16. Pure Proto-Salt of Iron.-A solution of protoxide of iron, without any admixture of peroxide, may be obtained by putting iron into an aqueous solution of sulphurous acid, and suffering the mixture to remain for a short time without contact of the air. When a solution of the ferro-cyanate of potash is added, a perfectly white precipitate is formed, which is the proto-ferrocyanate of iron.-Phillips, Phil. Mag., N. S., i. 72.

17. Action of Potassium on Oxalates.-When well-dried oxalate of lead, mixed with very small portions of potassium perfectly freed from naphtha, is heated in the bottom of a glass tube, air being carefully excluded by excess of the oxalate, a violent detonation suddenly takes place, before the heat is sufficiently great to effect the decomposition of the oxalate, when no potassium is present. The tube is spotted with metallic lead, the potassium is oxidized, and there is no carbon deposited. An examination of the gas resulting from this instantaneous decomposition may elucidate the nature of the oxalates, but hitherto the apparatus employed has always been broken by the explosion. Oxalate of copper, treated in the same way, has always occasioned strong detonations, and metallic copper appears.-Jour. de Phar., Phil. Mag. N. S., i. 145.

18. Analysis of the Triple Prussiate of Potash.—Mr. Phillips, by carefully experimenting with the crystallized triple prussiate of potash, obtained the following proportions per cent. of three of its elements :

the remaining 37.17 parts are assumed, according to the analysis of Berzelius, to be cyanogen.

the salt, which he considers as most probable, is as follows:

The nature and composition of

6 atoms carbon..

..36

42

1

3 hydrogen

1 atom oxygen..
iron

3

8

28

1171 atom ferro-cyanic acid

2 atoms potash

...96

213

Viewing this as the constitution of the salt, it is a di-ferrocyanate of potash, or composed of one atom of sand and two atoms of base.-Phil. Mag. N. S., i. 110.

19. Preparation of Medicinal Chloride of Soda.-Mr. Payen has published a process, by which he prepares this substance of

uniform strength, without involving the trouble of first preparing chlorine gas. For this purpose he has recourse to the mutual action of carbonate of soda and chloride of lime. M. Payen first ascertained the mean proportion of chlorine in the medicinal solutions of M. Labarraque, and then compared it with the proportion of chlorine in chloride of lime, represented by 98 degrees of Gay-Lussac's chlorometer. These experiments showed that 1 part by weight of chloride of lime of 98° was equivalent to 20 parts of medicinal chloride of soda; that 100 parts of this chloride of lime are completely decomposed by 138 parts of crystallized sub-carbonate of soda; and finally, that, by adding 62 parts of the last salt to the neutral solution of the chloride, its excess was sufficient to render the compound permanent. The following is therefore the formula for the preparation of the chloride of soda:

Chloride of lime at 98°
Crystallized sub-carbonate of soda.
Water

100 by weight

138

. 1800

The chloride of lime is to be dissolved, and the sediment well washed; carbonate of soda dissolved by heat is to be poured into the solution, the precipitate allowed to subside, the clear fluid decanted, and the solid matter washed on a filter. The collected solutions are neutral chloride of soda; 62 parts of the sub-carbonate of soda are then to be dissolved in the remainder of the water, and added to the preparation; the whole being then filtered, a limpid solution is obtained, indicating 5° by the areometer of Baumé. It is the pure chloride of soda.

If the chloride of lime be of any other strength than 98°, then the relation is easily ascertained by the chlorometer and a brief calculation, and the equivalent of the quantity above directed must be used.-Bull. Philom., 1826, 151.

20. Mode of Action of Disinfecting Chlorides.-The combinations of chlorine with lime and with the carbonate of soda, have lately been highly recommended as disinfecting agents, and apparently with some reason. The names which have been given to the substances, and the statement of their effects and mode of action have, however, been singularly irregular, vague, and uncertain; and it is, therefore, with some pleasure we refer to certain experiments and observations of a clear and satisfactory nature, by M. Gaultier de Claubry.

