526 



JvA TORE 



[March 30, 1899 



00 ■ 



one ten-thousanillh of a volt belween themselves from day to 

 day. Cells of the Hform vary about one-fifth of thai amount. 

 — Prof. J. D. Everell then read a paper by Dr. K. H. Barton 

 and Mr. W. B. Morton, on the criterion for the oscillatory 

 discharge of a condenser. The object of the paper is to 

 inquire how ihc condition for the oscillatory discharge of a con- 

 denser is modified when the ordinary differential ecjuation of the 

 second degree is supplemented by the terms added by Maxwell 

 to take account of the distribution of current in the (straight) 

 wire. The coefficients of these terms are relatively small, so 

 that the algebraic equation giving the periods is a quadratic 

 with small terms of higher order added. The effect of these 

 higher terms is, first, to introduce very rapid vibrations of small 

 amplitude ; and, ne\t, to displace the roots of the unaltered 

 quadratic. The nature of the discharge— oscillatory, or non- 

 oscillatory — may be taken to be determined by these principal 

 roots, and the critical case is when they are equal. The con- 

 dition for equality is obtained, by the property of the derived 

 function, as a series of powers of the small coefficients of the 

 equation, which may be carried by successive approximation as 

 far as is desired. The paper also treats the question by an 

 alternative, and more physical, method, which consists in 

 replacing the resistance, inductance, and capacity that occur in 

 the ordinary formula, by modified values. This gives the 

 criterion correct to the third order in the small terms. It is 

 shown that a condenser satisfying the critical condition on the 

 simple formula would, when the added terms are taken into 

 account, give an oscillatory discharge. Prof. Lodge said that 

 the result naturally to be expected of " throttling," viz. the 

 increase of resistance, and decrease of .self-induction, due to the 

 current keeping to the outside of the conductor, would tend 

 rather to damp out the oscillations than to favour them. Prof. 

 Everett observed that the equation was no longer a quadratic, 

 and that the quadratic criterion as to whether the discharge was 

 oscillatory or non-oscillatory, did not hold. The paper 

 appeared to be consistent with itself, and he considered that the 

 authors had satisfactorily proved, in their discussion of the 

 equation of current, that the effect of "throttling" was to 

 increase the tendency towards the oscillatory mode of discharge. 

 Prof. Lodge admitted that the quadratic criterion did not 

 hold ; he thought it most likely that the authors, who 

 evidently had gone into the matter with care, were right. At 

 the same time he wished to call attention to the singular and 

 unexpected character of their conclusion. If it turned out that 

 it was correct, i.e. that there was no slip in sign, it was a result 

 upon which he would desire to congratulate them. — The 

 President proposed votes of thanks, and the meeting adjourned 

 until April 2i. 



Chemical Society, March i6. — Prof. Dewar, President, in 

 the chair. — After the i>resenlation of a daguerreotype of Dalton 

 to the Society by the President, the following papers were 

 read : — The boiling point of liquid hydrogen as determined by a 

 rhodium-platinum resistance iheimometer, by J. Dewar. After 

 successfully overcoming the experimental difficulties, the author 

 has prepared considerable quantities of colourless liquid hydrogen 

 for the purpose of determining its boiling point. A pure plati- 

 num resistance thermometer gave the boiling point as 35" 

 absolute, whilst a rhodium-platinum resistance thermometer 

 gave the boiling point as 27" absolute ; by the use of a constant 

 volume hydrogen thermometer working under reduced pressure 

 the boiling-point of liquid hydrogen was found to be 20° abso- 

 lute. — Influence of substitution on specific rotation in the 

 bornylamine series, by M. O. Forster. The author has pre- 

 pared'and examined methylbornylamine, dimethylbornylamine, 

 ethylbornylamine, diethylbornylamine, «- and iso propylbornyl- 

 amine, butylbornylamine, benzylbornylamine, and ortho- and 

 para-nitrobenzylbornylamine in order to determine the influence 

 of substitution upon the specific and molecular rotations of 

 bornylamine. — Contribution to the characterisation of racemic 

 compounds, by A. Ladenburg. The author amends his 

 definition of racemism in the light of the experiments of Kip- 

 ping and Pope.— Rotatory powers of optically active methoxy- 

 and ethoxy-propionic acids prepared from active lactic acid, by 

 T. PurdieandJ. C. Irvine, ^iethylic methoxypropionate and 

 ethylic ethoxypropionatc, prepared from the la-vo-lactates by 

 »he action of alkyl iodides and silver oxide, have the specific 

 rotations -9553° and - 79 '69° respectively : this confirms the 

 previous conclusion that the high activity of the alkyl lactates 

 made from the silver .salt is due to the presence of alkyl- 

 oxypropionates. — On brasilin and ha;matoxylin (II.), by A. \V. 



