346 
range of temperature: but it has not 
hitherto been generally known, that from 
‘the fixed point above mentioned, a ca- 
pability for being softened commences 
and increases through a certain range of 
decreasing temperature, accordingly as 
the heat given to the steel falls short’of 
the fixed point, at the instant of being 
suddenly plunged into water, or other- 
wise suddenly cooled. In preparing 
steel articles which require to be pla- 
nished or hammer-hardened, this disco- 
very proves of important service, by ena- 
bling the skilfal workmen to heat his 
steel to the precise proper degree, under 
that fixed one (where no hardening or 
softening would ensue, as above men- 
tioned,) and suddenly then to plunge it 
under water ; by which proofs, the steel 
is found more uniformly and better 
softened, or annealed, than by any pre- 
viously known process. Steel-wires or 
rods, of the various sizes, and under one 
or two feet lengths, may be preserved 
perfectly straight in the hardening, by 
laying them, properly heated, on a thick 
flat cold plate of iron or other metal, 
(or, perhaps, a stone might answer,) and 
immediately rolling another such plate 
over them, and continuing the rolling 
operation, until the wires or rods are 
cold; by which simple means, the un- 
equal cooling, and the consequent warp- 
ing and setting of the steel, will be 
prevented ; and doubtless, flat plates of 
steel might by similar means be harden- 
ed ; using sufficiently large and very flat 
cooling plates, and adopting the princi- 
ple of the plate-glass grinder’s move- 
ments, in moving the upper plate. 
Mount Vesuvius—M. HumeBotprt, 
and M. Rose, an eminent chemist of 
Berlin, and M. Monrticetyi and M. 
Covec.i, all concur in contradicting 
the assertions of two Neapolitan che- 
mists, that the ashes ejected from Vesu- 
vius in the last great eruption, contain 
portions of gold and silver. M. Hum- 
boldt has also ascertained, from nume- 
rous measurements, that fiftecn to 
eighteen inches is the greatest thick- 
ness, independent of wind-drifts, of the 
dry ashes lately strewed on any of the 
plains near this volcano; and this thick- 
ness he believes to amount to three 
times as much as all the ashes collec- 
tively, which haye fallen over the same 
or similar plain spaces (accordingly as 
the wind. has ‘been different,) since the 
untimely death of the elder Pliny, in the 
Spirit of Philosophical Discovery. 
[Nov. 1, 
last year of Vespasian. The over- 
whelming of the Campanian towns ap- 
pearing to this naturalist to have, sud- 
denly happened, in a manner very 
different from dry ashes carried by the 
wind. 
Depth of Rain annually at Bombay. 
—Mr. BenJAmMin Noten, a resident at 
Bombay, in the East Indies, has for 
more than six years past carefully 
registered, by means of Howard’s 
pluviometer, at seven o'clock in the 
morning of each day, the depths of rain 
which may have fallen in the previous 
night and day. The annual totals of 
which depths are as follows :— 
In 1817 -+ «+200 103°79 inches, 
1818 81°14 
1819 coscescess 77°10 
1820 - T7*34 
1821 eccesesess 8299 
1829 seeeeeeees 112°61 
Whence it would appear, that the quan- 
lity of rain decreased annually to a 
minimum quantity in 1819, and since 
then increased again with considerable 
regularity ; and it is perhaps also worthy 
of remark, ihat this dry year in Bombay 
was the same in which the magnetic 
needle in England attained its greatest 
western variation; and when also the 
seasons of our climate were in so extra- 
ordinary a degree varied from their 
usual routine. Perhaps some of our 
ingenious readers may have access to a 
series of magnetic and rain observations 
in Bombay, sufficiently long kept to be 
able to show whether there are there 
constantly recurring periods of wet and 
dry seasons? and, it so, what have been 
the lengths of those periods, and dates 
of their greatest and least depths of rain? 
Or whether, if no such periods can he 
traced in the journals of years that are 
passed, the deficiency of rain in 1819 
and 20 had any notable connection 
with the magnetic phenomena of that 
place? 
Amongst the singular properties of 
Napthaline, a new substance is obtained 
by the distillation of the coal-tar made 
at the gas- works; offensive as the smell 
of this tar is, Mr. CHAMBERLAIN has 
found that the first product of the sub- 
limation of napthaline is a fluid, swect 
to the taste, and of a highly aromatic 
smell ; and that, if napthaline be tritu- 
rated in a mortar with nitric acid, a 
butyraceous compound is formed, which 
smells exactly like new hay. 
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BRITISH 
