300 



NA TURE 



[JULY 27, 1893 



Messrs. West, Newman, & Co., have just published a 

 book by Mr. S. T. Dunn on the flora of South-West Surrey, in- 

 cluding Dorking, Godalming, Farnham, and Haslemere. The 

 lastflora including this district was Brewer's, dated 1863. Another 

 -county flora is in preparation by Mr. W. H. Beeby. It need 

 scarcely be said that Mr. Dunn's little book is not intended to 

 take the place of these more complete floras, but it will serve 

 as a portable field guide to visitors. 



The sodium salt of the as yet little-known perchromic acid 

 has been isolated by Dr. C. Haussermann in the^state of well- 

 defined crystals, and is described in a communication to the 

 current number of ihc Journal fiir Praktische Ciiemie. The 

 possibility of the existence of an acid-forming oxide of chromium 

 higher than the trioxide CrOs has formed a subject of discussion 

 for many years. It was long considered that the deep blue 

 coloration produced upon adding hydrogen peroxide to a solu- 

 tion of chromic acid was due to the formation of the hydrate 

 of a peroxide of chromium. Both the first observer of this 

 interesting reaction, Barreswill, and Ascher in a subsequent 

 memoir, considered the peroxide to possess the composition 

 CrjO;, corresponding to the heptoxide of manganese, Mn.,Oj 

 present in the permanganates. Fairley has since attributed to 

 the blue compound the composition CrO|i.3H20. Latterly, 

 however, Moissan has adduced evidence in support of the view 

 that the substance is nothing more than a molecular compound 

 of chromic anhydride with hydrogen peroxide, CrOj. H.,0o. 

 The work of Haussermann is therefore particularly interesting 

 as showing that, whatever may be the truth concerning the blue 

 compound above referred to, a higher acid of chromium is 

 capable of existence. Moreover, it is not without some signifi- 

 cance that the formula of the anhydride derived by Hiiusser- 

 mann from the analyses of his sodium salt coincides with that, 

 CrO^, attributed by Fairley to the oxide present in the blue 

 compound. Haussermann finds that when sodium peroxide is 

 added in small quantities at a time to chromic hydrate suspended 

 in a small quantity of water and maintained at a low tempera- 

 ture by means of an ice bath, a somewhat violent reaction 

 occurs, rendering constant agitation necessary ; the chromic 

 hydrate dissolves, a brownish-yellow solution being produced. 

 When this liquid is allowed to stand undisturbed for a time in a 

 cold room, brilliant brownish red, transparent, monoclinic 

 crystals separate. These crystals are found upon analysis to 

 possess the'com position NaiiCr.Pij.aSH^O. Tliey rapidly efflor- 

 esce upon exposure to the air, falling to a brown powder. They 

 lose the whole of their water of crystallisation when placed in a 

 desiccator over oil of vitriol, or when heated to 100°. At a 

 temperature of 170° they explode with some violence, leaving 

 behind a quantity of sodium chromate mixed with sodium 

 hydrate. The anhydrous salt is tolerably stable and is only very 

 slowly attacked by cold water. Hot water, however, immedi- 

 ately decomposes it with formation of a solution of sodium 

 chromate and sodium hydrate and liberation of three molecular 

 equivalents of oxygen gas. 



Na8Cr.,0,5 + H„0 = aNajCrO^ + 2NaOH + 30.. 

 Analyses of the anhydrous salt agree with the formula 

 NagCrjOij, indicating an anhydride of the composition Cr.,Oi„ 

 ■or CrOu. It is most interesting that, upon the addition of dilute 

 sulphuric acid to the salt, the deep blue coloration above 

 alluded to is at once produced, as if it were due to the formation 

 of the free acid, the hydrate of CrOg. In a few minutes oxygen 

 commences to be evolved, and chromic sulphate is formed in 

 the solution. Alkalies are practically without action upon the 

 •salt, which would thus appear to be stable in alkaline solution. 



