2 8o 



NATURE 



[July 2 1, 1887 



the splendid new Broadbill, described by Mr. Bowdler Sharpe as 

 Calyptomena wliitehcadi at the last meeting of the Zoological 

 Society, there are nearly twenty other new species, including some 

 very remarkable forms of Arachnothera, Chloropsis, Cryptolopha, 

 and an apparently new genus of Campophagida:. These will all 

 be described in the October Ibis, by Mr. Sharpe. 



Dealing with the question as to the influence of small birds 

 in assisting the extinction of Aporia cratcegi, Mr. A. G. Butler, 

 in the current number of the Entomologist' s Monthly Magazine, 

 says he has collected in Kent for at least thirty years, and 

 during the whole of that time he has never seen any bird but a 

 sparrow attempt to catch a butterfly. Nor has he ever known 

 a small bird to eat a large caterpillar if it could get one that 

 could be more easily swallowed. " Of our indigenous species," 

 he says, "the robin and the great tit certainly select green 

 caterpillars in preference to others, and, when feeding their 

 young, I have watched both these birds with their mouths full 

 of the green pests of the gooseberry and currant. From obser- 

 vation of cage-birds I. should say that the finches certainly show 

 a similar preference, the green larvas of Mamestra being chosen 

 before the brown, though all are greedily devoured. " 



A BOLD attempt has recently been made to penetrate the 

 darkness surrounding the subject of the inter-molecular arrange- 

 ment of atoms, and to raise our ideas of the constitution of 

 chemical compounds beyond what is expressed by the orthodox 

 chemical formulae. It has long been felt that the chemical 

 formula of a substance as expressed in one plane on paper, 

 although invaluable as far as it goes, must of necessity be a very 

 misleading one, inasmuch as it in no way indicates the probable 

 position of the various atoms in space. This insufficiency has 

 been especially felt in the case of substances like tartaric acid, 

 where we have several distinct isomers acting quite differently 

 upon polarized light, and frequently forming right- and left- 

 handed hemihedral crystals, although expressed by the same 

 constitutional formula. Since the year 1874, when Van t' Hoff" 

 and Le Bel published their celebrated theory of the "asym- 

 metric carbon atom," the idea has been gaining ground that this 

 kind of isomerism must be due to different spacial arrange- 

 ment, and Van t' Hoff gave impetus to the theory by showing 

 that the existence of four isomeric tartaric acids could be 

 explained by imagining the four radical-groups to be variously 

 placed at the four corners of a regular tetrahedron, of which 

 an asymmetric carbon atom occupied the centre. During the 

 last few days a comprehensive paper has been issued by Prof. J. 

 Wislicenus, on the "Spacial Arrangement of Atoms in Organic 

 Molecules, and its Determination in Geometrically Isomeric 

 Compounds," further expanding Dr. Van t' Hoff's somev/hat 

 sceptically received ideas, proceeding to build up the spacial 

 constitution of a large number of unsaturated organic com- 

 pounds, and giving nearly 200 figures, of which the regular 

 tetrahedron representing CH4 is the base. Prof. Wislicenus 

 practically demonstrates that the cases of so-called abnormal 

 isomerism may be completely cleared up, and that existing 

 experimental data are generally sufficient to enable spacial 

 constitution to be determined. This remarkable paper will 

 doubtless give rise to much discussion, and appears likely to 

 lead to results which will mark a genuine advance in chemical 

 philosophy. 



In a paper to the Berlin Academy, Herr Liebreich lately 

 called attention to what he calls the "dead space" in chemical 

 reactions : a space, i.e., in which the reaction going on in other 

 parts of a uniformly mixed liquid does not occur, or occurs late, 

 or in less degree. It may be very well observed, e.g., in decom- 

 position of chloral hydrate by sodium carbonate (yielding chloro- 

 form) in a test-tube. A layer of i to 3 millimetres' depth under 

 the surface remains clear, and separate by a convex surface from 



the " reaction space," where the solution is turbid from droplets 

 of chloroform. Even after twenty-four hours' rest of the mixture 

 the two spaces can be distinguished ; and after mixture by 

 shaking again, the surface of separation is reproduced in a few 

 minutes. In horizontal capillary tubes the dead space appears 

 on both sides, and, if the liquid columns introduced are short, 

 no reaction occurs, as the dead spaces unite. Thus is explained 

 the absence of reaction in the case of ^^liquid absorbed in 

 vessels by glass pearls ; there is dead space everywhere. Contact 

 with air seems essential to the formation of dead space. Thus 

 if a vessel closed at one end, and holding the liquids above 

 named, be inverted, so that there is no air space above the 

 mixture, the reaction occurs uniformly throughout. But if the 

 upper end be closed with a fine animal membrane, the dead 

 space appears as in the former case ; and if the lower end be also 

 closed with fine membrane the dead space appears there too. 

 Herr Liebreich is studying the phenomena further. 



Some instructive experiments on atmospheric electricity are 

 described by Herr Nahrwold in Wiedemann's Annalen, No. 

 7 ; one being a suitable lecture experiment, showing the 

 action of electricity from points on finely divided matter in the 

 air. He thinks it established that such a stream of electricity 

 does not electrify the air itself statically (indeed that air and 

 other gases probably cannot be statically electrified), but only 

 dust particles in it. Further, a glowing platinum wire sends out 

 particles which diffuse in air that has been electrically freed from 

 dust, making a fresh charge possible. Here, too, the electricity 

 streaming from such wire does not statically electrify the air, 

 but the charges which are observed as atmospheric electricity 

 belong to fine non-gaseous particles given out by the wire, or 

 already present in the air. An experiment is also adduced to 

 show that at ordinary temperature negative electricity of high 

 potential streams more readily from solid conductors into atmo- 

 spheric air than positive. 



Electricity in the house has some important bearings on 

 hygiene. One of these M. Sambuc has recently called attention 

 to {Revue d^ Hygiene), in the liberation of hydrogen, where strong 

 batteries are used in which zinc is dissolved by sulphuric acid. 

 Besides the danger of shattering of the vessels, the hydrogen 

 spreading in the air may form an explosive mixture ; and it may 

 have a cooling effect through its great conductivity for heat. It 

 also deadens the voice and alters its timbre. Further, if, as may 

 be, the hydrogen is charged with sulphur, arsenic, phosphorus, 

 carbon, or silicium, there are other and greater dangers. A 

 chemist is known to have died from breathing a little arsenietted 

 hydrogen. These facts are not cited against the use of the 

 electric light, but to induce proper care in those who use it. 



The twenty-sixth volume ot the magnetical and meteoro- 

 logical observations made at the Government Observatory, 

 Bombay, containing the results for the year 1885, has just been 

 published, under the superintendence of Mr. C. Chambers, 

 F. R.S. Continuous registrations are obtained by means of 

 self-recording instruments (although not published), and eye- 

 observations are taken five times a day, as a check upon the 

 automatic records. The following is a summary of the principal 

 meteorological results : — The mean barometric pressure for the 

 year was 29 "826 inches, the difference of the greatest and least 

 mean daily pressure amounting to o 581 inch. The mean 

 annual temperature was 79° "2, and the greatest daily mean 

 was 87°'3 on June 6. The absolute maximum was 9I°'8 

 in June (being slightly lower than the maximum in the 

 shade at Greenwich on the 4th inst.), and the minimum 

 62°'i in February, giving a range of 2<)°"j. The rainfall mea- 

 sured by a gauge 4 J feet above the ground was 67*91 inches; 

 rain fell on 113 days, and mostly occurred between June and 

 September; the greatest fall was iO'29 inches on August 15. 



