that could be formed were thrown into it, and the effect invariably was, the extinction of the flame. It is impossible to conceive any lamp more easy to be kept in order, while at the same time it is as simple as any common portable lamp.

Thus have the public been put in possession of a contrivance which was long a desideratum, and which, not many months ago, was ranked among those objects which, however desirable, could hardly be hoped to be attained."

Voltaic Electricity.

M. Dobereiner having subjected mercury in contact with water to the voltaic action, and obtained an amalgam of that metal and hydrogen, at the negative poll, (See our No. for October last); ANDREW CROSSE, Esq. has carefully repeated the experiments, and varied them in almost every possible way. An account of his

experiments has been inserted in the 212th No. of the Phil. Mag. from which we have extracted the following results:

"From the foregoing experiments I venture to draw the following conclusions: that the change in the mercury from a fluid to a more solid substance, when in contact with the positive poll, is simply occasioned by the metal being oxided, which oxygen unites with the hydrogen from the negative wire when touching it, and restores it to its fluidity. That this is proved by its being difficult or impossible to fix the mercury under a fluid, which has power rapidly to dissolve the oxide formed. That phosphorus and sutphur are still simple substances, and have no metallic base; that carbon has never been metallized, as in that case it would in all probability form an amalgam with the mercury under naptha, instead of being deposited in its state of powder. That consequently ammonia, the fixed alkalies and lime, are the only substances mentioned in this course of experiments which contain a metallic base.”

Electricity of the Earth and Atmosphere.

On this subject, Ez. WALKER, Esq. in the continuation of his "New Outlines of Chemical Philosophy," published in the Phil. Mag. observes, that the electricity of the earth is as variable as that of the atmosphere; but as his experiments on this subject amount only to about two thousaud, he thinks they are not sufficient to determine the quantity of it. He, however, observes, that when the earth is very dry, it contains very little electricity, but after heavy rains, it is generally strongly electrified.

Philosophers entertain different opinions relative to the manner in which water and electricity ascend into the atmosphere; and on this meteorological question, Mr. Walker remarks-" The electrical spark being passed through the atmospheric air, light and heat are produced, which shows us the nature of combustion; but when it is passed through water, two gases are formed. The elements of heat and water produce oxygen gas, the elements of light and water

produce hydrogen gas, water being their common basis: consequently, by the attraction between the water on the surface of the ground, and the electricity in the carth, oxygen and hydrogen gases are found, and become atmospheric air. Large quantities of water and electricity are thus carried up into the atmosphere from the surface of the ground in a short time."

Electrical Conductor.

PROFESSOR HILDEBRANDT has recently made a set of experiments to ascertain which metal, when attached to the extremity of the prime conductor of an electrical machine, sends off the greatest visible stream of light. The metals he tried were all made into cones with blunt points, and were fixed to the top of a brass rod attached to the upper part of the prime conductor. The following is the order of the metals, according to the quantities of light they emitted, commencing with that which afforded the greatest, and terminating with that which emitted the least light.

Antimony, ( Bismuth,

(Iron,
Lead,

Soft Steel,

Hard Steel.

Alkaline and Earthy Salts.

A correspondent has addressed a communication to Mr. Tilloch, (See Phil. Mag. No. 212.) on the Solubility of Alkaline and Earthy Salts, as affected by an excess of acid; in the course of which he observes, that "Students naturally conceive that the bases of soluble salts are soluble in the acids which form these combinations-this very extensive error may include the whole class of selts; but as in this I allude to acids of the usual specific gravity, it is alone the permanent and efflorescent salts, which are precipitated by them."-The following are this writer's statements on this subject: viz.

Deliquescent Salts.

SMagnesia,

Nitrates

Ammonia,
Alumina.

Sulphate, Alumina,

Are not precipitated either on the addition of their acids of the usual specific gravity to a saturated solution, or an addition of the dry base to its acid.

Permanent and Efflorescent Salts.

Are not precipitated either on the addition of their acids to a saturated solution, or by throwing the dry base on its acid.

The author then observes, "Metallic salts are also subject to similar changes. We see then, that salts in general, alkaline, earthy, and metallic, partake with barytes of the property of being precipitated under similar circumstances by their respective acids; and generally, according to the greater or less solubility of salts in water, they are precipitated by their acids more or less concentrated."

New Triple Salt.

