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Yet, though thou wear'st the glory of the sky, 4. "There was neither tree, nor shrub, nor field, nor house,

Wilt thou not keep the same beloved name, nor living créatures, nor visible remnant of what human hands

The same fair thoughtful brow, and gentle eye, and reared."

Lovelier in heaven's sweet climate, yet the same? 6. " And I, creature of clay, like those here cast around, I Shalt thou not teach me, in that calmer home, travel through life, as I do on this road, with the remains of

The wisdom that I learned so ill in this,

The wisdom which is love,-till I become
past generations strewed along my trembling path ; and,
whether my journey last a few hours more or less, must still,

Thy fit companion in that land of bliss ?"
like those here deposited, shortly rejoin the silent tenants of

Doth Inflections, in conncxion.
some cluster of tómbs, and be stretched out by the side of
some already sleeping corpse."

Rule 1.- Exercise 1. “It is not a parchment of pédigree,

it is not a name derived from the ashes of dead men, that make 6. "I am charged withịpride and ambition. The charge is true, the only charter of a king. Englishmen were but slàves, if, and I glory in its truth. Who ever achieved any thing great in giving crown and scepire to a mortal like ourselves, we ask in letters, arts, or arms, who was not ambitious ?

Cæsar was not, in return, the kingly vìrtues." not more ambitious than Cicero. It was but in another way. 2. "The true enjoyments of a reasonable being do not conAll greatness is born of ambition. Let the ambition be a noble sist in unbounded indulgence,* or luxurious éase, in the one, and who shall blame it? I confess I did once aspire to be tumult of passions, the languor of indolence, or the flutter of queen, not only of Palmyra, but of the East. That I am. I

light amúsements. Yielding to immoral pleasures corrù pts now aspire to remain so.' Is it not an honourable ambition the mind; living to animal and trífling ones, debàses it: both, Does it not become a descendant of the Ptolemies and of Cleo- in their degree, disqualify it for genuine goud, and consign it patra? I am applauded by you all for what I have already over to wretchedness." done. You would not it should have been less.

3, “What constitutes a state :-"But why pause here? Is so much ambition praiseworthy, and more criminal? Is it fixed in nature that the limits of Not high raised båttlements, or laboured móund, this empire should be Egypt on the one hand, the Hellespont

Thick wall, or moated gate; and the Euxine on the other? Were not Suez and Armenia Not cities proud, with spires and turrets crowncd, more natural limits? Or hath empire no natural limit, but is

Not bays and broad-armed pórts, broad as the genius that can devise, and the power that can win.

Where, laughing at the storm, proud návies ride; Rome has the West. Let Palmyra possess the East. Not

Not starred and epangled courts,that nature prescribes this and no more. The gods prospering, Where low-browed baseness wafts perfume to príde! and I swear not that the Mediterranean shall hem me in upon

No !--mèn, -high-minded me'n,the west, or Persia on the east. Longinus is right,-I would

Men who their duties know, that the world were mine. I feel, within, the will and the power But know their rights, and, knowing, dare maintàin." to bless it, were it so.

Note. Concession and Unequal Antithesis.' "Are not my people happy? I look upon the past and the

Lx. “ The clouds of adversity may darken over the Christian's present, upon my nearer and remoter subjects, and ask nor fear the answer. whom have I wronged what province páth. But he can look up, with filial trust to the guardian bare I oppressed ? —what city pillaged ?-what region drained care of a beneficent Father."

2. “I admit that the Greeks excelled in acuteness and ver. with taxes :—whose life have I unjustly taken, or estates coveted or robbed ?-whose honour

have I wantonly assailed i satility of mind. But, in the firm and manly traits of the - whose rights

, though

of the weakest and poorest, have I Roman character, I see something more noble,-more worthy trenched upon: -I dwell, where I would ever dwell, in the of admiration." hearts of my people. It is written in your faces, that I reign helpless tools : we war against our opprèssors,-nut against

3. “We war against the leaders of evil,—not against the
not more over you than within you. l'he foundation of niy
throne is not more power than love."

our misguided bréthren.
4.

“Still, still, for ever
7. "How shall I know thee in the sphere which keeps

Better, though each man's life-blood were a river,
The disembodied spirits of the dead,

That it should flow, and overflow, than creep
When all of thee that time could wither, sleeps,

Through thousand lazy channels in our veins,
And perishes among the dust we tread ?

