oxide. An atom of carbonic acid weighs 2751; and an atom of peroxide of copper, 10. Therefore the carbonate of copper in the ore amounted to 16.736 grains. Hence the ore is composed of

I had not a sufficient supply of the ore to enable me to decide whether this 5 per cent. of loss be owing to the presence of water, or to an error in my mode of experimenting. I think it not unlikely that I may have lost a little of the copper, as I washed it repeatedly with water on a watch-glass, and poured the water off in order to get rid of the whole of the zinc solution. Now it is possible that a flock or two of the copper might have been carried off by the water without my perceiving it. The loss of half a grain of copper in that way would account for the greatest part of the loss. At the same time I am not aware of having lost any copper, and Klaproth found six per cent. of water in a specimen of blue carbonate of copper which he examined.

X. Death of Guyton de Morveau.

Some months ago M. Guyton de Morveau died in Paris, at a very advanced age. He was probably the oldest chemist in France, having been known as a writer for more than 40 years. His Digressions Academiques, the earliest of his writings with which I am acquainted, was published in 1773. As an experimenter, his merit was not very considerable; but he possessed a much more accurate knowledge of the history of the science than most other French writers. Several of the articles in the first volume of the chemical part of the Encyclopedie Methodique, which he wrote, are excellent, especially the article Acid. It was one of the earliest chemical tracts that I read, and I was indebted to it for a great deal of valuable information. There is a striking contrast between the volume which Morveau wrote of that work, and the various volumes which were contributed by Fourcroy, and the superiority is entirely on the side of Morveau. His reputation was much higher about the year 1787 than some years after. I ascribe this, in a great measure, to the praises lavished upon him by Mr. Kirwan. I shall take a future opportunity of giving a more particular account of the writings of this chemist, and of stating the chemical facts for which we are indebted to him.

XI. Indian Arrow Root.

This very agreeable starch is obtained from the roots of the maranta arundinacea, an American plant, which has been long cultivated in the West Indian islands, and which is said to grow wild in Jamaica. Tussac, in his Flore des Antilles, published in 1808,

gives it the name of maranta indica, and says that it came originally from the East Indies; and Bernhardi, Professor at Erfort, says that the maranta arundinacea and maranta indica are two distinct species; but both these statements are erroneous. The plant is not known in the East Indies; and the fecula known by the name of Indian arrow-root is extracted from the plant called maranta arundinacea by Plumier.

This plant grows to the height of about three feet, and dies down to the root every year. The roots are about 1 inch thick, covered with scales. These roots are washed clean, and pounded in a mortar. The powder is well washed, and the woody fibres separated from it. What remains is the starchy part. It has a beautiful white colour, and makes an exceedingly pleasant article of food when properly dressed. I have been assured that the article usually sold in London under the name of Indian arrow root consists chiefly of potatoe starch.

XII. Identity of Galvanism and the Nervous Influence Vindicated. By Dr. Wilson Philip.

SIR,

(To Dr. Thomson.)

Worcester, March 5, 1816.

In the account in the Annals of Philosophy of that part of a paper of mine which was read before the Royal Society on the 25th of last month, it is observed that I go rather further than my experiments will warrant when I conclude that the nervous influence and galvanism are the same. It is clear, it is observed, that the section of the nerve interrupts the nervous influence, and that my experiments, supposing them correct, show that galvanism puts an end to this interruption, but that it may do this merely by serving as a conductor to the nervous influence. It is impossible to receive a perfectly correct idea of all parts of a paper of this kind from hearing it once read. From the way in which the experiment was made, there seems to be no room for the explanation here pointed out; for the cut ends of the nerve were so far from being applied, or even made to approach each other, that the upper portion was wholly neglected, and the lower portion drawn out, and coated with the tin foil.

It has been remarked that this experiment should have been made on some other animal than the rabbit. This suggestion comes from a quarter of such authority in physiological questions, that I have felt myself called upon to attend to it. I have repeated the experiment on dogs, and found the result, both with regard to the stomach and lungs, in all respects the same as in rabbits. The galvanism was not applied in such force as to occasion any expression of pain, which it does if the power of the trough is more than occasions a slight twitching in the fore legs. From these experiments, as it is observed in the paper alluded to, one of two inferences appears to be unavoidable; we must either admit the identity

of the nervous influence and galvanism, or that there is a power different from the nervous influence yet capable of performing its most complicated functions, a supposition, I think, much harder to be granted than the other.

