Εικόνες σελίδας
PDF
Ηλεκτρ. έκδοση
[merged small][merged small][merged small][merged small][merged small][ocr errors]
[graphic]
[graphic]

CAPILLARY ATTRACTION.

Capillary Phenomena.--In the contact of solids and liquids, a series of phenomena are produced, to which the name of capillary phenomena is given, because that they are particularly observed in tubes, whose diameter is so small that it is comparable to the thickness of a hair.

The effects of capillary attraction are very various; but in all cases, they are the result of the mutual attraction of the liquid particles to each other, and to that attraction which subsists between these particles and solid bodies. Take, for example, the following phenomena : when we immerse a solid rod in a liquid which will wet it, the liquid, in opposition to the laws of hydrostaties, rises around the solid rod, as in the case of glass and water; and its supfáce, instead of being hori

When the liqaid is contained in a vessel so large as that zontal, takes a concave form, as shown in fig. 47; but, if a solid capillary attraction has no longer an effect on its level surface, rod be immersed in a liquid which will not wet it, as in the still the liquid rises or sinks on the sides of the vessel, accordcase of glass and metcury, the liquid, instead of rising, sinks ing as it wets or does not wet these sides, see figures E and F. round the solid rod, and its surface takes a convex form, as

Fig. E.

Fig. F. shown in fig. 48.

Water.

Mercury.

[blocks in formation]
[graphic]

Laws of Ascent and Depression in Capillary Tubes.-M. GayLussac has proved by experiment that the ascent and depres

sion of liquids in capillary tubes, are regulated according to These phenomena become more evident, when, instead of a the three following laws: Ist. There is an ascent when the solid rod, we immerse in the liquid getales tubes of small dia- liquid wets the tubes, and a depression when it does not wet meter, as shown in the following figures A and B. According them: 2nd, this ascent and depression are in the inverse ratio

of the diameters of the tubes, so long as they do not exceed Fig. A. Fig. B.

the tenth part of an inch :3rd, the ascent and depression vary with the nature of the liquid and with the temperature ; but they are independent of the substance of the tubes and of the thickness of their sides, if the latter be previously wetted. These laws hold good in & vacuum as well as in air.

The method employed by M. Gay-Lussac in the discovery of these laws was the following: 1st, lie measured the interior

[graphic]
[graphic]

Fig. G.

[graphic]

as these tubes are wetted or not wetted by the liquid, so do they produce an ascent or depression. This ascent or depression increases as the diameter of the tube diminishes, see figs. 49. and 50. When the tubes are wotted by the liquid,

[merged small][merged small][graphic]

the surface of the liquid takes the form of a concave meniscus (Greek crescent-shaped), as in fig. 49, and when the tubes are not wetted by the liquid, the surface takes that of a convex meniscus, as in fig. 50. The surface of the liquid assumes the diameter of the tubes, not directly, which would have been same concavity and convexity on the sides of the Hessel which very difficult, but by selecting those which presented the same contains the liquid according as it wete or does not wet the sectional area throughout their whole length, and weighing the sidee of that persely As shown in the following figures o end. De quantity of mercury which completely filled them; the density

[ocr errors]

•16

of the metal being known, it was then easy to deduce, from its other so as to form an angle, and be immersed in a liquid weight and the height of the column, the required diameter, which wets them, so that their line of contact be placed vertias shown in a former lesson : 2nd, he then, placed the liquid cally, the liquid will rise towards the vertex of the angle under consideration in a vessel ABCD, figure &, and vertically between the two plates, and its surface, from the highest to the immersed in it, the capillary tubes which were successively lowest point, will assume the form of the curve called an submitted to experiment; close by each tube, he placed a rod equilateral hyperbola. The asymptotés of this curve which is BF, tapering to a point, which, by the motion of a screw, was double, being traced on each plate, are the vertical straight made to reach the exact level of the liquid; then, by means of line in which the edges of the plates meet, which is common a cathetometer, he measured the vertical distance between the to both, and the horizontal straight lines which determine the upper extremity of the column of liquid in the tube, and the level of the liquid in which they are immersed, as shown by lower extremity or point of the rod which came in contact the dotted lines in the following figure 1. with the liquid. The heights which different liquids reach are by no means the same, as may be seen in the following

Fig. H.
table; for, in a tube whose interior diameter was about one
twonty-fifth part of an inch, the liquids rose to the different
heights here mentioned, above the level of the liquid in the
Vessel :
Liquids.

