LESSONS IN CHEMISTRY.-No. IV. THE only tests we have hitherto employed in our chemical investigations, are hydro-sulphuric acid, and hydro-sulphate of ammonia. Let the student now obtain the following:1. A solution (saturated) of prussiate of potash, also called ferrocyanide of potassium.

2. Infusion or tincture of gall nuts.

3. Hydro-sulphuret of ammonia already prepared, by transmitting sulphuretted hydrogen gas through liquor ammonia (hartshorn), until the latter refuses to dissolve any more.

4. A solution of potash procurable at the druggist's, under the name of liquor potassa. It must be kept in a glass stoppered bottle, and not exposed to the air more than absolutely necessary.

5. A solution of carbonate of soda (washing soda).

6. A solution of carbonate of ammonia (smelling salts). 7. A solution of ammonia (hartshorn).

The preceding, in addition to hydro-sulphuric-acid gas and solution, may be regarded as the principal tests for metals. Others will occasionally come under our notice, but these are the chief.

Having disposed of the effects developed on the solutions of manganese and zinc already employed by hydro-sulphuric-acid and hydro-sulphate of ammonia, let the student next observe the result of adding to each of these solutions respectively a solution of prussiate of potash. He will discover that this re-agent determines a white precipitate with either metal; and as a general rule it may be remembered, that yellow prussiate of potash (there is a red prussiate) determines a white precipitate with all common or calcigenous metals. To this general rule there are very important exceptions, which, however, had best be fixed in the memory as exceptions: thus, probably, even in the foregoing testing experiments the Fig. 19. reader may observe that the precipitate yielded by prussiate of potash is tinged bluish; if so, this result will depend upon the presence of iron, a metal which will scarcely be altogether absent from the solutions of zinc and manganese prepared by a novice in chemical operations. Let the student now proceed to test portions of zinc solution, and manganese solution, made according to preceding directions, with all the tests mentioned in the beginning of this article, and let him make notes of the results. Most of the tests will produce precipitates with both solutions, as the reader will see; and the prevailing character of the results is whiteness, or a tint approaching to whiteness. The operation of testing may be performed in conical wine-glasses, in test tubes, as they are called-instruments of the following shape, fig. 19, being glass tubes, open at one end, closed at the other, and so thin that the flame of a spirit lamp may be applied without danger of causing fracture. A third method of conducting test operations, and it is a very good one, consists in the employment of flat strips of window glass, upon which a single drop of the solution to be tested is laid, and another drop of the test solution, added to it by means of a straw, or a glass rod. In this way testing operations may be conducted with great facility. Care must be taken, however, when straws are employed, never to use one straw for more than one operation. Take next a solution of manganese, and a solution of zinc prepared as already described. Add hydro-sulphate of ammonia to either solution, and a sulphuret is of course the result. To either sulphuret add now, without necessarily decanting the fluid from which it has been thrown down, some distilled vinegar (acetic acid), and observe that all the sulphuret of manganese is soluble in this fluid, whereas all the sulphuret of zinc remains undisturbed. We have already determined that, supposing zinc and manganese † to exist in one and the same * Still with greater propriety termed hydrosulphurate. The remark applies to manganese in that kind of solution, which results from the treatment already described, and others attended with a similar result; in other words, to proicsalts of manganese.

solution, they admit of separation by transmitting through the solution hydro-sulphuric acid, which throws down all the zinc, and leaves the manganese, which latter may be subsequently wanted, thrown down by means of hydro-sulphate of ammonia. Another method of separating the two will now readily occur to the reader. Both may be thrown down at once by hydrosulphate of ammonia, and the sulphuret of zinc redissolved by means of acetic acid.

It would be undesirable at this early period of our studies to describe in greater detail the numerous analytical processes which may be had recourse to for accomplishing the separation of zinc and manganese, supposing both to exist in one solution, and supposing the manganese to be in the condition of a protosalt.

Recapitulation.-1. Two solutions yield respectively precipitates with hydro-sulphate of ammonia; therefore, these solutions contain metals of the calcigenous class.

2. The precipitates are white, therefore the metals in question are either manganese or zinc.

3. One solution yields a white precipitate, with hydro-sulphurate of ammonia, though not with hydro-sulphuric acid; therefore it must contain manganese.

4. One solution yields a precipitate both with hydro-sulphuric and hydro-sulphate of ammonia; therefore it must contain zinc.

5. Sulphuret of manganese may be separated from sulphuret of zinc, by the agency of acetic acid (distilled vinegar), in which sulphuret of zinc is insoluble.

