i5« 



NA TURE 



[February 13, 1908 



expected, shortly develop into a technological institute for 

 engineering purposes, and a technological institute for 

 chemical mailers will be established at Cawnpore. Another 

 matter of high importance referred to in the report is the 

 change recently made with the object of introducing more 

 practical work into the course for the degree of Bachelor 

 of .Science— a necessary step to meet the growing demand 

 for good teaching in science, which is evidenced by the 

 doubling, in five years, of the number of affiliated colleges 

 preparing for science degrees, and a large increase in the 

 number of undergraduates studying science. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, December 12, 1907.—" On the Scattering 

 of the 3 Rays from Uranium by Matter." By J. A. 

 Crowther. Communicated by Prof. J. J. Thomson, F.R.S. 



I he results of the experiments described are summarised 

 as follows : — 



(i) A parallel pencil of B rays is scattered in its passage 

 through matter, the scattering being practically complete 

 after the rays have traversed a thickness of material which 

 varies from 0-015 cm. for aluminium to 0-0002 cm. for 

 gold. 



(2) The scattering, after' correction for the loss of 

 energy, due to the absorption of the rays may be repre- 

 sented by an equation of thp form lil^ = e-'^'^, where d 

 is the thickness of the material traversed by the' rays, and 

 0- is the coefficient of scattering for the rays, I„ being 

 the initial intensity of a narrow parallel pencil of $ radia- 

 tion, crossing: a small fixed cross-section of the pencil, and 

 I the intensity crossing the same cross-section when a 

 thickness d of material is placed in the path of the beam 

 at a considerable distance from the fixed cross-section. 



(3) T'le ratio of the coefficient of scattering o- to the 

 coefficient of absorption A is approximately constant for 

 all the substances measured, its average value being about 

 13. The values of the ratio it p. where p is the density, 

 show similar variations to those for k/p. 



_ December 12, 1907. — " Preliminary Note on the Opera- 

 tional Invariants of a Binarv Ouantic." Bv Major P \ 

 MacMahon, F.R.S. 



Mineralogical Society, January 21.— Prof. H. A. MIers, 

 F.R.S., president, in the chair.— Zeolites from the neigh- 

 bourhood of Belfast : F. N. A. Fleischmann. The 

 author gave an account of a number of hitherto unrecorded 

 zeolite localities near Belfast which he visited in November 

 last. The localities described are quarries in the lower 

 basalt of the neighbouring hills, the most important being 

 two, the first situated on the north side of the hill, which 

 is locally known as Cat Carne, the second on the north- 

 east slopes of Collinward. The first quarry is the most 

 prolific in zeolites in the neighbourhood, yielding fine 

 specimens of apophyllite, analcite, chabazite, levynitc, 

 faroelite, &c. In the second quarrv cavities are rare, but 

 when they occur are, as a rule, 'large, and are usually 

 Imed with colourless tabular apophyllite crystals which 

 reach sometimes an inch and a half across, and are 

 associated with large hemispherical aggregates of natrolite. 

 — Striiverite and its relation to ilmenorutile : Dr. G. T. 

 Prior and Dr. F. Zambonini. The mineral was found 

 in the pegmatite of Craveggia, N. Piedmont. In its 

 crystallographic characters it is almost precisely similar 

 to rutile, tapiolite, and ilmenorutile (F. Z.). Chemically 

 '?• T' ^"^ '' '^ closely related to ilmenorutile, and contains 

 titanic, niobic, and tantalic acids with oxide of iron, in 

 proportions corresponding approximately with the formula 

 Fe(TaNb)30,,.4TiO,. At first it was thought to contain 

 zirconia as an essential constituent ; the supposed zirconia, 

 however, was shown on further examination to consist of 

 niobic and tantalic acids, which, after the fusion of the 

 mineral with KHSO, and treatment with water, had 

 passed into solution with the titanic acid. In the presence 

 of as much titanic acid as occurs in striiverite (40 per 

 cent.) it was found that the greater part of the niobic 

 and tantalic acids could thus pass into solution, and when 

 a dilute solution of sulphuric acid (5 per cent. H,SO,) 

 was used instead of water in treating the melt obtainrd 



NO. iqq8, vol. ■^y^ 



with KHSO^, the whole passed into solution. New 

 analyses of ilmenorutile from the Ilmen Mountains and from 

 Norway showed that the titanic r.:id has been previously 

 much over-estimated, and is present, in the first case, only 

 "P *o S3 per cent., and in the other to about 54^ per 

 cent. The mineral from the Umen Mountains was also 

 found to contain tantalic acid up to about 15 per cent. 

