*74 



NATURE 



[x\PRIL 20, 19 1 6 



country demands the serious attention of the Govern- 

 ment and the warm support of every true friend of the 

 nation. In the stress of war it would seem that every 

 reactionary influence finds its opportunity, with the 

 result that the strenuous ameliorative efforts of past 

 generations are to be brought to naught, and the fight on 

 behalf of children must be re-fought once more. It is, 

 however, satisfactory to find that some education 

 authorities take a firm stand against the insistent de- 

 mands of certain agricultural and industrial interests 

 that children shall be released from school at an untimely 

 age to labour in the fields and factories, and it is all- 

 important that enlightened public opinion should sup- 

 port their action. Yet it is greatly to be deplored, 

 having regard to the actual conditions of working- 

 class life in industrial centres, that certain education 

 authorities should, for reasons of so-called economy, 

 seek to close the schools to children under five and 

 to call upon the Government to raise the compulsory 

 school ag-e to six in order that children below that 

 age shall likewise be excluded, with the result that 

 the school life would be limited in certain areas to 

 five years instead of nine. But perhaps the most un- 

 wort'hv demand is that of the managers of textile 

 works in Lancashire, that the children in textile areas 

 shall be compelled, during- the war, to enter the fac- 

 tories. As the signatories well indicate, we owe it 

 in reverence for the dead that we refuse no sacrifice 

 In order to raise up a virile generation to justify their 

 noble devotion. 



SOCIETIES AND ACADEMIES. 



London. 

 Mineralogical Society, March 21. — W. Barlow, presi- 

 dent, in the chair. — Dr. J. W. Evans : A new micro- 

 scope accessory for use in the determination of the 

 refractive indices of minerals. The accessory — a 

 diaphragm with narrow slit adjustable in width — when 

 placed in the primary focus of the objective or any 

 point conjugate wdth it, serves several useful purposes. 

 If placed parallel to the boundary between the two 

 substances the refractive indices of which are to be 

 compared by the Becke method, it gives better results 

 than an iris diaphragm. In the case of doubly- 

 refractive sections or grains in which an axis of 

 •optical symmetry lies at right angles to the microscope 

 axis, the slit is placed parallel to the former axis, so 

 that the paths of all the rays of light traversing it lie 

 in a plane of optical symmetry and one direction of 

 vibration is always parallel to the axis of optical 

 symmetry, and a nicol is inserted so that the direc- 

 tion of vibration of the rays traversing it is parallel 

 to the same axis ; then the refractive indices of light 

 vibrating parallel to that axis of optical symmetry may 

 be investigated by the usual methods without the con- 

 fusion caused by the bifocal images described by Sorby. 

 — L. J. Spencer : A butterfly twin of gypsum. In a 

 well-developed twin-crystal, 6 in. across, from Gir- 

 genti, Sicily, in which the twin-plane is d(ioi), the 

 two individuals are situated on the same side of the 

 twin-plane instead of on opposite sides as in the 

 usual tvpe. — Dr. W. R. Jones : The alteration of 

 tourmaline. In a moist, tropical climate minerals 

 which are ordinarily regarded as stable break down 

 to an extraordinary degree. At Gunong Bakau, 

 Federated Malay States, tourmaline is found more or 

 less completely altered to a mica (probably phlogopite) 

 and limonite, the degree of alteration decreasing with 

 increasing depth from the surface, suggesting that the 

 change was caused by the percolation of water from 

 above. The freshness of tourmaline grains in sands 

 is very probab'y due to the removal of the altered 

 products by chemical and mechanical means. 



NO. 2425, VOL. 97] 



Zoological Society, March 21. — Dr. S. F. Harmer, 

 vice-president, in the chair. — Dr. T. Goodey : Observa- 

 tions on the cytology of Flagellates and Amoebae ob- 

 tained from old stored soil. This paper deals with 

 the cytology and nuclear changes during division of 

 three species of Flagellates and two species of Amoebae 

 obtained from soil stored in bottles at the Rothamsted 

 Laboratory for practically fifty years. One of the 

 Flagellates and the two Amoebae are new to science. 



Geological Society, March 22.^ — Dr. A. Harker, presi- 

 dent, in the chair. — Prof. S. J. Shand : The pseudo- 

 tachylyte of Parijs (Orange Free State) and its relation 

 to " trap-shotten gneiss " and " flinty crush-rock." The 

 rocks described as " pseudo-tachylyte " occur in irregu- 

 lar veins in the granite-gnei-ss of Parijs (O.F.S.). The 

 author first regarded them as igneous intrusions ; he 

 now compares and contrasts these rocks with the "trap- 

 shotten gneiss " of India and with " flinty crush- 

 rocks " from Scotland, Argentina, and Namaqualand. 

 The veins are irregular in form, dip, and strike; they 

 freely branch and anastomose, and not uncommonly 

 terminate blindly. The material consists of a dense 

 black base, holding fragments of granite ; these are 

 sometimes so numerous that the base is reduced to 

 the rdle of a mere cement between the rounded 

 boulders. Microscopically, the rocks fall into three 

 types, one of which is opaque and almost without 

 individualised grains or crystals, while the others 

 represent different stages of crystallisation of the first 

 type. The production of the veins involved a tem- 

 perature sufficient to melt the felspar of the granite, 

 and there has been recrystallisation of felspar in the 

 form of spherulites and microlites, and also of prisms 

 of hornblende. In this evidence of high temperature, 

 and in the absence of shearing phenomena in the 

 granite, the pseudo-tachylyte of Parijs differs from all' 

 known crush-rocks and has affinities with pitchstones 

 and tachylytes. Among the crush-rocks of Scotland, 

 the author recognises a passage from the mylonitic 

 type to a type in which fusion has been realised ; the 

 latter material is similar to the first of the Parijs types. 

 A chemical analysis of the pseudo-tachylyte shows that 

 the composition is that of a granodiorite, and is such 

 as might correspond to an average of the variable 

 dark gneiss in which the veins occur. It is suggested 

 that a " melt " of granite, produced by mechanically- 

 developed heat arising from the sudden rupture of 

 the granite, would differ from a normal magma of 

 granitic composition, and it is thought that the veins 

 represent the solid equivalents of such a melt. 



Physical Society, March 24. — Mr. F. E. Smith, vice- 

 president, in the chair. — Mrs. C. H. GriflBths : A new 

 method of determining ionic velocities. In the experi- 

 ments described the kathode, which consists of a hori- 

 zontal copper disc perforated with two holes, is 

 mounted in a cylindrical glass tube open at the lower 

 end. The whole is suspended from the beam of a 

 balance, and is immersed in a vessel of copper 

 sulphate. The anode is a copper spiral fixed in the 

 electrolyte some ' distance below the mouth of the 

 kathode vessel. From the rate of change of weight 

 of the suspended system during the passage of a 

 current the ionic velocities can be determined. — Dr. 

 S. W. J. Smith : Note on an explanation of the migra- 

 tion of the ions. The object of this note is to show i 

 how a familiar diagram, appearing in many text- l 

 books, can be improved in a wav which makes it easier I 

 to appreciate what happens at the electrodes in the | 

 simpler examples of Hittorf's method of determining 

 the migration constant. An attempt is made to give 

 precision' to an idea which is sometimes vaguely ex- 

 pressed and frequently ignored.-^Dr. S. W. J. Smith : 

 A method of exhibiting the velocitv of iodine ions in 

 solution. Dilute solutions of potassium iodide and 



