This precipitate, however, soon turns yellow, then brown, and is ultimately converted into black sulphide of silver, while free sulphuric acid remains in the liquid :—

Ag S2O3 + HO= AgS + HSO4.

All hyposulphites are decomposed by the action of the stronger acids, such as sulphuric or hydrochloric acid, and the So-hyposulphurous acid, as soon as it is set free, is immediately resolved into sulphuSul-rous acid and sulphur. Thus, on adding hydrochloric acid to a solution of hyposulphite of sodium, sulphurous acid is evolved in the form of gas, and sulphur is precipitated in the form of a yellow pow der :

duced by exposure to the air; hence the liquid emits dense white fumes in the air. This compound dissolves a large quantity of sulphur; and a solution, saturated while hot, deposits the sulphur in octohedral crystals on cooling.

Dichloride of sulphur is used for vulcanizing caoutchouc. For this purpose, it is dissolved in 50 times its weight of pure coal naphtha, and the articles of caoutchouc are immersed in the solution for a minute, then taken out, and dried without heat. By this process, the caoutchouc is made to take up a small quantity of sulphur, whereby it is greatly improved in elasticity and strength.

Protochloride of Sulphur, SCI.-Dichloride of sulphur absorbs chlorine gas in large quantities, and is converted into a deep red liquid. On boiling this liquid, a large quantity of chlorine goes off, and there remains a compound, having a specific gravity 1.620, boiling at 147°, and containing 16 parts of sulphur with 355 parts of chlorine. It is decomposed by water in a similar manner to the dichloride.

Sulphur likewise combines with bromine and iodine, but the compounds have not been much studied.

SELENIUM. Equivalent 40;—Symbol Sc.

an odour like that of hydrosulphuric acid, but produces very painful effects when inhaled through the nose. With metallic solutions it forms precipitates, consisting of metallic selenides.

With oxygen, selenium forms three compounds. Two of these-viz., oxide of selenium and selenious acid, are formed together, when selenium is burned in the air or in oxygen gas. Oxide of selenium, Se O, is a colourless gas, having the powerful horseradish odour above mentioned. It is but slightly soluble in water, and does not redden litmus.

Selenious acid, Se O,, is formed, together with the oxide, when selenium is heated in a glass tube through which oxygen gas is passed; it then sublimes in the cold part of the tube in white, four-sided needles. It is also formed by dissolving selenium in nitric acid, or in a mixture of nitric and hydrochloric acid. The aqueous solution of this acid and of its salts is decomposed by sulphurous acid, which takes away the oxygen, and separates selenium in the form of a red powder.

Selenic Acid, SeO3, is obtained in the form of a potassium-salt, by fusing selenium with nitre, (nitrate of potassium); and on dissolving the fused mass in water, and adding a solution of acetate of lead, a precipitate of seleniate of lead is formed, which, when suspended in water through This is one of the rarer elements. It which a stream of hydrosulphuric acid gas occurs associated with sulphur in the Lipari is passed, is decomposed, yielding sulphide Islands and other localities; also in com- of lead and an aqueous solution of selenic bination with several metals, lead, copper, acid. This solution, after filtration, may silver, &c. The methods by which it is be concentrated by heat, till it attains a obtained in a state of purity are too com-specific gravity of 2-6, in which state it has plicated to be described in articles necessarily so condensed as the present.

the composition HSeO4, corresponding to oil of vitriol, which indeed it resembles in Selenium, at ordinary temperatures, is a most of its properties. The dilute acid disreddish brown, brittle, solid, having an im-solves zinc with evolution of hydrogen and perfect metallic lustre. Its specific gravity is 4.3. It is insoluble in water; melts at 212° or a little above, and boils at 650°, giving off a yellow vapour. When heated in contact with the air, it emits a strong and peculiar odour, resembling that of horseradish.

Selenium forms, with hydrogen, a gaseous compound called Hydroselenic acid, or Seleniuretted Hydrogen, HSe, precisely analogous to hydrosulphuric acid; it is obtained, in a similar manner, by the action of dilute acids on selenide of iron, and has

formation of seleniate of zinc, ZnSeO. Selenic acid has not been obtained in the anhydrous state. Its salts closely resemble the sulphates, in colour, form, and chemical composition; indeed they can only be distinguished from the corresponding sulphates, by detonating when thrown on redhot charcoal, and by causing an evolution of chlorine when boiled with hydrochloric acid.

Selenium likewise forms definite compounds with chlorine, bromine, iodine, and sulphur.

[PRIZE.]

Each "theorem" he knew of keen dispute,
Each "problem dark "he solved with glance acute;
And wond'ring Science, at the boy's command

SOLUTION OF BIOGRAPHICAL ENIGMA, Oped all her treasures with delighted hand.

