Jan. 27, 1887] 



NA TURE 



311 



more precipilale fell down and the liquid retained a strong odour 

 of chlorine. The whole of the chromium would now be in solu- 

 tion, whilst the alumina would be in the precipitate. The 

 alumina was filtered off, well washed, and a portion tested in 

 the radiant-matter tube. It gave as good an alumina spec- 

 trum as did the original sulphate ; the crimson line being very 

 prominent. 



The alumina thus purified was a second time dissolved in 

 caustic potash and submitted to the chlorine purification. Again 

 in the radiant-matter tube the alumina gave its characteristic 

 crimson line spectrum. 



Many other experiments are given, and the paper concludes 

 as follows : — 



These experiments are perhaps too few to permit any im- 

 portant inference being drawn from them. There seems, 

 however, to be four possible explanations of the phenomena 

 observed : — 



(1) The crimson line is due to alumina, but it is capable of 

 being suppressed by an accompanying earth which concentrates 

 towards one end of the fractionations. 



(2) The crimson line is not due to alumina, but is due to the 

 presence of an accon .nying earth concentrating towards the 

 other end of the frac jnations. 



(3) The crimson line belongs to alumina, but its full develop- 

 ment requires certain precautions to be observed in the time and 

 intensity of ignition, degree of exhaustion, or its absolute freedom 

 from alkaline and other bodies carried down by precipitated 

 alumina, and difficult to remove by washing ; experience not 

 having yet shown which of these precautions are essential to the 

 full development of the crimson hne and which are unessential. 



(4) The earth alumina is a compound molecule, one of its con- 

 stituent molecules giving the crimson line. According to this 

 hypothesis alumina would be analogous to yttria. 



Zoological Society, January iS. — Prof. W. H. Flower, 

 F. R.S. , President, in the chair. — The Secretary read a 

 report on the additions that had been m.ide to the Society's 

 Menagerie during the month of December 18S6, and called at- 

 tention to a young male of the true Zebra {Eqiiiis zebra), pur- 

 chased December II ; and to a young male Indian Rhinoceros, 

 presented by H.H. the Maharajah of Cooch Behar, through the 

 kind intervention of Dr. B. Simpson, and received December 

 25. — Mr. F. \V. Styan exhibited and made remarks on 

 a series of Chinese birds' eggs which he had collected at 

 ICiukiang and Shanghai. — Mr. Howard Saunders exhibited 

 and read some notes on a skin of the Mediterranean Black- 

 headed Gull [Lanis mchinoccphalus), killed on Breydon Water, 

 near Great Yarmouth, and sent for exhibition by Mr. G. Smith, 

 of that town. This was stated to be the first absolutely authen- 

 tic occurrence of this southern species on the British coasts. — 

 Mr. Sclater exhibited and made some remarks on an example of 

 a rare Amazon Parrot (Chrysalis bodini) from British Guiana. — 

 Various other specimens were exhibited, and papers read. 



Edinburgh 

 Royal Society, January 17. — Sheriff Irvine, Vice-President, 

 in the chair. — Mr. John Murray read a paper on the total rain- 

 fall of the globe, and its relation to the discharge of rivers. 

 2243 cubic miles of rain fall annually on areas with inland 

 drainage. Such areas extend to 11,486,350 square miles. The 

 land draining directly to the ocean has an area of 44,211,000 

 square miles. If from this quantity we subtract all areas having 

 less than 10 inches of annual rainfall, we get 38,829,750 square 

 miles. The mean discharge from this area into the ocean is 

 6569 cubic miles annually. The total weight of substances car- 

 ried by this means to the ocean is rather more than 5,000,000,000 

 tons each year. — Mr. \V. Durham read a paper on chemical 

 affinity and solution. — The fourth part of a paper on thermo- 

 meter-screens was communicated by Mr. John Aitken. — Prof 

 Armstrong read a paper by Mr. A. C. Elliot, containing an 

 extension and improvement of Rankine's formula for the pres- 

 sure of earth on a retaining wall. — Prof. Tait communicated the 

 third part of his paper on the foundations of the kinetic theory 

 of gases. In the first division of this part the author discusses 

 the modifications which are introduced into his previous formulae 

 by the consideration of the effects of molecular attraction of 

 small range, but great intensity, on the behaviour of a group of 

 hard, smooth, impinging spheres. In the second division he 

 makes the assumption that the spheres are not perfectly hard, 

 but possess a definite coefficient of restitution. He then en- 



deavours to make an approximation to the conditions of the 

 liquid state by considering the action of spheres whose relative 

 speed of approach is such that, after impact, they are unable 

 to pass out of the range of molecular attraction in consequence 

 of the loss of translational energy by impact. 