Distinction between the Moist and Dry Processes of Analysis.— The moist process and the dry process are terms which, from long use, have become popularly familiar, though they by no means admit of any precise line of demarcation. There are few chemical analyses involving metals which do not require the agency of fire at some stage of their performance; again, there are few so called dry processes which do not require as adjuncts the employment of acids, and other moist chemical re-agents. As a general rule, it may be stated that the dry or igneous processes of chemistry are restricted to operations on the large scale-such, for example, as the smelting of metals. To this general rule, however, the blowpipe and its employment constitute one remarkable exception, all the processes conducted by means of this instrument being essentially small and delicate, sometimes almost microscopic. The blowpipe is now invaluable to the chemist, although its employment in this way dates from very recent periods.

Description of the Blow-pipe.--The greater number of my readers will have seen a blow-pipe, and probably will have seen it used, being employed very extensively by gas-fitters, jewellers, and some other artisans. The instrument consists in its simplest form of a bent tube, terminating in a fine jet, as represented in the accompanying diagram, fig. 20, and is

Fig. 20.

intended to cause the deflexion, by blowing through it, of a candle or a lamp-flame, as represented in fig. 21. The flame thus diverted from its upward course is necessarily limited in extent, but its heat in certain parts is very great, enabling the operator to obtain (on the small scale) most of the effects of a furnace.

a

Generally speaking, artizans who use an instrument in their trade acquire far more dexterity in its employment than philosophers or amateurs. So far as relates to the blow-pipe, however, there is a remarkable exception to this rule. The gas-fitter and jeweller use the blow-pipe as follows:-Taking deep inspiration, they blow as long as the one charge of air lasts; then stopping, they inspire a fresh draught of air; afterwards they set to work again. This would never do for the chemist, whose operations demand the solution of the apparently impossible problem: to breathe and to blow uninterruptedly. It is not possible to describe by mere words how this is accomplished, farther than the description is conveyed in a general direction, to consider the cheeks as a pair of

70

Fig. 21.

double bellows: always blow-
ing from the mouth, never from
the lungs.

The facility with which a ood jet can be produced and maintained, greatly depends upon the size of the terminal orifice, which, if too large, will require more air than can be readily supplied by the reservoir of the mouth alone. All delicately made blow-pipes are supplied with several jets of different sizes, but such refinements as these are unnecessary to the novice, who may proceed to a gas-fitter's shop, and purchase a blow-pipe for sixpence. Having purchased it, let him now determine the distance from his eye at which vision is most perfect; which being settled, let him cut the blow-pipe to correspond. This is a somewhat important direction, and should not be neglected.

charcoal has been thus fixed, a little excavation should be made at the point by means of a knife, and in this excavation the substance to be operated upon should be laid.

The Platinum Wire-loop.-In a vast number of blow-pipe experiments, the jet is not directed upon the unmixed substance, but upon a mixture of it and another substance with which it shall form a glass on fusion, and the nature of the substance is deduced from the colour of the resulting glass. In such cases, the support most generally employed, is a loop of platinum wire. A portion of the substance to be examined being fused into the loop, together with a flux, a glass results, filling the loop as it would the frame of a window. Various other blow-pipe supports are known to chemists, but the two already described are the most important, and will answer our present purpose.

Blow-pipe examination of Zinc and Manganese.-In our moist investigations on zinc and manganese, great care was taken to obtain these metals in certain states of combination: no such precautions will be necessary in our blow-pipe inquiries on The zinc specimen may be a piece of the metal The Blow-pipe-jet, and its Characteristics.-If a jet of air by the same. means of the blow-pipe be directed across the flame of a lamp itself; the manganese specimen a portion of black, or binoxide, or candle, just above, or a little on one side of the wick, a jet otherwise called peroxide; in other words, the ordinary black will be produced which will have, or should have, the follow-manganese-ore of commerce. Lay a small fragment of metallic zinc (about the size of a barleycorn) upon the charcoal, ing characteristics. and direct upon it the interior blow-pipe flame; remark how the zinc burns; and how a white powder remains: remark too this white powder is yellow whilst hot. Remember well these points, and compare them with the results to be obtained hereafter, by treating lead in a similar manner.

Fig. 22.