(Page 16);

He track'd each mighty orb that rolls through space;

By MISS CLEMENTINA GRANT, 9, Tavistock Place, Earth's chemic marvels 'twas his joy to trace;

Bishop Wearmouth,

IF ever Genius in a little hour

Scorn'd tedicus years, and burst from seed to flower,
If e'er to stripling boyhood she assign'd

The blossoms and the fruits of heart and mind;
"Twas when to Caledonia Nature gave
CRICHTON, the young, wise, wonderful, and brave!
The miracle of all precocious lore,
His country's pride and glory evermore.
Where lovely Tay, all queenly as she glides,
Bathes the "Fair City "* with her silvery tides;
And shows the Grampians, like a solemn dream,
Mirror'd at sunset in her glassy stream,
This Paragon, with every laurel wreath'd,
The light and breath of heaven first saw and
breathed;

And on the plain where Celtic clans once fought
With cruel rage, † his infant pastime sought.
But scarce the child had ceased its rosy play,
Ere Knowledge met him on his sportive way,
And smote him with such soul inspiring beams,
He leapt the gulph of mortal life's extremes,
From gathering shells upon her earliest shore,
To clambering mightiest cliffs of sternest lore.
Count but his years-so brief their petty span,
You scarce can deem that he was ever man;
Count his great spirit's powers and their employ,
You scarce can deem that he was e'er a boy;
Lo! on the classic banks of haughty Seine,
MEN with this wondrous stripling strove in vain.
There, in the college named from proud Navarre,
Ere twice nine periods of his natal star;
From challenged masters of all Art's domain
"Twas his the victor's stainless wreath to gain;
Baffle the proud, who deem'd their thrones secure,
And foil each practised disputant mature;
Till he who fill'd calm judgment's awful seat,
Voiced the strange triumph, and the strange defeat;
To wondering crowds the bright achievement told,
Gave the gemm'd ring, and piled the tribute-gold;
And the child-victor hence in rolls of fame
Of" ADMIRABLE CRICHTON" bore the name.
But dearer still to him than all the rolls
Of haughty Fame, were Learning's sacred scrolls;
Keenly he grasp'd all truth they could reveal,
And pluck'd their mystery forth with sleepless
zeal;

Drew the sunk jewels from their darkening dust,
And Wisdom's ore made pure from sullen rust;
Branded each cloudy error of the schools,
Each solemn foolery of learned fools:
Nay, showed (despite the schoolmen's threat'ning
rod,)

Where e'en the Stagyrite had falsely trod.

* PERTH. Sec Sir Walter Scott's Fair Maid of Perth. t The North Inch," a piece of beautiful meadow land at Perth, on the river bank, the general play-place of children, and scene of the clan combat in the Fair Maid of Perth. When scarcely eighteen, he challenged all the learned of Paris to dispute with him in the University on subjects drawn from any art or science, and in any one of twelve languages. The palm of superiority was finally assigned to him by the president, together with a diamond ring and a purse of gold.

Each secret of the floral world he knew;
Yet loved its beauties like an infant too!
And viewed with gaze of ecstacy and awe
His God's beneficence in all he saw.

Nor Science only mark'd him reach the goal-
ART's sacred splendours fired his conscious soul;
Touch'd by his pencil's magic, warm and true,
Divinest forms upon the canvass grew.

The laurel of the Dramatist he bore

The changeful sock with matchless skill he wore.
Whene'er he bade sweet Music's strains arise,
A charmed stillness crept o'er earth and skies;
And while through Beauty's region led by taste,
Grandeur and loveliness his soul embraced.

Yet, thus adorn'd and crown'd with all that asks
From other beings sternest toils and tasks,
With all of wisdom graced, and fancy too,
In Solon's heart or Plato's brain that grew;
Thus skill'd in every science, art, and tongue,
A laughing grace on all his motions hung.
With all of studious zeal and manly worth,
He danced the airy round of frolic mirth;
With all of strenuous diligence that e'er
Braced Aristotle's toiling soul to bear,
From peaks of fervid eloquence sublime,
That scarce a Tully had disdain'd to climb,
He bounded to the simple plains below,
And bade the streams of boyish rapture flow;
With graceful trifling pleased each lighter mind;
Charm'd every heart with manners bland and kind.
With gentleness of mien and glance and tone,
Placid in temper, pure in heart and warm,
That Epicurus might have joy'd to own;
"The glass of fashion, and the mould of form,"
Nature in him had all her treasures stored,
"The courtier's, scholar's, soldier's, eye, tongue,
sword."

Ah, word ill-fated!-word that bids me tell
What hapless doom this noblest plant befel;
The doom of "princely DION," when the sword
Of slaughtering treachery his bosom gored,-
Thy doom, O CRICHTON! when a "princely" wretch
Thee at his foot in murderous wrath could stretch:
Accurst in Mantua's records ever be
[thee!
The feast, the night, the hand, that slaughter'd
The hand and heart thine own had strove in vain,
In glory's race, and virtue's path, to train-
That in a moment made that festal time,
For ever and for ever black with crime.

Lo! by the tender light of many a star,
Wanders the stripling with his loved guitar;
And lo! where yonder fiercely treacherous band,
To sterner duties call his startled hand;
Six weapons strive to lay him in the dust-
One skilful weapon foils their every thrust.
Oh! wherefore paint with anguish'd tints anew
The monster prince, the paragon he slew→
Slew, like a demon, with the very blade
His generous victor at his feet had laid,
When goodness, to itself the deadliest foe,
Bared his pure bosom to the dastard's blow;
Black o'er his scutcheon spreads the blot of shame,
And thou, lost Italy, with cheek of flame,
For evermore shalt blush at CRICHTON's name!

Now, the gas, whose volume at the pressure w is V, will at the pressure P be condensed into the volume V. Hence the volume of the gas introduced, at the pres-periment respectively. Then the gas, whose sure P, must be