the surface of leaden vessels, and which is subject to become mixed with our food, thus operating as a poison, is this very substance, carbonate of lead.' with any degree of safety? The question has been long solved; we know exactly the conditions under which water may be conveyed through leaden pipes and stored in leaden vessels, and the reverse. Although we have developed our carbonate of lead by two processes, viz., bringing a solution of acetate of lead into contact The important practical deduction was arrived at by Dr. with atmospheric air, and still more copiously by urging Lambe, and it has since been amply confirmed, that the through it a stream of air from the lungs, yet a soluble carbo-presence of certain saline bodies, such as sulphates, chlorides, nate, say of potash or of soda, is the plan usually had recourse etc., prevent the solution of carbonate of lead by any carbonic to in the operation of testing. Perhaps, all things considered, a acid which may be there also. It should follow, then, that in portion of bottled soda-water will be the best for our immediate proportion as water is pure, in the ordinary sense of the term, purposes; nevertheless, a solution of sesquicarbonate of soda i. e. free from saline bodies, so its tendency of dissolving lead (the substance used for making soda-powders) will serve our turn. should increase, a deduction indeed perfectly accordant with Having taken a portion of solution of acetate of lead, add to what we see in practice. Rain-water (almost free from saline it portions of either of the preceding solutions until no further bodies) converts metallic lead into carbonate, and dissolves precipitate is deposited. Quickly pow filter the tested liquid that carbonate with facility. Very pure river water effects the by pouring it upon a little paper filter rested on a filter stand, solution in a less degree, and the majority of spring waters, as represented in fig. 25, and test the fluid which comes usually the most teeming with saline bodies, not at all. This Fig. 25. important discovery leads us to interdict entirely and absolutely the employment of leaden pipes for the conveyance of rainwater, or leaden tanks for the storing of the same, under any circumstances: an interdiction which should also apply to all waters, river or spring, which are more than usually free from saline bodies. Now absence of saline bodies causes water to become, as it is denominated in ordinary language, "soft;" hence any water having this character should be prevented coming into contact with lead, until its power of solution on the metal shall have been tested by actual experiment. through the filter, "the filtrate" as it is termed by chemists, with some delicate test for lead in solution; say, for example, hydrosulphuric acid. Almost certainly a black colour will be developed; a result which proves that, notwithstanding the absolute clearness of the filtrate, it nevertheless must have contained lead, whence it follows that the carbonate of lead under the conditions of our experiment was partially soluble. Let the operator next prepare another portion of carbonate of lead exactly as before, and having prepared it, expose it to the operation of boiling in a flat open vessel such as an evaporating dish. These directions having been followed, and the liquid allowed to cool, let it be filtered, and the filtrate tested as before. Most probably under these circumstances there will be either no blackness resulting, or at any rate the degree of blackness will be considerably less than before. The explanation of this diminution or total absence of blackness is as follows. Carbonate of lead is partially soluble in excess of carbonic acid gas; indeed the same remark applies to most, perhaps all other, so-called insoluble carbonates. Now, bottled soda-water contains an excess of carbonic acid; so to a large extent does sesquicarbonate of soda-hence our first result. The operation of prolonged ebullition in an open vessel evolved this excess of carbonic acid, and hence our second result. This reaction of free carbonic acid on carbonate of lead is much more important perhaps than the student thinks. Suffice it, nowever, to say, that water holding carbonic acid in solution, and free or comparatively free from all other substances, converts metallic lead into carbonate of lead so rapidly, and dissolves that carbonate with such extreme facility when formed, that such water becomes dangerously poisonous