142 
NATURE 
[Dec. 2, 1869 
BALLOONERS will rejoice at hearing that Messrs. Hachette 
and Co. have issued a magnificent work on the Aérial Voyages 
of Glaisher, Camille Flammarion, W. de Fonvielle, and Gaston 
Tissandier. The illustrations are excellent. 
Two handsome volumes devoted to the “Life and Letters of 
Faraday” haye been issued by Messrs. Longmans, and received 
by us just as we were going to press. The author is the 
Secretary of the Royal Institution, Dr. Bence Jones, whose 
delightful memoir of Faraday communicated to the Royal 
Society last year has been perused with pleasure by all scientific 
men. 
THE committee of the Council on Education have placed at 
the disposal of the University of Oxford two of the thirty 
exhibitions, value 25/. each, given by Sir Joseph Whitworth, to 
assist deserving students in competing for his scholarships in 
mechanical science. 
BOTANY 
Spontaneous Movements in Plants 
M. Lrcoca, of Clermont Ferrand, records in the Belgigue 
Hforticole some singular spasmodic movements in the leaves of 
Colocasia esculenta. ‘These motions bear no resemblance to those 
produced in the Sensitive plant by the warmth of the hand, but 
occur spontaneously independently of the action of the wind or 
of any external cause, at irregular intervals, and at different periods 
of the day and night. M. Lecocq describes the movement as a 
kind of trembling or quivering affecting the whole plant, suffi- 
ciently powerful to tinkle little bells attached to the branches, 
and on one occasion even to shake the pot in which the plant was 
contained, and to resist a pressure of the hand, the number of 
the pulsations varying from 100 to 120 per minute. He states 
that the Colocasia is destitute of the stomata with which the 
leaves of plants are generally provided, especially on their under- 
surface, and attributes the phenomenon to the incessant pulsations 
of the imprisoned sap. 
Decomposition of Carbonic Acid by Leaves 
M. P. P. DEHERAIN has been continuing his researches on 
the evaporation of water from the leaves of plants, and the de- 
composition by them of carbonic acid. His previous investiga- 
tion had established the fact that these two functions of the 
leaves proceed far? fassu, the same conditions favouring the one 
as the other ; and that both are determined by the degree and 
nature of the light to which the leaves are exposed, and not by 
the temperature. He now attempts to show that it is not the 
intensity only of the light which determines the rapidity of the 
evaporation of the water, and of the decomposition of carbonic 
acid; but that certain rays of light are far more efficacious than 
others. A careful series of experiments on the submerged leaves 
of Potamogeton crispus, accurately weighing the quantity of gases 
emitted, showed that under the influence of yellow light 26:2 c.c. 
of gas were exhaled, while under the influence of blue rays of 
the same intensity the plant disengaged only 5°8 c.c. of gas in 
the same time. A repetition of the experiment established the 
following laws,—Ist. That all the rays of light are not equally 
efficacious in determining the decomposition of carbonic acid, 
2d. That even with the same intensity yellow and red rays act 
more powerfully than blue or violet. 3d. That the relation 
which has been established between decomposition and evapo- 
ration is maintained also with respect to the relative influence of 
different rays of light. [Comptes Rendus.] 
New Coffee Fungus 
THE Rey. M. J. Berkeley forwards to the Gardener's Chronicle 
a letter from the well-known botanist, Mr. Thwaites, of Ceylon, 
in which he speaks of the consternation caused among the coffee- 
planters of that island in consequence of the rapid increase of a 
parasitic Fungus in the coffee-plantations, causing the leaves to 
fall off before their proper time, and endangering the safety of 
the crop. It is a singular fact that among more than one thou- 
sand species of Fungus which have been received in this country 
from Ceylon this particular one does not occur; not only is it 
an entirely new species, but it is with difficulty referable to any 
recognised section, being intermediate between the true moulds 
and the Uredos. Mr. Berkeley establishes from it a new genus 
flermileia, A. W. B 
CHEMISTRY 
Thallium Salts.—II. 