Heights.
Water

1.173 inch
Alcohol

0.479 Spirit of Turpentine 0.501 In the experiments of which these are the results, the liquids were kept at the same temperature; for in proportion as 'he temperature rises, the capillary phenomena are rapidly minished.

In the use of several apparatus, it is necessary to know the gebount of the depression of the mercury in glass tubes. The following table gives these depressions to the nearest thousandth of an inch, in tubes varying from 8 hundredths to 40 hundredths of an inch in diameter.

When the line of contact of the two plates is horizontal

instead of vertical, as shown in their sections represented in Diameters of Tubes.

Depressions of Mercwi'y. figs. 52 and 53, and the plates are placed so as to form a very •08 inch

•178 inch

small angle, a drop of water put between them is hollowed at •10

both its extremities into a concave meniscus, as in fig. 52, and •12

•117
•14
098

Fig. 52.
*083
•18

071
•20

061 .22

•053 .24

047
•26

•041
•28
.30

•032
32

028 •34 .025

Fig. 53, 36

022 38

·020 .40

•018 Laws of Ascent and Depression between two Plates Parallel or Inclined.-Phenomena analogous to those presented by capillary tubes, are produced between two bodies of any form immersed in a liquid, when they are sufficiently near to one another.

Mercury. For example, if we immerse in water two parallel plates of glass so near each other that the two curvatures formed at their contact with the liquid, are united, it is observed : 1st, is attracted towards the vertex of the angle of the two that the ? inverse ratio of the interval which separates them; and, 2nd, case with .mercury, the drop of the liquid is rounded that the height of ascent for a given interval, is the half of that at both its extremities, into a convex meniscus, as in $g. 63, which would have taken place in a tube whose diameter is and is repelled from the vertex of the anple. The directions of equal to this interval. If parallel plates are immersed in mer attraction and repulsion in these figures are indicated by the cury, depression takes place, but according to the same laws.

arrow heads. Fig. 51,

The force of attraction of a liquid to the sides of a vessel lies between two extreme cases; it is equal to that of the liquid to itself, or it is zero ; in the former case, the ascent of the liquid in tubes is the consequence; in the latter, depression is the result. Between these two extremes, there must be the case in which there is neither ascent nor depression; this occurs when the force of the attraction of the liquid to the solid is exactly equal to half of the force of the attraction of the liquid to itself. Water brought in contact with well polished steel appears to realise this partioular case ; for the liquid seems, on the approach of the metal, to experience neither elevation nor depression.

As already observed, every column of liquid elevated by

capillary action is terminated by a concave surface; and every I two plates of glass, A B and ac, fig. 51, be inclined to each column depressed, by & convez qurface. Io cylindrio tubos of

[graphic]

...

[ocr errors]

•036

Water.

[graphic]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]

sufficiently small diameter, these surfaces are hemispherical. and if left to itself, it will be attracted in the direction of the Between two parallel plates they are semicylindric. Since the arrow heads. iquid columns in tubes rise in proportion to the smallness of their diameter, it follows that the meniscus which appears at

