36 



NA TURE 



[May io, 1894 



reference to a paper by E. Fraenkel, published in the Deutsche 

 MedicinUche Wi>chenschrijt, on the treatment of fidy-seven 

 cases of typhoid fever by injection of a steiilised culture of 

 typhoid bacilli. Fraenkel slates that the results obtainable by 

 this method of treatment are superior to those of any other 

 method which has been previously employed. The earlier the 

 treatment commences the more successful are the results 

 obtained. The injections are said to be perfectly harmless 

 when made into the muscle, but cause much pain when 

 introduced subcutaneously. Dr. Kellogg contributes an article 

 on the "Relation of Modern Physiological Chemistry to 

 Vegetarianism, " which is to be continued. The other longer 

 papers are chiefly of medical interest. 



The explosive halogen compounds of nitrogen form the subject 

 of a memoir contributed to the current number of the Bcrichlc 

 by Dr. Seliwanow, of St. Petersburg. Pure trichloride of 

 nitrogen, NCI3, was prepared for the first time in a state of 

 purity in the year 1888, by Dr. Gattermann, in Prof Victor 

 Meyer's laboratory at Guttingen. It was shown to be an oily 

 liquid of so unstable a character that strong sunlight, or the light 

 waves emanating from a powerful artificial source such as burn- 

 ing magnesium, instantly provoke its extremely violent explosive 

 decomposition. By working in a dull light, however, Dr. 

 Gattermann succeeded in weighing a quantity of the liquid and 

 analysing it. He showed, moreover, that the crude liquid sub- 

 stance obtained by the action of chlorine on ammonium chloride 

 is a mixture of two or perhaps three different chlorides of nitro- 

 gen, and that the pure trichloride is only to be obtained by 

 subjecting this product, after remov.il of all sal-ammoniac by 

 washing and subsequently draining from water, to the action of 

 a rapid stream of chlorine. Iodide of nitrogen has frequently 

 formed the subject of investigation, and last year Dr. .Szuhay, of 

 Buda-Peslh, showed that the substance obtained by adding excess 

 of ammonia to a solution of iodine in potassium iodide consist-; 

 largely of the compound, NHL. The existence of an iodide 

 containing hydrogen had previously been indicated by Dr. Glad- 

 stone and -M. liineau, but it appears probable that in presence of 

 excess of iodine, the tri-iodide NI3 is also produced in large 

 <]aantity. That halogen compounds of nitrogen containing 

 likewise hydrogen are capable of existence would appear, there- 

 fore, to be fully proved by the work of Drs. Gattermann and 

 .Szuhay, and the latter chemist actually succeeded in preparing 

 a silver derivative NAglj, a substance as explosive as the iodide 

 of nitrogen itself. Dr. Seliwanow now brings forward evidence 

 to show that the formation of chloride or iodide of nitrogen by 

 the action of the halogens upon ammonia occurs in two stages, 

 hypochlorous or hypoiodous acid being first pro<luced. When 

 a dilute instead of a concentrated solution of iodine is employed, 

 no separation of iodide of nitrogen occurs, and the solution is 

 found to contain both ammonium iodide and hypo-iodous 

 acid HOI ; the latter is readily detected by means of a reaction 

 with potassium iodide in which iodine is libcr.itcd, which Dr. 

 Seliwanow has recently discovered during the course of his 

 work on certain organic derivatives of this acid. Upon in- 

 creasing the strength of the solution of iodine, iodide of nitrogen 

 at length commences to be deposited, and this is found to occur 

 at the expense of the hypo-io<lous .icid. Hence iodide of nitro- 

 gen appears to be formed directly by the action of ammonia 

 upon the unstable hypo-iodous acid produced in the first stage 

 of the reaction. A similar explanation is also shown to hold 

 with respect to the formation of chloride of nitrogen. It is 

 interesting to observe that Dr. Seliwanow actually proves the 

 existence of hypo-iodous acid in a solution of ammonia, a fact 

 which may perhaps be accounted for by the recent remarkable 

 discovery of Prof Victor Meyer that this so-called acid is rcilly 

 endowed with basic properties. When it docs react with am- 



NO. I 280, VOL. 50] 



monia, the chief product, as above shosvn, is iodide of nitrogen. 

