562 



NA TURE 



[April 12, 1894 



shown that there is a falling off of illuminating value when very 

 high yields of gas are obtained. While the best general results 

 may be obtained from carbonising at a fairly high temperature, 

 it is essential that the gaseous products should be enabled to 

 pass freely away and without encountering in the ascension-pipe 

 any absorbent of hydrocarbons such as thick tar. Mr. Hunt 

 has also tested the lime and air process for eliminating sulphur 

 compounds from gas. Daily tests were made of the amount of 

 oxygen in the gas from certain gas-works, and it was almost in- 

 variably found that when the oxygen went up the sulphur com- 

 pounds followed. From this experience it was concluded (i) 

 that oxygen, so far from assisting in the removal of sulphur 

 compounds, was actually prejudicial, at all events, when present 

 in any appreciable quantity ; (2) that it was of use mainly for 

 oxidation of the sulphuretted hydrogen by which economy of 

 lime was effected, and the spent lime, baing chiefly in the form 

 of carbonate, with a la'"ge percentage of free sulphur, was 

 rendered practically inodorous ; (3) that the quantity of 

 oxygen, either pure or as atmospheric air, which might be safely 

 employed, having regard to reduction of sulphur compounds, 

 varied with the CO.j present, i.e. the iessCO.j the more oxygen. 

 It further appeared that unless air could be almost completely 

 excluded, the lime and air process was less suitable for the 

 removal of sulphur compounds than one in which each impurity 

 was separately attacked. 



The final results of an elaborate investigation of the atomic 

 weight of barium are communicated by Prof. Richards, of Har- 

 vard, to the current issue of the Ze tsclirifl Jiir Anorganische 

 Cheniie. The care which has been bestowed upon the per- 

 fection of the analytical processes involved, and upon the pre- 

 paration of absolutely pure materials, together with the really 

 remarkable agreement between the large number of individual 

 values obtained, will doubtless cause this stoechiometrical con- 

 tribution of the Harvard laboratory to take high rank among 

 the more exact atomic weight determinations. A short time 

 ago, Prof. Richards gave an account in the same publication of 

 a series of determinations base 1 upoa the analysis of barium 

 bromide, from whic'i the value I37"43 for the atomic weight 

 of barium was derived. This numier is considerably higher 

 than the usually accepted value, 136 8, derived from the deter- 

 minations of for uer observers. In order to confirm his work. 

 Prof. Richards has since carried out a similar investigation of 

 the chloride of barium, an undertaking much more complicated 

 than that of the bromide, on account of the slight solubility of 

 silver chloride in water. Eleven series of experiments, including 

 altogether forty-nine individual atomic weight estimations, have 

 now been carried out, having for their objeet the deterrriination 

 of the ratio of barium chlo:ide to silver chloiide, of barium 

 chloride to metallic silver, of barium bromide to silver bro nide, 

 and of barium bromide to silver. The atomic weight finally 

 arrived at, if oxygen is valued at 16, is 137*43; the actuil 

 number obtained by use of the chloride was 137 '439, and that 

 derived from the bromide I37"430. Moreover, the highest and 

 lowest individual values obtained among the whole fifty separate 

 estimations were I37'42 and I37"45, an amount of accordance 

 which affords evidence of the extreme preeautions taken, and of 

 the high degree of accuracy attained. If the Stas value for 

 oxygen, 15 '96, is assumed, the atomic weight of barium is 

 i37'io, and if the new value, I5'88, is taken as comparative 

 standard, that of barium becomes I36'4i. It is interesting that 

 the experiments with barium chloride afford a means of in- 

 dependently ascertaining the atomic weight of chlorine, and the 

 number thus obtained is 35 "457, identical with the value ascribed 

 to it by Stas. 



The additions to the Zoological Society's Gardens during the 

 past week include a Brown Capuchin [Cebics fa'.iiellits) from 

 NO. 1276, VOL. 49] 



Guiana, presented by Mrs. Walter Palmer ; two Leopards 

 {Felis pardus, $ ? ) from south-east Africa, presented by Mr. 

