April 20, 1893] 



NATURE 



589 



Meyer's reaction is at once apparent. To prove the fact Dr. 

 Wislicenus shows that the silver salt of hyponitr )us acid may 

 actually be obtained from the solution at a certain stage of the 

 reaction, and the experiment forms the best method yet 

 lescribed of demonstrating the formation and properties of 

 hyponitrous acid. There is always a considerable amount of 

 hyponitrous acid present in the slowly-effervescing liquid ob- 

 tained by mixing solutions of hydroxylamine sulphate and 

 sodium nitrite at the ordinary temperature. Much more, how- 

 ever, is present for a few minutes when the liquid is warmed to 

 50-60°. At ihis temperature the decomposition is sufficiently 

 rapid to cause somewhat energetic effervescence, but by the 

 immediate addition of a solution of silver nitrate the greater 

 portion of the hyponitrous aci 1 can be fixed and precipitated in 

 the form of the bright yellow stable silver salt, AggNjOj. The 

 yield of the finely divided precipitate is about ten grams for 

 every hundred grams of hydroxylamine. 



When it is desirt-d to demonstrate this mode of formation of 

 hypi)nitrous acid upon the lecture table, solutions of about three 

 grams of hydroxylamine sulphate and the equivalent quantity of 

 sodium nitrite are previously and separately prepared. The 

 total amount of solvent water should not exceed two hundred 

 cubic centimetres. When the time arrives to perform the ex- 

 periment the two solutions are mixed and a little of the resulting 

 liquid immediately decanted into a test glass, silver nitrate 

 soluiion added, and the fact pointed out that the lesulting 

 precii)iiate of nitrite and sulphate of silver is white. The vessel 

 containing the main quantity of the liquid is then transferred to 

 a water bath warmed to 50°, when a rapid evolution of gas at 

 once commences. The issuing gas may rapidly be shown to 

 answer to the properties of nitrous oxide by inserting a glowing 

 splint, and almost immediately silver nitrate solution should be 

 added to the liquid, when the beautiful bright yellow silver salt 

 of hyponitrous ac'.d is precipitated. 



Notes from the Marine Biological Laboratory, Plymouth. — 

 Last week's captures include the Polychaeta /v^a/j«arm tuhicola 

 and Ainblyosyllis {Gattiola) spectalnlis ; the MoUusca Ovtila 

 pattila and Loligo media (136 mm. in length of mantle !) ; the 

 Decapod Crustacea Nika edulis, Ehalia Pennantii and Cran- 

 chii ; and the Tunicata Claveiina lepadifonnis, Archidistoma 

 as^gregatutii and Ferophora Listeri. The "gelatinous alga" 

 has now entirely x^^\2iZ^<\ Halosphara viridis, and both spherical 

 and elongated forms are being taken in the townets in great 

 profusion. A single specimen of the Cladoceran Podon, carry- 

 ing embryos, has been taken for the first time this year. Among 

 the many animals now breeding, the following have not previ- 

 ously been noticed : the Cephalopod Loligo media ; the Lep- 

 toslracan Ntbalia bipes ; the Schizopod Macromysis Jlexuosa 

 (= chamtrleon) ; the Macrura Pandaltts brevirostris and Hippo- 

 lytt Cranchii, and the Brachyuran Porcellana longicornis. The 

 Glaucothoe-siSigG of Pagttnis has also been taken. 



The additions to the Zoological Society's Gardens during the 

 past week include a Black-bellied Weaver Bird (Etiplec/esafer), 

 a]' Pin-tailed Whydah Bird [Vidua principalis), an Orange- 

 cheeked Waxbill {Eslrelda vielpoda), two Common Waxbills 

 [Esiielda cinerea) from West Africa, tsvo Auiaduvade Finches 

 {Estrelda amandava), two Indian Silver- bills (/1/«/«'« malaban'ca) 

 from India, presented by Miss Herring; a Greater Sulphur- 

 crested Cockatoo {Cacattia galerita) from Australia, presented 

 by Mr. IL IL Forsayth ; four Red-backed Buzzards {Biilio 

 erylhronotus) from the Falkland Islands, two presented by Dr. 

 Dale, and two presented by Mr. Vere Packe ; three Upland 

 Geese {Bernicla magellanica) from Patagonia, presented by Sir 

 Roger T. Goldsworthy ; a Herring Gull [Lams argen/alns) 

 British, presented by Mr. Thomas Owen ; an Alexamliine 

 NO. 1225, VOL. 47] 



l^anxaktGi [Palaornis alexandri) hom India, presented by Mr. 

