αγαθος becomes αγαθον to agree with ανδρα, and αγαθήν to agree with γυναικα. Compare the declensions of adjectives and nouns combined in the fourth and sixth lesson. As a general rule, a transitive verb, or a verb which has an object after it, has that object in the accusative case, as in the sentence just given—ανδρα αγαθον θαυμαζω. Many verbs, how- | ever, put their object in some other case; some require the genitive, and some the dative. Examples have already appeared. When two nouns come together in a state of dependence, the dependent noun is put in the genitive case: e. g., Ο Αλεξανδρος του Φιλιππου ην υἱος, Alexander was the son of Philip; where Φιλιππου is in the genitive case because it is in sense dependent on υίος. When two verbs come together in a state of dependence, the dependent verb is put in the infnitive mood: e. g. βουλομαι ύδωρ πινειν, I wish to drink water; where πινειν is governed in the infinitive mood by βουλομαι, the former being in sense dependent on the latter. ειναι. τρόπος 8. RECAPITULATORY EXERCISES FROM THE GREEK CLASSICS. 1. Μια χελιδων εαρ ου ποιει. 2. Παντα ο χρόνος προς φως άγει. 3. Πελοπι υίοι ησαν Ατρευς και Θυέστης. 4. Πολλα ανθρωποις παρ' ελπίδα γιγνεται. 5. Γυναιξι κοσμος (sc εστιν) ου τα χρυσία. 6. Οἱ τεττιγες ευφωνοι λεγονται 7. Μυρμηκων και μελισσων βιος πολυπονος εστι. Γιγνώσκει φωρ τον φωρα και λύκος λυκον. 9. Ου κτησις αλλ' ἡ χρησις των βιβλίων οργανον της παιδειας εστιν. 10. Η μεν | φυσις ανευ μαθησεως τυφλον, ἡ δε μαθησις διχα φύσεως ελλιπές. 11. Ο χρόνος τω γηρᾳ προστιθει την επιστημην. 12. Πολλαι ησαν αἱ της βουκερω Ιοῦς πλαναι. 13. Ανηρ ανδρα και πολις πολιν σώζει. 14. Επαμινώνδας ως αληθώς εν ανδρασιν ανηρ ην. 15. Γερων γεροντι γλωσσαν ἡδιστην έχει, παις παιδι, και γυναικι προσφορον γυνή. 16. Παντες οἱ των αρίστων Περσων παιδες επι ταις βασιλεως θύραις παιδευονται. 17. Ξίφος τιτρώσκει σώμα, τον δε νουν λόγος. 18. Η φρόνησις μεγιστον εστιν αγαθον. 19. Πόλεως ψυχη οἱ νόμοι. 20. Ἡ τυραννις αδικίας μητηρ εστιν. 21. Ο δειλος της πατρίδος προδοτης εστιν. 22. Οἱ αγαθοι ανδρες θεων εικονες εισιν. 23. Οἱ Νομάδες των Λιβύων ου ταις ημέραις, αλλα ταις νυξιν αριθμοῦσιν. 24. Χαλεπον εστι λέγειν προς γαστέρα, ωτα ουκ έχουσαν. 25. Ηφαιστος τω ποδε χωλος ην. 26. Η Μήδεια γράφεται τω παιδε δεινον ὑποβλέπουσα. 27. Ηθους βασανος εστιν ανθρωποις χρόνος. 28. Οἱ όφεις τον ιον εν τοις οδουσιν ἔχουσιν. 29. Ο Παρνασσος μεγα και συσκιον ορος εστιν. 30 Εν βοιωτια δυο εστιν επισημα όρη, το μεν Ελικων καλούμενον, ετερον δε Κιθαιρών. 31. Ο Νειλος εχει παντοια γενη ιχθυών. 32. Τίμα τους γονεῖς. 33. Ανάχαρσις την αμπελον είπε τρεις φερειν βοτρυς· τον πρώτον, ηδονης τον δεύτερον, μέθης τον τριτον, αηδίας. 34. Πονος ευκλειας πατηρ (sc. εστιν). Ωκεανου και Τηθύος παις ην Ιναχος. 36. Οἱ τεττιγες σιτούνται την δροσον. 37. Κλεανθης εφη τους απαιδευτους μονη τη μορφη των θηρίων διαφέρειν. 38. Αναχαρσις ονειδιζομενος οτι Σκύθης ην, είπε, τῳ γενει αλλ' ου τῷ τρόπῳ. 39. Κολάζονται εν άδου παντες οἱ κακοί, βασιλεις, δουλοι, σατραπαι, πένητες, πλουσιοι, πτωχοι. 40. Αἱ Φορκου θυγατέρες γραίαι ησαν εκ γενετης. 41. Ζήνων έφη, δειν τας πολεις κοσμειν ουκ αναθη μασιν, αλλα ταις των οικούντων αρεταις. 35. In giving the vocabulary of these recapitulatory exercises, I shali take each sentence in the order in which it stands, because the learner will here need more aid than he has hitherto received. VOCABULARY TO THE EXERCISES FROM THE CLASSICS. 1. Μια, one, from the numeral εἷς, μια, έν, one, χελιδών, nom. sing., fem., agreeing with μια ; χελιδων, χελίδονος, α swallow. 2. See note.