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4. Two nouns :

6. She made all nations drink of the wine."-(Rev. xiv. 8.) the object) to the verb commands, and the subject to the infinitiv

to remrin ; 80n, therefore, may be considered as the objective cas However, whether simple or compound, transitive verbs govern

: an object, that is, the action of the verb fälls on a noun which is before the infinitive to remain hence called the object of the verb. This is a case of dependence, The object, " bis-son to remain,” may be enlarged, thus':the uoun which is the object- is dependent on the verb.of which it

The man commands his son and daugliter to remaid. is the object. Tbe relation is one purely' of thought, for the rela

The man coinmands his only son to renain. tion involves in the noun no change of form. With the personal

Theman commands his son fortiwith to go home and remain there, pronoun there is a change of form, corresponding to the coange of sense, so that the nominatives I, we, they, become as objects, or All these constructions, and others of a similar kind, bold to the become in what is called the objective case, me, us, them. .

verb the same relation that I have indicated, that is to say, they The verb drinks may be resolved into these tervis, is drink- are severally

, the objects to the verb commands. These objects are ing, as

compound, and being compound, they may be resolved into their The sick man is drinking a beverage;

component parts, and the relations set forth which those parts

bear to each other, as well as that which they bear to their common. whence we learn that present participles have the same government head, the verb commands. ase thë verbg: to'which they belong.

Instead of the second object, a noun öight be given, as Intransitive verbs, though in general incapable of an object, may

The man teaches' his son Greek,
take an object in a noun of kindred meaning ; e. g.,
" Let me die the death of the righteous."-(Numb. xxiii. 10.)

Here the noun Greek (that is, the Greek language) holds to teaches
the relation which to remain bolds to commands.

It is not every
“Let us run the race that is set before us."-(Heb. xii. 1.)
Intransitives have the force of transitives also in certain idio- verb, however, which has after it two nouus as objects. But as in

Latin, so in English, verbs which siguify to learn and to teach may matic pbrases; e...,

have dependent on them two separate objects. He laughed him to scorn." (Matt. ix. 24.)

In some instances wbere two objects appear after a verb, the
“We ought to look the subject fully in the face.">Channing: construction is in reality elliptical ; c. g.,
“And talked the night away."---Goldsmith.

He gave his son a book;
The Object.

that is, in full, The object of a proposition may, as we have seen, appear in a

He gave a book to his son. variety of forms. The object also assumés several shapes. The So in the sentence, chiet variations may be presented as follows:

He bought his son a book ; The object of a proposition may be either

the construction really is, 1. A noun: The man drinks a'beverage.

He bought a: book for his son. 2. A pronoun: The man calls me,

You will now have the less difficulty in understanding How as 3. A noun and an infinitive: The mani bids his solli teřain.

sentence may be the object of a verb, asi He teaches his son satin.

The man says (that), he is ill. 5. A proposition: The man declares he is ill.

The words he is ill you will at once recognise as a sentence or Tf' dependent on the verb, that is, if it receives the action of the statement, and a little reflection will sbow you that the sentence Verb, the noun is the object of the verb; e. g.,

bears to the verb suys the relation of an object to its verb. The ** Préventing fame, misfortuné lends him wings,

conjunction that is merely áti expkanatory výord, or, indeed, an And Pompey's self his own sad story brings.

expletive.

Rowe's Lucan. A sentence as the object of the verb may also be eplarged: Èqually simple is the case of a pronoun viewed as the object of

The man.says he is sick and likely to die. a'verb; e. g.,

The man says he is sick and lias been giveit over by the faculty for ** “ Did I request thee, Maker, from my clay

long time. To mould me man?"-Milton.

