Fuly 6, 1871] 
NATURE 
195 

Peloryctes inquilina, by M. H. Zingera, will probably attract 
few English readers.—M. E. Regel publishes a portion of a 
second supplement to the enumeration of the plants collected 
by Sewerzow in 1857 in Central Asia. It includes the Ranuncu- 
laceze, Berberideze, Nymphzacez, Papaveracez, Fumariaceze, 
and Cruciferze. Several new species are described.—Another 
botanical paper is an abridged French translation of part of the 
Introduction to a Flora of Moscow, by M. N. Kauffmann, the 
translation being made by Mr. G. O. Clerc. The Flora, which 
is a Catalogue of the vascular plants of the Government of Mos- 
cow, will appear in future numbers.—We find in this number 
two entomological papers, both on Coleoptera, and one of them 
of great importance, namely, a Monograph of the Graphi- 
pteridze by the Baron Chaudoir. The other paper is a continua- 
tion, by M. Victor Motschoulsky, of his apparently interminable 
enumeration of the new species of Coleoptera collected by him 
in his journeys. It includes descriptions of species of Melaso- 
mata, and is illustrated with two plates.—M. G. Schweizer de- 
scribes an easy method of approximately finding the meridian 
line ; and M. A. Trautschold gives a short notice of some creta- 
ceous fossils from Ssaratof and Ssimbirsk. 
Paleontographica.—Beitrage ur Naturgeschichte der Vorwelt. 
Herausgegeben von Dr. W. Dunker und Dr. K. A. Zittel. Band xx. 
Lief 1., 1871. In this part of the well-known and most valuable 
** Palzeontographica,” Prof, Geinitz commences a monograph of 
the fossils of the Lower Quader and Lower Planer beds in the 
Saxon Elbe valley, which he regards as forming the lowest part 
of a great Quader-formation, including the Senonian, Turonian, 
and Cenomanian stages of the French geologists. His Lower 
Quader is equivalent to the Upper Greensand of English geolo- 
gists. It is well known that sponges are among the most abun- 
dant and striking fossils of our Upper Greensand, and the corre- 
sponding beds in the valley of the Elbe seem to be equally rich 
in remains of thislowest class of animals. With the exception 
ofa summary of the geology of the district, the whole of the 
present part of Prof. Geinitz’s work is occupied by descriptions 
of sponges, the species of which are beautifully figured in the ac- 
companying plates. Laying the reproaches of Oscar Schmidt to 
heart, Prof. Geinitz endeavours to arrange his fossil forms in ac- 
cordance with the system of that author, although, as he justly 
remarks, it is impossible in the study of fossil sponges to have 
recourse to those minute characters derived from the spiculz, 
which form the basis of recent attempts to classify the recent 
forms. He notices in all twenty-eight species, of which six 
appear to be new. 


SOCIETIES AND ACADEMIES 
LONDON 
Royal Society, June 15, ‘‘On a Law in Chemical Dy- 
namics.” By John Hall Gladstone, F.R.S., and Alfred Tribe. 
It is well known that one metal has the power of decomposing 
the salts of certain other metals, and that the chemical change 
will proceed until the more powerful metal has entirely taken 
the place of the other. The authors have investigated what 
takes place during the process. 
The experiments were generally performed as follows :—72 
cubic centimetres of an aqueous solution of the salt of known 
strength, and at 12° Centigrade, were placed in a tall glass; a 
perfectly clean plate of metal of 3,230 square millimetres was 
weighed and placed vertically in this solution without reaching 
either to the top or bottom ; the action was allowed to proceed 
quietly for ten minutes, when the plate was removed, and the 
deposited metal was washed off. The loss of weight gave the 
amount of metal dissolved, and represented the chemical action. 
The most complete series of results was with copper and 
nitrate of silver. 
In the earlier terms of this series, Zwice the percentage of silver- 
salt gives three times the chemical action. The close agreement of 
the observed numbers with those calculated on this supposition 
continues as far as the 9th term. The law then breaks down, 
and after about 7 per cent. the increased action is almost in 
direct ratio with the increased strength. 
The position of the plate in the solution was found to make 
no difference to this 2-3 law. 
Similar series of experiments were made with zinc and chloride 
of copper, zinc and sulphate of copper, zinc and nitrate of lead, 
iron and sulphate of copper, and other combinations ; and in 
eyery instance where the solution was weak and the action 