* This sentence contains nothing that the student ought not to know. I therefore leave him to ihe knowledge he has, or may have, already attained, and so in future shall I do without giving notice thereof. 3. Πελοπι from Πελοψ, Πέλοπος, a proper name, governed in the dative case by ήσαν; to Pelops there were, that is, Pelops had ; Ατρευς (5. εως), Atreus; Θυέστης (g. ου), Thyestes. Observe that the English y represents the Greek v. tations ; ελπιδα, acc. sing., from ή ελπις (g. ελπιδος), hope; 4. παρ' for παρα, against, παρ' ἐλπιδα, contrary to their expeewhy has the plural adjective woλa the verb in the singular? from χρυσιον, & diminutive of χρυσος, gold, and so denoting pleasing in sound, nom. pl., from εύφωνος (ευ and φωνή, α 7. μυρμήκων, gen. pl. governed by βιος, from ὁ μυρμης, μυρμηκος, an ant; μελισσών, gen. pl. governed by βιος, from μελισσα, ης, ή, α δδε, πολυπονος, ον (from πολυς and πονος), laborious. 8. γιγνωσκει (from γιγνώσκω, I know), indicative mood, active voice, third person singular agreeing with its subject, or nominative φωρ; φωρ, φωρος, δ, a thief; λυκος, ου, ό, a wolf. 9. χρησις, εως, ή, use ; όργανον, ου, το, a means, our organ. 10. ανευ, without ; τυφλον, from τυφλος, η, ον, blind; the blind thing; διχα, separate from; ελλιπες, from ελλιπης, ες, adjective is in the neuter gender, denoting disparagement, a defective (from λειπω, I leave). 11. προστιθει, adds, from προστιθημι, I add, επιστημη, ης, ή, understanding. that from βους and κερα ; Ιους, 1ο, from Iω, οὓς, πλαναι, wan12. βουκερω, Καving the horns of an or, from βουκερως, ω, and derings, from πλανη, ης, ή. 14. αληθως, truly; ως αληθως, very truly. 15. ήδίστην, sweetest, the superlative degree of ἡδυς, sweet προσφορον, pleasant, from προσφορος, ov, conducive to (προς and φέρω). tive of ἀγαθος. 16. αρίστων, the best, that is, noble, from αριστος, a superla 17. Ξίφος, ους, το, a sword; τιτρώσκει, wounds, from τιτρωσκω, Ι wound. 18. μεγιστον, the greatest, superlative from μεγας, great. 20. τυραννις, ίδος, ή, usurped power, tyranny; αδικίας, of injustice (a privative, and δικη, right, justice). 21. δειλος, η, ον, cowardly, ὁ δειλος, the coward; προδοτης, ου, δ, a betrayer, traitor. 22. εικονες, images, εικων, ονος, o, an image, 23. Νομάδες, the nomads, or wandering tribes, from νομας, αδος, and that from νεμω already explained ; αριθμούσιν, they number, from αριθμεω, I number, our arithmetic. 24. έχουσαν, καving, present participle from εχω, I have; it agrees with γαστέρα. 25. Ηφαιστος, Vulcan, χωλος, η, ον, lame. 26. Μήδεια, ας, ή, Medea ; ὑποβλέπουσα, scowling at, fromuro, under, and βλεπω, 1 look. 27. ήθους, of character, from το ηθος ; βασανος, ου, ή, a touchstone, test. 28. όφις, οφεως, ό,τα serpent; τος, ου, a dart, sting. 29. Παρνασσος, Parnassus, a mountain of Phocis, on whi and σκια, a shade. was Delphi; συσκιος, ον, overhung with clouds, from συν, wi 30. επίσημος, ον, distinguished, remarkable, from επι, on (here an intensive), and σημα, a sign, whence our semaphore, that is, a telegraph ; Ελίκων, Helicon; Κιθαιρών, Cithaeron; καλουμενον, called, named, participle agreeing with ro, that is, ορος ; έτερος, α, ον, other, the other. 33. Ανάχαρσις, Anacharsis; ειπε, said; ἡδονης depends on βότρυς ; μεθή, ής, ή, intoxication; αηδια (from a, not, and ἡδυς, sweet), disgust. 34. εύκλεια, ας, ή, glory, distinction. 35. Ωκεάνος, ου, o, Oceanus, Ocean considered as a divinity ; Τηθύς, ος, η, Tethys, a sea-goddess. 36. σιτεομαι, I feed on; δροσος, ου, ή, dew. 37. Κλεάνθης, Cleanthes ; εφη, said, απαίδευτος, ον, untaught, uneducated; μορφη, ης, ή, form ; διαφέρω, I differ. 