402 



NATURE. 



[December 5, 1912 



Tardigrada. This paper adds thirteen species to the 

 list ol Afri(;an Tardigrada ; twelve were described in 

 the author's previous paper, and Daday added a new 

 species, M. ietronyx. 



Institutiun of Mining and Metallurgy, November 21. — 

 Mr. Edward Hooper, president, in the chair. — Allan J. 

 tiark and \V. J. Snarwood : The metallurgy of the 

 Homestake ore. The round of operations after de- 

 livery of the mined ore to the mill bins may be sum- 

 marised briefly as follows : — The ore is fed to mortars 

 fitted with one inside amalgamation plate, when it is 

 crushed wet by gravitation stamps and thence passes 

 over a series of amalgamating plates. A special cone 

 system separates a small proportion of the coarsest 

 sand, which is reground and returned. A system of 

 cone classifiers, the last of the series provided with 

 bottom water feed, separates successive portions of 

 the fine slime. The sand is collected, drained, and 

 treated with cyanide solution, in vats from which the 

 residues are discharged by sluicing. The slimes over- 

 flowing the various cones are thickened in classifying 

 tanks having conical bottoms and peripheral overflow, 

 and the thickened slime is conveyed by a pipe line 

 to a cyanide plant, where it is collected and treated in 

 filter presses, which are discharged vvdthout opening 

 by means of an automatic sluicing device. Solutions 

 are precipitated by zinc dust. Concentration proper 

 is not practised, and no ore is sorted. From the time 

 the ore leaves the mine, no elevation is necessary, 

 and only a small proportion of the water has to be 

 pumped back at certain stages. Of the total ore 

 value 04 per cent is recovered, about 72 per cent, as 

 amalgam, and 22 per cent, by the cyanide process. — 

 J. W. Ashcroft : The flotation process, as applied to the 

 concentration of copper ore at the Kyloe Copper Mine, 

 New .South Wales. .'Xn adjourned discussion on this 

 paper, which had been introduced at a previous meet- 

 ing, gained additional interest from the fact that a 

 W'Orking model of the particular flotation process 

 referred to in the paper was exhibited, and samples 

 of well-known ores were treated before the members 

 present. 



Cambridge. 

 Philosophical Society, November 11. — Sir J. J. Thom- 

 son in the cliair. — Sir J. J. Thomson : The theory of 

 the motion of charged ions through gases. — Dr. 

 G. F. C. Searle : A simple method of determining the 

 viscositv of air. Air is compressed into a vessel of 

 volume S c.c. (about 10 litres) and is then allowed to 

 escape through a capillary tube of length I cm. and 

 radius a cm. into the atmosphere, the pressure of 

 which is P dynes per sq. cm. The pressure in the 

 vessel falls from p, to />., during t sees. Over a con- 

 siderable range of initial pressure the value of //^ is 

 found to be constant. The temperature of the air in 

 the vessel i_s maintained nearly constant by the sur- 

 rounding atmosphere. The method is convenient as a 

 rough and readv method in a large practical class. — 

 R. Whiddingfon : Note on the Rontgen radiation from 

 kathode particles traversing a gas. During some ex- 

 periments with a lime kathode it was noticed that 

 even when the beam of kathode particles was not per- 

 mitted to strike a target a comparatively strong radia- 

 tion could be detected, proceeding apparently from the 

 path of the kathode particles. The evidence goes to 

 show that this is a Rontgen radiation arising from 

 the encounters taking place between the kathode par- 

 ticles and the molecules of the residual gas within the 

 discharge tube. It has been shown that a metal plate 

 insulated and exposed to the action of these ravs may 

 charge un posltivelv, emitting negative particles of 

 verv nearlv the same velocitv as the kathodf^ particles 

 traversing the discharge tube. The potential applied 



NO. 2249, VOL. 90] 



to the discharge tube varied in these experiments 

 between 90 and 300 volts. — VV. L. Bragg : The diffrac- 

 tion of short electromagnetic waves by a crystal. The 

 paper deals with the interference phenomena observed 

 by Herren Friedrich, Knipping, and Laue when a 

 crystal is traversed by a narrow beam of rays from an 

 X-ray bulb. The theory which is put forv\ard by Laue 

 to account for these phenomena postulates the exist- 

 ence of definite wave-lengths in the incident radiation, 

 in order to explain the interference pattern of spots 

 obtained. The paper shows that, on the contrary, the 

 pattern obtained with the crystal of cubical zinc 

 blende used by Laue is in reality the most general one 

 possible for a continuous range of wave-lengths in 

 the incident radiation, if the arrangement of atoms 

 in the crystal is in accordance \yith the theory of 

 valency volumes of Pope and Barlow. The incident 

 radiation is regarded as a series of independent pulses, 

 and the inlerference maxima as formed by reflection 

 of these ]iulses in ideal planes in the crystal in which 

 the atomi can be arranged, this point of view leading 

 to greater simplicity of calculation. — H. E. Watson : 

 Experiments on the electrical discharge in helium and 

 neon. — H. C. Pocklington : Some diophantine impos- 

 sibilities. — (t. N. Watson : A class of integral functions 

 defined by Taylor's series.— .\. J. Berry : Notes on the 

 volatilisation of certain binary alloys in high vacua. 

 Experiments have been performed on the behaviour of 

 certain binary alloys when heated in high vacua with 

 the object of isolating intermetallic compounds (com- 

 pare Roy. Soc. Proc, 86a, 1911, 67). In the case of 

 alloys of copper and cadmium it was found that these 

 two metals are quantitatively separable. When alloys 

 of cadmium and magnesium are heated in vacuo, ooih 

 metals volatilise together, but no definite relation 

 between the composition of the residue and the dis- 

 tillate was established. The behaviour of the mag- 

 nesium lead alloys indicates that the compound 

 iMg„Pb is largely dissociated in the vaporous state. 



Manchester. 

 Literary and Philosophical Society, October 29. — Prof. 

 F. E. V\'eiss, president, in the chair. — Dr. Kurt 

 Loewenfeld : Importance of autograph documents in the 

 history of science (part i.). The author dealt with the 

 usefulness of historical studies for the student of 

 natural history, and the value of such studies for 

 education as a whole. The documents exhibited and 

 discoursed upon included many connected with John 

 Dalton, the last table of atomic weights as drawn up 

 bv Dalton, between 1818 and 1S27, amongst others; 

 also letters by William Henry. A letter by Charles 

 William Henry, inasmuch as it contradicts a statement 

 in his own biography of Dalton, proves that he is not 

 a trustworthy historian, and, as Charles William 

 Henry's biography supplies some of the most valuable 

 material for the important question of the genesis of 

 the atomic theory. Dr. Loewenfeld considered this 

 incident of importance. 



DflU.IN. 



Royal Irish Academy, November 11. — Count 

 Plunicett, vice-president, in the chair. — W. J. Dakin 

 and Miss Latarche : The plankton of Lough Neagh. 

 The paper gives the results of the first detailed quan- 

 titative plankton research carried out on the lakes of 

 the British Islands. Owing to the large area of the 

 lake surface and the moderate depth (40 ft.) Lough 

 Neagh is of particular interest. It is already famous 

 for the presence, in verv large numbers, of the Schizo- 

 pod Afv.'C!.'; rehcta. The authors have traced the 

 seasonal development and interrelation of both the 

 animals and plants by means of quantitative catches 