Attractions and Repulsions of Capillary Action. The attracthe surface is proportionally increased in currature, which fur- tions and repulsions which we observe among bodies floating niches us by its direction and force, or rather by the shortness at the surface of liquide, and which arise from capillary action, of its radius, an expression for the force which acts at the are regulated by the following laws: Ist, When two floating of ;

bodies are wetted by a liquid, as, for example, two balls of cork force which acts from the interior to the exterior or a traction; in water, a powerful attraction takes place as soon as they are and the convex meniscus, a force which acts from the exterior

no to the interior, or a compression. This view is verified by the exists between them. 2nd, When two floating bodies are not following experiments. Take an inverted siphon, having two

wetted by a liquid, as, for example, two balls of wax in water, unequal branches both in length and in diameter, as shown in a strong attraction takes place as soon as they are put in the the following figures 1o, 2o, 3o, and such that the capillary bodies are such that one is wetted by the liquid and the other

same circumstances as the former. 3rd, When two floating action is very marked, in the narrow branch, and almost nothing in 'he other branch, on account of its great diameter. not, as a ball of cork and a ball of wax in water, repulsion is Pour water into it at three different times, so as to make it observed to take place as soon as they are so near each other, assume the levels indicated by these figures.

that the two contrary curvatures of the liquid are found

The phenomena just described, depending on Fig. 1o.

the concave or convex curvature assumed by the surface of Fig. 29 Fig. 3o.

the liquid in which the bodies are placed, we shall inquire into the cause which determines the form of this curvature in our next lesson.

in contact.

[graphic]
[graphic]
[graphic]

LESSONS IN GERMAN.-No. LXXVIII.

B.

$ 91. COMPOUND PREFIX®S SEPARABLE.

[ocr errors]

Anheim (antheim, to-home); Unheimftellen, to put home to,

i.e. to refer to
Dabei (batlei, there-by); Dabeistehen, to stand close by.
Daber (tather, there-hither) ; Daher Aleichen, to sneak along.
Lakin (bathin, there-thither); Dahineilen, to basten away.
Dagegen (batgegen, there against); Dagegensein, to be against.
Danieder (bat-nieder, there-below); Daniederschlagen, to beat down.
Datan (tartan, there-to); Daranjeßen, to put or lay

thereto, i.e. to risk, to

atake.

Darauf (dar+auf, there-on); Daraufgeben, to give there-on, In fig. 1°, the level being very low in the branch a, it is

i.e. to give an earnest. elevated in the branch B to a height corresponding to the Darein (bartein, there-in); Dareinreden. to talk there-in, capillary action at that point, and the meniscus is concave

i.e. to interrupt. In fig. 2o, on pouring an additional quantity of water Danon (batron, there from); Davonlaufen, to run off, or into the branch A, up to the exact level of the extremity B,

away. the two surfaces are then of the same height, and both

Davor (tatvor, there-before); Davorliegen, to lie before, become plane ; in fig. 3°, on pouring an additional quantity of Damiter ba t-trider, there against); Dawiderhaben, to have (objecwater still into the branch A, up to the level which measures

tions) against. the capillary action in the branch B at that point, the

Dazu

(ta+31, there-to); Dazutsun, to do (in addition) water rises in the form of a convex meniscus, and exerts a

thereto; to add. force of compression sufficient to prevent any flow; but if the level at a be increased in height above this point, the water

Dazwischen(tatznijchen, there-be- Tazrijdenreten, to speak there

tween); in the midst. will then begin to issue by the narrow branch B.

Einher (einther, into-hither); Einherziehen, to draw along. Again, if in a conical tube, of which the following figures Entgegen (ent+gegen, apart-to

Entgegengehen, to go towards marked w and n, are sections through their axes, we introduce

wards) ; to go to meet. Entzmei (enttzwei, apart-two); Gntzweibrecen, to break or

burst asunder. erab (her tab, hither-down); Berabseßen, to put down; to

lower. Heran (bertan, hither-to): Heranführen, to bring on or

along. Herauf (her tauf, hither-on) ; Herauffahren, to drive or urge

Fig. W.

on.