The compound object in our model sentence will now be readily The construction of a noun and infinitive as the object of a understood, viz., verb may be slightly varied. For the noun, a pronoun may be

The man drinks a beverage made of wine and water. substituted ; as,

In this compound ohject, which consists of the words in italics,
The man bids me remain.

analysis shows us a noun, beverage, depending on the verb drinks ; Before most verbis thus related, the preposition to is placed ; as, a participle, made, agreeing with bererage, and therefore conjointly The man commands his son to remaini

with beverage dependent on drinks ; preposition, of, connecting In this construction the tô may be considered as a connective. made with wine and water; a noun, water, dependent on the preposiAnd here I may notice a vulgarism in the custom, among the tion of ; a conjunction, and, connecting water with wine ; and,

finally, another noun, wine, connected with water and the preposition uneducated, of prefixing for to the infinitive with to; as,

of, and consequently standing to the preposition of and to the senThe landlord is coming for to receive his rent.

tence generally in the relation held by the noun water. Like many vulgarisms now;. in use, this form of speech was once I must subjoin a few words respecting the object. good English, as may be seen by its appearance in our English Observe, then, that wine and wäter do not hold to drinks exactly translation of the Sacred Scriptures ; e. gig

the same relation which the words " bis son Greek" holds in the

above example. "They pressed upon him for to touch him."-(Mark jsi: 10.)

If so; a verb might be said to have several

objects; e. google Yet we retain the for in such põrases as For me to speak is of no avail;

The man bequeathed money, wire, books, and land.

It is true that the nouns form the object to the verb bequeathed, but. where the words " for me to speak” forma the subject to the they are a compound object made by repetition; whereas in the verb is.

proposition In the instance

The man taught his son Greek,
The man commands his son to remain,

the compound object is formed by addition. And in the construc-* is clear that the words " his son to remain” form a compound tion which assigns to certain verbs a double object, one of thoseöbject, and are'iä the same relation to the verb as is the single roun objects is a person, the other is a thing. Double objects, lika wimy in the eñsuing sentence :

single ones, may be augmented by repetition ; e. g., The man commands an army.

The man taught his wife, his sons, and his daughters Greek, In the previous sentence, son is at once the object (or part of The man taught his son Greek, Latin, German, and Frenck.

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Fig. 5.

The position of the objectis after the verb. And the observance tween the directions, AP and aq, of those forces; the reason of this law is in English wo imperative that by disregarding it you of this is plain, namely, that the point cannot move in both create ambiguity, if you do not change the object into the subject

directions at once; and as no reaand the subject into the object; e. go,

son can be assigned why it should Subject. Object.

A

move in the one direction more The father struck the son.

than in the other, it must move Subject. Object.

in some intermediate direction, The son struck the father.

and this direction is exactly that

of the resultant of the two forces As an instance of ambiguity from the inversion of the object,

P and Q. make this instance :

All problems which relate to “This power has praise that virtue scarce can warm,

the composition and resolution Till fame supplies the universal char." -Johnson,

RI

of forces depend upon the folWhich is the subject, and which the object? Do you mean that

lowing theorems, for the demon. power bas praise, or that praise bas power ?

stration of which we must refer our mathematical students When, however, the perspicuity of the sentence is not abated, to the Elementary Treatises on Statics, which are to be the object may, for the sake of emphasis, be placed before the found both in French and English. In particular, we would verb; e. g.,

mention the elegant demonstrations of M. Poisson, in his “ Silver and gold have I none."-(Acts iii. 6.)

Traité de Mécanique, imitations of which have been published Especially with pronouns.; 0..go,

in English Treatises on Mechanics, by Whewell, Pratt, Earn"Me he restored to mine office and him he hanged."-(Gen. xli. 13.) shaw, and many others. You may find sentences in which one. object stands before and

Composition and Decomeposition of Parallel Foron.-Theorem 1.another after the verb; e. go,

When two parallel forces are applied at the same point, their

resultant is equal to their sum, when they act in the same direc* Ye have the poor always with you, but me ye have not always: (Matt. xxvi. 11.)

tion, and to their difference when they act in contrary directions. Intransitive verbs have no object. The untaughtare apt to con

For example, if two men drag a load in parallel directions found the transitive with intransitive verbs, using the one for the force, that is, their resultant, will be denoted by 35 if they drag

15 , other. This error may be exemplified in the verbs

in the same direction, and by 5 if they pull in opposite direcTransitive: lay

raise

tions. In like manner, when a number of horses are attached Intransitive: lie

rise

to the same vehicle, and all pull in the same direction, it will Thus, they say,

be urged along the road as. if it were drawn by a single force He laid a-bed all day.