Dammed, like the dull canal, with locks and cháins,

And moving, as a sick man in his sleep,
For I shall feel the sting of ceaseless pain,

Three paces, and then faltering. better be
If there I meet thy gentle presence not ;

Where the extinguished Spartans still are free,
Nor hear the voice I love, nor read again

In their proud charnel of Thermopylæ,
In thy serenest eyes the tender thought.

Than stagnate in our marsh."
Will not thy own meek heart demand me there?

Exception. Emphatic Negation.'
That heart whose fondest throbs to me were given?

Exercise 1,
My name on earth was ever in thy prayer,

“I'll keep them all ;

He shall not have a Scot of them;
Shall it be banished from thy tongue in heaven ?

Nò, if a Scot would save his soul, he shall not."
In meador
heaven's thing wind

2. “Do not descend to your graves with the disgraceful f that

ere,

censure, that you suffered the liberties of your country to be ind,

taken away, and that you were mùtes as well as còwards. here?

Come forward, like mòn: proièst against this atrocious at

tèmpt.” past,

3. “I am not sounding the trumpet of war. There is no man who more sincerely deprecates its calamities, than I do."

4. “Rest assured that, in any case, we shall not be willing to rank làst in this generous contest. You may depend on us for whatever heart or hand can dò, in so noble a cause."

5. “I will cheerfully concede every reasonable demand, for

the sake of peace. But I will not submit to dictation." ill.

Rule II. Question and Answer.'-- Exercise 1. “Do you think these yells of hostility will be forgotten ?-Do you suppose

their echo will not reach the plains of my injured and insulted } scroll; ell

The penultimate inflection falle, when a sentence ends with the rising slide.

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WOOD:

country, that they will not be whispered in her green valleys,

Wilhelm Prill, Dewsbury, Yorkshire

James llall, and heard from her lofty hills : -Oh! they will be heard there:

Brooke Whiteley, yès, and they will not be forgotten.”

Thomas Muffit, 2. “I will say, what have any classes of you, in Irelanı, to

K. Simpson, hope from the French? Is it your property you wish to pre

Charles Curshaw, serve ? --Look to the example of Holland ; and see how that

CHEMISTRY. nation has preserved its property by an alliance with the French! Is it independence you couri?-Look to the example SIR.-Since the issue of your articles on Chemistry in the of unhappy Switzerland: sce to what a state of servile abase- POPULAR EDUCATOR, I have been studying them practically, and ment that once manly territory has fallen, under France! Is with perfect success. I find, however, many drawbacks incident it to the establishment of Catholicity that your hopes are di- to the carrying on of some processes alone, owing to some of the rected ?--The conduct of the First Consul, in subverting the experiments being inconvenient or dangerous without a room for

The purpose; the want of apparatus that would prove too expensive; power and authority of the Pope, and cultivating the friend. ship of the Mussulman in Egypt, 'under a boast of that sub and, above all, inability to carry on any interchange of ideas.

I believe that the consideration of these facts has deterred version, proves the fallacy of such a reliance.--Is it civil many from commencing the study of this useful branch of science, liberty* you require ?-Lock to France itself, crouching under who otherwise wouid have entered upon it with spirit

. As there despotism, and groaning beneath a system of slavery, unparal- may be many young students who like myself have prosecuted this leled by whatever has disgraced or insulted any nation.' study alone up to the present time, it has occurred to me to propose

to those who may be residing in the vicinity of Camberwell, to unite 3. “Shall I be left forgotten, in the dust,

and form a class for mutual improvement and advancement in When Fate, relenting, lets the flower revive?

various sciences; but more especially for the purpose of studying, Shall Nature's voice,-to man alone unjust, -

in deep earnest, Chemistry practically and theoretically. Bid him, though doomed to perish, hope to live?

The expense being then divided amongst us, would be compara. Is it for this fair Virtue oft must strive

lively trilling to each. The advantages of such a plan, when all are With disappointment, pénury, and páin?

resolutely determined to persevere in their object, would be great. Nò: Heaven's immortal spring shall ret arrive,

One or two have already joined in furtherance of these views.

Your well-proved willingness to advance all efforts in the cause of
And man's majestic beauty bloom agàin,
Bright through the eternal year of Love's triumphant rèign." progress, has induced me to request your insertion of this letter.

