March 2, 1893] 



NATURE 



429 



Mem. Soc. degli Speitroscopisti Ital. vol. xxi. 1892. — La 

 Grandissima Macchia Solare del Febbrajo 1892, by A. Ricco. — 

 This memoir is a description of an enormous sun-spot which 

 developed from some small ones that had been noticed during 

 three rotations before January 17. On February 5, they made 

 their grand entry on the solar face on the ea>t side, and by the 

 7th could be seen by the eye aided only by a smoked glass. The 

 whole spot was composed of a very large one surrounded by 

 smaller ones, and composed of great tongues of flame extending in 

 towards the nucleus, sometim.es arranged in a spiral manner. It 

 attained its maximum on February 11, when the whole patch 

 measured, in earth diameters, as follows : Total length, 20 ; total 

 breadth, 8 ; the more compact extended 8 in each direction. 

 After this the breaking up of the spot proceeded at a rapid rate, 

 and by rotation the spot passed out of sight on the i8th. On 

 the next rotation the diminution was much more marked. The 

 author gives six observations of latitude, eight drawings, and 

 several spectroscopic observations on the flames. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, February 23. — " On the Mimetic Forms of 

 certain Butterflies of the Genus Hypolimnas." By Colonel 

 C. Swinhoe, M.A. Communicated by Prof. E. Ray Lan- 

 kester, F.R.S. 



The object of this investigation is to study the changes under- 

 gone by the species of a small group of butterflies as they are 

 traced from one locality to another, and to ascertain the bearing 

 of these facts upon the theory of mimicry. 



We find the representatives of the Indian Hypolimnas bolina 

 in a long list of localities in Malaya, Polynesia, and Africa : the 

 local representatives differ from each other and from the Indian 

 form, but they agree in possessing in one or both sexes a more 

 or less superficial resemblance to some conspicuous species be- 

 longing to a specially defended group and inhabiting the same 

 locality ; the same is true of the three forms of the female of 

 Hypolimnas tnisippus. 



The facts afford the most convincing evidence of the truth of 

 the theory of mimicry enunciated by H. W. Bates. 



The study of these numerous but closely-related forms be- 

 longing to the genus Hypolimnas also throws light upon such 

 interesting questions as : — 



(i) The special liability of the female to become mimetic. 



(2) The ancestral form from which the various mimetic 

 varieties have been derived. 



(3) The mimetic resemblance to different species in the same 

 locality. 



(4) The divergent conditions under which mimicry appears 

 in closely-related species. 



(5) The relation between selection and variation in the pro- 

 duction of mimetic resemblance. 



Physical Society, February 10. — Annual general meeting. 

 — Mr. Walter Baily, Vice-President, in the chair. — The reports 

 of the Council and Treasurer were read and approved, copies of 

 the balance-sheet being distributed to members. From the 

 former it appears that the society now numbers 371 ordinary 

 members and 12 honorary members, and during the past year 

 the society has lost six members by death, viz. the Rev. T. 

 Pelham Dale, Dr. J. T. Hurst, B. Loewy, C. E. Walduck, G. 

 M. Whipple, and P. W. Willans. Obituary notices ac- 

 company the report. — The treasurer's statement shows 

 the financial condition of the society to be satisfactory. A 

 cordial vote of thanks to the Committee of Council on Educa- 

 tion for the use of the rooms and apparatus of the Royal College 

 of Science was proposed by Mr. Shelford Uidwell, sec )nded by 

 Mr. Blakesley, and carried unanimously. A similar vote was 

 accorded to the auditors, Mr. H. M. Elder and Mr. A. P. 

 Trotter, on the motion of Dr. Gladstone, seconded by Prof. S. 

 P. Thompson. Prof. Ramsay proposed a vote of thanks to the 

 oflficers of the society for their services during the past year ; 

 this was seconded by Prof. Fuller, and carried. Prof. Perry 

 responded. The following gentlemen were declared duly elected 

 to form the new council :— President : Prof. A. W. Rvicker, 

 F.R.S. Vice-Presidents: Walter Baily, Major-General E. 

 R. Festing, F.R.S.; Prof. J. Perry, F.R.S.; Prof. S. P. 

 Thompson, F.R.S. Secretaries : H. M. Elder, 50, City Road, 

 E.C. ; and T. H. Blakesley, 3, Eliot Hill, Lewisham, S E. 

