574 



NA rURE 



[April i6, 190 



the best secularly educated country in the world, tnul their 

 education policy thoroughly organised. 



An interesting comparison of examination statistics in 

 1906 with those in 1899 is made by Mr. G. F. Daniell 

 in Tfte School World for April. Dealing with the results 

 of the matriculation e.xamination of the London University, 

 the article shows that, whereas in 1899, out of 1250 candi- 

 dates, 842 selected a language and 402 a science " option," 

 3140 chose a linguistic and 2962 a scientific subject out of 

 a total of 3253 in igo6. In the senior local examinations 

 lield by the Cambridge University, the stunted condition 

 of the scientific side shown by the 1899 statistics gives 

 place in igo6 to a more reasonable balance of science and 

 the humanities, and, in the aggregate, the statistics of 

 the junior examination show that science subjects are now 

 receivijig fair attention in secondary schools in general. 

 -■Apparently, however, this cannot be said of the great 

 public schools. Referring to the statistics published by the 

 Oxford and Cambridge Schools' Examination Board, which 

 examines pupils from public and high schools, Mr. Daniell 

 remarks that out of 1027 candidates for the lower certifi- 

 cate of this Board, a total of thirty-four passes in the 

 first class was obtained in the science subjects — of these 

 .thirty-four, no fewer than half were in botany, the 

 successful candidates being mostly girls. .Among some 

 2200 candidates for the higher certificate, eighty-three 

 distinctions were obtained in science. It is justly pointed 

 out that " this grudging admission of the claims of experi- 

 mental science does not satisfy anyone who has realised 

 the importance of educating the nation, especially the upper 

 and middle classes, so that the future may find us not 

 w-anting in men of scientific intelligence." 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, February 14, IQ07. — " TheThermomagnetic 



.Analysis of Meteoric and Artificial Nickel-iron Alloys." 

 By S. \V. J. Smith. Communicated by Sir A. W. Riicker, 

 F.R.S. 



As the result of purely magnetic researches, the author 

 comes to the conclusion that a typical octahedral meteorite 

 (containing about 7 per cent. Ni and about 93 per cent. 

 Fe, and exhibiting very regular Widmanstatten figures) 

 consists mainly of an alloy of the two constituents con- 

 taining about 6J per cent. Ni. This alloy is kamacite. 

 The thin intervening bands of more nickeliferous material 

 (taenite) are shown in the same way to contain about 

 27 per cent. \i, but, further, to be a mixture of nickel- 

 richer and nickel-poorer constituents. 



The view most commonly accepted hitherto, as the result 

 of many careful chemical analyses, has been that taenite 

 contains at least 36 per cent. Ni. A critical examination 

 of these analyses shows, how'ever, that they are in accord 

 with the more certain conclusion derived from thermo- 

 magnetic data. 



In the investigation of a problem of this kind chemical 

 methods lead to ambiguous results, because it is impossible 

 to isolate (from a material like meteoric iron) the 

 secondary constituent (taenite) chemically without fear of 

 partial solution. On the other hand, the taenite can be 

 studied in situ by means of the change of its magnetic 

 properties with temperature, because these properties vary 

 in_ a markedly different w'ay from those of the main con- 

 stituent kamacite. Thus it can be shown that its proper- 

 ties correspond with those of the artificial 27 per cent, 

 alloy, just as those of the kamacite correspond with those 

 of the artificial 6J per cent, alloy. 



The inference from the experiments that taenite is a 

 eutectic mixture (of coarser structure originally than the 

 artificial 27 per cent, alloy, which is proved also to be a 

 mixture) is shown to be in accord with all that is known 

 concerning nickel-iron alloys, and to afford an adequate 

 conception of the way in which the characteristic structure 

 of meteoric iron has arisen. 



The behaviour of " irreversible " nickel-iron alloys 

 during changes of temperature is shown also to be closelv 



NO. 2007, VOL. 77] 



analogous to the behaviour of the metastable and labile 

 fluid solutions studied by Prof. Miers. 