Communications to be addressed to
Rule III. “Disjunctive " Or."'-Exercise 1. “Will you rise

T. G. LINSTEAD, 28, High Street, Newington Butts. like menpand firmly assert your rights, or will you tamely

London, 13th May, 1854. submit to be tràmpled on :"

2. “Did the Romans, in their boasted introduction of civilisation, act from a principle of humane interest in the welfare

ANSWERS TO CORRESPONDENTS. of the world? Or did they not rather proceed on the greedy and selfish policy of aggrandising their own nàtion, and ex. T. BOCock (Great Warley): His algebraic solutions are correct.-W.

Booth (Waterhead Mill): Very good, but not quite up to our mark.-A. tending its dominion?"

His "contemp ntion on the autumnal season" is as yet rather 3. "Do virtuous hábits, a high standard of morálity, pro premature ; we like fruits, poetical or otherwise, in their seasons.-W.C. ficiency in the arts and embellishments of life, depend upon Colchester): His solutions, amounting to 94 out of the 100 Problems,

are all correct and very well done. We are much gratified with his account physical formation, or the latitude in which we are placed :t Do they not depend upon the civil and religious institutions when he only began to study Algebra in the P. E., and in Cassell's Algebra,

be , which distinguish the country :"

is a very great achievemen!.

Excelsior: The knowledge of French is, in our opinion, most easily [The remaining rules on 'inflection,' as they are of less acquired ; but that of Greek is the most valuable to the man who wishes to frequent application, are thought to be sufficiently illustrated read the New Testament in the orieinal tongue; at the same time it is the by the examples appended to each rule. A repetition of these, most difficult of all.-AUDIENS (Portland-town): In Greek, the Gamma

has always the hard sound, as in English the g has before a, o, and . The however, may be useful as an exercise in review

Upsilon, whether spelt in English

words with yor u, always sounds in Greek like the French u.-E. H. W.: The Latin is completed in the P. E., but there are other books in the Latin Language on Mr. Cassell's list; study

them. CORRESPONDENCE.

R. F. T.: We are quite disposed to take the most favourable view of our

correspondent's motives, and also of his endeavours to solve the problem UNIVERSITY OF LONDON.

relating to the four balls. We confess, however, our inability to compre

hend his reasoning; but this may be as much, if not more, our fault than We have received the following names to be added to the Peti- nis; we are old, and accustomed to take Euclidean views of things; and tion for the removal of the restrictions in graduating at the as it seems that he cannot quite follow us in that direction, we must be University of London; they have been forwarded, as desired. content to remain as we are, ignorant of his peculiar method of explanation.

But heaven fortid that we should barbour any suspicion of evil intentions," Henry John Cockburn, Dewsbury, Yorkshire

we can't conceive how this entered his mind, for it never entered ours ! John Wilson,

do,

“ Honi soit que mal y pense." James Johnson,

A DEVBRONSIDE PLOUGHMAN: His answer to the “ Four Ball Query" is William Henry Shaw

Very nearly correct, and his solutions to the three hardest problems in the John Smithson, Senr,

"Centenary of Probleins" very good. Let him go on and prosper; persen Thomas Smith, David Watson,

verance overcomes all difficulties.-W. R. H. (Cowley): Thanks.-H.

Jones (Islington): The very thing he wishes is preparing.-G. H. (W.
Vinson Jessop,
Percival Muffit,

(Hampton): The pronunciation which he has given of gibier and c'est are Wm. Smithson,

quite correct.-SIMPLICITAS (Wemyss): We shall keep his suggestion William Partinson,

Hist: and Theo: Novice: Surely he knows that Hume, Gibbon, Hallam A. Wilson, and Macaulay are celebrated as Historical Writers; and that Hall

, Foster, John Smithson,

Wilberforce and Smith are celebrated as Theological Writers; all for

elegance and force; but he must beware of the infidel principles of Home John Richardson,

and Gibbon, and the flippancy of Macaulay; also of the heterodox opinions Zulius Hertz,

of Foster.-W.C. (Uxbridge) must really turn poet him.self; our cortes Malia Bertz,

pondent quite coolly asks us to paraphrase a passage of Milton's " Paradise Zulia Hertz,

Lost" for him, and insert it in the P. E.! What next?
Charles Brook,
Wm. Whiteley,

LITERARY NOTICE.
Theophilus Rügen

Now Ready,

CASSELL'S FRENCH DIRIONARY. • In paragraphs constructed like the above, the successive questions rise one above another, in inflection, so as at last to reach a very high note.

In Two Parte:-1. French an * + The above rule applies to cases in which the conjunction Or is, or may English Department by p.

