Images de page
PDF
ePub

ARTICLE XII.

Proceedings of Philosophical Societies.

ROYAL SOCIETY.

Dec. 10.-A paper, by M. Theodore de Saussure, was commenced, entitled 'Observations on the Decomposition of Starch by the Action of Air and Water at 'common Temperatures,

Dec. 17.-The above paper was concluded. A portion of starch simply boiled in water was exposed for two years under &. glass jar in a temperature between 68° and 77o. At the end of this time, about ld of it was found converted into saccharine matter, having all the properties of sugar prepared from starch by the action of sulphuric acid, according to the method of M. Kirchhoff. On observing this curious circumstance, the author was induced to examine more attentively the nature of the changes which took place. He found that, besides sugar, a species of gum was formed, similar to that obtained by roasting starch ; also a peculiar intermediate substance, which he denominated amidine, while a substance remained, insoluble in water and acids, which gave a blue colour with iodine, and was probably starch somewhat altered in its properties. The author states, that when air is present during the above process, water and carbonic acid gas are given off in considerable quantities, and that charcoal is deposited ; but on the contrary, that when air is excluded no water is formed, that only a little carbonic acid and hydrogen are extricated; and that no carbon is deposited. The author was unable to determine whether the presence or absence of air affected the quantity of sugar obtained. The paper was concluded with some remarks, which rendered it probable that water is fixed, during chemical operations, upon organized substances more frequently than is usually supposed.

At this meeting also, a paper, by C. Babbage, Esq. was read, on the solution of some problems relating to the games of chance. The object of the author was to show, that a certain series of questions, hitherto supposed to lie beyond the reach of analytical investigation, might be adapted to algebraic reasoning. Dec. 24.-A paper, by Capt. Duff

, R. N. was read, on the prevention of the dry rot in timber, by means of peat moss. The author, after stating the well-known effects of peat moss in preserving wood for ages unaltered, suggests that a set of experiments should be made to ascertain the effects of impregnating timber, both sound and already partially decayed by the dry rot, with the water from peat mosses, with the view of determining whether it possesses any power in preventing, or suspending, the insidious operation of that destructive agent.

LINNEAN SOCIETY. Nov.3.- A paper, by Dr. Leach, was read, on the Cymothoada, a family of Crustacea, with Sessile eyes.

Nov. 17.-The Society met ; but adjourned immediately on account of the death of the Queen.

Dec. 15.-A paper, by Joseph Sabine, Esq. F.R.S. and F.L.S. was read, containing an account and description of a new species of Gull (Larus Sabini), lately discovered on the west coast of Greenland, and which is characterized by having a furcate tail, like the Tern.

At this meeting also, part of a paper, by Joseph Smith, Esq. F.L.S. was read, entitled “Some Account of the Botany of Jersey, Guernsey, Alderney, and Sark.

[ocr errors]
[merged small][ocr errors]

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS

CONNECTED WITH SCIENCE.

I. Action of Iron on Water. M. Guibourt has shown by a set of experiments, which appear accurate, that iron has the property of decomposing water at the common temperature of the atmosphere. The decomposition is most rapid, when the quantity of iron bears a great proportion to the quantity of water. In that case, the temperature rises considerably, the decomposition goes on more rapidly in proportion as the temperature is more and more elevated. (Journ. de Pharm. June, 1818, p. 241.)

M. Robiquet has ascertained that the black oxide of iron formed by the action of water on iron at the ordinary temperature of the atmosphere, is exactly, similar to the oxide formed by the action of red hot iron on steam. Now it is well known that this last oxide is a compound of one atom of protoxide and one atom of peroxide. The octahedral iron ore of mineralogists is a similar compound.-(Ibid. p. 308.)

II. Carbonate of Iron. As far as we know at present, the only oxide of iron capable of combining with carbonic acid is the protoxide. Carbonate of iron found native is a compound of an atom of carbonic acid and an atom of protoxide of iron. I have never been able to succeed in my attempts to form a percarbonate of iron, though analogy leads me to suspect the possibility of the existence of such a salt.

III. Action of Prussian Blue on Starch. M. Vincent, an apc thecary in France, has published the following curious fact. If four parts of starch and one part of

prussian blue be mixed and triturated together in a mortar, 60 as to make as intimate a mixture as possible, and this mixture be boiled in a considerable quantity of water, the liquor, before it reaches the boiling temperature, acquires a green colour : it then becomes brown, and there remains a precipitate, which does not recover its blue colour, though treated with acids. The liquor has the property of forming a very fine prussian blue, when treated with a solution of sulphate of iron mixed with an equal volume of solution of chlorine. When the liquid is evaporated, no gluey substance is deposited ; but if it be reduced to a small volume, and allowed to cool, it gives a glutinous matter, which dries in the open air, and is again easily dissolved in water. The starch then is altered in its nature, and converted into a kind of gum.-(Ibid. p. 325.)

IV. Deaths in Paris during 1817. The following tables are so curious and so instructive that I have copied them from the annual report published in the Journal de Pharmacie. Deaths in 1817

21,386

19,805 Excess in 1817

1,581 These deaths consist of 13,555 who died in their own houses;

1816.

viz. :

3,929 $ 7,827

}

Males.