if retained for only a short time in leaden vessels. Practically we are all well acquainted with the fact that leaden pipes for the conveyance of water, and leaden cisterns for storing the same, are of the most frequent occurrence. Now all ordinary water holds carbonic acid in solution; how, therefore, can we convey such water in leaden pipes, or retain it in leaden vessels, The preceding facts admit of striking demonstration as follows. Take some carefully distilled water, immerse in it a piece of lead, and expose the whole in an open vessel to the action of the air. Under these circumstances carbonic acid will be absorbed from the air, and the lead will be rapidly dissolveda circumstance not alone demonstrable by testing, but by the easily recognised corrosion of the metal. Repeat now the experiment with this variation. Let the distilled water destined to come in contact with the lead, flow over the hand or arm previously. Under these variations of condition far less lead will be dissolved, probably none. I need scarcely indicate that the act of flowing over the hand or arm (any portion of the cutaneous surface would answer) causes the water to become charged with minute portions of common salt and other saline bodies, the results of cutaneous exhalation; consequently our mode of conducting the experiment demonstrates how powerful is the preservative action exercised by certain saline bodies. Discrimination between carbonate of lead and other white lead compounds.-Carbonate of lead may, like all other carbonates, be known by the circumstance of its evolving, on the addition of almost any acid, a gas, which does not smell like a burning brimstone match-such gas is carbonic acid. If the acid employed for the purpose indicated, be endowed with the property of dissolving lead, if for example it be the nitric, acetic, or some other acids-then coexistent with the evolution of carbonic acid is the production of a transparent colourless solution. If, however, the,sulphuric acid be used, then it follows, from a consideration of properties already explained, that a clear solution will not result, under any circumstances of heat or mixture; and if hydrochloric acid be used, it also follows that a colourless solution will not result under many circumstances of heat and mixture which have already been pointed out as effecting the solubility of the chloride of lead. Returning now to the turbid solution devoloped on the addition of sugar of lead to non-distilled water, the student will soon discover the turbidity to be due to the combined presence of carbonate, chloride, and sulphate of lead. For the purpose of isolating the carbonate, add acetic acid to perceptible sourness, and filter. By this treatment all the carbonate of lead will have been decomposed by the acetic acid, converted into acetate, and made to pass through the filter, where in the filtrate it may be caused to reappear by adding carbonate of soda or of potash. If the remaining insoluble matter be removed from the filter containing it and boiled with water in a little flask or disk, then filtered rapidly whilst hot, all the chloride of lead it contained will pass through the filter, and will be deposited from the filtrate on cooling the latter and adding alcohol: As for the sulphate of lead, that will remain on the filter, being perfectly insoluble in water. LESSONS IN GREEK.-No. XXVIII. THE PERFECT, PLUPERFECT, AND OTHER TENSES. REMARKS. the o may be considered as a connecting vowel, and μai the person-ending. This connecting vowel is seen in other persons of the same tense; thus, λυ-ο-μαι, λυ-ε-ται, λυ-ο-μεθον, λυ-ε-σθον, λυ-ο-μεθα, λυ-ε-σθε, λυ-ο-νται, where e and o are the connecting vowels,-vowels, that is, that unite the stem with the person-endings. augment and changing μαι into μην; thus, λυομαι, ε-λυο-μην. The Imperfect middle or passive is formed by prefixing the It may also be formed from the Imperfect active by changing the active termination or into the middle termination oμην. Μη αποδέχου, etc. I will arrange this sentence a little differently, and you will thus be aided to see its meaning-μη αποδέχου τους των φίλων (or των φίλων τους) χαριζομενους σοι προς τα φαυλα : in English, do not welcome those of your friends who gratify you in bad things. Προς (Latin, ad), in regard to, in. Πράττειν is of a wider signifcation than ποιειν : the former In forming the tenses of verbs compounded with pre-signifies to do, the latter to make; the