Dublin 

 Royal Society, December 15, 1886. — The physical properties 

 of manganese steel, by Prof. W. F. Barrett. The author pointed 

 out that Mr, J. T. Bottomley had sent a brief note on the feebly- 

 magnetic character of manganese steel to the Aberdeen meeting 

 of the British Association, and had kindly furnished him with a 

 specimen of this steel, and the name of the makers and patentees, 

 Messrs. Hadfield and Co., of Sheffield. The steel contains 

 12 to 14 per cent, of manganese. Through Messrs. Hadfield, the 

 author had obtained wire drawn from manganese steel, a process 

 that first presented great difficulties, but was ultimately accom- 

 plished with -ease by heating the steel to whiteness, and quench- 

 ing in cold water after a reduction through every two sizes had 

 been drawn. Sudden cooling softens this steel ; slow cooling 

 hardens it. A No. 19 S.W.G. wire (diameter 0-98 millimetre) 

 was thus obtained of two kinds — hard and soft ; the density was 

 7 '808. The electric conductivity was found by Prof. Barrett to be 

 very low. The No. 19 wire had a resistance of about an ohm per 

 metre, the exact specific resi-tance in C.G. S. units being 77>ooo 

 for I cubic centimetre ; ordinary iron is only 9S00, and Ger- 

 man silver 21,170 in the same units ; so that some use might be 

 made of manganese steel wire for resistance-coils in electric 

 lighting. The variation of resistance with temperature is now 

 being examined. The magnetic character of this steel was then 

 carefully tested by the author. Mr. Bottomley found the in- 

 tensity of magnetisation of this steel, after submitting it to the 

 most powerful magnetising force, was 2^55 in C.G. S. units, or 

 the magnetisation per gramme was o'Ol3 in C.G.S. Ordinary 

 steel gives a number varying from 40 to 90, and even 100, C.G.S. 

 units per gramme. So that, if ordinary steel of average quality be 

 100,000, manganese steel is 20. This represents the permanent 

 magnetism. Prof. Barrett, by different methods, has determined 

 the susceptibility — that is, the induced magnetisation — in a uni- 

 form field. Compared with iron as 100,00c, manganese steel was 

 found to be 300. In fact, it is very wonderful, judging by mus- 

 cular sense, to find no sensible force required to move this steel, 

 even in the most powerful magnetic field that could be obtained. 

 Hence, as the author suggests, the use of manganese steel for 

 the bed plates of dynamos and the plating of iron vessels is 

 obvious. Ships built of such steel would have no sensible 

 deviation of the compass. As e.xcellent castings can be obtained 

 from this steel, it ought to have many applications from its extreme 

 hardness, enormous tenacity, and feebly-magnetic character. 

 Dr. Hopkinson's important memoir on the magnetisation of 

 iron contains a measurement of the magnetic susceptibility of 

 manganese steel, of which Prof. Barrett was unaware until his 

 paper had been written. Though Dr. Hopkinson's method of 

 determination was wholly difterent, the ratio of the susceptibility 

 of iron to manganese steel which he obtained is fairly accordant 

 with the number obtained by the author, the composition of the 

 specimen being the same in both cases. As regards the tenacity 

 of manganese steel, the author had found the hard wire had the 

 extraordinary tenacity of no tons per square inch, or 173 '5 

 kilogrammes per square millimetre — a number confirmed by inde- 

 pendent tests which the chief engineer of the Irish Great 

 Southern and Western Railway Works had kindly made for 

 Prof Barrett. The tenacity of ordinary steel wire is from 80 to 100 

 kilogrammes per square millimetre, the best pianoforte steel wire 

 alone showing a higher tenacity than the manganese s;eel wire. 

 The soft manganese steel wire had a tenacity of only 48 tons 

 per square inch, with an elongation of nearly 20 per cent. The 

 modulus of elasticity was also determined by the author by direct 

 stretching. It was found to be lower than wrought iron, the 

 mean number for the hard manganese wire being 16,800 kilo- 

 grammes per square millimetre, the soft manganese wire having a 

 still lower modulus. The modulus for ordinary steel wire is 

 18,810, and for iron wire iS,6io kilogrammes per square milli- 

 metre ; so that, though hard manganese steel has an enormous 

 tenacity, it "gives" more than steel under sudden stress, 

 recovering itself, of course, if the limits of elasticity are not 

 passed. Obviously this is a most useful property for many pur- 

 poses to which the steel may be applied. Further experiments 

 on this interesting material are in progress in the Physical 

 Laboratory of the Royal College of Science. 