 The most reasonable view of the composition of these 

 minerals appears to be that thev are solid solutions of 

 tetragonal rutile (TiO,) with 'the crystallographicallv 

 similar tetragonal mossite or tapiolite, Fe(TaNb)„Oj.-^ 

 Twin structure : Dr. John W. Evans. The author adopts 

 as a definition of a twin crystal that it is a crystal con- 

 sisting of two component parts such that t<«) parallel lines 

 in general have not the same physical characters in the 

 same direction in the two components ; (b) one or more 



twin-planes " exist such that all lines parallel to (i) any 

 line in a twin-plane, or (2) the " twin-axis " normal to a 

 twin-plane, have the same physical characters in the same 

 or opposite directions in the two components. He shows 

 that this definition includes all twins by reflection, rota- 

 tion, or inversion ( = reflection-|-rotation), and divides twin- 

 axes into eleven classes according to the odd or even 

 cyclic characters of the twin-axis, the relations between the 

 terminations of the twin-axis, and the relations between 

 the disposition in space of the structure of the two com- 

 ponents. He describes twins as amphithetic, homothetic, 

 or antithetic according as lines parallel to the twin-plane 

 have in both components the same physical characters (i) 

 in both directions ; (2) in the same directions ; or (3) in the 

 opposite directions. — A simple method of drawing crystals 

 of calcite and other rhombohedral crystals, and of deducing 

 the relations of their symbols : Prof. W. J. Lewis. The 

 author described a simple method of drawing crystals of 

 calcite and other rhombohedral crystals, in which the prin- 

 cipal axis and the twin-axis lie in the plane of the paper. 

 The method is not well adapted for showing simple forms, 

 but with combinations and twinned crystals the drawings 

 closely resemble ordinary clinographic drawings, and are 

 much more easily and rapidly constructed. The geo- 

 metrical relations between the faces and the relations 

 between the Millerian and Naumannian symbols are readily 

 followed from these drawings. Some unusual twinned 

 crystals of calcite were shown and described ; one show-s 

 the form ■J9t7[ t\\'inned on foil), and another {l3.o.llf 

 twinned on the same law. — The structure of perowskite 

 from the Burgumer Alp, Pfitschthal, Tyrol : H. L. 

 Bowman. The examination of the optical properties and 

 etching figures of transparent cubic crystals from this 

 locality confirms the interpretation of the structure of 

 perowskite proposed by Baumhauer from the study of 

 crystals from the Ural Mountains and from Zermatt. The 

 crystals are mimetic, and belong to the orthorhombic 

 system, the " cubes " being formed by a combination of 

 basal pinacoid |ooi| and a prism llio} with an angle of 

 90°, and having a lamellated structure due to twinning 

 about faces of liicj and ]iii[. 



Geological Society. January 22.— Sir Archibald Geikie. 

 K.C.B., .Scc.R..S., president, in tlie chair. — The origin of 

 the pillow-lava near Port Isaac in Cornwall : Clement 

 Reid and Henry De^ey. The L'pper Devonian strata 

 around Port Isaac consist of marine slates, in which occurs 

 a sheet of pillow-lava. The pillows measure usually from 

 2 feet to 5 feet in diameter, but range up to 8 feet. The 

 individual pillows are disconnected. Their mutual rela- 

 tions seem to prove that they were soft when deposited. 

 Each pillow shows internally a central vacant space or 

 open sponge, succeeded by a thick shell of vi sicular lava, 

 followed by a shell of banded rock. The whole mass is 

 so vesicular that it must have been very light. The 

 association with fine-grained marine strata shows that this 

 lava was probably submarine. The specific gravity of the 

 whole mass must have been low, not greailv exceeding 

 that of sea-water. The lava seems to have been blown 

 out into thick-walled bubbles. The mass was for a time 

 in the spheroidal state, and the sheet could flow like a 

 liquid. This eruption seems to have been analogous to 

 that of Mont Pelee, described by Dr. Tempest .Anderson 

 and Dr. Flett, except that it was submarine instead of 

 subaerial. — The subdivision of the Chalk at Trimming- 

 lirini fXorfnIkI: R- M. Brydone. 



