72 



KNOWLEDGE & SCIENTIFIC NEWS. 



[April, 1904. 



Corrigenda. 



Owiiif,' to an unfortunate oversight, the author of the article 

 on the Ancestry of the Camel and writer of Zoological Notes 

 in the March Number had no opportunity of revising the 

 proofs ; the followin.t; corrections are therefore necessary. 

 P. 25, ist Col., line 17 from bottom, for ga:elhi rtMil f;ii:c!le. 



,t ,, 2iid ,, ,, 20 ,, top ,, are ,, is. 



.. ^fi. .. .. .. 10 ,. ,, ,, Li)ita ,, Uinta. 



BOTANICAL. 



The rare occurrence ofstamens developing inside the ovary has 

 been recently met with in a Caryophyllaceousplant, Mclandi-yum 

 ruhnim, and is made the subject of a paper by Professor F. 

 Bucbenau in the Bericlitc lier DeutscJitu Butuiiisclieii Gesdhcluift. 

 XXI. The material was collected in the neighbourhood of 

 Marburg, Germany, having tirst attracted attention on account 

 of the absence of petals. A closer examination revealed great 

 irregularity in the structure of the ovary and in the number of 

 the stigmas, and on making a section of the former it was 

 found to contain six to nine, sometimes ten, well-developed 

 stamens arising from its base, the central placenta, with the 

 ovules, being altogether wanting. Dr. M. T. Masters, in his 

 V'fgvtiilih- Teraioloi^y, refers to a Myrtaceous plant, Dicckca 

 itiosmicfoliii. in which a similar abnormality was found. The 

 ovary contained no ovules, but numerous stamens, in various 

 stages of development, were attached to the inside walls. In 

 other respects the flower appeared to be quite normal. 



The standard work on the flora of South Africa is, of course, 

 the Flora Ciipciisi.-i. which was begun bv Harvey and Sonder, 

 and is being continued under the editorship of Sir \V. T. 

 Thiselton-Dyer. This work, of which anew part hasjust been 

 issued, gives full descriptions, with synonomy and localities, of 

 all the known flowering plants of Africa south of the tropics, 

 and is necessarily bulky and expensive. Professor Henslow's 

 South Afruaii Fluu-crini; Plants, lately published by Longmans, 

 Green, and Co., will be welcomed by those who seek a handy 

 inexpensive work on the South African flora, but who do not 

 require the fulness of the Flora Capi-nsis. 



The very imperfectly known flora of Siam is being investi- 

 gated by Mr. F. N. Williams, who has commenced an enumera- 

 tion of the plants of this country in the last number of the 

 Bulletin lie VHcrhkr Boissier. His work is based on the material 

 in the Kew Herbarium. Collectors have paid very scanty 

 attention to this flora, and several sets of plants, said to be 

 from Siam, are shown to be from localities outside its boun- 

 daries, and cannot, therefore, be included in his enumeration. 

 Some preliminary remarks on the flora were made by the 

 same author in the Journal of Botany of September, 1903, 

 where he mentiors the interesting fact that the well-known 

 commercial product, Siam benzoin, is obtained not from Siam 

 but from a locality in the Lao province of French Indo-China' 



PHYSICAL. 



Chlorophacne. 



Chlorophane is the name given to those varieties of Fluorite 

 (Fluorspar Calcium Fluoride), which possess to a noticeable 

 extent the property of " thermo-luminositv," that is to say, 

 of spontaneously emitting light when heated. The tempera- 

 ture at which this phenomenon takes place is not the same in 

 all cases, but varies with different varieties of the mineral — 

 the heat required being generally between 300 and 400' C. 

 On first heating little or no light is emitted, until what mav be 

 called the " critical temperature " is reached, when the Chloro- 

 phane glows brightly and continues to glow for some hours 



after cooling to ordinary temperature, but more feebly. The 

 colour of the light varies, blue and green predominating. 

