Feb. 2 1, 1884] 



NA TURE 



399 



M. Jamin, but the actual values of the observed intensities always 

 fall short of the calculated intensities, the difference being least 

 with the steel mirror. 



The polisli of the mirrors was examined at the end of the 

 experiments by the method suggested by Prof. Stokes, and 

 described in the paper already referred to ; both the mirrors 

 stood the test satisfactorily, the polish of the steel being very 

 slightly the best. 



These experiments appear to show that the generally received 

 formuLr: for metallic reflection are approximately correct, but 

 that the actual intensity of the reflected light i-: always less than 

 the theoretical intensity, and that therefore, unless this be due to 

 defects in the metallic surfaces, the formula; do not completely 

 express the laws of metallic reflection. If, as appears to be the 

 case, a change in the reilective power of a plate can occur with- 

 out any change in the values of the principal incidence and 

 azimuth, it is necessary to regard the forniul.-e as only approxi- 

 mately true, and there is additional reason for thinking that, as 

 Prof. Stokes has suggested, three constants are required to define 

 a metal optically. 



Linnean Society, February 7. — Sir J. Lubbock, Bart., 

 president, in the chair. — Mr. Henry Groves of Florence and 

 Mr. F. L. Keays of Cobham were elected Fellows. — Mr. F. O. 

 Bower showed specimens of the leaf of Tomeia meiiziesii, with 

 adventitious buds situated at the base of the lamina. These 

 buds appear at the same point in all the leaves, and under nor- 

 mal circumstances, so that their development seems to be a 

 constant character of the species. Their origin is exogenous, 

 and the buds are found already present at the period when 

 ligiiification of the xylem of the young vascular bundles begins. 

 Mr. Bower compared this development with that already known 

 in Cardaminc pratouis and Athyrnnis ternaltis. — There was 

 exhibited, on behalf of Mr. Arthur C. Cole, a box containing 

 mounted preparations illustrative of his "Studies in Microscopic 

 Science," a work devoted to animal and vegetable histology, now 

 being issued in parts. — A note on the gemma; of Aiilacomnion 

 palustre was read by Mr. F. O. Bovver. Specimens kept in a 

 warm and damp atmosphere flourished well, but showed no sign 

 of sexual organs. It was found, however, that the ordinary 

 vegetative axes often bore towards their apices structures which 

 were undoubtedly of a foliar nature, with a special adaptation 

 for effecting asexual or vegetative reproduction of the plant. 

 Indeed, these gemm;e were found to be capable of immediate 

 germination when laid on damp soil or even floating on water. — 

 The second part of the Rev. A. E. Eaton's monograph on the 

 recent Ephemeridse or mayflies was read in abstract, its contents 

 being a descriptive account of the genera and species froui 

 Potamanthus to Callibetcs inclusive. — Another paper taken in 

 abstract was by the Rev. A. M. Norman, on European and 

 North Atlantic Crustacea. In this an attempt has been made to 

 gather together all the present known and recorded forms of the 

 group. Notices of many of the species are only to be found in 

 obscure periodicals, &c., difficult of access almost in every lan- 

 guage ; consequently, since the production of Milne-Edward's 

 "Histoire Naturelle des Crustaces " in 1834, the numbers have 

 increased nearly threefold — revision therefore being highly 

 necessary. — Mr. B. T. Lowne gave an interesting communication 

 embodying his researches on the compound vision of insects. 

 He compares the structures of the simple ocellus with those of 

 the compound ocellus (common in larval insects), and with those 

 of the compound eye. The compound eye, according to him, 

 is but composed of aggregated compound ocelli, or one of the latter 

 in the larval insect is merely equivalent to a single segment of a 

 compound eye. He refers to the development of the compound 

 eye, and points out that in many larva; during the moulting 

 stages the "segregate" retina is finally replaced by another. 

 He describes a deep, spindle-like layer in intimate connection with 

 the nervous structures, and which layer he regards as playing an 

 important part in the phenomena of compound vision rather 

 than that this kind of vision is solely dependent on the number 

 of corneal facets. 



Mathematical Society, February 14. — Prof. Henrici, 

 F.R.S., president, and subsequently Sir J. Cockle, F.R.S., 

 vice-president, in the chair. — Messrs. A. B. Basset and D. 

 Brocklebank were admitted into the Society. — The following 

 communications v.ere made : — On the intersections of a triangle 

 with a circle, by H. M. Taylor. — On the difference between the 

 number of (4« 4- i) divisors and the number of (4K -f 3) 

 divisors of a number, by J. W. L. Glaisher, F.R.S. — On a 

 general theory, including the theories of systems of complexes 



and spheres, by A. Buchheim.— Prof. Sylvester, F.R.S. , made 

 some remarks on matrices with reference to nonions, &c. (see 

 forthcoming paper in the American Journal of Mathematics). 