 The two equations for the formation of the latter are formulated 

 by Dr. Seliwanow as follows : — 



NH3-l-Ij-m20 = NH4l-l-HOI. 

 NH3-f3HOI = Nl3-lsH;0. 



The additions to the Zoological Society's Gardens during 

 the past week include a De Filippi's Meadow Starling 

 {Sturnella dc filifpi) from La Plata, presented by Sir Harry 

 B. Lumsden, C.B. ; two Common Peafowls {Pavo 

 cristaliis, 9 9 ) from India, presented by Mr. Richard Hunter ; 

 a Chicken Snake (Coluber quadrivilltilus) from Florida, 

 U.S A., presented by Master James W. Philips; a Common 

 Boa (/)oa constrictor), two Tree Boas (Ccra//«( hortiilanus), a 

 Thick-necked Tree Boa {Epicrates cenchris), a Carinated Snake 

 [Hcrpelodryas caritiatus) from Trinidad, presented by Messrs. 

 Mole and Urich ; a Ring-hals Snake {Scf'edoit hicmachates), 

 two Cape Vipers (Causus rhomlieatus) from South .\frica, 

 presented by Mr. J. E. Matcham ; a Jaguar (Felis onca, <J ) 

 from South America, two Plumed Ground Doves (Geopclia 

 plumifera), two White Storks (Cicoiiia a//>a), two Vivacious 

 Snakes {Tachymenis vivax), two Four-lined Snakes (Colubet 

 ijucuiriUiieatus), four Green Lizards (J.acerta viridis) European, 

 four Dark Green Snakes (Zamcnis atrot'irois), two Glass 

 Snakes (Fseudopus pallasi) from Dalmatia, purchased ; two 

 Senegal Touracons (Corythaix persa) from West Africa, 

 received in exchange; two Barbary Wild Sheep {Ovi> 

 tragelaphus, 9 9 ) born in the Gardens. 



OUR ASTRONOAflCAL COLUMN. 



The Moon's Apparent Diameter. — A recent number of 

 Cicl el Terre (April 2) contains an article on the moon's angular 

 diameter, by M. P. Stroobant, of which a translation, with 

 copious notes, appears in the Ol'serialory for May. The 



i methods employed in the determination of the apparent diameter 

 of oursalellile are (l) micrometer measures, (2) meridian passages, 

 (3) heliometer measures, {4) photography, (5) occultation of stars 

 by the moon, (6) eclipses. A comp.irison of the principal results 

 obtained during the present century by these various methods 

 indicates that occultalions give the most accordant values, and 

 M. Stroobant remarks that the method of occiill.itlon is thi 

 only one in which the apparent diameter of the moon is nm 

 augmented by physical or physiological causes. .Vccurak 

 observations of occullations indicate that the lunar diameter lia- 

 a value lying between 31' 5" and 31' 6', but M. Stroobant urges 

 that this approximation is not suflicienl. He concludes by say- 

 ing : — "The application of photography to the determination of 

 the exact instant of disappearance or of reappearance of a star 

 would permil, without doul)l, the attainment of great i)recision, 

 especially when these phenomena occur .it the dark limb of the 

 moon, or during eclipses, when a number of small stars can be 

 observed. . . . About every nineteen years the moon passes 

 over the Pleiades in conditions mure or less advantageous for 

 observation ; this phenomenon will occur next year. Might not 

 the occasion be profitably used in securing a number of photo- 

 graphs at various observations ? If these are sufficiently separ- 

 ated from one another, it would be possible to deduce a new 

 value for the parallax nf the moon." 



Gale's Comet. — This comet, for which we gave .in 

 ephemeris last week, is now very favourably placed for 

 observation in the northern hemisphere. Its track lies from a 

 point near f Hydrx (May 7) to near (,* Leonis (May 15). From 

 .South Kensington we have received the following report : — "The 

 comet has been clearly visililc to the naked eye for some days 

 past, and when viewed with an opcr.i glass is quite a conspicuous 

 object. Observed with the telescope it appears as a large 

 slij;hlly elongated nebulous mass with a central condensation, 

 but with no obvious tail. I'hc spectrum of the comet was 



I observed by Mr. Fowler on May 7, and was seen to consist of 

 the three carbon bands which have so frequently been recorded 

 in other comets. The bands were found to be coincident with 

 the corresponding bands seen in the spectrum of the blue base 