 Treasurer : Dr. E. Atkinson, Portesbery Hill, Camberley, 



NO. I 2 18, VOL. 47] 



Surrey. Demonstrator: C. Vernon Boys, F.R.S., Physical 

 Laboratory, South Kensington. Other members of Council : 

 Shelford Bidwell, F.R.S., W. E. Sumpner, Prof. G. Fuller, 

 J. Swinburne, Prof. J. V. Jones, Rev. F. J. Smith, Prof. G. 

 M. Minchin, L. Fletcher, F.R.S., Prof. O. Henrici, F.R.S., 

 James Wimshurst. — In response to invitations for suggestions 

 regarding the working of the society, Prof. S. P. Thompson 

 said all must appreciate the efforts of the late Council, and par- 

 ticularly of the honorary secretaries, in making the society better 

 known. But he could not help thinking that there were many 

 persons amongst teachers of physics and scientific amateurs 

 whose active sympathies it was desirable to engage, who were 

 not yet associated with the society. Perhaps the time of meet- 

 ing was not convenient for all, but he thought much might be 

 done by freely circulating particulars of what was going on at 

 the meetings. The daily papers merely announced the meetings, 

 but said nothing as to the place of meeting or the papers to be 

 read. In his opinion the society did not take the position in 

 the scientific world to which it was entitled, and he wished to 

 inspire members with a determination to bring its claims pro- 

 minently forward. — Mr. Blakesley pointed out that almost all the 

 scientific and technical papers gave full announcements of the 

 meetings and of the papers to be read. — Mr. W F. Stanley 

 said Friday afternoon was not convenient for scientific men 

 engaged in trade. — The meeting was then resolved into an 

 ordinary science meeting. — Dr. J. H. Gladstone, F.R.S., read a 

 paper on some recent determinations of molecular refraction 

 and dispersion. The paper relates to the new metallic 

 carbonyls, the metals indium and gallium, sulphur, and 

 to liquefied oxygen, nitrous oxide, and ethylene. The 

 carbonyls were found to be extremely refractive and enor- 

 mously dispersive. For iron pentacarbonyl, Fe(C0)5, the 

 molecular refraction for the line a of hydrogen was found to be 

 about 68'5, and the molecular dispersion between 7 and a of 

 hydrogen 6'6. For nickel tetra-carbonyl, Ni(CO)4, the corre- 

 sponding numbers are 577 and 5*93. In discussing the results 

 it was pointed out that if the molecular refraction of CO be 

 taken as 84, the value expected in organic substances, then the 

 atomic dispersions of nickel and iron come out greatly in excess 

 of the known values as determined from solutions of their salts. 

 The author considers the most probable explanation of the 

 excessive refractions and dispersions of the carbonyls is to be 

 sought in the peculiar arrangement of the CO, and on optical as 

 well as chemical grounds accepts the ring formulae indicated by 

 Mr. Mond in his lecture at the Royal Institution, viz. : — 



Ni 



o=cr 



^c=o 



Fe 



o=c/^c=o 



c c 

 o o 



and 0=Cl iC=0 

 C 



On this supposition the molecular refraction of CO comes out 

 1 1 "9 from the nickel compound and 1 1 '3 from the iron ore, whilst 

 the molecular dispersion (7 — a) is about i '3 in each case. For 

 indium and gallium the atomic refractions calculated from 

 latest data are 137 and ii'6 respectively. Sulphur has been 

 examined in the states of solid, liquid, and gas, and also in simple 

 chemical combination and in solution, all the resulting numbers 

 for its atomic refraction being remarkably concordant. For the 

 line C this is about 16. The dispersions in all the different 

 states are also in close agreement. Numbers relating to carbon 

 and chlorine are also given. The specific refractions of oxygen, 

 nitrous oxygen, and ethylene in the liquid states bad been re- 

 cently determined by Profs. Liveing and Dewar. For liquid 

 oxygen the refraction equivalent (3 '182) differs little from that 

 deduced from gaseous oxygen at ordinary temperatures (30316), 

 and also corresponds fairly closely to the 30 obtained by Landolt 

 from organic compounds. Liquid nitrous oxide gave 11 "418 

 and 1 1 '840 as the molecular refractions for the red ray of 

 lithium and the line G respectively. In discussing these num- 

 bers it was pointed out that nitrogen in nitrous oxide was not 

 in the same condition as nitrogen in ammonia. The latest de- 

 terminations with liquid ethylene gave the molecular refraction 

 for the line A as 17 '41, the theoretical value being 17 "40, thus 

 showing very close agreement. — Mr. E. C. C. Baly made a 

 communication on separation and striation of rarefied gases 

 under the influence of the electric discharge. 