Water

[ocr errors]
[ocr errors]

Heraut (her taus, hither-out); Herausfahren, to drive out.
Herbei (her #bei, hither-along); Herbeirufen, to call by or to-

wards.
Fig. M:

Herein (her tein, hither-into); Hereinfahren, to drive in or into.
Hernieber Hert-nieder, hither-down); Herniederblichen, to look under.
Hcrüber (Her trüber, hither-over); Verūberfommen, to come over.
Herum (her fum, hither-around); Herumgeben, to give or hand

around.
szerinter (her founter, hither-under); Herunterfahren, to drive down.
Hervor (her t-vor, hither-for-

Hervortreten, to step forward. Mercury.

ward);

Szerzu (her+zu, hither-to); Herzutreten, to step towards. a drop of liquid, it will take the former or the latter form, Hinab (hintab, thither-down); Hinabtreten, to step down. According as it wets or does not wet the sides of the tubes : 1 Hinan (hin+an, thither-to); Hin intreten, to step up to.

[ocr errors]

up);

Hinauf (hintauf, hither-on or Hinaufziehent, to pull up. Umhin (um-+-hin, around thith- Umyinfönnen, to be able there up);

er); about; to forbear. Szinaus (Hintaus, thither-out); Hinauswerfen, to throw out.

Doran (vor+-an, before-to); Voranstellen, to place before. Hinein (hintrin, thither-into); Hineingießen, to pour into. Vorauf (vor-fauf, before-on or Voraufsteigen, to mount on beHintan (hint(en) Fan, behind-to); Hintanseßen, to put behind;

fore; to ascend, to undervalu

Boraus (vort.aus, before-out); Vorausschen, to see or spy out Hinterher (finter+her, after-hither); Hinterhersehen, to see after

beforehand; to anticipate. wards.

Borbei (vort þei, before-by); Vorbcireiten, to ride along be. Sinüber (Hin-tüber, thither-over), vinübertragen, ta carry over.

forc; to ride past. žinum (Hin fum,thither-around); Binumflattern, to flutter there Vorher (sort-her, before-hither); Cornerschen, to foresee.

about.

Vortīber (vor t-über, before-over) ; Pvrüberfalrer, to drive along Hinunter (hintunter, thither-un- Hinunterspringen, to leap down

past in a caach. there.

Bernes (vort-weg, before-away); Potwegneljmen, to take away Hinweg (hintweg, thither-away); ģinwegnehnien, to take away.

before; to anticipate. Hinzu (hintzu, thither-towards); Hinzueilen, to hasten away.

Zuvor (zu-+-sor, before-to); Zuvorthun, to do before; to Ueberein (überfacin, over-into); llebercinfomincn, to come over

excel, into, i.e. to agree.

Zürüd (zutrüd, back-to); Zurückfohren, to return. Umher (um ther, around-kither); Umberschauen, to gaze around. Zusammen (zu+sammen, to-gether); Zusammenseßen, to put to

gether.

der);

$ 92. PARADIGM OF A COMPO UND VERB SEPARABLE.

Anfangen, to begin.

[graphic]
[graphic]
[blocks in formation]

INFINITIVE.

he may

PLUR. SING.

begin

Present Tense. Present Tense. Present. 2. fange (bu) an, anfangen, or anfangend,

begin thou, anzufangen, to beginning. 3. fange (er) an, begin. 1 fangen(wir)an 2.Fanget (ihl) an, 3.fangen (sie) an.

PLUR. SING

begin.

1 ich habe

3 er hat

PLUR. SING.

angefangent,

Perfect Tense. Perfect. angefangen yas angefangen, ben, to have

·began. begun.

begun

angefangen,

you have

3fie haben

Present Tense.

Present Tense. Ilich fange an, I begin.

id fange an,

I

may 2 du fängst an, thou beginnest. du fängst an, thou mayst 3 er sångt an, he begins. er fängt an, wir

wir fangen an, we may 2 ihr fanget an, you begin. ihr fanget an, you may 3 sie fangen an, they begin. fie fangen an they may Imperfect Teise.

Imperfect Tense. i ich fing an, I began. i finge an, I might 2 ou fingst an, thou didst begin. du fingest an, thou mightst 3 er fing an, he began.

er finge an, he might wir fingen an, we began. wir fingen an,we might 2lihr finget an, you began. ihr finget an, you might fie fingen an, they began. sie fingen an, they might Perfect Tense.