equal to the same of all the forces of the different animals The hen has lain an egg.

employed. The price of butchers' meat has risento

Theorem 2.When two parallel forces, which act in the same The lark rises itself in the sky.

direction, are applied at the extremities of a rigid straight line The principal parts of the verbs are:

(a rod), their resultant is equal to their sum, acts in the same Transitive: lay laid laid

direction, and its point of applieation divides the straight line raises raised raised

into two parts, which are inversely proportional to the numbers Intransitive: lie lay

lain

which express the intensity of the forces. Thus, in fig. 6, if rise )

risen
Accordingly, the statements that stand-above ought to be,

Eig. 6.
He lay a-bed all day.
The hen bas laid an eges

A
The price of butchers' meat has been raised.
The-lark raises itself in the sky.

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ON PHYSICS OR NATURAL PHILOSOPHY.

No. III.

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ON THE COMPOSITION AND RESOLUTION OF FORCES.

Afb denote the rigid straight line, A and B its extremities, P and Composants andResultants.-When several forces, such as s, the parallel forces, A P and Be their directions, and c the P, and a, are applied to the same material point; A, fig. 4, and point of application of their resultant R; then co, parallel to

produce an equilibrium at that AP or BQ, will be its direction, and p:e::BC:CA, that is, if Fig. 4.

point, it is evident that the action the force p be two, three, &c., times the force e in magnitude, of any one of these forces, for then the part BC will be tuo, three, &C.,, times the part ac in example s, resists the combined magnitude. Whence it follows, that when the forces p and a action of all the rest; for were the are equal, the point of application of their resultant divides the force s to act in the direction AR, straight line AB into two equal parts. Conversely to this procontrary to its own direction, a S, position, any single force R applied at the point c in a given it would produce the same effect rigid straight line, A B, may be resolved into two parallel forces as the two forces P and Q, acting P and Q, whose sum is equal to R, if their points of application, in the directions A P and AQ Every A and B, be in the same straight line with the point c, and if force which produces the same they be so divided, that they are to one another in the inverse effect as a combination of any ratio of their distances from c; that is, if BC:AC':: P:Q. number of forces is called the

To find the resultant of any number of parallel forces act resultant of such forces, and these ing in the same direction, we have only to find by the preced considered in relation to their resulting theorem the resultat of two of these forces, then the

ant, are called component forces, or resultant of this resultant force and another of the given forces, P composants.

and so on, until all the given forces have been compoundedi When a body is put in motion by the action of several. The last resultant thus obtained will be a force equal to the forces, it can be demonstrated that the motion always takes sum of the given forces, and having the same direction; and place in the direction of the resultant of all the forces. Thus, its point of application will be determined. if a material point, as at A, fig. 5, be acted on by two forces, P Composition and Resolution of Forces acting on a Single Point and a, it will move in some intermediate direction, RA, be- If two forces, as P and a, fig. 7, act on a single material point

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at A, and AP and AQ be the directions of these forces, we can

ON MOTION. determine their resultant by the following theorem. Before we enunciate this theorem, let us take on the straight lines A D curvilinear according as the path described by the moveable body

Diffcrent Kinds of Motion.--Motion is said to be rectilinear or and a Q; parts a B and a c having to each other the saine ratio is a straight line or a curve; and either of these motions may be

as the intensities of the forces; uniform or variable. Uniform motion is the most simple kind of Fig. 7,

let us then complete the paral- motion, and is that in which the moveable body describes lelogram A B D C, by drawing equal spaces in equal times. Every momentary force produces BD parallel 10 AC, and cu

a motion which is rectilinear and uniform, when the moveable

and let draw the diagonal a D. This body is not subjected to the action of any other force, and

meets no resistance to its progress. Under the momentary figure is the parallelogram of forces, and the theorem which action of a furce, the moveable, when left to itself, will continue

to preserve, in consequence of its inertia, the direction and the expresses the relation between the composants P and Q and action of the force. Under the continued action of forces, à

velocity which were communicated to it by the momentary their resultant R, is called The

moveable may likewise be made to preserve uniform motion; Theorem of the Parallelogram

as in the case where the resistances opposed to the motion of Forces; viz., if any two forces acting on a material continually destroy the increments of velocity which such