An explanation is given of the important fact that an 

 artificial nickel-iron alloy containing about 27 per cent. 

 Ni is a " magnetic invar," of which the magnetic quality 

 remains practically constant over a range of about 300*^ C. 

 after the alloy has been cooled to the temperature of liquid 

 air. 



Further development of the thermomagnetic method is 

 to be looked for in cases in which chemical and micro- 

 graphic methods cither fail to remove ambiguity or are 

 inapplicable; meanwhile, if the interpretation of the 

 thermomagnetic data considered is held to be established, 

 a good many doubtful points in the relationship between 

 iron and nickel ill their alloys have been made clear. 



January 23, 1908. — " Dietetics in Tuberculosis : Principles 

 and Economics." By Dr. N. D. Bardsvwell and J. E. 

 Chapman. Communicated by Sir T. Clifford .Mlbutt, 

 K.C.B., F.R.S. 



February 13. — " The Decomposition of Ozone by Heat." 

 By Prof. E. P. Perman and R. H. Greaves. Com- 

 municated by Principal E. H. Griffiths, F.R.S. 



The rate of decomposition of ozone lias been measured 

 under various conditions, with the following results : — 



(i) In a glass vessel the reaction is approximately of the 

 second order. 



(2) The relation be'tween the rate of decomposition and 

 temperature may be expressed by the formula log k = a + bt. 



(3) The rate of decomposition is very largely influenced 

 by the extent of the surface with which the ozone is in 

 contact. 



(4) The reaction is of the first order when the ozone is 

 in contact with a porous substance (clay-pipe stems) or 

 some oxides. 



(5) Metallic surfaces have but little effect on tlie de- 

 composition. 



(61 Water vapour accelerates the decomposition, and the 

 acceleration is proportional to the amount present. 



(7) Nitric oxide greatly accelerates the decomposition. 



(8) The rate of decomposition is a linear function of thei 

 oxygen pressure. A greater effect is produced by diluting 

 with nitrogen than by simply reducing the pressure of the 

 oxygen. 



(9) At 100" the reaction appears to be very slightly 

 reversible. 



(10) Finally, the decomposition appears to take place 

 mainly (if not entirely) at the surfaces with which the 

 ozone is in contact, and pressure measurements give no 

 indication of the number of molecules reacting. 



Mineralogical Society, March 17. — Prof. H. A. Miers, 

 F.R.S., president, in the chair. — The occurrence of met.'i- 

 morphic minerals in calcareous rocks in the Bodmin and 

 Camelford areas : G. Barrow and H. H. Thomas. The 

 pneumatolytic action is not contemporaneous with the 

 thermo-metamorphism produced by granite intrusions ; the 

 gaseous intrusions are later, and often produce their 

 greatest effect beyond the zone of " contact action." The 

 species of mineral produced depends on the nature of the 

 rock penetrated by the gases. In killas, tourmaline i; 

 commonly produced, but in calcareous rocks, axinite and a 

 variety of other minerals result from the pneumatolysis. 

 In the Bodmin area the minerals formed by pneumatolytic 

 action in the calc-flintas are axinite, liedenbergite, epidote, 

 yellow garnet, actinolite, and another amphibole occurring 

 in minute dark-brown needles. In the Camelford area the 

 minerals are mainly due to contact metamorphism. The 

 most conspicuous are yellow garnet, epidote, and idocrase, 

 a mineral which has not hitherto been recorded from Corn- 

 wall. — .\ protractor for use in constructing stereographir 

 and gnomonic projections : A. Hutchinson. A short 

 historical account was given of the stereographic projec- 

 tion, and a protractor designed to facilitate its construe - 

 tion was shown. By the aid of this protractor the radi: 

 of both great circles and small circles can be readih 

 determined. It can also be applied to the construction 

 of the gnomonic projection, and to measuring the angles! 

 between planes and zones. — Supplementary notes on the 



