27S 



NATURE 



[July 19, 1894 



two successive minima comes out as I '178 years. In round 

 numbers, therefore, the variation has a period of I'lS years, 

 that is, 431 days, which agrees with ihat found by Mr. 

 Chandler. The mean amplilude of the oscillation is o ■4+. As 

 to the annual variation, M. Gonnessiat is inclined to think that 

 it lias no real existence. He points out that one batch of 

 observations discussed by Mr. Chandler, was like those made 

 at Lyons, and hence refraction and errors of delineaiion intro- 

 duce apparent annual changes in the results. In the case of 

 observations made in the prime vertical by Horrebow's method, 

 it is argued that refraclion would show itself in the results, not 

 only by its effects on the zenith distance of the same star in the 

 course of a year, but also on the same day, when the conneciion 

 bstween the groups observed is established. It is further 

 remarked that the intensity of gravity, which determines the 

 phase of the annual term, is far from being constant at any 

 single place, and that its variation with the longitude does not 

 appear lo have been established. For these reasons M. 

 GDnnessiat holds that it is necessary to exercise "une certaine 

 reserve a I'e'ard du second terme de la formule de M. 

 Chandler." 



Photographs of the Moon. — At the meeting of the Paris 

 Academy of Sciences on July 9, MM. Loewy and Puiseux ex- 

 hibited som; marvellous photographs of the moon, obtained by 

 means of the great coudL equatorial of the Taris Observatory. 

 In the communication which accompanied the photographs, the 

 advantages of multiplying good lunar |)hotographs were pointed 

 out, and the various methods employed in the work were passed 

 in review. One of the enlargements on paper, shown to the 

 Academy, represented the moon on a scale of I 'So metres for its 

 diameter, and five lunar pictures on glass were exhibited at the 

 same time. S^me years would be required lo make a drawing 

 showing all the details visible on one of the plates obtained 

 with an exposure of about a second. The negatives are larger 

 than those obiained with the Lick telescope, and they bear con- 

 siderable magnification without loss of de6niiion. Hut such 

 negatives cannot always be obtained. .M.\I. Loewy and I'uiseux 

 say that, of fifty or sixty evenings employed in lunar photo- 

 graphy, only four or five gave really first class results. A com- 

 plete series of negatives, tracing the moon through its phases, 

 has not yet been obtained at Paris, but what has been done has 

 furnished material for experiments in making enlargemens. This 

 part of the work is really as important as that of taking the 

 negatives. From the results, MM. La;*yand Puiseux on- 

 clude that a complete lunar atlas of the dimensions pro- 

 posed by Prof. .S. P. I-angley can be made by means of the 

 great f<7Ki/t'' telescope at the Paris Observatory without the ex- 

 penditure of much time and work. A comparison of the 

 enlargements wi h previous representations of the same regions 

 shows that real progress has been made. Another great step 

 in advance will have been made when all the phases of the 

 moon have been reproduced photographically in pictures so 

 dearly defined as those just obtained. 



FURTHER CONCERN fNG THE NEW IODINE 

 BASES. 



A FURTHER contribution to the chemistry of their recently 

 ■"■ discovered iodonium bases, by Prof. Victor Meyer and Dr. 

 Hartmann, will be found in the present issue of the llcrichle. 

 In their two former communications, an account of which will 

 found in Natire, vol. xllx. pp. 442 and 467, in addition to the 

 free parent base (Cr.U.-.ljl.OH, descriptions were given of the 

 iodide (C,H.,),I. I, the chloride (C„H.-.ijI.CI, the bromide (C,iH.); 

 I.br, and the pyrochromale [(C„ll.',>jl].j Cr^O?. .Several 

 new tails are no« described, most of which crystallise well, and 

 teveral are endowed with properties of a particularly interest- 

 ing character. The similarity to the salts of thallium becomes 

 even more apparent as the reactions of the dciivatives arc 

 elalwrated. I he hydroxide h.as already been shown to be an 

 easily soluble and an alkaline suljstance ; the carbonate is like- 

 wi»e nolublc in water and exhibits an alkaline reaction, and the 

 halogen compounds are similar in colour, solubility, and other 

 physical pro()erties lo the corresponding thallium salts. 



The iiilraU, (C,U,.,),I.NO,, is obtained as a while crystal- 

 line precipilale when a concenlralcd solution of the free base 

 u neutralised with concentrated nitric acid. It is readily 

 loluble in hoi water, and crystallises on cooling in the form of 



NO. I 290. VOL. 50] 



small plates or under particular conditions of concentration in 

 compact spear-like crystals. It melts at I53°-154° to a clear 

 liquid which soon commences to decompose with evolution of 

 gas. When larger quantities are heated they explode with 

 some violence. The nitrate is also produced when the chloride 

 is treated with fuming nitric acid ; upon the addition ol twice 

 as much water and allowing the liquid to cool, well-formed 

 crystals of the nitrate are deposited. 