Well-saturated chloride of lime, being dissolved in water, was submitted to the action of a current of carbonic acid gas; chlorine was quickly disengaged, and by continuing the operation a sufficient length of time the whole was expelled; the liquor no longer possessed bleaching powers, and carbonate of lime had been formed and precipitated, except a small portion dissolved by the excess of carbonic acid.

Air passed slowly through a saturated solution of caustic potash, was then made to traverse a solution of the chloride of lime: no chlorine was liberated; no effect of any kind produced.

The carbonate of lime resulting from the decomposition of the chloride of lime by carbonic acid, retains no chlorine in combination.

The chloride of soda is equally decomposed by carbonic acid, only more slowly, in consequence of the solubility of the salt produced, A specimen of chloride of lime, being examined as to the quantity of muriate that it might contain, was found to have exactly the same quantity before and after decomposition by carbonic acid gas.

A filtered solution of the chloride of lime was exposed to air on the 13th of August; on the 10th of October it no longer contained chlorine, did not affect litmus, and the precipitate from it proved to be carbonate of lime. A stronger solution of the same chloride, exposed to air, on the 16th of August, was found in the same state as the last on the 10th of October.

Notwithstanding that these experiments sufficiently indicated the manner in which these compounds acted on the putrid miasmata floating in foul air, some further experiments were made in the following manner :-Air was passed through blood, which had been left to putrefy for eight days; being then passed through a solution of the chloride of lime, carbonate of lime was deposited, and the air was rendered inodorous and completely purified. In a second similar experiment, the fetid air was passed through a saturated solution of caustic potash, before it arrived at the solution of chloride; the latter then had no effect upon it, and the air retained its insupportable odour. Another experiment was made with air left for twenty hours over putrescent blood; the portion of it, which was passed directly through the chloride, was perfectly purified, but when previously freed from carbonic acid, the chloride had no effect upon it.

It is easy to explain the preference given in many cases to the application of chlorides, as disinfecting agents, above fumigation by chlorine. The carbonic acid in the air, arising from the decomposition of animal matter, liberates the chlorine from its combination; and as this action is slow, the chlorine is less susceptible of affecting the animal economy, but readily decomposes putrid miasmata. It is, therefore, a true fumigation by chlorine, only less violent than those made directly by the gas, and continuing for a longer time.—Annales de Chimie, xxxiii. 171.

21. Deleterious Effects of Carbonic Acid Gas.-The conclusions to a memoir, by M. Collard, on this subject, are as follows:i. Animals plunged into carbonic acid gas do not die, as in hydrogen or nitrogen, from the want of air only. ii. That the experiments by which Bichat, Nysten, and other modern authors, have endeavoured to establish a contrary statement, are inexact in numerous points. iii. That carbonic acid gas exerts a special deleterious action,

iv. That this action principally affects the brain and nervous system. v. That the best remedial process for accidents occasioned by carbonic acid gas, consists, probably, in excitations of the diaphragm produced by the voltaic pile.—Bull. Univ. C. ix. 321.

22. New Acids obtained from Animal Substances by Alkalies.— MM. Chevreul and Gay-Lussac, by treating animal substances with alkalies, have obtained various acids remarkable for their property of neutralizing bases, and in which nitrogen enters as an element. They are occupied, at present, with these acids, and will publish their results as soon as they are completed.-Annales de Chimie, xxxiii. 335.

23. Sugar of Melons.-The melon has occasionally been thought of as a source of sugar, and its juice submitted to processes calculated to separate that principle from the accompanying but deteriorating matters. M. Payen has lately applied analytical processes to the juice of a melon cultivated near Paris, and from 100 parts of the liquid obtained 1 parts of sugar, perfectly well crystallized in rhomboidal parallelopipeds, and having the taste and other properties of cane-sugar, with which it appeared to be identical.-Bull. Philom. 1826, p. 135.

