APRIL 1, 1897 | 
NATURE 
527 
formation of carbon dioxide takes place, and at continued higher 
temperatures the amount, which is at first large, does not remain 
so but steadily falls off, indicating the decomposition of a definite 
limited quantity of some substance. Secondly, the large amount 
of carbon dioxide produced in the first few hours after wetting 
coarsely-ground dry seeds. This cannot be attributed to the 
action of micro-organisms, and is hindered by the action of 
chloroform and other poisons. Thirdly, the varying production 
of carbon dioxide by the action of volatile poisons and of fatal 
temperatures on living leaves. Finally, the post-mortem pro- 
duction of carbon dioxide brought about by subjecting recently- 
killed leaves to the action of a temperature of 100° C. This 
amount was shown to vary with the method of killing adopted, 
and evidence was forthcoming to show that in this, as in 
the other cases, those substances which easily oxidise with 
liberation of carbon dioxide are in some way to be associated 
with normal respiratory processes. —On the leaves of Bennetiites, 
by A. C. Seward. In this paper the author described some 
specimens of /Vzlamsonia gigas Carr. and Zamites gigas L. 
and H., from the Jurassic rocks of the Yorkshire coast, and now 
in the Natural History Museum, Paris. In recent years it has 
been customary to discredit or entirely deny the correctness of 
the earlier views as to the generic identity of Zamztes gigas and 
Welléamsonta. A recent examination of the specimens in the 
Paris Museum convinced the author that /’¢//zamsonza is the 
inflorescence of Zamztes gigas. The conclusions now arrived 
at enable a Bennettitean inflorescence to be connected with a 
definite form of fronds. 
PARIS. 
Academy of Sciences, March 22.—M. A. Chatin in the 
chair.—The President announced tc the Academy the loss it had 
sustained by the death of M. Antoine d’Abbadie, Member of 
the Section of Geography and Navigation.—On the Phanerogams 
without seeds, forming the division of the Inseminez, by M. Ph. 
van Tieghem. An outline of a new classification of the Phanero- 
gams.—On the mechanical work performed by muscles, by M. 
A. Chauveau. An extension of a preceding paper, giving details 
of experiments with isolated fresh muscles from frogs. The 
muscle was weighted with different loads, stimulated witha rapidly 
alternating current, and the heating effects produced measured 
with a thermo-electric couple.—On an angular multi-divider, by 
M. Guillerminet.—On an electric commutator capable of being 
adjusted from a distance, by M. C. Gros.—On the perihelia of 
the planets, by M. Delauney.—On autoradioscopy, by M. 
Foveau de Courmelle.—On the geometry of the triangle, by M. 
Labergére. —On the successive differentials of a function of 
several variables, by M. Moutard.—On the determination of the 
group of transformations of a linear differential equation, by M. 
F. Marotte.—On the latent heats of evaporation and the law of 
Van der Waals, by M. Georges Darzens. The author has shown 
in a preceding note that the Van der Waals equation Ma/T.= 
7 (T/T) (where M is the molecular weight, A the latent heat of 
vaporisation at the absolute temperature T, and T, the absolute 
critical temperature) may be put in the form MA/T=F (T/T,), 
where the first term is independent of the critical temperature. 
The exactness of the law of corresponding states may be in- 
directly verified by plotting on squared paper the values of Ma/T 
as ordinates against T/T, as abscissce, and seeing if the resulting 
points, either for one substance at different temperatures, or for 
different substances, lie on a continuous curve. It was found 
necessary to divide the substances taken into groups in order to 
get the points to lie on a curve. Thus benzene, chloroform, 
carbon tetrachloride, sulphur dioxide, nitrous oxide, and carbon 
dioxide form one group ; water, acetone, and ether form another. 
—Stereoscopy of precision applied to radiography, by MM. T. 
