Miscellaneous Notices. 
339 
1829.] 
mena. They are found in formations of every character. And what is more import- 
ant, we are to consider that in no case do their peahs exhibit an outline at all vol- 
canic, being' almost all sharp spiracles, and in no single instance that I know of 
truncated cones. Amidst the innumerable peaks existing in the remote and inacces- 
sible, as well as invisible depths of this vast region of snow, it is impossible to say, 
what may or may not exist, and therefore it may be said, that we cannot speak 
possitively as to their non occurrence. It is at the shine time curious, that no 
specimens of rocks of volcanic, or even trap origin, have yet been found within these 
mountains; even granite is very rare.” 
2. Syphon Hydrometer. 
The Journal of Science and Arts has given a description of two 
Syphons applied to the measurement of the specific gravities of 
liquids, invented by Mr. Meikle. The first consisted of a double 
syphon, a, into one leg of which a column of pure water was intro- 
duced, and into the other, a column of the liquid whose specific 
gravity was required. The chief difficulty with this instrument was 
in cleaning the interior tubes, where the liquids might be apt to be- 
come mixed. 
An improvement afterwards suggested itself to the inventor ; a 
common Syphon h. of two equal legs was made to dip into two ad- 
jacent glass vessels containing the liquids : but in this form of the 
instrument, allowance must be made for the difference of the capil- 
lary action of the tube upon the two liquids ; besides which, it is ne- 
cessary to have sufficient liquid to till a glass cylindric tube, which is 
sometimes inconvenient. 
A third form still presents itself, imssessing greater advantages 
than either of the foregoing. 
It is that of a syphon of three tegs. Into the upper orifice of it, the 
required liquid may he carefully poured, and very little will suffice 
to fill the tube halfway up. The whole instrument is then to be 
plunged into a vessel of water, which enters at the lower orifice, and 
by the intervention of the air, elevates a proportionate column of the 
other liquid, the height of which, and of the water, maybe read off 
on a scale graduated upon one, or all of the tul>es. The allowance 
for capillary attraction need now only be applied for to the water 
tube, and will therefore be a constant number : and indeed it will 
be reduced nearly to nothing, inasmuch as the water cannot enter 
the lower orifice of the syphon without affecting the level of the 
liquid in the other branch, on account of the air between them, and 
the same force which raisesthc capillary water in one column, raises 
a proportional weight of the liquid in the other tube. It all follows 
that the height of the capillary column will only he half as much 
as it would be iu an open tube. 
3. On making Ice . 
The experiment of Professor Leslie, in which, by means of sulphuric acid and an 
air pump, he froze water in the middle of summer, is doubtless familiar to most 
of our readers. An apparatus on this principle, but on a very large scale, was brought 
out to this country sometime ago, with the view of establishing the manufacture of 
ice in some quantity, for the use and consumption of the good people of Calcutta. 
We had not an opportunity of seeing it ourselves, but we have understood that the 
air pump was to be worked by a small steam engine. Whether it ever received a 
fair trial we know not, but it is generally supposed, that the experiment has failed. 
The only account we could ever get of the matter is that the ice produced, was not 
only in small quantity, but so imperfectly sob'dified, as to render its transport to any 
distance precarious. We wonder it did not occur to the conductors of the experi- 
ment to mix common salt with it, by which the temperature would he reduced at 
once from 32° to 0°. Such an improvement of the power of the machine might 
have insured the success of the experiment. Suppose for instance, two lbs. of ice 
were the produce of the sulphuric acid and air-pump ; and allowing that only half 
this quantity was real solid ice, the other half being water of the temperature of 32°, 
mix half a pound of muriate of soda, and the result would be, a mass of three pounds 
at the temperature 13°. Or as muriate of lime might be imported from Europe at 
a very trifling charge, — suppose li lbs of the latter, mixed with the 21bs of slush 
ice, the resulting temperature on 3£lbs should be 5°. 