forces tend to communicate to the moveable. We see an

point be represented in mag example of this in the motion of a train on a railway, where nitude and direction by the two adjacent sides of a paral, the motion is produced by the continued action of a certain lelogram, their resultant will)be represented in magnitude and force, but that motion is nevertheless still uniform ; this result

of , drawn from the point where these two sides meet. Thus, in the air, the friction of the rails, &c., a resistance which in

from the loss of force due to the continued resistance of the parallelogram A B C D, if A B and A c represent in magnitude creases as the velocity increases, and which soon establishes and direction any two forces p and e, acting on a material such an equilibrium between the moving and resisting forces, point at a, then will the diagonal D, drawn from the as produces the uniform motion required. point A, represent in magnitude and direction the resultant B

Velocity, and Law of Uniform Motion.- In uniform motion, of these two forces; in other words, the direction of the result. ant r of the forces P and Q, will be the straight line A R, and the space described in a unit of tirne is called velocity. the resultant R will contain the unit of force as many times

This unit, although entirely arbitrary, is generally a second as the diagonal A D contains the linear unit of measurement, of time. From the definition of uniform motion, it is plain which was applied to the determination of the lengths of AB

that in this species of motion the velocity is constant, that is, and A c, in order to make them represent the forces P and Q.

always the same; as, for example, in two units of the time, the Conversely, a single force applied to a material point may space described is double

, in three units triple, in four units Se decomposed into two other forces applied to the same

quadruple, &c., that of the space described in one unit. This point, and having their directions in given straight lines, law is usually expressed by saying that in uniform motion the that is, straight lines which shall make given angles with spaces described are proportional to the times, or in other words, the direction of the resultant and with each other. For the spaces described increase with the times. if we construct on the given straight lines a parallelogram, This law may be represented by a very simple formula ; let whose diagonal represents in magnitude and direction thé v denote the velocity, t the time, and 8 the space described. given force, then its sides will represent in magnitude and Now since v denotes the space described in a unit of time, the : direction the required composants. The solution of problems space described in 2, 3, 4, &c., units of time will be 2v, 3v, 4v, relating to forces acting on a single point will be seen by the &c.; and generally, in the time t, it will be tv; hence, we mathematical student to resolve itself into the application of have the formula s=to. From this formula we have v=$ trigonometry to the determination of the sides and angles of

t; the parallelogram of forces. Thus, if p and a represent any hence we say, that in uniform motion, the velocity is the ratio two forces in numbers, and a denote the angle between their of the space described to the time employed in describing it. directions, then their resultant { will be represented in num- Variable Motion is that in which a moveable body describes bers by the following formula:

unequal spaces in equal times. This species of motion may be varied in an infinite number of ways, but we shall at present

only consider that in which it uniformly varies. When a number of forces are applied to the same point in described in equal times constantly increase or decrease by the

Motion Uniformly Variable is that in which the spaces various directions, their resultant will be found by applying same quantity. In the first case, the motion is said to be the preceding theorem first to two of these forces, and then to uniformly accelerated ; such is the motion of a falling body, the resultant thus obtained and a third of these forces, and so when the resistance of the air is removed. In the second case on successively till the last force has been taken into the the motion is said to be uniformly returdėd; such is the motion account. The last resultant thus obtained will be the result- of a stone thrown vertically upwards from the ground. ant of all the forces combined.

Motion uniformly varied arises from a constant force, that is, The effects of the composition and the resolution of forces are a force continually acting with the same intensity; and it is frequently presented to our notice. For example, when a boat considered either as a power or a resistance, according as the rowed by oars crosses a river, it does not make way in the real motion is accelerated or retarded. direction in which the oars propel it; neither does it advance

