June 2, 1887] 



NATURE 



119 



- same phenomena have been observed with sulphur, showing 

 I parallelism between the states of these two substances under 

 he physical or chemical conditions determining those states. — 

 'tiethod for determining the specific activity of the intra- 

 nuscular exchanges, or of the coefficients of the nutritive 

 md respiratory activity of the muscles in repose and 

 it work, by M. A. Chauveau. The author here de- 

 icribes the technical processes adopted in carrying out 

 ihe experiments, the results of which have already been commu- 

 nicated. — The earthquake of February 23, by M. Albert Offret. 

 A summary description is given of all the seismic apparatus 

 affecte<l by the disturbance. With very few exceptions all those 

 Iwithin the whole area of the earthquake yielded some indica- 

 Itions, the interpretation of which is reserved for future consider- 

 n. — On the history of the Phylloxera of the vine, by M. P. 



'■ afitte. The existence is denied of the two distinct species 



cimined and described in a recent communication by M. 



Donnadieu under the names of /'. 7'aslatrix and P. pemphigoides. 

 — On Cremonian quadratic groups, by M. Autonne. Having in 

 a previous paper considered the properties of an isolated quadra- 

 tic Cremonian, the author here explains how such substitutions 



Mne together to form Cremonian quadratic groups. — On a 

 •IS of regulating and gauging the dischatge of open canals, 

 M. II. I'arenty. A theoretic solution is given of various 

 lems connected with the discharge of open canals, with the 



\v of determining automatically the quantity of water supplied 

 ia a given period, the total discharge at a given moment, the 

 proportional discharge from one artery through several diverg- 

 rills, and similar questions. — On a general law for the 

 iir-tensions of dissolvents, by M. F. M. Raoult. By the 

 .^.-.carches here described the author arrives at the general law 

 that one molecule of a non-saline fixed substance by its solution 

 in 100 molecules of any volatile liquid diminishes the vapour- 

 tension of that liquid by a nearly constant fraction of about 

 o 0105 of its value. The law is completely analogous to 

 that announced by the author in 1882 regarding the lower- 

 ing of the freezing-point of dissolvents. — On the compressi- 

 bility of cyanogen compared with its refraction, by MM. J. 

 Chappuis and Ch. Riviere. In order to com.plete their studies 

 on the refraction of cyanogen and the comparison of the 

 measured indices with the corresponding specific weights, the 

 authors have undertaken the present researches on the com- 

 pressibility of this gas, on which only a few imperfect data were 

 incidentally supplied by Kegnault. — On the polarization of 

 copper by the extension of its surface in contact with a con- 

 ducting fluid, by M. Krouchkoll. Lippmann having determined 

 the polarization of mercury by increasing its surface in contact 

 with a conducting fluid, the author has made a series of studies 

 to ascertain whether the same phenomenon applies to the solid 

 metals and to certain organic expansive substances, such as 

 gelatine and coagulated albumen. The present note is confined 

 to the study of copper in contact with distilled water, and with 

 water containing 2 per cent, of ordinary sulphate of soda. The 

 results of experiments with other ductile metals are reserved for 

 a future communication. — Note on a stroke of lightning, com- 

 municated by the Minister of P sts and Telegraphs. A series 

 of phenomena are described, which occurred during a thunder- 

 storm at xMortree (Orne), on April 24. Fragments of incan- 

 descent stones fell in large quantities, some about the size of a 

 walnut, of a grayish-white colour, which crumbled between the 

 fingers, emitting a distinct smell of sulphur. The others, which 

 were of smaller size, looked exactly like coke. Some plaster 

 was also detached from the front of a neighbouring house and 

 transferred to the window of a house on the opposite side of the 

 street. During another storm, on May 13, great havoc was 

 done by the electric fluid at Eza (Maritime Alps), where it made 

 a broad and deep fissure 20 metres long in the side of the moun- 

 tain, detaching a solid mass measuring several hundred cubic 

 metres. 



Berlin'. 



Meteorological Society, May 3. — Professor von Bezold, 

 President, in the chair. — Dr. Schultz spoke on the contrast 

 between the popular names given to meteorological phenomena 

 and their real nature as determined by means of instruments. 

 Thus, for instance, the sirocco wind in Italy is spoken of as 

 " heavy," whereas the barometer indicates a diminished pressure. 

