i86 



NATURE 



[June 25, 1891 



THg third volume of the Photographic Recorder is completed 

 by the June number. The volume is admirably illustrated, and 

 -contains a valuable record of all that has been dona in connec- 

 tion with photography during the past year. 



Messrs. W. F. Browx and Co., Montreal, are printing 

 for the Government of Canada "Contributions to Canadian 

 Palceontology," by J. F. Whiteaves, Paleontologist and Zoologist 

 ■to the Canadian Survey. Part iii. of vol. i. has just been 

 •issued. It deals with the fossils of the Devonian rocks of the 

 Mackenzie River basin. 



A NOTE by M. Moissan upon the action of fluorine upon 

 phosphorus trifluoride is communicated to the current num- 

 ber of the Bulletin de la Societe Chimique. A short time 

 ago M. Moissan described a mode of preparing the gaseous 

 trifluoride of phosphorus. The method consisted in gradually 

 adding phosphorus tribromide to warm zinc . fluoride, wash- 

 ing the gas first through water, in which it is sparingly 

 soluble, and afterwards drying by means of pumice moistened 

 with sulphuric acid and collecting over mercury. In order 

 to study the action of free fluorine gas upon phosphorus tri- 

 fluoride as thus prepared, a special piece of apparatus was de- 

 vised, constructed entirely of platinum and fluor-spar. It consisted 

 of a platinum tube fifteen centimetres long, closed at each end 

 by transparent plates of fluor-spar, through which the phenomena 

 attenditag the reaction could be observed. The platinum tube 

 was fttted with three side tubes, two of which were placed op- 

 posite each other about the centre of the tube, and served for the 

 admission of the fluorine and phosphorus trifluoride respectively ; 

 the third or exit tube was of somewhat wider diameter than the 

 entrance tubes, and was bent so as to serve as a delivery tube 

 over a mercury trough. The whole apparatus was first filled 

 with phosphorus trifluoride, and then the fluorine entrance tube 

 was connected with M. Moissan's now well-known apparatus for 

 the preparation of fluorine. As soon as the fluorine came in 

 contact with the phosphorus trifluoride a yellow flame was pro- 

 duced and intense action occurred, with the production of 

 phosphorus pentafluoride. The flame appears to be a compara- 

 tively low temperature one. On collecting the gaseous product 

 over mercury, it was found to consist very largely of phosphorus 

 pantafluoride, readily capable of absorption by water, and a small 

 proportion of unaltered trifluoride which could be absorbed by 

 potash. This reaction of fluorine with trifluoride of phosphorus 

 •is thus analogous to the conversion of phosphorus trichloride into 

 pentachloride by the action of gaseous chlorine. An interesting 

 reaction has also been observed by M. Moissan to occur between 

 spongy platinum and these gaseous fluorides of phosphorus. 

 When pentafluoride of phosphorus was passed over spongy 

 platinum gently heated in a platinum tube, a partial decomposition 

 was found to occur, and the issuing gas was admixed with tri- 

 fluoride, and also with free fluorine. The existence of the latter 

 in the free state was abundantly shown by its action upon crystal- 

 lized silicon. When, however, the temperature of the tube was 

 raised to dull redness, a volatile compound, containing platinum, 

 phosphorus, and fluorine, was obtained, which was carried forward 

 by the gaseous current and deposited in crystals in the cooler 

 portion of the tube. When this crystalline substance is heated, 

 it melts to a viscous liquid, which decomposes at a bright red 

 heat. Analyses show that it is a fluophosphide of platinum, 

 probably of the composition aPFj.PtF^, analogous to one of 

 the similar chlorine compounds discovered by Schutzenberger, 

 2PCI3. PtCl4. M. Moissan expresses the hope that by employing 

 some such dissociating compound as this a purely chemical iso- 

 lation of fluorine may some day be achieved. 