 J. Gardiner Muir ; a Vulpine ^hi^SLnger [Phalangisla vulpina, 

 S ) from Australia, presented by Mr. Raymond W. Cooper ; 

 a Crab-eating Opossum {Didelphys canciivora, i ) from St. 

 Vincent, presented by Mr. G. Stephen; a Tawny Owl 

 {Syrnium ahico) British, presented by Mr. G. L. Hunt ; a 

 Greek Tortoise ( Testudo gracd) European, presented by Miss 



Leigh; a Elaps {Elip's, sp. inc.), a Pointed Tree 



Snake {D yiophis acuminata), a Clouded Snake {Lep- 

 tognathtis nebulosis) fro.n Trinidid, W.I., presented by 

 Mr. R. R. Mole; a Tarantula Spider {Mygale, sp. inc.) from 

 Trinidad, W. f., presented by the Rev. S. D. Wright ; a Mala- 

 ha.v Va.vra.kQQi (Palwornis coluiuboides) from India, deposited; 

 four Bahama ducks {D ifila hahain nsis, i i, ? 9) from 

 South America, two Mandarin Ducks {OEx galericjilala, 9 9 ) 

 from China, a Spotied-billed Duck {Anas pcecilorhyncha, 9 ) 

 from India, a Ruddy Sheldrake {Tadonia casarca, 9) Euro- 

 pean, four White-backed Pigeons {Coluviba leu.onola) from. 

 India, purchased ; a Burrhel Wild Sheep {Ovis bnrrhel, i) 

 from the Himalayas, received in exchange. 



OUR ASTRONOMICAL COLUMN. 



Denning's Comet. — Astronomische Nachrichten (No. 3222) 

 contains the following elements, computed by M. Schulhol, foY 

 the comet discovered by Mr. Denning on March 26 : — 



T = 1894 February I3'20392 Paris Mean Time. 



.r = 132 14 31 '6 J 

 ^= 75 51 46-1 MeanEq.1894. 

 i = 6 31 14-0 ) 

 log </ = 0*084720 

 These elements resemble those of comets seen in 1231 and 

 1746. 



Epheincris for Birhn Midnight, 

 1S94. R.A. DecJ. 



h. 111. s. , , 



April 12 ... 10 47 37 ... -f 23 14*6 



13 ••• 50 7 ••• 22 45-5 



14 ••• 52 33 ••• 22 16-9 



15 ... 54 57 ... 21 48-6 



16 ... 57 18 ... 21 207 



17 ... 10 59 36 ... 20 53-3 



18 ... II I 51 ... 20 263 



The Natal Observatory. — The superintendent of the 

 Natal Observatory has issued his report for the fiscal year 

 1892-93. The principil series of obstrvations made du.ing 

 this period was the comparison of the declinations de- 

 duced from observations made at the observatories in the 

 northern and southern hemispheres, by a co uparison by Tal- 

 cott's method, of the zenith distances of northern stars and 

 southern circumpolar stars. The opposition of Mars in 1892 

 threw a deal of extra work upon the observatory. Thirty- 

 eight sets of meridian observations of the planet were obtained, 

 and sixty-two sets of ob^ervalions taken on opposite sides of the 

 meridian towards the eastern or western horizon. The whole 

 scries of these observations have been completely reduced and 

 tabulated, ready for the final discussion for obtaining the value 

 of the solar parallax and distance of the sun as soon as the 

 meridian observations of the planet, made in the northern, 

 hemisphere, have been leceived. The observations made at 

 the Cape observatory supplement th )se obtained at Natal, and 

 the two sets combine to fjrm a complete set extending over the 

 whole period of opposition. This year will bring another 

 favourable opportunity for determining the solar distance from 

 observations for the opposition of Mars, and the observatory 

 will be far better equipped for observing this opposition than, 

 was the case during the last one, and if the weather be favour- 

 aide a very satisfactory series of observations shuuld be obtained, 

 during this, the last, opportunity until the year 191 1. 



A New Comet. — The following announcement has been sent 

 out by the Astronomer Royal :— '' Bright comet Holmes, April^ 

 9. Right Ascension, I7h. 58m. ; North Decimation, li" io'.'* 