Velocity, and Laws of Uniformly Accelerated Motion. In motion in the direction of the current; but it is urged along in the uniformly accelerated, the spaces described in equal times not direction which exactly corresponds to the resultant of the iwo being equal, the velocity is no longer the space described in a forces which act upon it, viz., the force which puts the oars in unit of the time, as it is in uniform motion. In the former motion and the force of the current in the river. In like man- species of motion, we understand by the velocity at a given ner, when several men are employed to ring a great bell each instant, the space which, commencing from that instant, would by a short rope attached to the main rope, the resultant of their be uniformly described by the moveable in every second, if united forces acts along the main rope as the line of its direc- the action of the accelerating force were instantly to cease, tion, and their individual forces form the composants, their that is, if the motion were to become uniform. For example, lines of direction being that of the short ropes at which the if a moveable were to acquire a velocity of 60 yards per second, ringers pull, in order to produce the desired effect. When after the lapse of ten seconds, during which it had proceeded any number of forces are in equilibrium about a point, any one with uniformly accelerated motion, and if the uniformly of them may be said to be the resultant of all the rest, but its accelerating force were suddenly to cease its action after these direction, of course, ia contrary to that of the balancing force; 10 seconds, the moveable would, in consequence ofoits inertia, and the resultant of any number of forces in equilibrium, is continue its motion uniformly at the rate of 60 yards per nothing.

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On this principle, every uniformly accelerated motion, what

LESSONS IN CHEMISTRY.No. III. ever may be its increments of velocity, is reduced to the two following laws :

RESUMING the consideration of the metal zinc, the learner will let. The velocities increase proportionally to the times ; remember that he has dissolved a portion of this metal in sul. that is, after a time, double, triple, quadruple, &c., any given phuric acid and water; that he has evaporated this solution time, the velocity acquired' is double, triple, quadruple, &c., to dryness, and redissolved the dried mass. He will have now greater than that after the given time. The action of the obtained a colourless solution of sulphate of zinc: that is to continued force, indeed, which produces any accelerated mo- say, a solution of oxide of zinc in sulphuric acid. However, I tion, may be compared to a series of equal impulses which only at the present time desire the learner to remember the succeed one another at equal but infinitely small intervals of single fact, that the zinc is by some means held in solution by time. Now, as each of these impulses produces in each inter- the liquid employed, i.e. sulphuric acid and water. The exact val a constant velocity, which is continually added to that state of its combination we need not discuss just now, this which the moveable already possessed in the preceding interval, point will come under discussion hereafter. The zinc is there, it follows that the velocity goes on constantly increasing by and we require to obtain it, or at least satisfactory evidence of equal quantities in equal times.

its existence; that is our proposition. How is this to be 2nd. The spaces described are proportional to the squares of accomplished? A person conversant with Chemistry would the times employed in describing them; that is, if we denote almost arrive at the conclusion that zinc was present by the the space described in 1 second by 1, the spaces described in peculiar taste of the liquid. And indeed the sense of taste is 2, 3, 4, 5, &c., seconds will be denoted by 4, 9, 16, 25, &c., a very valuable test: a far more precise indication, however, is which are the squares of the former.

afforded by hydro-sulphuric acid, or its watery solution, as we These laws are mathematically demonstrated in the scientific shall see. If the learner pour a little of the sulphate of zinc treatises on Dynamics, or the laws of motion ; when we come into a test tube ; that is to say, a little glass tube of the followto treat of gravity, we shall exhibit their experimental

ing shape, or a wine glass, and add to this

Fig. 14. demonstration.

sulphate of zinc a portion of the hydro-sulMomentum, Measure of Force.-The momentum of a body is

phuric acid solution already procured, a white the product of the number expressing its mass by that expres

powder will fall, this white powder being & ing its velocity. Thus, if a body moves with a velocity of 10

combination of sulphur and zinc, and therefore feet per second, and its mass is represented by 20, then its

called sulphuret or sulphide of zinc.

Let the reader impress upon his memory momentum is said to be 200. When a force communicates a certain velocity to a given mass, the momentum can be taken

the fact that sulphuret or sulphide of zinc as the measure of this force. Thus, if a body moves with a

is white, and that it is the only metal which velocity of 20 feet per second, and its mass is represented by

yields a white compound with the same agent, 10, then its momentum is, as before, said to be 200; whence,

applied in the same manner. in this case, the moreable has the same force as in the pre

İf a sufficient amount of hydro-sulphuric ceding case. The momentum of a body is frequently called

acid solution be poured into the sulphate of its quantity of motion.