Notes from the Marine Biological Station, Plymouth. —Last 

 week's captures include a colony of a tall (i J ins.) variety of the 

 VO. 1239, VOL. 48] 



Hydroid Coryiie vermicularis, Hincks, the Polyzoan Pedicellina 

 echUtata, and the Tunicata Pkallnsia maminillata and Ascidia 

 depressa. An incursion of the Cladocera Podon and Evadne 

 has characterised the floating fauna ; and with these have been 

 taken Cirrhipede Nauplii, CyphonaiUcs larvse, and countless 

 numbers of minute Obelia medusae. The following animals are 

 now breeding :— The Cephalopod Sepiola atlanlica, the Mala- 

 costraca Chelitra terebrans, Limnoria lignoriim and Eupagurus 

 Prideauxii, and the Echinoderm Echinus acutus. 



The additions to the Zoological Society's Gardens during 

 the past week include two Great Eagle Owls {Btiho maximus), 

 European, presented by Lord Hill ; two Barbary Turtle Doves 

 (Turtur risorius var.) from the Pescadore Islands, China, 

 presented by Mr. Theodore A. W. Hance, C.M.Z.S. ; three 

 Giant Toads (Bufo tnarintis) from Brazil, presented by Mr. 

 Adamson ; a yellow-cheeked Lemur {Lemur xanthoiiiystax) 

 from Madagascar, a Banded Ichneumon {Herpestes fasciatus) 

 from West .\frica, deposited ; a Black A'ps (Cynopithecus niger) 

 from the Celebes ; two Black-headed Mynahs (7 emenuchus 

 pagodarum), two Manyar Weaver Birds [Ploceus manyar), two 

 Red-headed Buntings [Einherizaluteola) from India, purcha.sed ; 

 two Dominican Gulls [Lartts dominicus) bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Discovery of the New Co.viet.— The new comet 

 seems to have been noted by a number of observers before 

 they had seen its discovery announced. Mr. Edgar Richards 

 writes to us as follows in a letter dated July 13 : — 



" On Sunday last, the gth inst., at 9.30 p.m., the members of 

 the Astronomy Club, composed of several of the lady guests of 

 the Cliff House, Minnewaska, N.Y., U.S..'\., saw in the north- 

 western heavens a most brilliant comet with well-defined 

 nucleus and bright tail. The comet was in the constellation 

 Lynx, and its tail extended towards the North Star. Its 

 motion was very rapid in a south-westerly direction, and 

 the tail was momentarily increasing in length as lonj as 

 the comet was visible. The Club suffers from the dis- 

 advantage of not possessing a good telescope, so observa- 

 tions have to be made una■^si^ted. No notice in the newspapers 

 of such a comet having been seen and noted, the ladies were 

 filled with enthusiasm to be, as they supposed, its first dis- 

 coverers." 



" Monday night the comet was found to be near the feet of 

 the Great Bear, and much diminished in brilliancy, proving 

 that it was rapidly receding from the earth." 



It seems desirable, for the sake of cometary history, to give 

 the following translation of a note by M. Tisserand in Comptes 

 Rendus, No. 3. 



" On the loth July last, in the morning, I received a telegram 

 from M. Quenisset, of the staff of the Juvisy Observatory, 

 announcing that he had the previous night, the evening of the 

 9th July, discovered a bright comet, visible to the naked eye, 

 whose approximate co-ordinates he gave. I at once transmitted 

 a telegram to Kiel. The following morning, July 11, there 

 came a telegram from Kiel, announcing that the comet had 

 been seen on July 8 at Utah, U.S.A. by Mr. Rordame. It is 

 therefore certain that Mr. Rordame has discovered the comet, 

 but that M. Quenisset has announced it first. Perhaps it will 

 be convenient to call it the Rordame-Quenisset co;net ; there 

 are analogous precedents." 



Comet Finlay (i886 VII.).— The following is the ephemeris 

 of this comet for the present week : — 



I2h. Paris Mean Time. 



R.-\. (app.) Dec), (app.) 



1893. h. m. s. (, , „ 



July 27 ... 5 I 13-6 ... +214739-8 



28 ... 5 26-9 ... 21 56 136 



29 ... 9 38-5 ... 22 4 19 



30 ... 13 483 ... 22 u 56-4 



31 ... 17 562 ... 22 19 61 



Aug. I ... 22 2"4 ... 22 25 48-6 



2 ... 26 6-6 ... 22 32 4'6 



3 ... 5 30 90 ... 22 37 544 