French Department carefa!' be understood,

one large handsome Oc*

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David Black,

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Seth Ward,

John Wilson,

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Richard Aniz,

Alex. Ward,

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1st. Ebullition commences at a fixed temperature, which is ON PHYSICS, OR NATURAL PHILOSOPHY. different in different liquids, but which, under the same pres

sure, is always the same for the same liquid. No. XXXVII.

2nd. Whatever may be the intensity of the source of heat, (Continued from page 145.)

the temperature remains stationary, from the moment when

ebullition commences. The following in a table of the lemEVAPORATION AND EBULLITION.

peratures of ebullition in some liquids, at the standard pressure

of the atmosphere :Accéleration of Evaporation. It has been already observed in a former lesson, that evaporation is a slow production of vapour TABLE OF THE BOILING POINTS OF LIQUIDS. at the surface of a liquid. It is in consequense of spontaneous evaporation that wet clothes dry in the air, or that an open Liquids.

Boiling Pointe, vessel full of water is completely emptied of it at the end of a Sulphurous Acid (Liquid) 100 Cent, or 140.0 Fahr. certain time. It is evaporation which takes place at the sur- Hydrochloric Ether

11

51 .8 face of seas, lakes, rivers, and the ground, which produces the Sulphuric Ether

98 6 rapours that rise in the atmosphere, condense into clouds, and Alcohol

79

174 2 fall in the form of rain. Four causes have an influence on the Distilled Water

100

212 0 rapidity of the evaporation of a liquid; 1st, the temperature; Essence of Turpentine

150

302 2nd, the quantity of the vapour of the same liquid already dif. Phosphorus

290

551 fused in the surrounding atmosphere; 3rd, the renewal of the Concentrated Sulphuric Acid 325

017 atmosphere; 4th, the extent of the surface evaporated. As to Mercury

602 the first cause, the increase of temperature accelerates the Sulphur

440

S21
evaporation by the excess of the elastic force which it produces
in the vapours. In the case of the second, as the evaporation

Several causes produce a variation in the boiling point of a
of a liquid will be stopped in a space saturated with the same liquid, viz. 1, the substances' held in solution ; 2, the nature of
liquid; and as it only attains its maximum in an air com the vessel; and 3, the pressure.
pletely freed from that vapour; it is evident that between

1st. When a substance is dissolved in a liquid, and it is these two extremes, the rapidity of evaporation will vary either not volatile or less than the liquid in quantity, the according as the surrounding atmosphere is more or less ebullition is retarded in proportion to the quantity of the already charged with the same vapour." As to the third cause, substance held in solution. the renewal of the atmosphere, its effect may be explained on

Water which boils at 100o Centigrade, boils at the followthe same principle. For if the air or gas which envelopes a ing temperatures, when saturated with the different salts :liquid be not renewed, it will be quickly saturated, and all

Saturated Mixtures.

Boiling Points.
evaporation will then cease. The influence of the fourth cause
is self-evident.

Water and Marine Salt 1099 Cent, or 2280.2 Fahır.
Do. and Nitrate of Potassa 116

240 •8
The Lars of Ebullition. To the rapid production of rapour,

Do, & Carbonate of Potassa 135

275 0 in bubbles of a larger or smaller size, in the same liquid, we

Do. & Chloride of Calcium 179

354 .2
gire the name ebullition or boiling. When in a vessel, a liquid,
such as water, is heated at its lower strata, the first bubbles

Acid solutions present similar results; but substances held
which make their appearance are only those of the air held in purely in suspension in water, as earthy matters, wood sharings,
solution in the water, which are disengaged on the application etc., do not raise the temperature of ebullition. At this point,
of heat. When these are dispelled, then small bubbles of also, it is important to refer to the experiments of Rudberg,
Tapour begin to rise from all the heated points of the sides of formerly cited under the subject of the Graduation of the There
the vessel; these traversing the upper strata of the liquid, mometer, experiments in which this philosopher shewed that
which have a lower temperature, are condensed before they when the temperature of the ebullition of water is above 100°
teach the surface. The formation and condensation of these centigrade, in consequence of the substances held in solution,
first bubbles of vapour are the cause of the singing noise which the temperature of the vapour which rises from it is still 100"
commoniy precedes ebullition. Lastly, large bubbles begin Centigrade, as in the case of pure water, provided the atmin
to rise and burst at the surface of the liquid, and the continu spheric pressure be at the standard point, viz. 29-922 inches.
ance of this process constitutes the phenomenon of ebullition, 2nd. Gay-Lussát observed that in a glass vessel, water
see fig. 192

