402 



NA TURE 



[Feb. 27, 1890 



over a water-bath a slow disengagement of bubbles was found to 

 occur. After allowing the reaction to complete itself during the 

 course of a few days, the liquid, which had become turbid, was 

 filtered, allowed to cool, and again filtered from a little more 

 flocculent material which separated out, and finally concentrated 

 and allowed to crystallize. A large quantity of hemispherical 

 crystal aggregates then separated, which were found on analysis to 

 consist of the new salt, ZnCl2.2NH.,OH. Several other methods 

 of obtaining it were investigated ; it may be obtained by 

 treating an aqueous solution of hydroxylamine hydrochloride, 

 NHgOH. HCl, with zinc oxide or carbonate, or with a mixture 

 of zinc sulphate and barium carbonate, or by treating an alcoholic 

 solution of hydroxylamine with zinc chloride. But the best 

 method, and one which gives 97 per cent, yield, consists in dis- 

 solving ten parts of hydroxylamine hydrochloride in 300 c.c 

 of alcohol in a flask provided with an inverted condenser ; the 

 liquid is then heated to the boiling-point and five parts of zinc 

 oxide added, the boiling being continued for several minutes 

 afterwards. The clear liquid is then decanted and allowed to 

 cool. After the deposition of the first crop of crystals, the 

 mother liquor may be returned to the flask and treated with a 

 further quantity of zinc oxide, four repetitions of this treatment 

 being sufficient to obtain an almost theoretical yield of the salt. 

 The white crystals are then washed with alcohol and dried in the 

 air. They resist the action of most solvents, water only slightly 

 dissolving them, and that with decomposition. Organic solvents 

 are practically without action upon them. When heated in a 

 narrow tube, as in attempting to determine the melting-point, 

 the salt violently explodes. If a quantity is heated to about 

 120° C, in a flask connected with a couple of U -tubes, the second 

 containing a little water, gas is abundantly liberated, and drops 

 of hydroxylamine condense in the first U-tube together with a 

 little nitrous acid. The water in the second tube is found to 

 contain hydroxylamine, ammonia, and nitrous acid, while fused 

 zinc chloride remains behind in the flask. A similar cadmium 

 salt was also obtained, CdCl2.2NH20H, in brilliant crystals 

 which separated much more quickly than those of the zinc salt. 

 This cadmium compound is much more stable under the action 

 of heat, gas being only liberated in the neighbourhood of 

 l9O°-20O°, and only a little hydroxylamine distils over. The 

 barium salt, BaCU.2NH20H, is a specially beautiful substance, 

 crystallizing from water in large tabular prisms, which are very 

 much more soluble in water than either of the salts above 

 described. 



The additions to the Zoological Society's Gardens during the 

 past week include an Esquimaux Dog {Canis familiaris $ ), 

 bred in England, presented by Mr. W. Tournay ; two Barbary 

 Turtle-Doves [Ttiriur risorius) from North Africa, presented 

 by Miss Teil ; a Bonnet Monkey {Macaciis siniais ? ), a 

 Macaque Monkey {Mmuciis cynomolgiis i ) from India, a 

 Common Raccoon {Procyon lot or) from North America, de- 

 posited ; a Green Monkey {CercopitJiccus callitrichtis) born in 

 the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 Objects for the Spectroscope. 

 Sidereal Time at Greenwich at 10 p.m. on February 27 = 



8h. 30m. 43s. 



Remarks. 

 (i) "Very bright; veiy large; at first very gradually, then 

 very suddenly much brighter in the middle." The spectrum of 

 this nebula has not yet, so far as I know, been recorded. 



