1826.] 
decay.in|timber-or other, substances; arising 
from jdxy-rot-and: other causes, | He pro- 
poses; by boiling the, wood! in a,solution of 
metallic and, other poisonous matters, ‘to 
introduce between, its, fibres»,and \into its 
poreswery minute, particles.of these, for the 
purpose of preventing the growth. cf: yege~ 
table fungt or'animalcule..7, Dry-rot in tim- 
ber; according to, the! views.of the. patentee, 
arises from, the, decomposition. of vegetable 
fluids;which,all kind,of timber-contain, and 
which in, eertam,situations.seem to. be fa- 
yourable to, the, propagation. of fungi and of 
worms; he.alse considers that neither ani- 
mal nor vegetable germination can proceed 
in contact with.such. mineral poisons as he 
proposes..to employ—sulphate, or acetate 
of copper—white arsenic, &c. 
‘Terrestrial Magnetism. —Some of the 
phenoniena arising from ‘partial terrestrial 
magnetismrare deserving of notice, and may 
account for many accidents which have 
arisén to vessels which have depended for 
their course almost entirely upon the com- 
pass. .Thus it is always asserted and be- 
lieved, that in approaching the small island 
of Fetlar, or Theodore’s Island, one of the 
Shetland group, the compass always points 
directly to the laid, on whicheyer side the 
ap roach is made. 
New Mines of Platinum.—M. Roussin- 
gault, a celebrated French chemist, has re- 
cently discovered a mine of platinum at An- 
tioquia, in the department of Cundinamarca, 
in Coitnibia, ‘Hitherto this precious me- 
tal; so valuable,in the. arts, had only been 
found in the Uralian mountains in Russia, 
in Brazil, and .in}theprovinces of Choco 
and» Barbacoas, on the.coasts-of the South 
Sea;-but-always im alluvial-lands, where it 
could only be met with accidentally ; but in 
this ease!there, can bey no doubt that the 
metal exists ii real)yeinsin the’ valley De 
Osos (being very | near. the ‘province . of 
Choco; from which itis separated only by 
a branch, of ;the Cordillera of the Andes, 
which cireumstance, accounts for the pre- 
of the! same metal in the alluvial soils 
valley De Osos) ;, and it-is sufficient 
to pound. the, materials which these veins 
contain, -in, orderto obtain from them by 
washing the gold,and platinum which they 
contain, Mines} of platinum have recently 
been found in-the Uralian mountains, in the 
government of ‘Perma, so extremely rich, 
that,thepriee of) platinum) fell, nearly one- 
third at St. Petersburgh; and hence we 
may retisonably expect that this’ valuable 
Lwillseease tovbear that high price at 
Hit has hitherto been sold.—Le Globe. 
@ Fall of Leaves.—\n the first volume 
af . Memoirs of the Society of Natural 
istory of Geneya, Professor Vaucher has 
givensa yery probable solution of the phe- 
nenon, of the fall of leayes.. If the point 
erence of a leaf-stalk, he says, be ex- 
atthe moment of separation, it will 
sd that it forms, a clean and per- 
y defined section. This species of cica- 
“M.M. New Serics—Vor. II, No. 11. 
Varieties, 
553 
trix, of which the impression is also seen 
upon the’twig, is differently figured, aecord- 
ing to the:confurmation of the leaves. ‘In 
some it presents the appearance of a horse- 
shoe, in others a heart, the segment of -a 
civele, &c., but always’ similar ‘in ‘trees of 
the same species; but ifthe leafestalk be 
attempted to be broken elsewhere than’ at 
its ordinary point of separation, the fibres 
are Jacerated and torn; and proof is thus 
afforded that means for* their separation 
have been previously prepared by nature at 
one exclusive point, without reference to 
exterior causes. The fibres of a leaf-stalk, 
in place of being a simple prolongation:of 
those of the twig, are therefore separated 
from it at the point where this cicatrix is 
seen. There appears, indeed, no real con- 
tinuity between them; and the temporary 
union which connects the leaf-stalk with 
the twig is merely kept up by a kindof 
adhesive substance, which, when the pur- 
poses of the leaf to the parent-plant are 
served, is dried up and dissolved. This 
adhesive substance is probably formed by 
some portion of the parenchyma interposed 
between the two systems of fibres. . While 
this parenchyma is under the influence of 
the vegetable action, it is impregnated with 
vegetable juices, it fulfils its vital functions, 
adhesion is maintained, and any attempt.to 
remoye the leaf produces laceration. But 
in autumn, when this . vegetable ‘action 
ceases, the interposed parenchyma haying 
dried up, no longer preserves the continuity 
with, the stem, the union is dissolyed; and 
the leaves necessarily fall. The. point. of 
separation is to be perceived exteriorly in 
the form of a circular ring, at the point 
which separates the leaf-stalk, from. the 
stem. This ring is. easily. perceptible in 
most trees. It is particularly marked.in the 
leaf-stalks of compound leayes, the fall. of 
which present more varieties in. their.ap- 
pearance than simple leaves. _ At the same 
time, the solution of continuity which takes 
place in compound leayes is not of the same 
nature as that which occurs in simple leayes. 
This natural separation, howeyer,-is not a 
phenomenon peculiar to. the -leayes. of arbo~ 
rescent stems ; itis equally,seen in the pe- 
duncles which support .the male flowers of 
a great number of plants—such as the wal- 
nut, the willow, &c.; and it,is_ still, more’ 
distinctly marked in the pericarps... The 
different ways in which these. pericarps 
open at the moment of maturity,, and the 
constancy of the mode, of opening in the 
same species, cannot be explained. without 
having: recourse to the supposition of a 
peculiar organization, to a primitive solder, 
similar to that which retains the leaf-stalks 
in their places. NER 
Acoustics.—It is stated, in the account 
of Captain Parry’s third voyage, that, at 
Port Bowen Lieutenant Foster kept. up.a 
conversation with his assistant at a distance. 
of 6,696 feet, or about one statute mile and 
two-tenths, : fs 
4B 