boiled at a higher temperature than in a metallie Vessel; a phenomenon which he attributed to the affinity of plass for water. For instance, he found that when distilled war diled in a brass vessel at the standard temperature and tesure, the water did not enter into the state of eh. *lass vessel till the temperature was 101° instead on it and press sure being the same; and when the glass rexx. w** rabbed with concentrated sulphuric acid, or potassa, toinen tasa, vrature of the water rose to 1050 and 106 Centigrade ytre builing. Yet a simple fragment of metal placed at the buik ind of the vessel was sufficient to restore the temperature of ebullition

to 100° Centigrade, and at the same time to disingie the Fire

violent concussions which accompanied the button of the saline or acid solutions in glass ressels.

Vreuter, in the case of substances held in solution, the fein;y:arire of ide vapour is not influenced by that whilh the water asumes in ines vessels. At the standard pressure, ihe intuiure

pour is still 100° Centigrade as in brass Visnes cording to the tables of the classe ane ropar nd of steam given in our last least, the seen 00° Centigrade, the temperature at w.vater r the standard pressure, the raput sta8 recisely equal to this foru:r.

Taple in muliats, de

* た

Fig. 192.

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Fig. 193.

produce ebullition, must also increase or decrease. In order) notwithstanding the elastic force of the steam which tends to to prove that the temperature of ebullition is lowered when raise it. the pressure is diminished, we place under the receiver of an In order to close the apparatus most completely, before the air-pump, a vessel containing water at about 30° Centigrade lid is firmly fixed to the vessel, some thin lead place is interor 86o Fahrenheit, and exhaust the receiver. The liquid will immediately be observed beginning to boil with great rapidity, although in a closed vessel; it is because the vapour is drawn off by the machine as fast as it is produced. In the same manner, in consequence of the diminution of the pressure of the atmosphere at the tops of mountains, water boils below 1000 Centigrade. On Mont Blanc, for example, water boils at 849 Centigrade or 1830.2 Fahrenheit. This property has been recently applied in a small apparatus, called the hysometer (from the Greek hysis, water or rain, and metron, measure), which shews the height of the place according to the temperature at which water boils. If the pressure be increased instead of being diminished, ebullition is retarded. Thus, when the pressure is two atmospheres water does not boil till the temperature rises to 1210 Centigrade or 2490.8 Fahrenheit. A table of the boiling points of water at different elevations above the level of the sea is here added, in order to impress the mind of the student with the facts now stated.

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Places.

.

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Altitudes.

Ileights of Boiling

Barometer. Points.

Feet. Inches Fahr. Farm of Antisana .

13455 17.9

1870 Town of Micuipampa

11870 19.0 190 City of Quito

9541 20.7 194 Caxamarca

9383 20.9

194.4 Santa Fé de Bogota

8731 21.4 195-8 Mexico

7471

22.5 198.2 Hospice of St. Gothard

6808 23.1 1992 Maurin, Lower Alps .

6210 23.6 200

posed between the edges of the digester and its cover. At the St. Remi

5263 24 4 202

bottom of a cylindrical hole which passes through the cylinder Heas, Pyrenees

4807 24.9 203

s and the piece o, a small orifice is made in the lid, and is Briançon.

4285 25.4 204

covered by a disk, on which a rod n is made to rest. This rod, Palace of San Ildefonso .

3789 25.9 204.8

which traverses the cylinder s and its base o, presses against Baths of Mont d'Or.

3412 26.3 2068

the disk by means of a lerer A moveable at its extremity a, A Pontarlier

2717 27.0 205.3 weight p, which moves along the lever A a, is employed to act Madrid

1995 27.7 208.2

on the rod n with a greater or less force, in proportion as it is Augsburg

1558 28.2 209

nearer to or further from the extremity A, according to the Geneva

1221 28.5 209.4

well-known property of the lever. As the load or pressure on Moscow

984 28 8 210-2

the disk can thus be varied, it is regulated so that when Prague

587 29.2 210 8

the steam in the interior of the vessel has reached a cer. Lyons.

532 29-3 211

tain tension, say six atmospheres, the disk may be raised, and Dresden.