Perfect Tense.
I have

ich habe I may have
2
bu haft thou hast bu Habest

begun, &c. he has

er habe wir haben we have

wir Haben 2 ihr habet

ilir Yabet they have

fie haben Pluperfect Tense.

Pluperfect Tense. Ilid hatte I had

ich Vätte I might have 2)du hattest thou hadst bu Vättest

begun, &c. 3 er yatte he had

er hätte 1 wir hatten we had

mir Vätten ihr hattet

ihr hättet
3/ fie vatten
they had

sie hätten
First Future Tense.
First Future Tense.

First Future, 1 ich werte I shall

ich werde (if) I shall be- id, würde 204 wirst thou wilt du werdest

du würdest 3 er wirs

he will
er Twerbe

er würde 1 wir werden

we shall
wir werden

wir würden
2 ihr werdet
ihr wertet

ihr würdet 31 sie werden

they will
sie werden

sie würden
Second Future Tense.

Second Future Tense. Second Future. 1lich werde

I shall have ich werde (if) I shall ich würde 2 du tvirst

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

begun, &c. du werdest have begun, du würdest 3/et wird

er werbe

&c. er würde 1 wir werden wir werden

wir würden 2) ihr wertet

ihr werdet

ihr würdet 3 sie werden fie werben

sie würden

OXIX and

[blocks in formation]

UNIVERSITY OF LONDON.-No. IV.

La Chenille.
At the request of numerous students of the POPULAR Edo- Un jour, causant entre eux, différents animaux
CATOR, we insert the following papers; they will give valuable

Louaient beaucoup le ver à soie : information, not only to those who aspire to the honour of

« Quel talent,” disaient-ils, “ cet insecte déploie becoming members of the University, but they will form a En composant ses fils si doux, si fins, si beaux, body of useful exercises also to those who have been our Stu

Qui de l'homme font la richesse !" DENTS since the commencement of our Lessons in the various Tous vantaient son travail, exaltaient son adresse, branches of learning in this work.

Une chenille seule y trouvait des défauts,

Aux animaux surpris en faisait la critique,
MATRICULATION EXAMINATION.--1853.
..

Disait des annis, et puis des si.

Un renarà s'écria : “Messieurs, cela s'explique, (N.B.-Candidates are prohibited, under pain of instant

C'est que madame file aussi." -FLORIAN. dismissal, from introducing any book or manuscript into the Examination-Room, and from communicating with each other during the Examination. Candidates are required to attend

Tuesday, July 5.-Morning, 10 to 1. in person on one of the last three days of the week immediately preceding the Examination, to pay their Fees and write their ARITHMETIC AND ALGEBRA.-(Examiner, Rev. Prof. names in the Register. If the Candidate fail to pass, the Fee

HEAVISIDE.) will not be returned to him, but he will be admissible to any

1. In dividing one whole number by another, what does the fucure Matriculation Examination without the payment of any quotient determine : Divide 243584 by 346, and explain the additional Fee.]

steps of the operation. ASS EXAMINATION.

2. Show that any number will be divisible by 12, if its two JUIY. 4. MONDAY. Afternoon, 2 to 4, French; 4 to 6, German. last digits be divisible by 4, and the sum of its digits be divisible 5. TUESDAY, Morning, 10 to 1. Mathematics. Afternoon, 3 to 54180 into its prime factors.

by 3 also. What are the prime factors of a number : resolve 6, English History.

3. Find the simple interest on £4572 16s. for 9 years at 41 6. WEDNESDAY. Morning, 10 to 1, Greek Classic and History. Afternoon, 3 to 6, Chemistry.

per cent.

If the three per cent. stock be at 98, and the three and a 7. THURSDAY. Morning, 10 to 1, Mathematics. Afternoon, quarter per cent. stock be at 101, which stock is it most advan3 to 6, Natural Philosophy.

tageous to buy? What income will £5000 invested in the 8. FRIDAY. Morning, 10 to 1, Roman Classic and History. three per cent. stock produce? Afternoon, 2 to 5, The English Language.