zinc, all the inetal will be thrown down in this In mechanics, therefore, these principles are established,

condition of sulphuret or sulphide, and accord. that, in equal masses, the forces are proportional to the

ingly this process is sometimes followed in velocities; and that, in equal velocities, the forces are pro

the course of analysis. The student, however, portional to the masses; in other words, that a force double

will not fail to perceive that, supposing the another imparts to the same mass a double velocity; or, to

solution of sulphate of zinc to be very strong, a double the same mass, an equal velocity. Now, let there be very large portion of hydro-sulphuric acid solution must be two forces F and f acting upon the two masses M and m, and added, a treatment which would, under many circumstances, communicating to them the velocities V and v respectively. If produce an inconvenient bulk of liquid. This being the case, we suppose a third force P such that it communicates to the it follows that when hydro-sulphuric acid is merely used as a mass M the velocity v, we shall then have, according to the test or indicator, it is commonly employed in the state of preceding principles, the following proportions :

aqueous solution; when, however, it is employed as a separator,

then the more convenient plan is to cause it to permeate the (1.) F: P :: 1 :v, and

metalliferous fluid as a gas; this remark brings me to the (2.) P:f:: M:m: whence,

consideration of the mechanical arrangement necessary to the

use of this gas. V

Р M we have

and Р

f Now, multiplying these two equations term by term, and! cancelling the common factor P, we have

F MV

; whence

f (3.) F:f:: MV: mv ; that is, any two forces are to each other as their momenta or the quantities of motion which they commu. nicate to any two moveables. Thus we see that if we take for the unit of force the momentum which the unit of velocity would communicate to the unit of mass, forces may be measured by their quantity of motion. This species of measurement is equally applicable to instantaneous and to continued forces; but in the case of con:inued forces, we only Ifa mixture of oil of vitriol and water (about 1 to 6 by measure) consider the velocity which the force communicates in a be poured upon sulphuret of iron sulphuretted hydrogen, or second.

sulphuric acid gas, will be liberated, as we have seen; but as Forces being proportional to their momenta or quantities of thus liberated it usually carries before it little particles of liquid, motion, it follows that for the same force the product mv is i.e. sulphuric acid and water, consequently it is not well adapted constant; that is, if the mass become twice, thrice, &c., to be employed as a delicate precipitating agent. To speak more greater, the velocity will become, twice, thrice, &c., smaller. precisely, the gas requires to be passed through water in smal. This conclusion is drawn from proportion (3) above demon- bubbles, or washed, by means of an apparatus similar to that strated; for by making F=f, we have mv=mv; whence, it represented in fig. 15; A and B are two wide-mouthed eight or follows (Cassell's Arithmetic, p. 101) that M:m::v: V; that ten-ounce bottles, to each of which is adapted a cork, and each of is, the velocities communicated by the same forces to two which corks is perforated with two holes, as represented. Predifferent masses, are to one another in the inverse ratio of viously to securely fixing the cork of the vessel a, some fragments these masses.

of sulphuret of iron are thrown in; the bottle is then corked

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Fig. 15.

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water is now poured into the vessel B, and the latter is also form of a circle. Then bending the disc on itself, form a semicorked. It will be evident now, from the merest consideration circle. Then binding the semi-circle on itself form a quadrant. of the various parts of this apparatus, that if a mixture of sul. Lastly draw the quadrant into this form, fig. 17, and the filter is phuric acid and water be poured into A, all the sulphuretted hy- complete. Large filters require to be supported on funnels; drogen liberated will be obliged to traverse the water B before small filters may and indeed are better used without funnels, it can finally escape; in other words, it will be washed. A portion they may be rested on the edge of the glass itself; but a far of the gas is absorbed by the water, but this matters not; the better method consists in using a filter support made of porcemaximum of absorption is soon arrived at, and the gas comes lain, and of the shape annexed. Fig. 18. over uninterruptedly so long as it is developed. Only one matter remains to be spoken of in connexion with the apparatus just

Fig. 18. described, it relates to the portion marked r. This consists of a small tube of india-rubber vulcanized by preference, and which is interposed between the two glass tubes. By this arrangement not only does a flexible joint result, but the bent glass tube admits of being removed and another placed in its stead; for, as a general rule, the same tube should not be used for testing consecutively two fluids of different compositions. In most large towns, vulcanized rubber tubes of any length may be readily procured, and the operator, having become possessed of them, may cut them into lengths according to his necessities; but supposing them not procurable, the reader