B

Take the platinum loop, moisten it with the tongue, dip it It will be made up of a small central blue conical flame, ex- into some powdered carbonate of soda: remove it: fuse the tending from A to B, fig. 22, lying within a second and larger carbonate by directing upon it the apex of the blue cone: let cone, a, b, consisting of a reddish-yellow scarcely perceptible halo. It is not always that the jet can be obtained so pure as here the fused bead cool: when cool moisten it with the tongue described; but this degree of purity should be always aimed at, again, and apply to it a portion of powdered black oxide of a very small portion, just as much as could be manganese-but and will sometimes even by a novice be accomplished. The taken up on the point of a needle. Direct now the outer flame most heating portion of the flame thus developed corresponds of a blow-pipe jet on the loop, and observe the result. The with the point B; consequently, if our object be the mere fusion bead fuses, it becomes green when hot, and bluish green when of a refractory body, to the action of this point should it be cold. Repeat the experiment, substituting borax for carbonate exposed. This portion of the flame, moreover-indeed every of soda: the bead is now violet red in the external, colourless in part of the blue cone, possesses a deoxydizing power, that is to the internal flame. These appearances are characteristic of say, it takes away oxygen from any substance which may be manganese, but the appearances lately described are characterexposed to it. The external faint halo, on the contrary, im-istic of zinc; no other metals yielding similar results under parts oxygen, and is therefore called the oxydizing flame. similar treatment: the student may therefore form some The blow-pipe is not only useful to the chemist as a means of effecting the fusion and working of glass tubes, but it enables opinion already, concerning the value of the blow-pipe as an instrument of chemical analysis. him to operate in the dry way on all the metal or minerals containing them, giving rise to characteristic appearances from which the existence of any particular substance may be

inferred.

Apparatus necessary to be employed in connexion with the Blowpipe. In the first place, we require a source of flame, and this varies according to the different purposes for which the blowpipe is employed. If used for glass-blowing operations, the flame is usually such as results from the burning of a large mass of cotton wick, placed in a pan containing tallow, or a tin dish, and the blow-pipe having a very large jet, is usually worked by means of a pair of bellows. This, at least, is the arrangement usually employed by artizans in glass, such as barometer-makers, thermometer-makers, &c. In laboratories, gas is sometimes used as the source of flame, being more convenient; but the result is not so good. This bellows blow-pipe the student need not possess; all the glass blowing that he will require may be accomplished by the mouth blow-pipe, as will be described hereafter. For purposes of mineral analysis, and to such we are especially directing our attention at present, the very best flame, according to our opinion, is that of a wax or spermacetti candle; but the flame of a common tallow dip will answer most purposes.

Supports.-Charcoal.-The maximum heat which the blow-pipe jet can exert results from the contact of the blue apex with a piece of well burned charcoal. Of course, some means must be devised for holding this charcoal, and consequently there are instruments sold under the name of charcoal-holders; they are unnecessary, however-a charcoal-holder satisfactory in every respect may be constructed for the occasion, by taking a slip of tin plate about six inches long by two inches wide, and bending one end twice at right angles on itself, in such a manner that

[The following is a representation of a Glass Blower's table, with double bellows worked by the foot, and blow-pipe, lamp, &c. Such an apparatus can be had in London, complete, for four guineas.]

it may grasp and firmly hold a piece of charcoal. When the always containing iron, lime, and other extraneous materials.

We have friends in eating and drinking, but not in misfortune. In the city the king is the guardian of the laws. Obey, Ο young man, the magisαστε οιν trates. Ο child, strive after honourable deeds. The possession of virtue is alone sure, The city has (to the city are). many towers. Good laws bring honour to the city. Follow nature. The soldiers fight for the deliverance (σωτηρια) οἱ the city. Ο citizen, avoid insurrection,

Here belong the adjectives in uς, εια, υ, which in declension | depart from that of masculine and feminine substantives in this only, that the genitive of the masculine singular has the common form εος, and not έως, and that the neuter plural has sa : thus, γλυκυς, street.

EXERCISES.-GREEK-ENGLISH.

Αἱ γυναῖκες τῳ κοσμῳ χαιρουσιν. Οἱ Ἕλληνες σεβονται Δια και Ποσειδώ και Απολλω και αλλους θεους. Ταῖς γυναιξιν ἡ αιδως πρέπει. Οι κύνες τον οικον φυλάττουσιν. Ο κυβερνητης την ναύν ιθύνει. Αἱ σταγονες του ύδατος πέτραν κοιλαίνουσιν. Της γυναικός εστι τον οικον φυλάττειν. Γυναικος εσθλής εστι σωζειν οικίαν. Αει εν πιπτουσι Διος κυβοι. Οι κυνες τοις ανθρωποις ωφέλειαν και ήδονην παρεχουσιν. Αἱ τῶν μαρτύρων μαρτυρίαι πολλακις απιστοι εισιν. Ίστοι γυναικων έργα και ουκ εκκλησιαι (sc. εισιν). Κομιζε, ω παι, την της κιστης κλεῖν, Ω Ζευ, δέχου την του άτυχους δεησιν. Καστωρ και Πολυδευκης των νέων σωτηρες ησαν. Γυναικι παση κοσμον ἡ σιγη φέρει. σωζε την Οι Αιθίοπες την τριχα μελαιναν εχουσιν. γυναι, Αίδου Αιακός τας Τῳ κτενι τας τρίχας κτενιζομεν. κλεῖς φυλάττει.