"Wie acid sulphate, [C^\^.X.\i^O^, is produced in solution 

 when a moderately concentrated solution of the base is feebly 

 acidified with concentrated sulphuric acid. Upon evaporation 

 to small bulk over a water-bath and allowing to cool the salt 

 crystallises in compact aggregates. It is so largely soluble in 

 water that it cannot be recrystallised from that liquid, and in 

 order to free the salt from adhering sulphuric acid the crystals 

 are dissolved in the minimum quantity of alcohol and a quantity 

 of ether added, which precipitates the salt in clear colourless 

 crystals. It reacts acid to litmus, and the crystals melt like 

 those of the nitrate at IS3°-IS4' to a clear liquid which decom- 

 poses at a higher temperature. 



The acdalc, (C.iH.J.J.OCjIIjO, has been obtained under 

 somewhat peculiar circumstances. It was shown in the previous 

 communication that iodobenzene was .ittacked by ctustic soda 

 after agitation of the mixture for some little time, and that the 

 solution, which contained the iodonium base, yielded a while 

 precipitate with acetic acid. This precipitate consists of the 

 impure acetate of the base. If the liquid is filtered immediately 

 after the addition of the acetic acid, when it is quite warm 

 (about 30 ) owing to the heat of the reaction, the clear fihrate 

 deposits crystals of the pure acetate, which melt with decom- 

 position at 120°. 



The perioiiiJe, {C^^.\.\.\^. — This interesting compound^ 

 analogous to the iodine addition products of the alkyl ammonium 

 iodides, is obtained by mixing the iodide of the base with a 

 little alcohol and triturating with an alcoholic solution of iodine. 

 The combination occurs almost instantaneously with production 

 of a brownish-red precipitate, which crystallises from alcohol in 

 magnificent dark red, almost black, and exceptionally lustrous 

 crystals which melt at 138°. 



Doithli siilts. — The chloride forms characteristic double sails 

 with mercuric chloride, gold chloride, and platinic chloride. 

 The mercuric chloride compound, ^C,|H.,)2t.CI. IJg.CL, is 

 obtained as a while precipitate upon the addition of corrosive 

 sublimate solution to a solution of the chloride of the base. It 

 crystallises from water in highly refractive colourless needles 

 which melt at 172° with decomposition. The gold sail, 

 (CoH5)jI.Cl. AuClj, obtained by preci|)italion with gold 

 chloiide, crystallises from hot water in yellow needles melt- 

 ing at 134-135^ with decomposition. The platinochloride, 

 [(CoM,,).jl.Cl]jPtC!4, is obtained by use of chloroplatinic acid 

 as a lleah-coloured precipitate which is very difiicultly soluble 

 even in boiling water, and only crystallises from the solution in 

 microscopic needles. Its melting point is l84"-l85", and de- 

 composition occurs upon fusion. 



Sulphides. — It was a point of considerable interest to ascer- 

 tain whether the similarity of the iodonium bases to thallium 

 would be carried as far as ihe formation of insoluble sulphides. 

 This is indeed found to be the case, and the sulphides are in 

 external appearance mast remarkably similar lo the freshly 

 precipitated sulphides of lead, thallium, and antimony. When 

 a solution of the free base is mixed with ammonium sulphide a 

 bright orange-red precipitate, very similar to antimony sulphide, 

 is produced. If the experiment is carried out with ice-cold 

 solutions and the product is maintained at 0°, the ])recipitatc is 

 quite stable. If it is performed at the ordinary temperature, 

 however, in a very short time the orange precipitate begins to 

 hiss anil seethe, while clouds of vapour arc projected oui of the 

 liquid, and tlic solid precipitate rapidly changes to a mobile oil. 

 Analyses and fractional dislillalions show thai the solid orange 

 precipitate is the Irisulphide of the base 



(C„IIj).jI.S.S.S.I(C„Ho).,, 



and that this substance decomposes at Ihe ordinary temperature 

 into phcnylirisulphide and iodobenzene. 



[(CoH^yjjS, = 2CeHJ -t- (C„H5),S,. 



The normal sulphide, (C„H,,\I . S . I(CoII...)j, has been ob- 

 tained by the action of sodium sulphide, Na^S, which precipi- 

 tates it as a bright yellow precipitate. It rapidly changes at 

 the ordinary lcm|>crature, in the same manner as the Irisulphide, 



