September 7, 1893] 



NATURE 



447 



Whether this be indeed ihe case or not, can of course only be 

 tested by actual working during a sufficiently long period of 

 time. The method as described by Herr Kassner is briefly as 

 follows. Calcium plumbate in the form of spongy porous 

 pieces is first exposed to the action of moist furnace gases, 

 which have been previously well washed, at a temperature not 

 exceeding loo° C. The calcium plumbate under these conditions 

 rapidly absorbs the carbon dioxide contained in the furnace 

 gases, becoming thereby decomposed with formation of calcium 

 carbonate and free peroxide of lead ; that is to say, the acid 

 properties of carbon dioxide are superior to those of lead per- 

 oxide, and so the former expels the latter from its state of com- 

 bination with lime. This decomposition is unaccon-.panied by 

 any change of form, the spongy pieces of material remaining 

 precisely the same in shape and texture, like the 

 pseudomorphs of mineralogy. The product of this first 

 operation, when fully saturated with carbon dioxide, is 

 transferred to a strongly constructed retort heated to redness, 

 when oxygen is rapidly disengaged. The evolution of the oxygen 

 is facilitated by le.iding superheated steam through the 

 retort. When the peroxide of lead has yielded up most of its 

 available oxygen, carbon dioxide commences to be evolved, and 

 subsequently the issuing gas is pure carbon dioxide, which i* 

 collected separately. The carbon dioxide evolved during the 

 intermediate phase is removed from the oxygen by allowing the 

 gases to pass over a further quantity of calcium plumbate, which 

 absorbs it entirely, allowing only pure oxygen to escape. The 

 last phase in which pure carbon di )xide is evolved is carried on 

 to completion, after which the residue is readily reconverted 

 into calcium plumbate, for use in a subsequent operation, by 

 driving a current of air through the retort. 



In addition to Kassner's process, above described, another has 

 been patented by Peitz, in which instead of furnace gases pure 

 carbon dioxide is employed. Le Chatelier has also recently 

 published a paper upon the subject, in which, however, he does 

 not appear to have been acquainted with the whole of Kassner's 

 publications. Le Chatelier concludes that calcium plumbate 

 gives up its available oxygen by merely heating it to a tem- 

 perature of 200° higher than that employed in Brin's process in 

 the case of barium peroxide, and that the heated residue absorbs 

 oxygen from the air again much more rapidly than the 

 latter substance. Kassner has already previously stated 

 these facts, and now asserts that his indirect method 

 possesses two great advantages over the direct one proposed by 

 Le Chatelier, namely, that a lower temperature is required, and 

 a consequent saving of fuel and wear of retorts effected, and that 

 pure caibon dioxide is obtained as a very valuable byproduct. 

 The very fact, however, that there are so many possible modes 

 of treating calcium plumbate, goes far to indicate that there is at 

 least some ground for the proposal to employ it as a substitute 

 for barium peroxide. 



Notes from the Marine Biological Station, Plymouth. — La?t 



I week's captures include the Polychrete Eunice Harassii, the 



I Decapod Piriniela dcntictilata, and the Opisthobranchs Henmva 



j bifida, Emblelonia pulchra, Antiopa hyalina, and Tliecacera 



feunigera. The floating fauna retains its recent character, 



Miiggiiva atlan'.ica, Evadne Nordmanni and Ophiuroid Plutei 



j having been especially plentiful. The larvze of I'olygordius, 



I Magflona, Nerine, Phoronis and of several Crustacea Djcapoda 



have been taken ; and Miiller's Polycla:! larvsc have made theit 



i first appearance, although as yet only in small numbers. 



"i'idium has been scarce, but other Nemertine larva; fairl) 



ruerous. Doliolum 'Pritonis, first recorded a fortnight since, 



, has been represented by several specimens in almost every haul 



I of the tow-nets. The following animals are now breeding :— 



The Pulyclads Euryhpla cornula and Slyloslomuin variahiU, 



NO. 1245, VOL. 48] 



the Polychtete Ophryotroeha(^m\^e aquarium), and the parasitic 

 Isopod PUurocrypla Galathea. The Gymnoblastic Hydroids 

 Perigonimus repens and Podocoryne carnea are giving off 

 medusas. 