simple, the law of three times the chemical change for twice the 
strength was found to hold good. 
It was proved that the breaking down ot the law at about 
3'5 per cent. of salt in solution was irrespective of the quantity 
of the liquid, or of the time for which the plate was exposed, 
With 72 cub. centims. of a 1°41 per cent. solution of nitrate of 
silver, the rate of action remained sensibly the same for as long 
as twenty-five minutes, notwithstanding the constant deposition 
of silver. This apparently paradoxical result is due to fresh 
relays of the original solution being brought up to the plate by 
the currents produced, and that period of time elapsing before 
any of the products of decomposition are brought back again in 
their circuit. 
When it was perceived that within easily ascertainable limits 
the chemical action is the same for similar consecutive periods of 
time, experiments were made in far weaker solutions. It was 
only necessary to lengthen the time of exposure. It was thus 
found that the law of three times the chemical action for twice 
the strength of solution holds good through at least eleven terms 
of the powers of 2; in fact, from a solution that could dissolve 
one gramme of copper during the hour, to a solution that dis- 
solved only 0‘000001 gramme, a million times less. 
The manner in which the silver is deposited on a copper plate 
was examined, and the. currents produced were studied. At 
first a light blue current is perceived flowing upwards from the 
surface of the plate, presently a deep blue current pours down- 
wards, and these two currents in opposite directions continue to 
form simultaneously. A similar phenomenon was observed in 
every case where a metallic salt attacked a plate of another 
metal. The downward current was found to be a solution of 
almost pure nitrate of copper, containing about three times as 
much NO, as the original silver solution, while the upward 
current was a diluted solution of the mixed nitrates. Moreover, 
the heavy current took its rise in the entangled mass of crystals 
right against the plate, while the light current flowed from the 
tops of the crystalline branches. It was evident that when the 
fresh silver was deposited on these branches, and the fresh 
copper taken up from the plate, there was not merely a trans- 
ference of the nitric element from one combination to another, 
but an actual molecular movement of it towards the copper 
plate, producing an accumulation of nitrate of copper there, and 
a corresponding loss of salt in the liquid that is drawn within 
the influence of the branching crystals. Hence the opposite 
currents. 
The amount of action in a circuit of two metals and a saline 
solution must have as one of its regulating conditions the con- 
ducting-power of that solution. It appeared by experiment that 
a strong solution of nitrate of silver offers less resistance than a 
weak one ; and it was also found, on adding nitrate of potassium 
to the nitrate of silver, that its power of attacking the copper 
plate was increased ; that the augmentation of the foreign salt 
increased the action still further ; and that the 2-3 law holds good 
between two solutions in which both the silverand potassium salt 
are doubled, though it does not hold good if the quantity of 
foreign salt be kept constant. Similar results were obtained 
with mixed nitrates of silver and copper. 
While these later experiments offer an explanation of the fact 
that a solution of double the strength produces more than double 
the chemical action, they do not explain why it should produce 
exactly three times the effect, or why the ratio should be the 
same in all substitutions of this nature hitherto applied. The 
simplicity and wide range of the 2-3 law seems to indicate that 
it is a very primary one in chemical dynamics. 
“On Cyclides and Sphero-Quartics.” By John Casey, LL.D. 
Royal Institution of Great Britain, July 3.—Sir Henry 
Holland, Bart., M.D., F.R.S., president, in the chair. Wil- 
liam Amhurst Tyssen Amhurst and Lawrence Trent Cave 
were elected members. 
Royal Geographical Society, June 26.—Major-General 
Sir Henry C. Rawlinson, K.C.B., president, in the chair. 
The following new fellows were elected: Thomas Brassey, 
M.P.; T. B. Baker, C.B.; D. Chinery (Consul-General 
for Liberia); Commander C. D. Inglis, R.N.; William 
Charles Jackson; G. W. Kennion; Alfred Morrison, Wii- 
liam G. Margetts, Colonel R. Maclagen, R.E. ; Captain 
G. S. Nares, R.N.; and James Rickards. <A letter was 
read from Sir Roderick Murchison, giving Dr. Kirk’s views of 
Dr. Livingstone’s position, as communicated in a recent letter 
from Zanzibar, dated the 3oth April last. It appeared that 