6,5992 Females.

6,956 S

13,555 The remainder consist of 276 dead bodies deposited in the Morgue, and 7,827 who died in the hospitals, viz. Males.

3,8987 Females. The number of persons who died of the small-pox in 1817 was 488, viz. Males...

2502

486
Females.
The number in 1816 was.

150
Excess in 1817.

336 The 276 dead bodies deposited at the Morgue in 1817 con

236

sisted of

Males...

205

276
Females.

71
The number of drowned in 1816 was.. 278
And that of suicides..

188
Suicides in 1817.

197

If we admit that at least one half of the drowned persons underwent a voluntary death, the number of suicides in 1817 will amount to 335, or to more than six every week.

In 1808, 1809, 1810, the annual number of suicides was from 50 to 55. This number has increased progressively since 1812.

V. Saffron supposed to prevent Sea Sickness. M. Cadet, who spent part of the summer of 1817 in London, mentions that when he crossed the channel from Calais to Dover, he observed an English gentleman with a bag of saffron suspended over his stomach. On inquiring the reason, he was told by the gentleman that it was a practice which he always followed when crossing the channel, because it preserved him from sea sickness. The remedy was found out, he said, in the following way. A small merchant, who had occasion to make frequent voyages, was always tormented with sea sickness when on ship-board. One day he embarked, after purchasing a pound of saffron, which he put under his shirt in order to avoid ying duty for it. He escaped without experiencing any sea sickness, though the sea was rough. Ascribing this lucky escape to the saffron, he communicated his discovery to several of his friends, who made repeated trials of the remedy, and always with success.

I have translated the above passage from the Journ. de Pharm. July, 1817, p. 335, though far from implicitly believing that saffron is likely to oure this hitherto incurable malady; but that the alleged cure may be generally known, and that its efficacy may be tried by those who have occasion for the remedy,

VI. Purification of Platinum. The Marquis of Ridolfi has proposed a method of purifying platinum, which seems worth the attention of those who have occasion for platinum vessels for the purposes of manufacture, as it would materially diminish the price of that expensive metal. It is obvious that the platinum will not be obtained quite free from lead; but it is not probable that the small portion of that metal still left in it would render it injurious to the sulphuric acid makers, who are the manufacturers that chiefly employ platinum upon a great scale.

Ridolfi separates mechanically such foreign bodies as can be detected by the eye in crude platinum. He then washes it in dilute muriatic acid. The next step of the process is to fuse the crude metal with four times its weight of lead, and to throw the melted alloy into cold water. It is then pulverized, mixed with its own weight of sulphur, and thrown into a hessian crucible previously heated to whíteness. A cover is placed on the crucible, and it is kept at a red heat for 10 minūtes. When allowed to cool, a brilliant metallic button is found under the scoriæ, composed of platinum, lead, and sulphur. A 'little more lead is added, and the alloy is fused a second time. The sulphur

[ocr errors]

separates with the new scoriæ, and there remains an alloy of platinum and lead. This alloy is heated to whiteness, and while in this state, hammered upon an anyíl with a hot hammer. The lead is squeezed out, and the platinum remains.

Platinum obtained in this way is as malleable and ductile as the finest platinum. Its specific gravity is said to be 22.630. If so, it must be alloyed with lead; for pure platinum is not so heavy:

VII. Reumic Acid. Some years ago a paper by Mr. Henderson, on the acid of rhubarb, was inserted in the Annals of Philosophy. The result of his experiments led him to consider it as a peculiar acid, which he distinguished by the name of reumic acid. The only characteristic property, however, by which he was able to distinguish it, was that of dissolving mercury.

A set of experiments on the juice of the rheum ponticum has been lately made by M. Lassaigne, with a view of verifying the results obtained by Mr. Henderson. The juice of this plant is abundant, and very acid; but the acid possesses all the characters of the oxalic, and has no action whatever upon metallic mercury. The reumic acid, of course, does not exist as a peculiar acid. (See Ann. de Chim. et Phys. viii. 402.)

VIII. Perchloric Acid. Sir Humphry Davy has verified the curious discovery made some years ago by Count von Stadion, of a combination of chlorine and oxygen, containing more oxygen than chloric acid, and which, therefore, may be distinguished by the name of perchloric acid. A particular account of the experiments of Count von Stadion will be found in the Annals of Philosophy, ix. 22. I have likewise given an account of this curious acid in the last edition of my System of Chemistry, IX. Aurora Borealis at Sunderland. By Mr, Renney.

(To Dr. Thomson.) SIR,

Bishopwearmouth, Nov. 4, 1818. On Saturday night, the 31st ult. between seven and eight o'clock in the evening, was observed, at Sunderland, that beautiful phenomenon the aurora borealis, in a more singular form than I have at any time before seen it. Due north appeared a very dark dense cloud, nearly in the form of a segment of a circle; the altitude about 150, from behind which issued upwards equally fine radii, about 20° in length, and gave light equal to the twilight in summer, casting a sensible shadow against a wall, facing the north, and had a very fine appearance. The remainder of the hemisphere was perfectly clear. **About 11, the cloud had the same appearance, but the radii very much altered; in some

« PrécédentContinuer »