38. ονειδίζω, Ι reproach, Anacharsis being reproached ; Σκύθης, a Scythian. 39. Koλalw, I punish; ev çdov, douq is understood, in the abode of Hades, in hell; σarpawns, ou, ò, a satrap or governor of a province; TEVNS, NTOS, poor; πTwxos, n, ov, begging; οἱ πτωχοι, beggars. 40. ypala, n, old, an old woman, grey-haired. 41. dev, that it was necessary, proper; avanμa, Tos, To, an offering, public monument, from ava, up, and rionu, I place; TWV OLKOVVTWY of their inhabitants, from oucew, I inhabit, compare oικoς and οικια. (To be continued). ON PHYSICS OR NATURAL PHILOSOPHY. No. VII. MOLECULAR FORCES. Nature of Molecular Forces The phenomena which bodies constantly exhibit lead to the conclusion that their particles are always under the action of two opposite forces, one of which tends to make them attract, and the other to repel, one another. The first, which is called molecular attraction, varies in the same body only with the distance of the particles; the second, which is produced by heat, varies with the intensity of the agent and with the distance of the particles. From the mutual relation of these forces, and from the disposition and arrangement which they give to the particles, arise the different states of bodies, namely, solid, liquid, and gaseous. Molecular attraction only acts at distances incalculably small. Its effect is nothing at any sensible distance, a property which distinguishes it from gravity and universal gravitation, which act at all distances. We are ignorant of the precise laws according to which molecular attraction operates. According to the manner in which it is viewed, it receives the different names of cohesion, affinity, and adhesion. Cohesion is the force which unites similar particles of matter to each other, that is, matter of the same kind, as for instance two particles of water, or two particles of iron. This force is almost nothing in gases, sensible in liquids, and very great in solids. Its intensity is diminished when the temperature of a body is raised, while the repulsive force arising from heat is increased. Hence, when solid bodies are heated, they ultimately become liquid, and even pass from this state into the aeriform or gaseous state. Cohesion varies not only with the nature of the bodies, but also with the arrangement of their particles. To the modifications which cohesion undergoes in different circumstances are to be attributed the different qualities of tenacity, ductility, and hardness. In liquids, taken in large quantity, gravity overcomes cohesion. Hence liquids, constantly yielding to the action of gravity, and assuming no particular form of their own, take always that of the vessels in which they are contained. In small drops of liquids, however, cohesion overcomes gravity, and they assume the spherical or spheroidal form. This may be seen in the drops of dew suspended on the leaves of plants; and the same phenomenon is observed when a liquid is poured on a plane horizontal surface and does not wet it, as mercury upon wood. The same experiment can be made with water, if the surface be previously rubbed or sprinkled with a light powder, such as lamp-black, &c. Affinity is the attraction which takes place between heterogeneous substances; in water, for instance, which is composed of two atoms of hydrogen to one of oxygen, it is affinity which unites these two bodies; but it is cohesion which unites two particles of water. Hence, it is evident that in compound bodies cohesion and affinity act together, while in simple bodies it is only cohesion that unites