1825.) 
- The Analysis of Gazeous Mirtures, such as 
occur in the distillation of gas from coal, or 
oil, for the purposes of illumination, is 
likely to be considerably improved, by em- 
ploying platinum as a re-agent, as was done 
by Sir Humphrey Davy, several years ago, 
in the state of fine wire, and more recently 
by M. Deebereiner in a spongy state; as 
has been shewn by Dr. Henry in the 
“© Philosophical Transactions :”’ but who re- 
serves for a future communication the 
most interesting of the illustrations of the 
nature of the gazes, from coal and oil, to 
which these improved modes of analysis 
have led him. 
Silicum, or the supposed metal of silex, 
or flinty earth, has, by a process which 
M. Berzelius describes in the “ Annales de 
Chimie,” been obtained in its separate state, 
and proves to be of a dark nut-brown 
colour, without the least metallic lustre. 
When rubbed on bright steel, its friction is 
considerable, but it does not afford a glis- 
tening streak; it is incombustible in at- 
mospheric air; and in oxygen, it under- 
goes no change from the flame of the blow- 
pipe, and appears to belong to the class of 
the most infusible bodies: this, and its 
want of power to conduct electricity, ex- 
clude it from the class of metals. and bring 
silicum near to boron and carbon, and per- 
haps it may hereafter bear the name of sili- 
con. 
silicum, and 51°6 oxygen. 
Ulmin, or the peculiar gum of the black 
elm-tree, has lately been ascertained, by 
M. Deebereiner, to be easily derivable from 
gallic acid; and to be composed of an 
atom of oxide of carbon (=12 carbon+8 
oxygen) and an atom of water (=I hy- 
drogen +8 oxygen). 
Titanium Metal, a Component of Mica.— 
M. Peschier, of Geneva, first discovered, 
and M. Vauquelin has lately confirmed the 
observation, that all the known varieties of 
mica contain titanium, although in very 
minute proportions ; always less than one 
per cent. 
The uniform Flasticity of Steel in all dif- 
ferent states of hardness, has been established 
by aseries of experiments, by Mr. T.'Tred- 
gold, which are described in the last part 
of the “‘ Philosophical Transactions ;” and, 
in conclusion, he offers an explanation of 
. the phenomena of hardening steel, as fol- 
lows, viz. by the high temperature which 
is given to the metal previous to hardening, 
its whole bulk is increased ; and, in plung- 
ing the same into cold water, the latter 
extracts heat from the superficial parts of 
the steel more rapidly than the internal 
parts can impart their heat: and so, very 
quickly after the cooling commences, the 
superficial crust of the steel has contracted 
in bulk, and set in that state, whilst the in- 
ternal parts remain expanded; but, shortly 
after, these internal parts Jose their heat, 
Moxruty Mac. No. 410. 
Spirit of Philosophical Discovery. 
Silica appears composed of 48-4 
441 
and would also contract, but are prevented by 
the external crust : and thus these internal 
parts of the hardened steel remain in a 
state of tension, which, experimentally, is 
known considerably to lessen the cohesive 
force or strength of hardened, as com- 
pared with soft steel: and thus, observes 
Mr. T., we are led to expect, that any 
other metal might be hardened, if we could 
find the means of abstracting heat with 
greater velocity than its conducting power. 
Fusible Alloys of Metals produce Cold in 
Liquefying.—M. Deebereiner has discover- 
ed, that if 118 grains of filings of tin, 207 
grains of filings of lead, and 284 grains of 
pulverized bismuth (which are the proper 
constituents of a fusibie metal) be incor- 
porated, in a dish of calendered paper, with 
1,616 grains of mercury, the temperature 
instantly sinks, in a mean state of the air, 
from 65° to 14° of Fahrenheit ;. and, from 
various circumstances, M. D. infers that, if 
the experiment were made somewhat un- 
der 32°, the temperature would descend 
so low as the freezing-point of mercury. 
Using a more complicated mixture, viz. 
lead 412, combined with 404 of mer- 
cury: this, again, mixed with 284 of bis- 
muth, previously combined with 404 of 
mercury ; and then adding 808 grains more 
of mercury, this fysible mixture fell no less 
than 51°, viz. from 68° to 17°.—Schweig~ 
ger’s Journ, 
The Face of a Steeple Clock, illumined by 
Gas, may be reudered equally readable by 
the inhabitants, in the night as in the day : 
this has now, for some years, been exem- 
plified at the Tron Church, in the city of 
Glasgow. A gas-lantern, whose exterior 
(except on the side next the steeple, where 
it is glazed) tastefully represents the bird 
called the phenir, is supported at several 
feet distant from, and level with the upper 
part of the clock-face, by two supports 
acting braceways to each other, and stea- 
died, laterally, by two chains proceeding 
from the corners of the steeple: the main 
of these supports is the gas-pipe, which 
supplies the lantern, and the other is also a 
gas-pipe used for lighting the lantern. It 
effects this by means of numerous equi- 
distant smal]l holes, or narrow cross slits in 
its side, and is called the flash-pipe. At 
sun-set, ‘when the lantern is to be lighted, 
the lamp-lighter, by means of their cocks 
fixed within his reach in the street, turns 
the gas into both these pipes, and, after 
waiting a proper time for the gas to ascend 
to the Jantern, he applies his flambeau to_ 
the jet of gas issuing from the lowest of 
the holes in the flash-pipe, the flame from 
which instantly communicates to the jet 
next above it, and soon, until in a few mo- 
ments this chain of flame enters the lantern, 
and lights the burner of the main pipe; 
which being perceived by the illumination 
on the clock-face, the flash-cock is then 
turned off, and no further attendance is 
3 L neede.. 