295 29 6 211.4

the steam permitted to escape. In this way the bursting of Paris Observatory

213 29.7 211.6

the apparatus is prevented; and hence the name of this Rome,

150 298 211.8

mechanism is derived, viz. the Safety-valve, the beautiful inven

tion of Papin. The digester, being two-thirds filled with water Confined Vapour.-Hitherto we have supposed that the and carefully closed, is heated on a furnace. The water can vapours were produced in an indefinite space where they thus be raised to a temperature far above 100° Centigrade, could freely expand. It is only on this condition that ebulli- and the tension of the steam can be carried to a great number tion can take place; in a close vessel, the vapours which are of atmospheres, according to the load given to the safety-valve.

roduced not finding any vent, their tension and their density If the valve be then opened, a jet of steam escapes with a increase as the temperature increases, but the rapid disengage-blast and rises to a great height. The water in the vessel, ment which constitutes ebullition is impossible. Consequently, / which had not till then entered into the state of ebullit on, wliile in an open vessel the temperature of a liquid does not now actually boils, and its temperature is reduced to 100° Exceed that of ebullition, in a close vessel it may rise much | Centigrade. heyond that point. The liquid state, however, hus a limit,

The apparatus of Papin can be rendered useful in increasing for according to the experiments of \I. Cagniard-Latour, if the dissolving power of liquids, by affording the means of water, alcohol, or ether, be introduced into strong glass tubes, raising them to a temperature much higher than their point of and the latter be hermetically scaled after the air has been ebullition; and this is the reason why it is called the Digester. expelled by boiling the liquid, it is found that by the appli.

The Latent Caloric of Vapour.- According to the second law cation of a sufficient quantity of heat, a period will arrive of ebullition, the temperature of liquids remains stationary when cach liquid will suddenly disappear, and be transformed during the period of this phenomenon hence we conclude into a vapour whose volume will scarcely differ from that of that in vaporisation, as well as in fusion, there is an absorption ihe liquid. Thus, he has found that sulphuric ether is of a considerable quantity of heat, of which the sole effect is to heit in a space less than that of double of its volume in the liquid into the aeriforin state; for this quantity of heat does liquid state, and that then the tension of the vapour is equi- not act on the thermometer, because the vapour which is provalent to the pressure of thirty-eight atmospheres.

duced is always at the same temperature as the liquid, or Pupin's Digester.-M. Papin, a French physician, who died rather at one a little lower than it. There is, therefore, latent in 1710, appears to have been the first philosophor who calorie, as in the case of fusion, formerly explained, and it is studied the effects of the production of steam in a closu vessel. called the calorie of elatsticity, or the culoric'uf vaporisation. The apparatus called l'apin's digester is a bronze cylindrical Whatever may be the ternperature at which nuy vapour is vessel D, fig. 193, furnished with a cover which can be closely produced, there is always the its(3ption of latent caloric

. and Ermly shut by means of a screw, is shown in the figure, For example, if we pour on the hand a volatile liquid, such as

ether, we feel a very sensible degree of cold, which proceculs pressure. These two cylinders are made of lead, surrounded fiom the caloric of elasticity absorbed by the liquid which is with copper, and strengthener with iron hoopis. Thick plates vaporised. Mr. Southern announced the law, that the quantity of irin are applied to the ends of each, and these are conof heat necessary to vaporise a given weight of water is nected with each other by rods of the same metal. It was always the same, whatever may be the temperature at which considered that, constructed in this manner, the cylinders the vaporisation takes place. This law has not been yet proved could resist the pressure of 1,200 atmospheres. experimentally; but it is not in opposition to the theory of In the receiver, about 3} imperial pints of carbonic acid vapours as hitherto developed.

were liquefied, the temperature being about 15° Cent., and the The caloric absorbed by vapours may become a source of pressure 50 atmospheres. When the stop-cock of the le. very intense co'd, capable of solidifying mercury, and even the ceiver was opened, the carbonic acid issued from it with gases, as has been demonstrated by experiments yet to be great force, and passed again into the seriform state.