Chemical Society, February 7.— Dr. W. H. Parkin, pre- 

 sident, in the chair. — It was announced that a ballot for the 

 election of Fellows would be held at the next meeting of the 

 Society (February 2i). The following papers were read : — 0]i 

 the expansion of liquids by D- Mendeleeff; translated from 

 the Russian by B. Brauner. In this paper the author, principally 

 from data furnished by Thorpe (C/zew. Soc. Journ. Trans., 1880, 



P- I4l)> gives the equation V — as expressing approxi- 



\ — Kt 

 mately the expansion of liquids, k is named the " determinator 

 of expansion." It is a coefiicient characterising each liquid, just 

 as each liquid has a specific gravity, boiling point, &c. The 

 author states that the above expression, although many liquids 

 deviate sligiitly from it, is sufficient in the majority of physico- 

 chemical investigations. — Researches on secondary and tertiary 

 azo-compounds, by R. Meldola, No. 2. The author describes, 

 in continuation of his former researches, the action of diarotised 

 paranitraniline upon tertiary monamines. In the case of di- 

 methylaniline the resulting product is paranitrobenzenazo- 

 dimethylaniline. This, on reduction with ammonium sulphide, 

 furnishes an amido-compound, which is a most delicate test for 

 nitrous acid. The nitro-azo compounds of the meta-^eries could 

 not be reduced by ammonium sulphide without complete decom- 

 position. The author concludes that the ;3-naphthylamine 

 compounds of para- and meta-nitrodiazo-benzene do not contain 

 an amido-group, as they yield with nitrous acid nitroso deriva- 

 tives. — Note on the nitrogenous matters in grass and ensilage 

 from grass, by E. Kinch. The author has determined the 

 albuminoid and non-albuminoid nitrogen in a sample of grass 

 and in the ensilage made from the grass. In the grass 9 per cent, 

 of the nitrogen was non-albuminoid ; in the ensilage 55 per cent, 

 of the nitrogen was non-albuminoid. The albuminoids were 

 determined by the phenol, the copper hydrate, the mercuric 

 hydrate, and the lead hydrate methods. The author poiuts out 

 the importance of this serious diminution in the albuminoids, 

 with reference to the food- value of ensilage. — On the influence 

 of the temperature of distillation on the composition of coal-gas, 

 by L. T. Wright. The author fiads that more gas is obtained 

 at high temperatures, but that it contains more hydrogen and 

 less hydrocarbons. 



Physical Society, February 9. — Prof. R. B. Clifton, presi- 

 dent, in the chair. — Annual General Meeting. — The motion to 

 make past presidents permanent vice-presidents was carried, and 

 the articles of the Society altered accordingly. — Prof. Clifton 

 read a report on the business of the past year, which showed 

 that steady work had been done by the Society. Dr. Atkinson 

 read the balance-sheet, showing a flourishing condition of the 

 Society. A proposal to adopt certain letters to indicate mem- 

 bership of the Society when placed behind the name was, on 

 the motion of Prof. G. Forbes, supported by Prof. Adams, 

 Prof. McLeod, and others, held in abeyance for the present. 

 The officers and Council for the ensuing year were then elected, 

 and were as follows: — President: Prof. F. Guthrie, F.R.S. ; 

 Vice-Presidents: Profs. R. IJ. Clifton, F.R.S., W. E. Ayrton, 

 F.R.S., W. Chandler Roberts, F.R.S., Dr. J. Hopkinson, 

 F.R.S., Lord Rayleigh, F.R.S.; Secretaries: Prof. A. W. 

 Reinold, M.A., Mr. W. Baily, M.A. ; Treasurer : Dr. E. 

 Atkinson ; Demonstrator : Prof. F. Guthrie ; other Members of 

 Council: Mr. Shelford Bidwell, M.A., LL.B., Mr. C. W. 

 Cooke, Prof. F. Fuller, Mr. R. T. Glazebrooke, F.R.S., Mr. 

 R. J. Lecky, F.R.A.S., Prof. H. McLeod, F.R.S., Dr. Hugo 

 Miiller, F.R.S., Prof. J. Perry, Prof. S. P. Thompson. 

 Honoraiy Member, Prof. H. A. Rowland. Prof. Clifton then 

 resigned the chair to Prof. Guthrie, whose zeal for the Society 

 he warmly praised. Prof. Guthrie expressed his high apprecia- 

 tion of the courtesy and kindness of the retiring President while 

 in the chair. Mr. \V. Lant Carpenter proposed a vote of thanks 

 to the Lords of the Committee of Council on Education ; Mr. 

 Whipple moved the cordial thanks of the meeting to Prof. Clifton ; 

 Mr. Griffith and Prof. Adams proposed a vote of thanks to the 

 secretaries, demonstrator, and treasurer ; Prof. G. C. Foster 

 proposed a vote of thanks to the auditors. — The meeting was 

 then resolved into an ordinary one, and the Secretary read a 

 paper by Dr. O. J. Lodge and J. W. Clark on the phenomena 

 exhibited by dusty air in the neighbourhood of strongly- 

 illuminated bodies, which we hope to print next week. 