The additions to the Zoological Society's Gardens during 

 the past week include a Malayan Bear {Ursus , !iia!ayamis,<)) 

 from Malacca, presented by Mr. E. Sydney Wooduvis": ; a 

 Feldegg's Falcon {Fako JeU'ggi) from Morocco, and two White- 

 shafted Francolins (Fraiicalinus leucoueptis, 9 9) from North- 

 east Africa, pre ented by Lord Lilford, F.Z.S. ; two Common 

 Buzzards {Buleo vulgaris) from Europe, presented by Mrs. 

 Henry Goodbun ; a Ring Ouzel (Turdus torquatus, i) from 

 British Isles, presented by Mr. Samuel Radcliflfe ; two Sul- 

 phury Tyrants (Pilaiigus sulpltuialus) from South America ; a 

 Chukar Partridge (CaccaHs chukar) from North-west India, 

 and a Bamboo Partridge {Batnlnisicola ihoracicd) from Noith 

 China, presented by Mr. H. H. Sharland ; a Land Rail {Crex 

 firaUnsis) from British Isles, presented by Mr. W. Stanley ; an 

 Arabian Baboon {Cynocephalu! hamadryas, 9 ) from Arabia, 

 and a Hairy Tapir ( Tapirus roulini) from Columbia, deposited ; 

 two Sun Bitterns {Eurnpyga helias, i 9 ) from South America, 

 four Patagonian Cavies {Dolichotis patachonica, S i 9 "i ) bred 

 in France ; an Elliot's Pheasant (P/iasianus ellioti, i ) from 

 China, three Chilian Teal {Querqiiedula creecoides) from Ant- 

 arctic America, and two Viscachas {^Lagosloi/ius tricJiodactylus, 

 i 9 ) from Buenos Ayres, purchased. 



OUR ASTRONOMICAL COLUMN. 



The Transit of Venus of 1874. — The reports and draw- 

 ings of the New SouthWales observersof this transit have already 

 been published by the Royal Astronomical Society, so that the 

 volume which we have received, containing the observations, 

 published by authority of her Majesty's Government in New 

 South Wales, cannot be looked upon as containing much that 

 is new. Mr. Russell, the Government astronon.er, under whose 

 direction this work has been compiled, seems to have taken 

 great pains in bringing it out, for besides a long introduction 

 summing up the results, and separate accounts of each of the 

 reports, the book is illustrated with several photographs and 

 drawings, a froniispiece containing photographs of the observers, 

 and is bound in a very elaborate cover. The value of this pub- 

 lication lies in the fact that each observer's record is published 

 in full, and is accompanied by numerous printed diagrams, which 

 help to make more clear the various descriptions of phenomena 

 that were noticed. Passing over the observations of contacts, 

 we may refer to some of the physical phenomena which seemed 

 to have claimed attention. With regard, first, to the black drop, 

 it seems that only those who were using telescopes of small aper- 

 ture, i^ to 2 inch, and low power eyepieces, saw it, while on the 

 photographs not the slightest trace of it could be seen. The 

 evidence, as far as the New South Wales ob.-ervations go, 

 shows, as Mr. Russell states, that " the black drop does not 

 seem to be due to the atmospheric conditions, but rather to the 

 imperfections of telescopes of small apertures and low power." 

 The curious " faint tremulous shaking," as noticed at lire times 

 of the planet's ingress and egress, are put down to the temporary 

 unsteadiness in the atmosphere. Three important phenomena 

 which seem to have been generally observed were the rings of 

 light and the halo seen surrounding the planet, and the ring of 

 light round that part of the planet projected on the sky. Mr. 

 Russell is of opinion that the atmosphere of Venus probably 

 does not extend far enough to produce the observed phenomena 

 of the halo, but, per'iaps, a part of it could be attributed to the 

 haze in the atmosphere caused by the forming of moisture at that 

 time. The bright ring, described as very brilliant, was 

 found to affect the chemicals more than the sun itself, as shown 

 on the photographic plates ; its brilliancy accounts for it being 

 only seen on the limb not projected on the sun, and it is sug- 

 ijested that perhaps under favourable conditions this halo might 

 be seen when the planet is lost in the sunlight. 



The Planet Venus. — Some time ago we noticed in these 

 columns a short monograph on the "Planet Jupiter and his 