 S. Hulme ; a Banded-tailed Tree Snake [Ahcetulla liocercus), a 

 — Snake (Dipsas cenchoa) from Trinidad, presented by Messrs. 

 Mole and Urich ; six Green Tree-frogs {Hyla arborea) European, 

 presented by the Rev. Clifford D. Fothergill ; a Moorish Toad 

 {Bufo mauritanica) from Tuni?, a Banded-tailed Tree Snake 

 {AhiBltilla liocercus) from Trinidad, deposited ; two Red Oven 

 Birds {Ftirnaritts ru/us), a Melancholy Tyrant {Tyranus vielan- 

 cholicus) from the Argentine Republic, a white-eyebrowed 

 Wood Swallow [Artamiis superciliosits) from New South Wale*, 

 six Edible Frogs [Rnna esculenta) European, purchased ; a 

 Gayal {Bib js frontalis, i ) born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Photographic Chart of the Heavens. — M. Loe^fy 

 in Comptes Rendtis (No. 13) for March 27 adds a lew more 

 words with regard to the scheme which he has suggested for 

 determining the coordinates of the centres of the cliches. With- 

 out such a method as his, or at any rate one that has for its 

 object the same end (that is, of shortening the work), it seems 

 that the work of determining the positions of the chief stars 

 will extend over some period. With 22,054 plates covering 

 169 cm. and corresponding to a portion of the sky 4°'7 square, 

 the average number of ^tars up to the eleventh magnitude is 

 estimated as 250. Now it is nut necessarily certain that o\ 

 on all of these plates there will be stars whoe positions 

 are accurately known, and further, even if accurate places had 

 once been obtained, our knowledge of their proper motions is 

 not considered advanced enough to apply them in such an 

 instance as thi*. Only the two following ways, then, seem 

 to be left: — (i) To observe afresh with our meridian 

 circles as many (say six) stars a< will appear on each cliche 

 and deduce their positions (thus eliminating proper motion), or 

 (2) to adopt a system of triangulaiion, assuming we know the 

 places of some of the more important position stars. M. Lce*y's 

 method is based on the latter, in which he groups the cliches 

 together ; for instance, the first grou()ing would contain as 

 many as sixteen square degrees, but the second, third, &c .would 

 cover just twice this number. With legard to " le probl^me 

 du rattachement " he says, " Malgre tons les soins pris pour 

 executer les photographies dans des conditions toujours sembla- 

 bles, il est impossible que les coordonnees mesurees sur deux 

 cliches voisins soient immediatement et ligoureusement com- 

 parable. Chacun d'eux, en effet, repre^ente la projection d'une 

 portion de la sphere celeste sur un plan determine, et les plans 

 de projection relalifs a deux plaques voisines sont inclines Tun 

 sur I'autre d'un certain angle. Les poses ont pu etre effectuees 

 a des epoques ties differentes ; on ne saurait done s'attendre k 

 ce que la situation des plaques par raj^port a I'axe de la lunette, 

 I'oiientation I'echelle des mesures soient ideniiques dans les 

 deux cas. Par suite il est necess'aire de faire subir aux grandeurs 

 mesurees certaines corrections, si Ton viut qu'elles constituent 

 un systeme unique et homogene de coordonnees." In his first 

 memoir M. Lcewy ha already given the formulas, &c., for re- 

 duction, and in the one 10 which we refer below he gives us an 

 application of his method. 



In Comptes Rendtis for April 4 (No. 14) M. Lcewy states the 

 resulis that he has obtained in applying his method of deter- 

 mining the coordinates of the stars on the cliches for the 

 Photographic Chart. As it would be impossible to give an idea 

 of this computation without entering into the subject at some 

 length, it seems best that we should leave it quite alone and 

 refer our readers to the journal itself, from which he will get full 

 information. Suffice it for us to say that in the different 

 methods of " raccordemenl " based on twenty-six well deter- 

 mined positions, the probableerror of the equatorial coordinates 

 amounts nearly to ±o"i, but "conime il faut encore admettre 

 les erreurs reelles plus fories qui les valeurs iheoriques calculees, 

 il devient evident que le degie d'exactitude obtenu, bien que 

 suffisant, est loin d'etre exaaeie." 



Catalogue of Southern Star Magnitudes. — In 

 vol. xii. no. I of the Memoirs of the American Academy of Arts 

 and Sciences will be found the results in catalogue form of Mr. 

 Edwin Sawyer's determinations nf the ma'.iiutu'les of southern 

 stars from 0° to - 30° Declination to the yih magnitude inclusive. 