οικίαν.

ENGLISH-GREEK.

Ornament becomes a woman.

Ω

Ornament becomes women.

They

It is the business of women to guard the house.
bring the keys of the house. The keys of the house are
brought to the mother. The Athenians had (to the Athe-
nians were) many ships. Jupiter had (to Jupiter were)
The
many temples. The fish emerge out of the water.
steersman guides the ship. The ship is guided by the steers-
man. You worship Jupiter and Apollo.

5. Ν. πολυς πολλη πολυ

μεγας μεγάλη μεγα

G. πολλου πολλής | πολλου μεγάλου μεγαλης μεγάλου D. πολλῳ πολλη πολλῳ μεγαλῳ μεγαλη μεγαλῳ πολλὴν πολυ

Ρ. Ν.

4. πολυν
μεγαν μεγάλην μεγα
V. πολυ πολλη πολυ
μεγα μεγάλη μεγα
πολλοι πολλαι πολλα μεγαλοι μεγαλα μεγάλα
πολλων πολλων πολλων μεγάλων μεγάλων μελαλων
The other parts are regular.

G.

VOCABULARY.

Αφθονία, ας, ή, freedom from
envy (a, not) abundance.
Αιγυπτος, ου, ή, Ægypt.
Αλεξανδρος, ου, ό, Alexander.
Κροίσος, ου, ό, Croesus.
Προσοδος, ου, ή, approach, in-

come.

Σιτος, ου, ό, wheat, corn.
Φοβος, ου, ό, fear ; φοβον έχειν,
to have fear, that is, to
cause fear.
Μακεδων, ονος, ο, a Macedo-
nian.

| Ιλιας, άδος, ή, the Iliad.
Αλγος, ους, το, pain, grief.
Εθος, ουρ, το, custom ; plural,
manners, morals; hence our
ethics.

| Παθος, ουρ, το, suffering.
Ολιγος, ή, ον, small; pl. few.
Οφελλω, I nourish, augment,

aid.

Προσαγορεύω, I name, call.
Μέγα, adverb, greatly, very.

EXERCISES. GREEK-ENGLISH.

SECTION II.

ON ANIMALCULITE CONTRIBUTIONS TO THE FORMATION
OF ROCKS.

You have seen how the growth, the decay, and the successions
of vegetable life, have contributed to the formation of the
crust of the earth. You are now invited to examine the contri-
butions which animal life has made to produce some of the rocks
on our globe. There are animal organisms which are really the
spontaneous and hard-working architects of rocks and moun-
tains. This lesson will not refer to those which are piling up
rocky masses by their direct agency, but to those whose
remains contribute to the formation of soil, plains, and hills.

We will begin with the contributions of the smallest and the minutest animal existences, the majority of which can be detected only by powerful microscopes, and with those of some others that are just visible to the naked eye. These diminutive organisms are called animalculæ, or little live things. They are sometimes called Infusoria, on the ground that they are discovered in all vegetable infusions, in the waters of the seas, rivers, lakes, ponds, and puddles, and in liquids used for domestic purposes.

66

This is

These agents cannot be seen with the naked eye. They belong, as Dr. Mantell has said, to an invisible world.” They make their invisible agency to be known by their works. The Sacred Scriptures teach us that "the things which are seen were not made of things which do appear." & primary article in the creed of every intelligent geologist. He applies it to account for the creation of all the worlds of matter as the results of the power and skill with which the Supreme Artist combines invisible gases, and says "let the dry land appear." The same article can be applied to the large and innumerable rocks and hills which have been produced, not of course by one immediate fiat, but by the slow and invisible agents which He had created and appointed to execute the work.

The forms, the structure, and the instincts of these animalculites belong to the science of Palæontology. Our concern now is, to exhibit them as contributing agents to the formation of | the earth's crust. The science of chemistry, and the microscope, I have shown that some extensive rocks and high mountains are nothing but enormous masses of animalculite relics, or immense sepulchres in which their remains are entombed. So extensively and so abundantly are their relics found in soils and rocks, that you may well ask, with the poet YOUNG, " where is the dust that has not been_alive ?” The composi tion of several rocks show that the different tribes of these ani.

Πολυν οινον πίνειν κακόν εστιν. Οἱ βασιλεῖς μεγάλας προσο- | malculites were countless, that various kinds of them appeared