By means of this little apparatus a filter may be rested on should be able to manufacture a substitute out of india-rubber the edge of its corresponding glass, or removed at pleasure, sheet. The best material for this purpose is the rubber manu- with the greatest facility. Whatever is the size of the filter factured into sheets, but even the native bottle rubber will employed, it should be wetted with distilled water before the answer perfectly well.

liquid to be filtered is poured upon it. A special apparatus is Supposing the artificial sheet rubber to be procured, it may employed for wetting filters and washing precipitates collected be formed into tubes simply by warming it before the fire, upon them. The apparatus is of the following kind. winding it round a glass rod or tube, pressing the sides closely

A thin flask slightly flattened at its base, in such a manner together, and cutting them off by a sharp pair of scissors. that it can stand without support, is furnished with a perfoThus treated the two cut edges will adhere, and a tube will rated cork and two tubes, as represented in the diagrain, a result. Fig. 16.

mere casual examination of which will suffice to show that, if

air be blown in through the tube a, water will emerge in a jet. Yig. 16.

from the tube B, fig. 19. This jet may be so nicely regulated, that even the most delicate filter paper can be wetted without any fear of rupture.

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Fig. 19,

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If, however, the artifcial sheet rubber cannot be procured and the bottle rubber has to be substituted, the latter material requires to be boited in water for a considerable time, in order that the necessary amount of adhesiveness may be inparted to it. Generally speaking, india-rubber tubes, thus manufactured, are strong enough for all uses to which they are applied ; if additional strength be desired, it can be imparted by first constructing one tube, then overlaying it with another, the seam of which does not correspond with the first, but is on the opposite side of the tube.

The two bottles forming the compound apparatus just des By means of a little filter, as just described, it may easily be cribed, are usually attached for convenience to a slab of wood, determined when the point corresponding with the total precias represented in fig. 15. The apparatus is procurable com- pitation of zinc has been arrived at, and this operation may be plete at the philosophical instrument shops, but I strongly considered as the type of thousands which constantly occur in recommend the young chemist to manufacture this and similar the course of chemical analysis. apparatus himself.

Here we may, with advantage, take leave of zinc for a time, Return we now to the metal zinc. By passing a stream of and begin the consideration of another metal; not that we hydro-sulphuric acid through it sufficiently long, the whole of have nothing more to say concerning zinc, but that our future the zinc will be thrown down. The operator may know when remarks will most profitably come before the reader by way this point has been arrived at, by filtering a little of the solu- of comparison. We will take up another metal, and that tion from time to time, and testing the filtrate or fluid which metal shall be manganese, a very abstruse metal in many passes through the filter. This remark leads us to another respects. The abstruse points, however, connected with it I digression-the operation of filtering, so necessary to the pro- shall omit, merely directing the student's attention to two secution of chemical investigations. The usual material points--a means of obtaining it in solution, and a means of employed by chemists, as a filtering agent, is paper. Filtering precipitating or throwing it down from this solution. paper is of various kinds. The coarser sort is made chiefly of We succeeded in dissolving zinc by means of diluted sulwool, and is of a brown colour; the finer sort resembles in phuric acid. We cannot readily dissolve manganese, or, more its general aspect white blotting paper, which indeed may be used properly, commercial black oxide of manganese in this manner.

Concentrated sulphuric acid, and oil of vitriol, dissolves a Plg. 17,

portion of it readily; but I shall have recourse to an indirect process of solution, as follows:-Rub together in a mortar two parts by weight of manganese, and one part by weight of salammonia. Put the mixture into a crucible of silver or platinum, if the reader possess one of these instruments; if not, into a white gallipot, and heat to dull redness over a powerful flame of gas or spirit, or a charcoal fire in preference; but a common ire

will do: allow the mixture to cool, add distilled water, and as filter paper, if the true material cannot be obtained. The filter. The filtered solution contains manganese held in soluway to make a filter is this : first cut out the paper into the tion by chlorine. How the chlorine got there, or why it

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