NA TURE 



[November 



1922 



numbei of phi b graphs were taken of the ends of 



tlic tracks 1 1 •■ raj : from polonium in both air and 



argon, using C. T. R. Wilson's expansion method. 



dden bends made by the tracks due to 



collision with the atomic nuclei, and the actual form 



oi thesi bends is obtained from measurements of 

 the double images given by the special camera 

 designed for the work by Shimizu. The frequency 

 of occurrence of bends of given type are consistent 

 with the existence of an inverse-square law of force 



between the u-particles and the nuclei, when their 

 distance apart lies between 6x10'" and io~ 9 cm. 

 for argon, and 3X10- 12 and 5 x to -10 cm. for air. 



rhe velocity of the a-particles along the latter part 

 of their tracks was also calculated from the frequency 

 of the bends and found to be much lower than had 



been expected. Velocities so low as 10 cm. per 

 second were obtained, and the relation connecting 

 the velocity v and the range r was found to be roughly 

 of the form &002J, instead of the form tooj! found 

 by Marsden and Taylor for the early part of tracks 

 by other methods. No anomalous effects were dis- 

 covered as regards frequency or type of collision. — 

 J. H. Jones : The kinetic energy of electrons emitted 

 from a hot tungsten filament. When allowance is 

 made for experimental and secondary effects the 

 distribution of energy agrees with that given by 

 Maxwell's law. Of experimental errors the most 

 serious are probably due to difficulties of measuring 

 the small currents involved and the temperatures. 

 These lead to uncertainties which in individual 

 experiments may amount to so much as 10 per cent. 

 The secondary effects probably arise from con- 

 tamination of the heated surfaces. This tends to 

 increase the apparent energy of electrons emitted 

 and the increase may amount to so much as 20 per 

 cent. The abnormal electron energies found by 

 Ting, which were as much as 100 per cent, in excess 

 of the Maxwell distribution value, do not appear 

 under satisfactory experimental conditions. — W. 

 Wilson : The quantum theory and electromagnetic 

 phenomena. From the point of view of the quantum 

 theory such systems as atoms possess stationary 

 -1 rtes which are subject to conditions expressed by 

 the equations — 



fp,dqW = n.h. 

 The paper is chiefly concerned with an extended 

 form of these quantum restrictions in which the 

 momenta, p„ are replaced by more general momenta, 

 w„ involving the components of the vector potential 

 oi the external field to which the system is subjected. 

 — S. Marsh and A. E. Evans : On measurements of 

 electrode potential drop with direct current and 

 alternating current electrolysis. Electrodes of polished 

 platinum, platinum-black, gold and nickel were used, 

 ni rmal sulphuric acid serving as the electrolyte. 

 With direct current, anodic and cathodic effects 

 were examined ; with alternating current, the 

 frequencies ranged from 25 to 80. Experiments were 

 also made with various current densities. With all 

 the metals examined, the cathodic drop increases 

 with time, the curves (especiallv with polished 

 platinum) resembling saturation curves in radio- 

 ai tivity. The anodic drop decreases at first and 

 then rises similarly to the cathodic curve. With 

 alternating current the electrode drop den <- 

 during an interval depending on the frequency and 

 thereafter increases slightly. The cathodic curves 

 probably represent the effect of occlusion, while the 



ni de 1 urves represent the opposing effects of oxida- 

 ! ii 11 and occlusion. 



Royal Microscopical Society, October 18. — Prof. 

 F. J. Cheshire, president, in the chair. — R. Chambers : 

 New apparatus and methods for the dissection and 



NO. 2/69, VOL. I io] 



injection of living cells. With the new apparatus 

 there is a complete absence of lost motion, and 

 continuous and accurate control of the needle in 

 every direction under an immersion lens. The 

 needle is maintained in one plane while it is being 

 moved. Adjusting devices facilitate placing the 

 needle or micro-pipette in position. The instrument 

 consists essentially of rigid bars which are screwed 

 apart against springs, the movements of the needle 

 tip being in small arcs of a circle with a radius of 

 about 2\ in. There are three horizontal bars which 

 are forced apart by two screws. When the screws 

 are reversed, spring hinges at either end holding 

 the bars together in pairs return them to their 

 original position. A similar pair of vertical bars 

 attached to the horizontal ones controls up and 

 down movements of the needle. With this instru- 

 ment the most delicate operations in micro-dissection, 

 such as puncturing blood corpuscles or even cutting 

 up chromosomes, can be performed. A new micro- 

 injection apparatus is also described, as well as 

 methods for making the needles and the moist- 

 chamber. 



Zoological Society, October 24. — Dr. A. Smith 

 Woodward, vice-president, in the chair. — J. P. 

 Hill and R. H. Burne : The foetal membranes and 

 placentation of Chiromys madagascariensis. — R. I. 

 Pocock : The external characters of the feetus of 

 Chiromys madagascariensis. — R. Kirkpatrick and 

 J. Metzelaar : On an instance of commensalism 

 between a hermit-crab and a polyzoon. 



Society of Public Analysts, November 1. — Mr. P. A. 

 Ellis Richards, president, in the chair. — C. Ainsworth 

 Mitchell : The colorimetric estimation of pyrogallol, 

 gallotannin, and gallic acid. A ferrous tartrate re- 

 agent is used. The violet coloration produced is due 

 to the pyrogallic group and, applied quantitatively, 

 affords a measure of that group in different com- 

 pounds. The reaction throws light on the con- 

 stitution of gallotannin ; the results for tannin from 

 China galls are more in accordance with the formula 

 recently suggested by Nierenstein than with that 

 previously accepted. To estimate gallotannin in 

 the presence of gallic acid the substances are estimated 

 together colorimetrically in terms of gallic acid or 

 pyrogallol. The tannin is then precipitated with 

 quinine hydrochloride and the gallic acid estimated in 

 the filtrate. The difference between the two results, 

 multiplied by a factor, gives the gallotannin. The 

 method has been applied to the estimation of tannin 

 and gallic acid in various natural and commercial 

 products. — H. E. Annett and M. N. Bose : The estima- 

 tion of narcotine and papaverine in opium. Small 

 quantities of opium (1-2 grams) only were available from 

 plants used in selection experiments on the poppy. In 

 estimating narcotine and papaverine an old observa- 

 tion of Plugge's, that on addition of sodium acetate to 

 an aqueous opium extract, narcotine, papaverine, and 

 narceine are precipitated, was used. Given the right 

 conditions, the first two are precipitated completely ; 

 the narceine carried down can be washed away with 

 water, and in the washed precipitate after further puri- 

 fication narcotine can be estimated polarimetrically. — 

 H. E. Annett and R. R. Sanghi : The estimation of 

 codeine. Codeine is extracted by toluene from an 

 aqueous alkaline extract of opium, converted into the 

 hydrochloride, purified by re-extraction with toluene, 

 and finally ci inverted into hydrochloride and weighed as 

 sin h. Theprocessisanimprovementof thatpreviously 

 described by Annett and Son. — J. R. Nicholls : The 

 estimation of morphine. If a 50 per cent, alcoholic 

 solution containing morphine liberated by means of 

 ammonia is shaken with half its volume of chloroform, 