Mr. GRIGER, an apothecary of Carlsruhe, having evaporated the liquid that remained after the preparation of muriatic acid from a mixture of sulphuric acid and common salt, which he had rendered as free as possible from the cystals of Soda it contained, procured a salt possessing the following properties:

It cry-talized in transparent rectangular oblong or square tables, from the size of one-fourth to one-half of an inch, and one-third of a line in thickness. Some small crystals also appeared nearly of a cubical form. Its taste was cooling, and similar to that of sulIt dissolved in twice phate of soda; and it did not effloresce. its weight of water, at the temperature of 68°; and when the solution became cool, crystals of common sulphate of soda were deposited. Analysis gave for the component parts of this salt,

Sulphuric acid

Muriatic acids
Soda......

Water of crystalization

23.800

0.176

18.524

57.500

100.000.

Sea Water.

Mr. PFAFF, a very able chemist of Kiel, has carefully analysed the waters of the Baltic, which wash the coasts of Germany at that town, and obtained the following results. The specific gravity of the water was 1014; and 100 grains of it contained,

He also shows that muriate of lime and sulphate of magnesia are not incompatible salts, as has commonly been supposed; but that they may exist together in solutions sufficiently diluted with water. Dr. Murray, of Edinburgh, also arrived at a similar conclusion, from his analysis of the waters of Dunblane and Piteaithly.

Boilers for Steam of High Pressure.

T. GILL, Esq. states in the Phil. Mag. for December last, that Mr. Trevithick, who first brought the high pressure engines into use, contrived several methods for preventing such accidents as lately occurred in Well-street, Goodman's-fields. Mr. G. observes, that," in the first place, he proposed enclosing the safety-valve in such a manner, that no one could get access to it, to increase the load beyond that intended; and secondly, in addition to the recurved tube with mercury (which can be adjusted with precision to any pressure intended to be employed, and will blow out before the steam, when the pressure rises even a single pound higher) he drilled a hole in the boiler, which he plugged up with lead, at such a height from the bottom, that the boiler could never boil dry, without exposing the lead to be melted; and consequently, making an opening for the steam, which, by its escape into the fire, extinguishes it.

This contrivance is calculated to prevent the bursting of the boiler, by forcing cold water into it, when allowed by carelessness to become dry, and to get red hot. Metal plugs should always be riveted into such boilers. They should be made of a fusible mixture, that will melt whenever the contents of the boiler attain a certain degree of heat. This should never be omitted, even when the boiler is of the best form, which certainly is that contrived by Mr. Woolf." As some of these safeguards appear not to be so generally known as they deserve to be, we should be glad if our insertion of them in this place should draw the attention of those who make use of such boilers, to the precautions which are absolutely necessary for the safety of all those concerned in their employment.

Alcornoque.

A new medical substance has recently been brought from Martinique to Germany. It is the root of an unknown plant, which the Indians call Alcornoque. Dr. Rein of Leipzig has analysed it, and found it to contain the following constituents: viz.

Pollen of Tulips.

THEODORE VON GROTTHUS has lately analysed the pollen of tulips, and found 26 grains of it to contain the following ingredients:

Fibrous vegetable albumen.....

Dried vegetable albumen

Soluble vegetable albumen

Malate of lime with some malate of magnesia

Malie acid....

Malate of ammonia

Nitre......

Fibrin

Hydrophobia.

A successful case in the treatment of this disorder by Eloodletting, has lately occurred in Germany. A young woman had been bitten in the foot by a dog, and the wound bled a little; four days after which, she felt herself unwell; and on the 8th day Dr. Vogelsang of Goerlitz opened a vein, but the blood stopped flowing when about eight ounces had been taken. The Doctor conceiving that the effect of blood-letting in this disorder very probably consisted in the collapsus vasorum, occasioned by a sudden evacuation, he caused a large orifice to be made, and 29 or 30 ounces flowed in a considerable stream; when the patient fainted, notwithstanding the use of sal-ammoniac. When recovered she was caused to swallow a calomel powder, and about a quarter of an ounce of mercurial ointment was rubbed on her throat. About a quarter of an hour afterwards she fell into a gentle sleep, and on waking felt great weakness, accompanied with a violent head-ache; and vomited a great quantity of phlegm. About eight minutes after this, she ate a slice of bread and butter, and drank a dish of coffee, and by the 30th day she was quite recovered.

Eatable Nests.

Those nests which are built by the hirundo esculenta, in some of the East India islands, and are in such great esteem, as articles of luxury, in China, have been analysed by M. DOBEREINER; and found to be composed of the following substances: viz.

Mucus. Albumen. A trace of gelatine. A peculiar substance, insoluble in water, alcohol, and most other re-agents, bearing some resemblance to fibrin; but constituting in fact a distinct animal body. Of this the greatest part of the nest is composed. It swells, becomes transparent and gelatinous like tragacanth, when Aug. Rev.

NO. XI.

VOL. II.

Z