6o6 



NA TURE 



[October 22, 1903 



knowledge of the physiology of the cell, and the sections 

 devoted to this subject have been carefully revised for the 

 new edition now available. 



With the advance of scientific education in this country 

 scientific instrument makers are continuously bringing out 

 improved forms of apparatus. We have recently received 

 from Messrs. Brewster, Smith and Co. an improved form 

 of a " double surface condenser." This is one of the most 

 compact and efficient condensers which has come before our 

 notice. We have tested it for condensing such volatile sub- 

 stances as ether, carbon disulphide, and acetone, and have 

 found that even with rapid distillation the condensation is 

 very complete. Generally speaking, in order to condense 

 these substances satisfactorily, it is necessary to employ a 

 very long condenser ; of course, this means using a great 

 amount of bench space. As the new condensers are used in 

 a perpendicular position, the saving in space is very great. 



Messrs. Brewster, Smith and Co. have also sent us a 

 " new Bunsen burner and midget furnace." It can hardly 

 be said that the Bunsen burner is new, but the combination 

 of furnace and burner is very convenient. The makers 

 claim that marble is reduced to quicklime in ten minutes. 

 This will, of course, to a large extent depend upon the 

 quantity of marble taken in the first place — we find that 

 from one to one and a half grms. is readily reduced to 

 quicklime in twenty minutes. These little furnaces are not 

 only useful for reducing calcium carbonate to lime, but 

 also work very well in fusion experiments. 



The measurements by Biltz and Preuner of the density 

 under different pressures of sulphur-vapour at 448° have 

 usually been regarded as indicating that the vapour is com- 

 posed of Sg and S^ molecules, and that the molecule S, does 

 not exist. The application to the isothermal of the law of 

 mass-action, discussed by Preuner in the Zeitschrift fiir 

 physikalische Chemie, shows that this theory is inadequate, 

 and that the vapour must contain molecules intermediate 

 in complexity between S^ and S^. The proportions by 

 volume of the constituents are calculated to be, under 

 104 mm. pressure, 292 per cent. S^, 19.0 S^, 19-7 S^ and 

 32-1 Sj, and under 453.4 mm. pressure, 778 Sg, 15-1 S,, 

 47 S^ and 2-4 Sj. 



SiNXE Beckmann showed that iodine in all solvents has 

 the molecular weight I,, it has been suspected that the 

 formation of violet or brown solutions is dependent upon 

 the extent to which the iodine combines with the solvent. 

 By means of comparative experiments on the solubility of 

 iodine and the periodide N(CH3).jI„, described in a recent 

 number of the Zeitschrift fiir physikalische Chemie, Strom- 

 holm has obtained evidence that iodine actually combines 

 with water, alcohol and ether, forming brown solutions, 

 whilst the violet solutions in carbon disulphide, benzene and 

 chloroform contain uncombined iodine ; similarly it is shown 

 that iodine has little tendency to combine with methyl iodide 

 when dissolved in ether, or with sulphur dissolved in carbon 

 disulphide. 



The additions to the Zoological Society's Gardens during 

 the past week include a Black Lemur and young {Lemur 

 macaco) from Madagascar, a Brazilian Hare {Lepus 

 brasiliensis) from Brazil, eight Hamsters (Cricetus frumen- 

 tarius), a Snow Bunting {Plectrophenax nivalis), four 

 Lacertine Snakes (Coelopeltis monspessulana), two Dark- 

 green Snakes (Zamenis gemonensis), a Vivacious Snake 

 (Tarbophis fallax), European ; three Cuban Snakes (Lio- 

 cephalus andreae) from Cuba, two Garter Snakes (Tropi- 

 donotus ordinatus), a Prickly Trionyx {Trionyx spinifer) 



NO. 1773, VOL. 68] 



from North America, a South Albemarle Tortoise {Testudo 

 vicina) from Galapagos, a Wrinkled Terrapin {Chrysemys 

 scripta rugosa) from the West Indies, two Amboina Box 

 Tortoises {Cyclemys amboinensis) from the East Indies, two 

 Annulated Terrapins (Nicoria annulata) from Western South 

 America, a Horned Lizard {Phrynosoma cornutum) from 

 Mexico, a Carinated Lizard {Liocephalus carinatus) from 

 the West Indies, two Hispid Lizards {Agama hispida) from 

 South Africa, two Scoresby's Gulls (Leucophoeus scorebii) 

 from Chili, deposited ; a Tasmanian Devil (Sarcophilus 

 ursiniis) from Tasmania, received in exchange. 



OUR ASTRONOMICAL COLUMN. 



Search-Ephemeris for Comet i8g6 v. — A further portion 

 of the search-ephemeris for Giacobini's comet (1896 v.), 

 published by Herr M. Ebell in No. 3898 of the Astrono- 

 mische Nac'hrichten, is given below. As will be seen from 

 this ephemeris the computed brightness is now decreasing, 

 although the comet should be in a favourable position for 

 observers in the northern hemisphere : — 



paper contributed to No. 26, vol. iii., of the British Optical 

 Journal, Sir Howard Grubb describes a novel feature in 

 geodetical instruments which replaces the half-silvered, 

 half-plain piece of glass generally used in such instruments 

 by a piece of glass having a thin film of lead sulphide de- 

 posited on its surface. This film both reflects and transmits 

 the incident light, and by varying its thickness the propor- 

 tion of transmitted to reflected light may be varied. 



Taking the case of the prismatic compass as an illustra- 

 tion, the rays of light from the object the position of which 

 is to be determined are transmitted by the film of lead 

 sulphide, and, at the same time, the previously collimated 

 ravs from the compass card are reflected by it. As both 

 sets of rays are parallel, and the reflection of the card is 

 superimposed on the image of the distant object, parallax 

 does not interfere in the observations, and the position of 

 the eye may therefore be changed without introducing any 

 error into the reading, thereby rendering it possible to make 

 the readings much more quickly and accurately than when 

 using the older forms of reflecting-transmitting apparatus. 



The Path of Comet 1894 I. (Denning). — No. 2 of the 

 Mitteilungen of the Heidelberg Observatory contains a 

 paper by Dr. P. Gast on the observations and calculations 

 of the path of comet 1894 I. 



The first part is devoted to a series of new observations 

 of the comparison stars made during the year 1902, and is 

 followed by a collection of the observations of the comet 

 which were made at various observatories, then the various 

 observations are compared among themselves and with the 

 computed elements of this comet. The paper concludes 

 with a discussion of the perturbations produced by Jupiter 

 and the finally deduced elements. In a supplementary list 

 the positions of eighty-eight reference stars for the year 

 1900 are given, the value of the precessional constant, the 

 secular variation, and the star's proper motion being stated 

 in each case. 



Observations of Mars. — In the October number of the 

 Bulletin de la Soci^t^ astronomique de France, MM. 

 Flammarion and Benoit publish the results of their observ- 

 ations of Mars made at Juvisy during the last opposition 

 of that planet. Although the planet was nearer to the 

 earth during this opposition than it was in 1901, the un- 

 favourable meteorological conditions prevented the making 