The additions to the Zoological Society's Gardens during the 



past week include three Stoats {Mustela erminea), European, 



presented by Mr. J. S. B. Borough ; an Oc&\ai{Felis pardalis S ) 



from South America, a Red-tailed Buzzard {Buteo borealis), a 



NO. T T 30, VOL. 44] 



Laughing Gall (Larus atricilla) from North America, presented 

 by Sir Henry Blake, K.C.M.G. ; a Tawny Eagle {Aquila 

 ficEvioides) from Africa, presented by Mr. K. G. Hay ; a 

 Blue-fronted Amazon {Chry satis astiva) from South America, 

 presented by Mrs. A, G. Mussey ; a Grey-breasted Parrakeet 

 {Bolborhynchus monachtcs) from Monte Video, presented by 

 Mr, J, R. George ; four Common Quails {Coturnix communis)^ 

 British, presented by Mr. J. C, Gie ; two Chinese Geese {Anser 

 cygnoides) from China, presented by Captain Creaghe ; an 

 Egyptian Gazelle {Gazella dorcas) from Egypt, two Abyssinian 

 Guinea Fowls {Nuinida ptilorhyncha) from Abyssinia, two 

 Blossom-headed Parrakeets(/'(i/^er«w cyanocephalus) from India, 

 a Meyer's Parrot {Pcnocephalus meyeri) from East Africa, three 

 Tibetan Crossoptilons {Crossoptilon tibelanum) from Tibet, a 

 Temminck's Tragopan ( Ceriornis teminincki i ) from China, 

 deposited; a Vinaceous Amazon {Chry satis vinacea), from 

 Brazil, purchased ; two Heloderms {Helodenna suspecttim) from 

 Arizona, U.S.A., received in exchange ; a Burrhel Wild Sheep 

 {Ovis burrhel), two Mule Deer {Cariacus macrotis <J ? ), a 

 Bennett's Wallaby {Halmaturus bennetti i ), two Impeyan 

 Pheasants (Laphophorus impeyanus), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 Transit of Mercury. — The Government Astronomer at 

 Sydney (Mr. C, Todd, C.M,G.) writes as follows regarding the 

 transit of Mercury :— Good observations of the transit of Mer- 

 cury were secured at the Observatory, on Sunday the lOth, At the 

 ingress the conditions were extremely favourable, the sun's limb 

 and the planet when projected on the sun's disk being exceed- 

 ingly well and sharply defined, but at the egress the sun's limb 

 was boiling and the planet was somewhat woolly, rendering it 

 difficult to fix the exact time of internal contact, I observed 

 with the 8-inch equatorial refractor, assisted by Mr. Cooke ; and 

 Mr, Sells observed with an 8-inch reflector. 

 The observations were as follow : — 



Observer — C. Todd, Power 125. 



l^G-&.-i.%%.— External Contact. 



Times, 

 h. m. s. 



A. About one-third on^ 91011 



Internal Contact. 



B. Contact tangential 9 13 6*5 



C. Black drop still clinging to limb 9 13 22*0 



D. Rupture of black drop ; planet clear of limb 9 13 49*5 



Egress — Power 80. Internal Contact. 



E. Formation of black drop touching limb ... 2 o I4'i 



F. Tangential contact 2 o 43'8 



External Contact. 



Indentation still visible 2 4 14-8 



,, ,, barely noticeable ..24 25*8 



Sun's limb complete 2 4 31 '8 



Observer— Mr. Sells. 



Ingress. — Internal Contact. 



a. Planet nearly on disk, but not quite ... 9 12 51 "3 



b. True contact, momentarily seen 9 13 13-2 



c. Planet pear-shaped ; point of pear touching 



sun's limb 9 13 507 



Egress, — Internal Contact. 



a. Pear-shaped contact 2 o 34*6 



b. True contact 2 i 28"6 



External Contact. 



c. Last seen ; or sun's limb judged to be com- 



plete 2 4 48'6 



Observations of Telluric Lines.— The May number of 

 the Mejnorie delta Societa degli Spettroscopisti Italiani contains a 

 paper by G. B. Rizzo on the telluric lines in the solar spectrum. 

 Signer Rizzo has compared the intensities of the lines A, B, 

 and o at Bosco Nero and on the Rocciamelone Mountain. In 

 order to express the variation in the mass of air (e) traversed, 

 calculations have been made of the values at the diff"erent alti- 

 tudes of P sec ^, where P is the atmospheric pressure, and f ie 

 the sun's zenith distance. The following is a comparison of the 



