MISCELLANY. 
Variations of the Boiling Foint of Water, according to the nature of 
the Vessels. — M. F. Marcet has made a series of careful experiments upon 
the variability of the boiling point of water, according to the different 
nature of the vessels in which the ebullition took place. The follow- 
ing are the results of his researches on this point : — 1, the boiling point 
of water in glass vessels is at 100°. 3 and 102° (cent.) according to dif- 
ferent circumstances, and especially according to the variety of the glass. 
In these cases, the temperature of the vapour of the water is constantly 
the same, and some hundredths of a degree lower than when the water 
boils in metallic vessels. 2. Whatever may be the nature of the ves- 
sel in which the ebullition is performed, the temperature of the aqueous 
vapour is always inferior to that of the water which gives rise to it. 
The mean of this difference, in glass vessels, is about 1°.06, while in 
metallic vessels, it is but as 0°.15 to 0°.20. There is but one excep- 
tion to this rule, and that is where the interior of the vessel in which 
boiling is accomplished, whether it be of glass or of metal, is covered 
with a thin coating of sulphur, or gum-lac, or any other substance which 
exercises a repulsive action on the water; the boiling water and the 
vapour are then of the same temperature. 3. Contrary to the opinion 
generally admitted, the boiling point under a high pressure is not low- 
est in metallic vessels, but in glass vessels, when the latter are lined 
interiorly with a layer of the above-mentioned substances. 4. In glass 
vessels, the internal surface of which is perfectly smooth, and devoid of 
all foreign matter, we may carry the temperature of water or of alcohol 
to several degrees above the boiling point, before ebullition is induced ; 
we may thus bring the temperature of water up to 105° before ebulli- 
tion takes place. If the experiment does not succeed, it is owing to the 
presence of foreign matters adhering to the internal surface of the glass. 
We may insure success by making choice of a new globe, and heating 
therein sulphuric acid, until it reaches X 150°, subsequently washing it 
out with perfectly pure water. — London Med. Times. 
New Method of preparing Oxygen. — M. Balmain prepares oxygen by 
heating in a retort a mixture of three parts of bichromate of potash with 
four parts of concentrated sulphuric acid. This mixture furnishes, at a 
gentle heat, a great abundance of pure oxygen k gas, which amounts to 
but a third of the expense of the same quantity of oxygen prepared by 