Bit a noticed. Moreover, the quantity of latent heat absorbed by part of the liquid only was restored to the gaseous state, different liquids during vaporisation is capable of being ascer- because the latent caloric absorbed, during this change of state, tained by calculation.

is 90 considerable, that the other part of the liquid, giving out

its caloric of liquefaction, is solidified in white Aakes, crystalLIQUEFACTION OF VAPOURS AND GASES.

lised in the fibrous form. When carbonic acid is reduced to

the solid state it then vaporises very slowly. It can be proved, Liquefaction of Vapours.—The liquefaction or condensation of then, by means of an alcohol thermometer, that its temperature vapours is their passage from the neriform to the liquid state. is about -80° Centigrade or -112° Fahrenheit. Yet placed on Three causes may operate in condensation ; lowering of the hand, it does not produce so powerful a sensation of cold temperature, compression, and chemical affinity. The two as might be expected, which arises from the want of conformer causes require that the vapours be in the state of tact; but if it be mixed with ether, the cold is so intense, that saturation, but the latter produces the liquefaction of the a solid fake of carbonic acid placed on the flesh disorganises most rarchied vapours. Thus, a great number of sults absorb, it as much as a severe burn. Such a mixture solidities in a by condensation, the vapour of water contained in the atmos- few seconds four times its weight of mercury. phere. The vapour which exists in the atmosphere presents,

Distillation.-Distillation is an operation which has for its when the temperature is lowered, a particularly curious object the separation, by vaporisation, of a volatile liquid from phenomenon ; it does not return immediately to the liquid certain substances which it holds in solution. This operation state, but is transformed into hollow vesicles like soap-bubbles, is founded on the transformation of liquids into vapour by the but extremely small; the water is then said to be in its action of caloric, and on the condensation of vapours by the resicular state. It is in this state that the vapour of water process of cooling. The apparatus employed for distillation forms clouds, and that it becomes visible during the process are called alembics or stills. Their form may be varied in a of ebullition. At the instant of the condensation of vapours, variety of ways, but they are always composed of three princitheir latent caloric becomes free, that is, sensible to the pal pieces: 1st, the cucurbite B tig. 194, a copper vessel tinned thermometer. This is proved by making a current of steam (vapour of water at 1000 Cent.) pass into a vessel of water at

Fig. 194. the ordinary temperature of the atmosphere. The liquid is rapidly heated, and soon reaches the temperature of 100° Cent. It is thus considered that the quantity of het so restored by the condensation of the steam is exactly equal to that which was absorbed in its formation; a fact which appears sufficiently

Liquefaction of Gases.—Gases being only vapours very much expanded, are, like then, capable of being liquefied. But being very much above the point of their liquefaction as to temperature, we can only bring them to that point by compression or by a reduction of temperature, which varies with each gas. In some, compression alone is sufficient; for most gases, both processes of liquefaction inust be simultancouely employed. Tew gases have resisted the combined action of these iwo causes, and it must be admitted that those which, like oxygen, hydrogen, nitrogen, the binoxide of nitrogen, and the oxide of carbon, have not been liquefied, would be so it We could only subject them to a sufficient pressure and reduc

It was formerly remarked that Mr. Faraday has liqutfiel a
great number of gases that were considered as permanen!
gues. His process consisted in enclosing, in a siphon-forma, which contains the liquid to be distilled, and of which the
glass tube, substances which, by their chemical action, pues lower part is built in a furnace; and, the heal or helm a, which
sated the gases which were to be compressed; so that those rests upon the cucurbite, and allows the vapour to escape by a
substances being contained in one of the branches of the tube, lateral neck x ; 3rd, thé icorm c, consisting of a long tin or
the gas, in proportion as it was generated, was compressed in copper tube, wound in a spiral form, and placed in a vessel
the other, and liquefied. The gas might, in this manner, be filled with cold water; the object of the worm being to con-
subjected to pressures of from 40 to 60' atmospheres. The dense the vapour by cooling it.
tube was also reduced in temperature by means of frigorific Suppose now that it was required to distil the water of a
the apparatus, indicated
the pressure. It was by this process holds in solution, and which are inostly sulphate

of lime, carthe temperature of on Ct, and under a pressure of 35 thirds filled with it, and then heated; the water boils, and the

steam which arises from it passes through the worm where it 1. Thilorier constructed an apparatus, by which severa' is condensed; the water proceeding from this condensation is. pounds of liquid carbonic acid could

be prepared at once. His then delivered into the receiver D. The steam, which is con: Faraday, is composed of two cylinders communicating with the worm ; it is therefore necesssary to renew this water con: Generator, are put bulphuric acid and the bicarbonate of soda, this purpose, a tube », constantly supplied with a current of which are employed in the preparation of carbonic acid; in the cold water, conducts this water into the lower part of the Oker, which is the receiver, the gas is liquefied by its own vessel; whilst the warm water, which is lighter, rises to the

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