NO. 1535, VOL. 59] 



Gilbody and W. H. Perkin, jun. From a study of the 

 oxidation products of dimethylbrasilin, the authors conclude 

 that brasilin and ha;maloxylin have the following con 

 stitulions : — 



I 



Oil I C-CII..- 



A, 



oii^A'c- 



-Clio— oil 



VV 



C(OH) 



V 



OH 



Y'yC(OH) yOH 



CH., CH., OH 



Brasilin. Hrcmatoxylin. 



— Crystallisation of dynamic isomerides. A correction, by T. 

 M. Lowry. 



Geological Society, March S.— W. Whitaker, F.R.S., 

 President, in the chair. — An analysis of the genus Micraster, 

 as determined by rigid zonal collecting, from the zone of Khyn- 

 (honeUa Ciivieri to that of Miirasler corangtiinuin, by Dr. 

 A. W. Rowe. The author has endeavoured to show, by means 

 of rigid zonal collecting on a large scale, from the white chalk 

 of the southern and south-eastern coast-sections of England, 

 that the genus Micraster is one and the same form gradually 

 evolving from the more simple to the more complex. In doing 

 this, he also contends that the genus may be divided into defi- 

 nite groups, each or several of which are absolutely diagnostic 

 of the various chalk zones, as defined by Barrois. The con- 

 clusions arrived at point to the regular and continuous de- 

 position of the white chalk, and strikingly confirm the general 

 accuracy of Barrois's zoning. The paper gives a minute com- 

 parison and description of the genus Micraster from a general 

 point of view, and from that of a group, and deals particularly 

 with the essential details of the test of the especial groups 

 characteristic of each zone. The author claims that, so far as 

 Mierasler is concerned, each zone is marked by a definite facies 

 of essential characters of the test, which are purely horizontal, 

 and that all species and varieties, however divergent they may 

 apparently be, occurring at any given horizon, are stamped 

 with the impress of these marked horizontal features. The 

 author proves that, while in an isolated instance, one may be 

 unable to decide the horizon in the white chalk whence a 

 specimen cf Micraster was derived, in the ninety-nine other 

 cases the diagnostic features described by him point unerringly 

 to the exact horizon, and thus afford a valuable aid to strati- 

 graphical geology, especially as the essential zonal features of 

 the test are easily made out in the field, — On a sill and 

 faulted inlier in Tideswell Dale (Derbyshire), by 11. H. 

 Arnold-Bemrose. The compact dolerite in the marble-quarry 

 in Tideswell Dale has been generally described as a lava ; but 

 Sir A. Geikie, in his "Ancient Volcanoes of Great Britain," 

 suggested the possibility that it might be a sill. In the present 

 paper the author endeavours to prove that the rock is really a 

 sill. 



Entomological Society, March 15. — Mr. G. H. Verrall, 

 President, in the chair. — Mr. Tutt exhibited a very fine series of 

 Epuiiiia luliilcnta captured by the Rev. C. R. N. Burrows last 

 autumn near Mucking in Essex. This series, while agreeing in 

 the main » ith Borkhausen's typical form, varied inter se in such a 

 manner as to give almost parallel forms to those so well known 

 from Scotland and Ireland, yet they had the ordinary blackish- 

 fuscous ground colour, and not the intense black peculiar to the 

 latter. Mr. Mcrrifield showed some Lepidoptera collected in 

 the latter half of .May and the first week of June, near Axolo 

 (Venetia), Riva, and Bozen. They included some very fine 

 specimens of Syriihi/nis carthami, a very large Syntoiiiis phegea, 

 and examples of I'ararge egeria intermediate in colour between 

 the Northern and Southern European forms. Mr. G. T. 

 Porritt exhibited a series of extreme forms of Arelia iubricipeda, 

 \At.fasiiala, and also some examples of what appeared to be a 

 new form of the species. Mr. O. E Janson exhibited an in- 

 florescence of Araujia albens, Don., together with a butterfly 

 which had bciii entrapped by getting its proboscis jammed in 

 one of llie ll.iuuf. It was found at Monte Video. 



Royal Microscopical Society, March 15. — Mr. E. M. 

 Nelson, President, in the chair. — The President called attention 

 to a fine example of Wilson's screw-barrel microscope which 

 had been presented by the Treasurer. The instrument was 

 probably 150 years old, and would be a valuable addition to the 

 Society s collection, — The President then said Mr. Curties had 

 sent for exhibition an old microscope made by Chevalier, eirea 