Marie and H. Ribaut. The theoretical development of the 
subject is first given, and then measurements from a series of 
experiments bearing out the results of the preceding analysis. — 
The action of nickel upon ethylene, by MM. Paul Sabatier and 
J. B. Senderens. The nickel used in these experiments was 
reduced by hydrogen from the oxide at as low a temperature as 
possible; as it was found that this metal gave the most rapid 
reaction. The property of acting upon ethylene, however, is 
not lost even if the nickel oxide is reduced at a red heat. The 
reaction between the nickel and the ethylene takes place at 
about 300°; and the main reaction appears to be according to 
the equation C,H, = C + CH,, although hydrogen is also pro- 
duced by what is apparently a secondary reaction, the amount 
NO. 1431, VOL. 55 | 
increasing with the temperature of the nickel. No such pheno- 
menon occurs when the nickel is replaced by copper, cobalt, 
iron, or by platinum or palladium black.—Researches on the 
monazite sands, by MM. G. Urbain and E. Budischovsky. The 
hydrated earths were treated with acetylacetone, and the result- 
Ing acetylacetonates fractionally recrystallised from alcohol and 
benzene. The lowest atomic weight obtained from the fractions 
was 95, the highest 112.—A reaction of carbon monoxide, by 
M. A. Mermet. A solution of potassium permanganate, acidified 
with nitric acid, and containing silver nitrate, is decolorised by 
carbon monoxide. With air containing ‘002 to ‘0002 of its 
volume of carbon monoxide, the decolorisation was complete in 
from one to twenty-four hours. Upon this reaction is based the 
determination of small quantities of CO in rooms. —On isolaur- 
onolic acid, by M. G. Blanc. Isolauronyl chloride, treated with 
zinc methyl in ethereal solution, yields an isomer of camphor, of 
which the oxime, semicarbazone, hydrazone, and reduction pro- 
ducts are described. —On a new method of storing acetylene, by 
MM. Georges Claude and Albert Hess. It has been found that 
acetone is a good solvent for acetylene, one kilogram of acetone 
dissolving 300 litres of acetylene under a pressure of 12 atmo- 
spheres.—On the mineralogical constitution of the island of 
Polycandros, by M. A. Lacroix. The south-eastern portion of 
the island consists of white or greyish-white limestone deposits, 
the remainder consisting of mica and chlorite schists —On the 
part played by phenomena of superficial alteration in metalliferous 
strata, by M. L. de Launay.—On the gradual loss of lime in 
basic eruptive rocks of the region of the Pelvoux, by M. P. 
Termier.—Work carried out by the Geographical Service of the 
Expeditionary Corps of Madagascar, during the campaign of 
1895, by M. R. Bourgeois. —The movement of lunar rotation, 
by M. D. A. Casalonga.—On an apparatus called a kineometer, 
by M. Aug. Coret.—The problem of aviation, by M. Th. 
Colombier. 
AMSTERDAM. 
Royal Academy of Sciences, January 30.—Prof. van de 
Sande Bakhuyzen in the chair.—Prof. Engelmann, referring to 
experiments made by Dr. Woltering and himself at Utrecht, 
treated of the rate at which stimuli of various intensity are pro- 
pagated through muscular fibres.—Prof. van Bemmelen made 
a communication concerning the chemical metamorphosis of 
phosphate in fossil bones.—Prof. van der Waals described an 
inquiry made by himself, in accordance with the molecular 
theory of a mixture developed by the author (Arch. Neer/., 
t. xxiv.), into the extent to which the complexity of the mole- 
cules of asolvent may influence the magnitude of the decrease 
of vapour-tension by dissolved salts. He arrived at the con- 
clusion that the decrease of vapour-tension is determined solely 
by the magnitude of the molecules of the solvent when in the 
state of vapour.—Prof. Engelmann presented, on behalf of Mr. 
E. G. A. ten Siethoff, of Deventer, a paper entitled ‘ An 
explanation of the optical phenomenon in the eye, discovered 
by Dr. P. Zeeman.” Dr. Zeeman described (Report of the 
meeting of the Physical Section of the Royal Acad. of Sc., 
February 25, 1893; Nature, vol. xlvii., 1893, p. 504; and 
Zeitschr. f. Psych. und Phys. d. Sinnesorg, vol. vi., 1894, 
p- 233-234) a subjective optical phenomenon, which occurs. 
when a slit, brightly illumined, preferably by monochromatic 
yellow light, is observed in the dark. Then a bluish-violet line 
of light is seen, curved like the outline of a pear, whose axis. 
stands perpendicularly upon the middle of the slit. When re- 
garded with the right eye, the point of the light figure is turned 
to the right (to the left when seen with the left eye), and the 
rounded side slightly overlaps the illumined slit. The observ- 
ation of the phenomenon is easiest with yellow or white light ; 
still, Dr. Zeeman succeeded in observing it when using any of 
the three hydrogen lines. The subjective optical phenomenon 
observed by Dr. Zeeman ought, in the author's opinion, to be 
conceived as an entoptical, complementary after-image of the 
macula lutea and its surroundings, caused by the percinient 
elements posterior to it being stimulated. This after-image is 
violet-coloured with any kind of light, because in the place 
indicated yellow light always prevails, in consequence of the 
elective absorption of the yellow pigment.—Prof. Kamerlingh 
Onnes read a letter from Mr. Edm. van Aubel, of Brussels, 
concerning the experiments of Dr. Zeeman, mentioned at a 
previous meeting, ‘‘On the influence of magnetism on the 
nature of the light emitted by a substance.” 