former, therefore, may positions, you will do well to drop the preposition while so be used with adverbs in a general sense, as κακως πραττειν, to doing, restoring it afterwards. For instance, in ενδύω I drop do ill; that is, to be in bad circumstances. the ev, and form the stems according to rule; thus, δυ- δυσα εδυσ- δεδυκα εδεδυκ- ; εν-ε-δε-δυ-κ, that is, ενεδεδυκ. So with καταλύω ; λυ- λυσ- ελυσε λελυκ- ελελυκ; κατελελυκ; where observe that kara loses its final a before the vowel ɛ. I have accented the proper names, as Diodorus, Sardanapalos, etc., according to the Greek, the rule being that in proper names, as well as generally, a long vowel in the Greek should receive the stress of the voice in English. EXERCISES.-GREEK-ENGLISH. Οἱ στρατιωται των πολεμίων δισχιλιους διακοσίους έξηκοντα πεντε πεφονευκασιν. Φερεκύδης έλεγε, μηδενι θεῳ τεθυκεναι. Νεος πεφυκως πολλα χρηστα μανθανε. Ο μαντις τα μελλοντα καλως πεπροφητευκεν. Τα τεκνα εν πεπαιδευκας. Μηδεια τα τεκνα πεφονευκυία έχαιρεν. Οἱ Λακεδαιμ νιοι Πλαταιας κατελελύκεσαν. Σαρδαναπᾶλος στολην γυναίκειαν ενεδεδύκει Οτε ήλιος κατεδεδυκει, οἱ πολέμιοι επλησίαζον. Αλεξανδρος επιδιωκων Δαρείον, τον Περσών βασιλεα, πολλων χρημάτων εκεκυριεύσει. ENGLISH-GREEK. The conjunction & requires an indicative or optative mood, the conjunction ear takes a subjunctive. Μετ' αυλων, with futes; that is, to the sound of futes. tive, from ελαύνω, I drive: the n is the temporal augment, ε Ηλαυνεσθην, the third person, dual number, Imperfect indicabeing lengthened into ŋ. EXERCISES.-GREEK-ENGLISH. Δυο ανδρε μαχεσθον. Γενναίως μαχώμεθα περί της πατρίδος. Αναγκαιον εστι τον υἱον πείθεσθαι τῳ πατρι. Πολλοι αγαθοι πενονται. Νόμοις τοις εγχωρίοις έπεσθαι καλον εστιν. Μη αποδέχου των φίλων τους προς τα φαυλα χαριζομένους. Εκαστος ήσυχος μεσην την όδον ερχεσθω. Οἱ πολῖται τοις νομοις πείθεσθων. Τω αδελφω μοι έπεσθον. Ει βουλει καλως Εαν βουλη καλως πραττειν, εργαζου. πράττειν, εργαζου. μετ' αυλων εστρατεύοντο. Ψευδόμενος ουδεις λανθανει πολυν χρονον. Οἱ Λακεδαιμονιοι Είθε παντες ανευ οργης βουλευόιντο. Δυο καλω ίππω εις την πολιν ηλαυνεσθην, Εαν πενῃ, ολιγοι φιλοι (σε εισι σοι). ENGLISH-GREEK. I have slain ; they have slain ; he had slain; they will slay ; he slew (first Aorist); we will slay; we have slain ; we That man is poor and has few friends; I am poor; he was had slain; they will sacrifice; they have sacrificed; they had consulting; they two were consulting; I consult; he consacrificed; they sacrificed; the soothsayer sacrificed to the sults; thou wishest to do well; work; if (sav) you wish to god: the soothsayer has sacrificed to the god one hundred | do well, work; they work; he works well; he was working; oxen; I educate my children; I was educating my children; ye were working; ye two were working; we work; I fight; I will educate my children ; I educated my children ; I have I was fighting; they were fighting; they fight bravely; you educated my children; I had educated my children; fight; you were fighting; Ο soldiers, fight bravely for your Alexander destroyed Babylon; Alexander had destroyed country; it is honourable to fight for one's country; I follow Babylon; the boy puts on a woman's garment; the boy has thee ; he follows me; they follow me; we follow the general ; put on a woman's garment; the boy had put on a woman's we were following the army ; obey the laws, Ο boys. garment; the boy will put on a woman's garment. Present and Imperfect Middle or Passive. The Present middle or passive is formed from the stem of the Present active by adding ομαι, as λυ- λυ-ομαι, Οι ομαι, The Perfect and Pluperfect Middle or Passive. The Perfect middle or passive may be formed directly from the perfect active by changing και into μαι; as, Perfect active λελυκα, Perfect middle λελυμαι. The Pluperfect middle or passive may be formed from the | l'evw, I let taste; in the Perfect by changing μai into unv, and prefixing the augment &; as, Perfect λελυμαι, Pluperfect ε-λελυ-μην. VOCABULARY. Φονεύω, φονεύσω, πεφονευκα, TεDOVEVμaι, I kill, slay, murder. Epovrεvw, I plant in (ev, and PUTEU, I plant). Ίδρυω, ίδρυσω, ίδρυμαι, I sit down, place, build. Κατακλείω, κλείσω, κεκλεισμαι | (from λg, a key), I shut up. Λεγομαι (Latin, dicor), I am Akра, aç, i, a summit, a fort Αυτονομία, ας, ή (αυτος, self, ment, freedom. middle, I taste (with genitive). ETITηdevw, I attend to, I prosecute, practise. Πορεύω, I bring, bring forward; in the middle, I go, proceed, travel. Hoλrua, aç, " (from woλ; hence our