 Summers are spoken of as wet and dry, according as they are 

 accompanied by much or little rain, without taking into account 

 the usually opposed indications of the psychrometers ; similarly our 

 sensatioas of heat and cold are often directly opposed to the indi- 



cations of the thermometer. The speaker further brought forwar* 

 meteorological observations which he had made in Rome ancJ 

 the Riviera, and which showed occasionally, among other things, 

 the anomaly that the temperature in the shade was higher than 

 in the sun, especially when the thermometer in the sun was 

 exposed to a str ng wind. In the course of the elaborate dis- 

 cussion which foil )wed upon the above communication, the 

 President explained the larger part of the anomalies which had 

 been described, and laid stress upon the diff'erence between 

 physical meteorology and the influence of temperature and 

 moisture on the living organism. Alterations of atmospheric 

 pressure have no eflfect on healthy human beings, although they 

 must on sickly people, inasmuch as a diminution of pressure must 

 lead, as a consequence, to an increased evolution of gases from 

 the soil, and their accompanying miasmas. The idea of sultri- 

 ness has not as yet been defined from a physical point of view ; 

 probably in connexion with this it should be borne in mind that 

 the air is occasionally supersaturated with aqueous vapour, as 

 shown in the experiments of Robert von Helmholtz, and that in 

 this case a commencing condensation may be accompanied by a 

 real evolution of heat. Prof. Schwalbe explained the conditions 

 as to dampness, which had been brought forward by the speaker. 

 Dr. Assmann explained, in connexion with this communication, 

 an experiment which he had made with a view to determining 

 the real temperature of the air, and which ha:l given good 

 results. The bulb of the thermometer was surrounded by a 

 very perfectly reflecting cylinder of polished silver open below 

 and closed above, but communicating by a lateral tube with an 

 aspirator : by this method the air was drawn past the bulb of 

 the thermometer in a constant current, while at the same time 

 all external heat is prevented from reaching the thermometer by 

 means of the reflecting cylinder. This thermometer indicates 

 exactly similar temperature, both in the sun and in the shade. 

 In conclusion. Dr. Sklarek mentioned experiments on the radia- 

 tion of heat fro:n the human body, which showed, in opposition 

 to the laws of radiation from non-living bodies, that the human 

 body radiates more heat from exposed parts of its surface, which 

 are usually covered with clothes, when the difference of tem- 

 perature between the skin and the surroundings is less than when^ 

 it is greater. This anomalous behaviour may be explained by^ 

 the supposition that, when the difference of teaiperature (between 

 the skin and the surroundings) increases, the physical properties 

 of the skin and its radiating powers undergo some change. 



Physical Society, May 6. — Prof. Du Bois-Reymond, 

 President, in the chair. — Dr. Kbnig spoke on Newton's law of 

 the mixing of colours (see report on the meeting of the Physio- 

 logical Society of April 29). In connexion with this, Prof, von 

 Bezold communicated the fact that he had observed during his 

 experiments on the mixing of colours, so-called neutral points in 

 the spectrum, not merely when working with dichromatic, but also 

 with normal trichromatic eyes. When, for instance, the intensity 

 of a spectrum is greatly diminished (this may be most simply 

 brought about by inserting a diaphragm with a small opening 

 into the collimator) and a direct-vision spectroscope is used, then 

 only three colours are seen at all — namely, red, green, and violet : 

 between red and green and between green and violet there are 

 neutral points. If the intensity of the light is still further dimin- 

 ished, then the neutral points undergo a change of position ; 

 the red extends to beyond the line D, and the neutral point at 

 the line F moves in the opposite direction. This last fact was 

 no longer recollected with any great exactness by the speaker, 

 inasmuch as the experiments had been made many years ago, 

 but the moving of the neutral point near D towards the green he 

 described as existing without doubt. This appearance of the 

 spectrum of light of small intensity was regarded by Prof, von 

 Bezold as a proof of the truth of the Young-Helmholtz theory of 

 colours. A second observation had reference to the mixing of 

 colours with white. According to the Newton-Grassmann theory 

 of the mixing of colours, every spectral colour, when mixed with 

 white, must maintain its "tone "in the sense of the word as 

 used by the French ; this observation has, however, shown that 

 not only red, but also violet, if mixed with white, takes on a 

 purplish tone. — Prof, von Bezold made a further communicatinn 

 to the effect that Dr. Sprung had observed a series of notches 

 on the curve of his barograph between six and seven o'clock on 

 the morning of May 3, without any thunderstorm having taken 

 place : the cur\'es of a Bourdon aneroid barometer, and of the 

 barograph at the Landwirthschaftliche Ilochschule, showed the 

 same irregularities. This irregularity of the curve of atmospheric 

 pressure repeated itself on the morning of May 4 between 3 and 4 