4. Explain the principle on which vulgar fractions are added together.

13 17 19 23 29 Monday, July 4.--Afternoon, 2 to 4.

Add together

15' 20' 21' 25' 30 FRENCH.-(Examiner, M. DELILLE.)

What fraction of a guinea added to 4s. 6d. is equal to 15 Translate into English:

shillings: Is a proper fraction increased or diminished by L'homme appelé à commander aux autres sur les champs de adding the same number to its numerator and denominator?

13 bataille a d'abord, comme dans toutes les professions libérales,

5. Express as decimal fractions.

What is the une instruction scientifique à acquérir. Il faut qu'il possède

10 1000000 les sciences exactes, les arts graphiques, la théorie des fortifi- distinction between decimals and whole numbers as respects cations. Ingénieur, artilleur, bon officier de troupes, il faut the prefixing and affixing ciphers to the right and left of the qu'il devienne en outre géographe, et non géographe vulgaire, significant digits: qui siit sous quel rocher naissent le Rhin ou le Danube et dans Quel bassin ils tombent, mais géographe profond, qui est plein

Divide •365 by 20. de la carte, de son dessin, de ses lignes, de leur rapport, de If in obtaining the quotient you cut off the cipher from the lcur valeur. Il faut qu'il ait ensuite des connaissances exactes divisor and actually divide by 2, what corresponding change sur la force, les intérêts et le caractère des peuples; qu'il sache should be made in the dividend : leur histoire politique, et particulièrement leur histoire mili

6. Perform the operations indicated below:-taire : il faut surtout qu'il connaisse les hommes, car les liom

(1.)

36.01---2:987564. mes a la guerre ne sont pas des machines ; au contraire, ils y deviennent plus sensibles, plus irritables qu'ailleurs, et l'art

(2.) 2.745 X 45.674. de les manier d'une main délicate et ferme fut toujours une

(3.) 233.8268-346. partie importante de l'art des grands capitaines. A toutes ces

(4.) 6.25_000125. connaissances supérieures, il faut enfin que l'homme de guerre ajoute les connaissances plus vulgaires, mais non moins néces

(5.) V2119-6816. saires de l'administrateur. Il lui faut l'esprit d'ordre et de

Verify the result of (4.) by vulgar fractions. détail d'un commis ; car ce n'est pas tout que de faire battre les hommes, il faut les nourrir, les vêtir, les armer, les guérir. 7. Why must the decimal eqvivalent to recur: fina that

7 Tout ce savoir si vaste, il faut le déployer à la fois et au milieu des circonstances les plus extraordinaires. A chaque mouve- decimal. Find the vulgar fractions equivalent to the recurring

decimals. ment il faut songer à la veille, au lendemain, à ses flancs, à ses derrières ; mouvoir tout avec soi, munitions, vivres, hôpitaux;

(1.) 71717171. calculer à la fois sur l'atmosphère et sur le moral des hommes ; et

(2.) •80654654. tous ces éléments si divers, si mobiles, qui changent, se compliquent sans cesse, les combiner au milieu du froid, du chaud, de la Find the value of •33333 of 2} guineas. faim et des boulets. Tandis que vous pensez à tant de choses, 8. State the rule of signs when one algebraical term is mula le canon gronde, votre tête est menacée; mais ce qui est.pire, tiplied by another. des milliers d'hommes vous regardent, cherchent dans vos Add together 73_44, 3x+54, 92-y. traits l'espérance de leur salut; plus loin, derrière eux, est la

From (2a+30)2 take (a--26). patrie avec des lauriers ou des cyprès ; et toutes ces images, il

Multiply -2a35+-2ab2-3ab3 +264 by al-2ab faut les chasser, il faut penser, penser vite; car une minute de plus, et la combinaison la plus belle a perdu son à-propos, et

Divide (3.6–10) by (34+5). au lieu de la gloire, c'est la honte qui vous attend.-THIBRS, Find (142a)3

« ΠροηγούμενηΣυνέχεια »