police, policy, politic, political, polity), a state, constitution, government. Πυλη, gate. REMARKS. ης, η, α door, and vouoc, law), self-govern-historical tense, and because the action depends on the words REMARKS. KEKλELOW, let the door have been shut; this, which is something like the literal rendering of the imperative Perfect passive, scarcely makes sense in English. The force of the Perfect lies in representing the active as already done, and so in denoting despatch, as in our vulgarism, have done, that is, cease immediately. EXERCISES. GREEK-ENGLISH. Οἱ πολέμιοι επι την ημετεραν πολιν στρατεύονται. Περι της των πολιτών σωτηριας βουλευσομεθα. ̔Ο πατηρ μοι έλεγεν ότι TopEVσOLTO. Οι Ελληνες επι τους Πέρσας εστρατευσαντο. Εις την άκραν, into the citadel ; εις with the accusative, instead | Αναπαυσώμεθα, ω φίλοι. Προ του έργου εν βουλευσαι. Παντες '0 πατηρ αναπαυσαμενος of εν with the dative, being used, because motion is implied; τιμης γευσασθαι βούλονται, we, however, in English say in such a case, in the citadel. πορεύσεται. Αἱ πυλαι της νυκτος κεκλείσονται. Εαν τοιουτος ανηρ την πολιτείαν επιτηδευμ, αυτη ευ βεβουλευσεται. EXERCISES.-GREEK-ENGLISH. Οἱ λῃσται πεφονευνται. Δύο αδελφω ύπο του αυτου διδασ καλου πεπαιδευσθον. Η βασιλεία ύπο του δήμου λελυται. Τοις θεοις ύπο των Αθηναίων πολλοι νεφ ἱδρυνται. Η θυρα κεκλεισθω. Προ του έργου εν βεβουλευσο. Πασιν ανθρωποις εμπεφυτευμένη εστιν επιθυμία της αυτονομίας. Οἱ λῃσται πεφονευσθων. Οἱ πολεμιοι εις την ακραν κατακεκλεισθαι λεγονται. Ξενοφωντος υίω, Γρύλλος και Διόδωρος, επεπαιδευσθην εν Σπαρτη. ENGLISH-GREEK. He has been murdered; the boys have been murdered; the soldiers had been slaughtered; he has been shut up; ye have been shut up; ye had been shut up; they have been shut up; the two men had been shut up; the oxen are said to have been shut up; I have been well educated; thou hadst been well educated; they have been well educated; I had been ill educated; thou hadst been ill educated; the trees have been well planted; the trees had been ill planted. The Future and First Aorist Midille, and the Perfect Future The Future middle is formed from the Future active by changing the personal-ending of the active-that is, w-into the personal ending of the middle that is, ομαι, as λυσ-ω, λυσ-ομαι. The o here may be considered as a connecting vowel, and the mood be divided thus-Av-o-o-pai. Of each of these four parts the Student should give an account. The first Aorist middle is formed from the Future middle by prefixing the augment and changing oua into any; thus, λυσ-ομαι, ε-λυσ-αμην; or it may be formed from the first | Aorist active by simply adding μην; thus, ελυσα, ελυσα-μην. The Perfect Future, or, as it is sometimes called, the third Future (also the Paulo-post-futurum), is formed from the second person singular of the Perfect middle or passive by changing at into oμai, as λeλvoai, λeλvo-opai; where, again, o may be accounted a connecting vowel as well as the modal vowel, or vowel marking the indicative mood: for the optative, o becomes of, as λeλvooμnv; that is, is added to o. I give the parts of πάνω : πανω, παύσω, πεπαυκα, πεπαυσμαι; the Future middle, παυσομαι; first Aorist middle, επαυσαμην; Perfect Future, πεπαυσομαι. VOCABULARY. ENGLISH-GREEK. I shall have been educated; he will have been educated; we shall have been educated; they will have been planted; he will have been slain; the general will march to the city ; the general marched to the city; the general may have marched to the city; the general might have marched to the city; we shall have consulted respecting the safety of our native land; he will consult respecting thy safety; he consulted respecting the safety of the citizens; they ceased; they will have ceased; he will cease; the two men ceased; we will cease, O friends; the friends travel; the friends will travel; the friends travelled. The First Aorist and the First Future Passive. The first Aorist passive is formed from the stem of the Perfect active by changing into Ony, and by changing the reduplication into the syllablic augment, as λελv¤, ελv@ŋv. The first Future passive is formed from the first Aorist passive by dropping the augment and changing v into σopai, Ως ελύθην, λυθήσομαι. Συνθηκων λυθεισων : this is what is called " the genitive Пavw, I make to cease; in the | Avanavw, I cause to rest; in absolute," and corresponds with "the ablative absolute" in middle, I cease or stop. Latin; the treaty being broken. the middle, I rest. |