(2) Duner classes this with stars of Group II., but states that 

 the spectrum is very feebly developed, and expresses a doubt as 

 lo the type. As I have before remarked, Mr. Lockyer's dis- 

 cussion of the stars of this group seems to indicate that the 

 spectra which are described as " feebly developed " really repre- 

 sent stages in the passage from one group to another. If, for 

 example, we consider a rather faint star with the banded spec- 

 trum a little more developed than in the case of Aldebaran, its 

 spectrum would no doubt be described as "feebly developed," 

 if classed with Group II. In such a case the star would be 

 more condensed than those in which the spectrum is said to be 

 well developed, and the flutings would have almost entirely 

 given way to lines. Line absorptions would therefore indicate 

 that the star belonged to a late stage of the group. On the 

 other hand, if the star be at a very early stage of condensation, 

 the flutings would still only be feebly developed, and might be 

 accompanied by bright lines. In any case, further examination 

 is necessary, as the star may belong to an early stage of Group 

 VI., and not to Group II. at all. 



(3) A star classed by Vogel with stars of the solar type. The 

 usual differential observations are required. 



(4) A star of Group IV. (Vogel). The usual observations 

 are required. 



(5) A "superb" example of stars of Group VI. (Dimer). 

 The principal bands are very wide and dark, and the secondary 

 bands 4 and 5 are also well seen. Bands 7 and 8 are doubtful. 



(6) This variable will reach a maximum about March 7. The 

 period is about 360 days, and the magnitudes at maximum and 

 minimum are 8"2 ± and < 13 respectively. The star is not 

 included in Duner's catalogue, but Vogel states that the si>ec- 

 trum is of the Group II. type. Observations before and after 

 maximum, with special references to changes of spectrum, 

 should be made. 



Note on the Zodiacal Light. — In favourable localities the 

 zodiacal light should now be visible in the evening, and as further 

 spectroscopic observations are desirable, it may be convenient to 

 briefly summarize here the results already obtained. Angstrom 

 first observed the spectrum at Upsala, in March 1887, and noted 

 the presence of the chief line of the aurora spectrum, at a wave- 

 length stated as 5567. Respighi, in 1872, also observed thisi 

 line, in addition to a faint continuous spectrum, and believed 

 this to demonstrate the identity of the aurora and zodiacal light. 

 He found, however, that at the same time the bright line was 

 visible in almost every part of the sky, and this led to the sug- 

 gestion that it originated from a concealed aurora. Prof. Piazzi 

 Smyth, in Italy, observed nothing but a faint continuous spec- 

 trum, extending from about midway between D and E to F. 

 A. W. Wright's observations led him to the following con- 

 clusions : — " (i) The spectrum of the zodiacal light is continuous, 

 and is sensibly the same as that of faint sunlight or twilight. 

 (2) No bright line or band can be recognized as belonging tc 

 this spectrum. (3) There is no evidence of any connection be- 

 between the zodiacal light and the Polar aurora " (Capron'^ 

 " Aurorae," p. 69). Mr. Lockyer believes the zodiacal light tc 

 be due to meteoritic dust, which is to a certain extent self 

 luminous, as indicated by the bright line in the spectrum, and 

 argues in favour of a connection between aurorse and the zodiaca j 

 light (Proc. Roy. Soc, vol. 45, p. 247). He says: — "Thtj 

 observations of Wright and others, showing that the spectrun ! 

 is continuous, are not at variance with Angstrom's observation, ! 

 for we should expect the spectrum to be somewhat variable. I j 

 is probable that the observations showing nothing but continuou j 

 spectrum were made when the temperature was only sufficien ; 

 to render the meteoritic particles red hot. That the zodiaca | 

 light does consist of solid particles, or, at all events, of particle 

 capable of reflecting light, is shown by the polariscope." H 

 also quotes from a letter in which Mr. Sherman, of Yale Col I 

 lege, states that he has reason to believe that the appearance c j 

 the bright line in the zodiacal light has a regular period. { 



On January 20 I saw the zodiacal light very well at Westgate( 

 on-Sea, but was unable to detect anything beyond a fain 

 continuous spectrum. I 



Mr. Maxwell Hall's observations at Jamaica (see NatUKI| 

 February 13, p. 351) also record continuous spectra, but wit | 

 remarkable changes in the region of maximum intensity. _ H | 

 suggests comparative observations with the spectrum of twiligh j 