MM. LAMy AND DEs CLOISEAUXx have again examined the 
thallous salts named below. The fervo-cyanide— 
Tl,FeCy, + 2Aq. 
has a beautiful yellow colour, a density of 4°641, and is readily 
dehydrated by heat. Exposed to dry air, the crystals gradually 
lose their transparency. Water dissolves more of this than of 
potassic ferro-cyanide ; the actual solubility is shown by the 
following numbers— 
100 grm. water dissolve at 18°. . , 0°37 grm. ferro-cyanide 
” 0 yy at IOI”. . | 3°93 5, » 
The crystalline type to which this salt belongs is a doubly oblique 
prism. It exhibits a high degree of double refraction ; fine 
plates of it, cut parallel to the plane of cleavage, show a well- 
defined system of rings under the polariser. The crystals are 
very fragile. 
Thallous tartrates and paratartrates are remarkable for the 
readiness with which they yield large and brilliant crystals. 
Aydro-thallous tartrate, C,H,T1O,, generally crystallises in beau- 
tiful white prisms, which have a silky lustre, due to the presence 
of a number of longitudinal striz ; it is soluble in 122 parts of 
water at 15°, and in 6 parts of water at 101°. The density of the 
crystals is 3496, and they are, as already found by Lang, optically 
and geometrically isomorphous with hydro-potassic tartrate. The 
neutral tartrate is prepared by adding thallous carbonate to boil- 
ing aqueous hydric tartrate, until alkalinity ensues. On cooling, 
large, transparent, lustrous crystals make their appearance ; their 
specific gravity is 4°658; they are unalterable in air at the 
ordinary temperature; at 100°, however, they become opaque 
and anhydrous. They dissolve in five times their weight of water 
at 15°, and in a tenth of their weight of boiling water. The 
formula of this salt is— 
2[C,H,T1,0,]. Aq. 
It crystallises in forms belonging to the clino-rhombic system — 
Plane angle of the base ...,... 106° 59/26” 
Plane angle of the lateral faces LOU beanie 
Obliquity of the primitive prism . . . 110°23/00" 
The double refraction is very energetic. The plane of the optic 
axes is normal to that of symmetry. The acute bisectrix is nega- 
tive and perpendicular to the horizontal diagonal of the base. 
The horizontal dispersion is pretty decided, as is also the proper 
dispersion of the optic axes, p being < v.  Sodio-thallous tar- 
trate— C,H,NaT1lO, + 4Aq. 
is prepared in the same manner as common Seignette salt, with 
which it agrees not only in composition, but also in figure; but 
it differs from that body in the orientation of its optic axes. The 
crystals are soluble in half their weight of water at 20°, and 
effloresce when handled. The acute bisectrix of the optic axes is 
negative and normal to the base ; the dispersion, though con- 
siderable (with p > v), is much smaller than in the common 
Seignette salt. When redissolved in water, and allowed to 
evaporate spontaneously, the above compound yields a more 
complex tartrate, having the formula— 
C,H,TINaO, + C,H,T1,O,, 
and crystallising in the rhombic system. As regards form, it may 
be referred to a right rhomboidal prism of 98°40’, differing chiefly 
in height from the tartrate just described. The acute bisectrix is 
positive. Thallio-stibiosylic tartrate— 
C,H,4Tl(SbO)O, + Aq. 
is less soluble in water than the corresponding potassic salt, The 
crystals are quite permanent, and have the specific gravity 399. 
Although geometrically isomorphous with the potassic salt, the 
two tartrates differ completely in optical properties. At 15° to 
20° the optic axes are perfectly united for all the colours of the 
spectrum ; but at 70° they separate to the extent of 20°—25°, in 
the plane passing through the principal diagonals of the bases of 
the primitive prism. Their acute bisectrix is negative; dispersion 
inappreciable. Dithallous paratartrate is anhydrous, has a density 
of 4°659, and is capable of crystallising in two distinct forms. 
The two forms, which both belong to the clino-rhombic system, 
are distinguished by the following numbers— 
Normal. Irregular. 
Plane angle of the base... .... 68°55'56" 80°16' 22” 
Plane angle of the lateral faces . . . 90°16'24” 95° 9/36” 
Obliquity of the primitive prism. . . 90°20/00"” 96°45'00" 
In both, however, the dispersion is weak, with p> vy; the 
acute bisectrix is positive and the separation of the optic axes 
