° 37' W., the most southerly meteorological 

 station on the earth, established by Amundsen as his 

 winter station during his Antarctic expedition. The 

 observations were taken daily from April i, 1911, to 

 January 29, 1912, at 8 a.m., 2 p.m., and 8 p.m. loca} 

 mean time, from a Kew pattern station barometer 

 hung on a wall of the kitchen of the hut. A Richard 

 barograph was also installed close to the barometer, 

 and a Wild-Fuess barometer was kept, but the read- 

 ings were not used for the computations, as they were 

 not so trustworthy as those of the Kew pattern baro- 

 meter. The height above sea-level of the barometers 

 was 1 1- 1 metres. Hourly values for each hour of the 

 whole period are given, together with means and 

 deviations. The pressure appears to vary from ber 

 tween about 710 and 765 mm., and the monthly means 

 show a maximum of 753-23 mm. for December and 

 a minimum of 72660 mm. for October. The figures 

 are also given for harmonic analysis, and the pressures 

 of the different seasons are compared. 



Korea (Chosen) has developed a thoroughly 

 systematic series of meteorological stations, and re- 

 cently the results of observations for the lustrum 1911-15 

 have been compiled at the Meteorological Observatory 

 of the Government-General of the peninsula. The shores 

 are washed by the Yellow Sea and the Sea of Japan, 

 and the geographical surroundings render it compar- 

 able in many ways with those of Italy. Observations 

 are published for nine stations, fairly well scattered over 

 Korea, and extending from Syeng-chin in the north to 

 Mokpo in the south. One-half of the stations com- 

 menced observing in 1904, so that results are avail- 

 able in these cases for fourteen years. Pressure re- 

 sults at the several stations agree remarkably well 

 inter se. which shows great care in the organisation, 

 and the corrected mean for all stations combined, for 

 the lustrum, is about 30 in., which agrees admirably 

 with the mean value for the year given by the Meteoro- 

 logical Office on its mean pressure chart, given in a 

 recently published barometer manual. Practically all 

 meteorological elements are dealt with for the lustrum 

 and for each station. For the several stations the 

 monthly means are given deduced from four-hourly 

 observations, for which the values are also printed 

 for the several elements, so that most valuable details 

 are available. Five-day means are also given for the 

 various data. 



The double compounds of the metallic halides with 

 ether hitherto known are those with glucinum and 

 titanium chlorides and with aluminium, mercuric and 

 stannous bromides. The Journal of the Chemical 

 Society for September contains a description by Messrs. 

 A. Forster, C. Cooper, and G. Varrow of the pre- 

 paration of double comoounds of ferric chloride with 

 ether and with benzyl sulphide. The former com- 

 pound, C^H.nOjFeClj, obtained by the interaction of 

 anhydrous ferric chloride and dry ether, is a dark red, 

 highly deliquescent solid soluble in benzene, but decom- 

 posed' by alcohol or water. When heated it evolves 

 pure ethyl chloride. The substance in ethereal solu- 

 tion reacts with dry ammonia, giving brick-red, amor- 

 phous compounds of varying composition. Benzyl 

 sulphide ferric chloride, (CrH7)2S,FeCl,, obtained by 

 mixing ethereal solutions of its two components in 

 molecular proportions and allowing to stand for some 

 hours, forms minute lemon-yellow crystals soluble in 

 chloroform and slightly so in alcohol, but insoluble in 

 ether or acetone. The crystals rapidly become brown 

 NO. 2513, VOL. 100] 



on exposure to moist air, this reaction distinguishing 

 them from tribenzylsulphinium chloride ferrichloride. 

 Benzyl sulphide ferric chloride is slowly decomposed 

 into its two constituents by water; with alkalis the 

 products are benzyl sulphide and ferric hydroxide. If 

 a solution of equimolecular proportions of benzyl 

 sulphide and cyanide in dry ether is added to an 

 ethereal solution of ferric chloride, tribenzylsulphinium 

 cyanide ferrichloride, (C,H;),SCN,FeCl3, is formed. 

 This substance is obtained as lemon-yellow crystals 

 insoluble in ether, but soluble in alcohol and chloro- 

 form. When treated with excess of ammonia in 

 alcoholic solution the substance gives tribenzyl- 

 sulphinium cyanide, (C,H;)jSCN, which forms large 

 white prisms, m.p. 41°, readily soluble in organic 

 solvents, but only" slightly so' in water. In con- 

 tact with water the cyanide corhpletely dissociates in 

 a few hours. 



The solving of formulae involving more than two 

 variables by means of curves, alignment charts, iso- 

 metric charts, etc., is now well known, and a good 

 deal has appeared recently on these methods. Special 

 slide rules have also been employed to a large extent, 

 and are designed to solve problems connected with 

 special trades. The first instalment of an article on the 

 design of special slide rules, by Mr. A. Lewis Jenkins, 

 appears in the Engineering Magazine for November, 

 and contains much that will be of interest to any who 

 may be called upon to produce a special instrument 

 of this type. 



Owing to the failure of several reinforced concrete 

 floors in the United States within ten or a dozen years 

 of their construction. Prof. H. J. M. Creighton, of 

 Swarthmore College, has examined a large number of 

 reinforced concrete structures in which cracks were 

 developing, and gives the results of his investigations 

 in the Journal of the Franklin Institute for November. 

 He finds that in every case the cracks run along the 

 reinforcing rods, and are due to the deteriorating action 

 of salt and brine on the concrete. Solutions of the 

 chlorides react with the lime and the silicates in the 

 concrete, and penetrating to the iron of the rein- 

 forcement convert it into oxide and hydrate, which 

 occupy more space than the metal and force the con- 

 crete apart. It is therefore necessary to waterproof 

 reinforced concrete structures which will be in contact 

 with brine, to cease to use in the concrete beach gravel 

 which has not been thoroughly washed with fresh 

 water, and never to add salt to the concrete to prevent 

 it freezing during building operations in oold weather. 



An interesting article on gear planers appears in 

 Engineering for December 14. The most remarkable 

 advance which has been made in the formation of the 

 teeth of gear wheels is in the substitution of methods 

 of generation for those of form-cutting. The principle 

 is simple, and the results are precise. A master gear, 

 either a rack or a pinion, imparts the correct shapes 

 to the teeth of any gears of the same pitch. The basis 

 tooth is that of the rack, with flanks having a pre- 

 determined pressure angle. This may be embodied in 

 a worm-like hob ; or a rack tooth can be used to 

 generate a master pinion ; or the tooth may be employed 

 directly as a cutter; or several teeth can be included 

 in a length of rack, sufficient in number to make con- 

 tact with all the teeth that can be in mesh with the 

 largest wheel to be generated in the system. The 

 relative movements of the cutter and the blank are 

 identical with those that will occur in the actual rack 

 and its generated gear. Wheels produced thus will 

 engage correctly with the rack and with each other, and 

 require no corrections or easing. The cutter is fed 