Both this experiment, and the experiments on rabbits, relating to the same subject, were made in the presence of several medical Gentlemen, who expressed their entire satisfaction in the result. I remain, Sir, your obedient humble servant,

SIR,

C. P. WILSON PHILIP.

XIII. New Spectacle Glasses.

(To Dr. Thomson.)

March 6, 1816.

I have been informed that the French of late have been trying plano-cylindrical glasses with the plane surfaces in contact, and the axes at right angles. These have been used as lenses; and it is said that Dr. Wollaston is in possession of one of this construction. Any information which you can give your readers on this subject cannot fail to be interesting to them.

During the cold weather of January, 1814, a bubble of air (like that which you described a few months ago) was discharged from the spirits of wine of one of Six's thermometers. It measured 16.9°, and was reduced by the application of heat, although it was not then known that any such process had been used with success.

S.

The spectacle glasses alluded to by my correspondent consist of two segments of cylinders applied at right angles to each other. The object, I conceive, is to destroy the effect of spherical aberration. As far as I have been able to learn, this species of lens has not been found to answer well in this country, though I am not quite sure that they have undergone a fair trial.

XIV. Uric Acid.

Gay-Lussac mixed uric acid with 20 times its weight of peroxide of copper, put the mixture into a glass tube, and covered it with a quantity of copper filings. The copper filings, being heated to a dull red heat, heat was applied to the mixture. The gas which came over was composed of 0.69 carbonic acid and 0.31 azote. He conceives that the bulk of the carbonic acid would have been exactly double that of the azote had it not been for the formation of a little carbonate of ammonia. Hence uric acid contains two atoms of carbon and one atom of azote. This is the same proportion as exists in cyanogen. (Ann. de Chim. vol. xcvi. p. 53.) To what, then, are we to ascribe the difference between hydro-cyanic acid and uric acid? Does uric acid contain an atom of oxygen combined to cyanogen, while hydro-cyanic acid consists of the same base united to an atom of hydrogen?

XV. Meteorological Table. Extracted from the Register kept at Kinfauns Castle, N. Britain. Supposed Lat. 56° 234. Above the Sea 129 feet.

Mean

Morning, 8 o'clock. Even., 10 o'clock. Mean of gar-No, of days,

No. 1. On a conical detached hill above the level of the sea 600 feet.... 45.70

XVI. Combination of Prussic Acid and Oil of Peaches. Brugnatelli, by distilling a great quantity of water on the leaves of the peach, obtained an oil, which was kept for eight years in a

well-stopped phial. At the end of that time a considerable number of crystals had separated from the oil. These crystals had the following properties :

A strong smell of peach blossoms; a taste at first sweetish, then sharp and burning. The crystals were confused; but some of them were translucent plates. The specific gravity was 1.300. When thrown upon the surface of water, it moved about with great rapidity, like camphor in the same circumstances. Potash digested with this substance threw down Prussian blue from persulphate of iron. When exposed to the sun for some days, it separated from the oil with which it was contaminated. It then became white, lost its smell, was insoluble in water, but soluble in alcohol. The alcoholic solution, by spontaneous evaporation, gave very brilliant four-sided prisms, whose bases were squares. It was not acted on by nitric acid in the course of 24 hours. Brugnatelli considers this substance as a combination of prussic acid and oil of peaches. (Ann. de Chim. vol. xcvi. p. 96.)

ARTICLE XII.

New Patents.

MARQUIS DE CHABANNES, Russel - place, Fitzroy-square, London; for a method of conducting the air, and regulating the temperature, in houses and other buildings, and warming and cooling either air or liquids in a much more expeditious, and consequently less expensive, manner than hath hitherto been done within this kingdom, which is applicable to various useful purposes, and will be of great public advantage. Dec. 5, 1815.

CHRISTOPH DIHL, Frith-street, Soho, London; for certain improvements in the method or apparatus of distillation. Dec. 5,

1815.

JAMES LEE, Old Ford, Middlesex; for certain improvements in the methods before invented by him of preparing hemp and flax; and by which also other vegetable substances may be rendered applicable to many of the purposes for which hemp and flax are used. Dec. 5, 1815.

Samuel Clegg, of the gas works, Peter-street, Westminster; for an improved gas apparatus. Dec. 9, 1815.

DAVIS REDMUND, Johnson's-court, Fleet-street, London; for a machine for the manufacture of corks and bungs. Dec. 9, 1815, ROBERT KINDER, Hill-street, Liverpool; for a method of propelling ships, boats, and other vessels. Dec. 9, 1815.

ROBERT DICKINSON, Great Queen-street, Lincoln's Inn-fields, London; for an improvement in the hooping of barrels. Dec. 17,

1815.