24. Method of Destroying the Empyreumatic Odour of Alcohol, by Dr. Witting. The purification of alcohol by chloride of lime is not expensive. The action is chemical, and analogous to that of bleaching; the empyreumatic parts are entirely destroyed. The following is the manner in which it has been employed: two ounces of the chloride were mixed with spirit into a uniform clear fluid, which was then put into a distillatory apparatus, with 150 measures of spirit; all the joints were then luted, and the distillation commenced. The first measure of product had a slight odour of chlorine, and was preserved apart for rectification; the rest of the produce was perfectly pure. The chloride made use of should, when dissolved in 26 parts of water, bleach vegetable colour with which it may be mixed.-Bull. Univ. E. vi. 333.

25. On the Colouring Matter of the Madder, by MM. Robiquet and Colin.-Diffuse the ground madder in three or four parts of water, submit the whole to strong pressure, and repeat the washing thrice; macerate the residue in a water-bath in five or six parts of water, containing half a pint of alum; filter, and precipitate the fluid by sub-carbonate of soda. The precipitate should be carefully washed; the macerations are to be repeated in alum-water until the colour is exhausted. By this means a result is obtained in three hours, which otherwise would require months, and everything induces the supposition that the diminution in price of madder lakes, resulting from such simple methods, will permit their employment even on stained papers.-Globe, Nov. 11.

III. NATURAL HISTORY.

1. Subterraneous Noises heard at Nakous.-Nakous is situated three leagues from Tor, on the Red Sea. This place is celebrated because of certain sounds produced there at all hours of the day and night. When Mr. Gray, of Oxford, visited Nakous, he heard from beneath his feet a continued dull noise, which soon changed into pulsations, more and more intense, similar to the beats of a time-piece. The next day, Mr. Gray heard the sounds during a whole hour, the weather being clear and serene; and he concluded that the effect could not be produced by the passage of air through certain crevices in the soil and rock, every examination for such fissures in the soil or rock having failed.

The following account of the same place is by M. Seetzen, and was published in 1812:-There is near Tor, a mountain, not only the most remarkable in certain respects of any in Arabia Petræa, but in the whole world. It is called el Nakous, and is three leagues north of Tor: two years ago I had heard it spoken of by the Greeks, first, of the convent of Sinai, afterwards, at Suez; but the description being accompanied with fabulous recitals, induced When I gained me to suppose the whole a monkish invention. more information at Wady el Nachel, not only were these first accounts confirmed, but new prodigies added.

M. Seetzen then goes on to state, that, “ accompanied by a Christian Greek and some Bedouins, I departed for the mountain on the 17th of June, at five o'clock in the morning: after a quarter of an hour's progress, we arrived at the foot of a majestic rock of sandstone; the mountain, perfectly naked, was entirely composed of it. I found many Greek and Arabic names on the rock, and some even in Coptic characters, proving that the place had been visited for ages. At mid-day we arrived at the part of the mountain called Nakous: here, at the foot of the chain, we found an insulated rock. On two sides the mountain presented two surfaces, so highly inclined that the white and slightly-adhering sand which covered them was scarcely supported, and slided at the slightest vibration, or when the burning rays of the sun destroyed their slight adherence. These two sandy surfaces were about 150 feet in height; they re-united behind the insulated rock, forming a sharp angle, and, as well as the adjacent surfaces, were mingled with steep rocks, most frequently formed of a friable white sandstone.

"The first sound was heard at one hour and a quarter after midday. We climbed with difficulty up the sand-bank, a height of 70 or 80 feet, and stopped under certain rocks, at which it is the custom to listen. Whilst creeping, I heard the sound from under my knees, which induced me to suppose that the slipping of the sand was the cause, and not the effect of the sonorous vibration. At three o'clock, the sound was again heard more strongly, and continued for six minutes; then ceasing for about ten minutes,