SCIENTIFIC SUMMARY. 
273 
results of experiments made on tlie leaves of the common acacia (. Robinia 
pseudacacia ). He finds that when the leaves of this tree are well expanded 
in bright sunlight, the application of from ten to twenty smart blows with 
the finger upon the terminal leaflet will cause all the leaflets of the leaf to 
fold up and go to sleep, just as they do at night. In one case the leaflets 
occupied five minutes in closing ; in another instance four minutes and a half. 
The leaflets close one after the other, commencing with those nearest the 
terminal leaflet. Mr. Phipson observed that the leaves required from two to 
three hours of exposure to the sun before they were again fully expanded. 
CHEMISTRY. 
Action of Phosphonium Iodide on Carbon Disulphide. — It has been noticed 
by Hans Jahn ( Ber . Chem. Gesells., 1880, xiii., 127), that if phosphonium 
iodide and carbon disulphide be heated together in sealed glass tubes to 120° 
or 140° C., the latter is converted, by the hydrogen liberated by the breaking- 
up of the iodide, into marsh-gas and sulphuretted hydrogen, in accordance 
with the equation : — 
C S a + H 8 = C H 4 + 2 H 2 S. 
At the same time, however, a crystallizable body makes its appearance in the 
form of red needles, which is, probably, a molecular compound of the disul- 
phide and the iodide ; by treatment with water it is converted into an amor- 
phous, white, easily-changeable compound, which, according to the result of 
analysis, appears to have the composition C 5 S 2 P 6 H 6 Ol2* By the action of 
water on the pure phosphonium iodide in presence of carbon disulphide no 
such compound is found. Its formation from the two bodies may, however, 
be represented as taking place in the following manner : — 
5 CS 2 + 6PI 2 + 12 H 2 0 = C 5 S 7 P 6 H 6 0 12 + 12 HI + 3H 2 S. 
When boiled with water in closed tubes, the compound decomposes into car- 
bonic acid, sulphuretted hydrogen, phosphorous acid and amorphous phos- 
phorus, in accordance with the equation : — 
C 5 H 7 P 6 H 6 0 12 + 6H 2 0 = 5C0 2 + 7H 2 S + 4HP0 2 + 2P. 
As in the above compound, the atomic ratio between phosphorus and iodine 
in respect to oxygen is as 1 : 2, the assumption may be held that at the tem- 
perature above referred to (120° — 140° C.) the decomposition of phosphonium 
iodide takes place in accordance with the equation : — 
2 H 4 P I = P I 2 + H 3 P + H 5 . 
The new Elements found in Gadolinite and Sctmarskite. — Since the publica- 
tion of the paper on Terbium by Marignac and Delafontaine, in March 1878, 
announcements have appeared respecting no less than ten new earths, mosan- 
drin, philippin, ytterbin, decipin, scandin, holmin, thulin, samarin, and two 
others without names. As was to be expected, so extraordinary an increase in 
the number of a series of bodies which are exceedingly difficult to separate 
and hard to characterize has not been allowed to pass without question. 
Delafontaine ( Compt . Rend. 1880, xc. 221) in his investigation on the composi- 
NEW SERIES, YOL. IV. NO. XV. 
T 