 Hagenbach found that the spectrum of phosphorescent Fluorite 

 consisted of onl}^ nine bands, four blue, two green, two yellow, 

 and one orange. .As the relative intensity of these bands is 

 continually changing, it is easy to understand the different 

 colours pre,sented by different varieties of this mineral. The 

 pure white Fluorite does not possess the properties of Chloro- 

 phane, apparently the presence of some other salt or impurity 

 is necessary, as in the case of phosphorescent Calcium Sul- 

 phide. 



* * * 



ChlorophaLne a.rvd P.adium. 



Madame Curie states [Chanual .V.ai, \'ol. L.X.X.WUL, 

 No. 2293, p. 223), that: "Fluorite when heated undergoes a 

 change, which is accompanied by the emission of light. 

 If the Fluorite is afterwards subjected to the action of 

 Kadium an inverse charjge occiu's. which is also accom- 

 panied by an emission of light." This being so, what 

 effect would be produced by first acting upon the Fluorite 

 with Kadium, and then applying heat ? The following 

 experiment was devised for the purpose of ascertaining 

 this. A small crystal of Chlorophane was exposed for six hours 

 at a distance of two millimetres from 10 milligrams of Kadium 

 Nitrate (Giesel's preparation) in such a manner that only the 

 (3 and 7 rays acted upon it. The initial fluorescence excited 

 under these conditions was fairly bright, and persisted after 

 removal but slightly diminished in intensity, and when kept 

 at uniform temperature fell to half value in two to three days, 

 dying down to negligible quantity in six to seven days. The 

 changes in thermoluminosity were very marked, a very slight 

 rise in temperature, such as that produced by placing the 

 crystal in the palm of the hand, sufficing to increase the 

 luminosity about 100 percent. This increase is at the expense 

 of the duration of retained fluorescence. The "Alpha" rays 

 of Kadium are without appreciable effect on Fluorite. Careful 

 observations made with a Bismuth plate covered with a 

 deposit of Markwald's Kadio-tellurium (Polonium ?) of sufficient 

 radio-activity to cause a piece of Willemite to glow brightly 

 when in close contact, gave only negative results. It would 

 be of great interest to know the exact nature of the change 

 occurring in the chlorophane, whether it is of a chemical or 

 physical kind. — Ernest L. Arnibrecht, M.P.S. 



[N.B. — The writer also finds that the above properties are 

 not confined to Chlorophane, but are also shown by Kunzite, 

 with which very pretty experiments may be made on above 

 lines.] 



Wireless Telegraphy Experiments between 

 Germany and S\veden. 



The Berlin Gesellschaft fiir Drahtlose Telegraphic some 

 time ago installed two wireless telegraphy stations on the 

 Norwegian Loffoden Islands, the two points chosen being 

 50 km. distant and separated by high continuous rocky masses, 

 so as to oppose serious obstacles to the passage of the electric 

 wave. These stations were designed for dry cell operation, in 

 order to ascertain whether communication over distances as 

 high as 50 km. would be possible with such small amounts of 

 electric energy. This, however, was found not to be the case 

 as the primary energy of a limited number of dry cells proved 

 insufficient, a cpnsumption of about 200 watts being necessary 

 to overcome the obstacles on the passage of the electric waves. 



The experiments between Germany and Sweden, as con- 

 templated for some time past, were begun on December i6th, 

 when wireless telegraphy communication was secured between 

 Oberschiinweide, near Berlin, and Karlskrona, a Swedish naval 

 station, over a distance as high as 450 km. The results so 

 far obtained are said to be quite satisfactory. 



The " Telefunken " system used is a combination of the 

 Braim and Slaby-Arco schemes which, we learn, is being fre- 

 quently used with the Swedish Navy. 



The Nationa.! Physical La.boratory. 



One of the prominent even tsof the past month w.is the annual 

 visitation and inspection of the important standardizing and 

 testing laboratory at Bushey House, Teddington. Erstwhile 

 a Koj'al domicile, the mansion and adjacent buildings are now 