the particles. Affinity is the form of attraction to which we refer all the combinations and decompositions of chemistry. Every cause which tends to weaken cohesion increases affinity. The latter is, in fact, increased by the state of division in a body; it is also increased by the liquid or the gaseous state of a body. This force is particularly developed by a body when it is disengaged from combination with another body and isolated or left free to yield itself to the action of other bodies for which it may have an affinity. This force also exhibits very variable effects, according to the elevation of the temperature of bodies. In certain cases, by separating the particles and diminishing cohesion, heat produces combinations. For example, between sulphur and oxygen the affinity is without effect at the ordinary temperature, while at a high temperature these bodies combine and produce a fixed compound called sulphurous acid. In other cases, on the contrary, heat destroys combinations, by communicating to their elements unequal expansibility. Hence many metallic oxides are decomposed by the action of heat. Adhesion is the molecular attraction exhibited in bodies which stick together by contact. Two plates of glass, for example, when placed in contact with a weight upon them, adhere so strongly that they cannot be separated without breaking, after the weight is removed. The force of adhesion acts between solids and liquids, and between solids and gases. Adhesion between solids is not merely the effect of atmospheric pressure, for its action is exhibited in a vacuum. This force increases in proportion to the degree of the smoothness of the surfaces in contact, and to the length of the duration of contact; for the resistance to their separation is greater in proportion to the time that their contact has continued. Moreover, adhesion between solid bodies is independent of their thickness a fact which indicates that the molecular attraction acts at indefinitely small distances. When solid bodies are immersed in water, alcohol, and most other liquids, they are found covered with a coat of the liquid when taken out of it; and this is simply the effect of adhesion. Adhesica is produced between solids and gases, similar to that between solids and liquids. Thus, if we immerse a plate of glass or of metal in water, we perceive air-bubbles floating on the surface. Now, in this case the water does not penetrate the pores of the plate, but the air-bubbles arise only from the expulsion of the air which surrounded the plate like the coating of a liquid. A series of phenomena proceeding from molecular attraction, under the names capillary attraction, endosmose, absorption, and imbibition, shall be brought under our notice in the sequel. PARTICULAR PROPERTIES OF SOLIDS. Having explained to the student the principal properties of matter common to solids, liquids, and gases, we shall in this lesson treat of some particular properties of solids; such as the elasticity of traction, the elasticity of torsion, the elasticity of flexure, tenacity, ductility, and hardness. Elasticity of Traction. In our second lesson we explained the nature of elasticity in general, and referred chiefly to that developed by pressure. In solids, however, elasticity is developed also by traction or extension, by twisting or torsion, and by flexure or bending. In ascertaining the laws of the elasticity of traction, M. Savart employed an apparatus represented in fig. 18. This A cathetometer or vertical measurer, as the derivation from the Greek implies, is a brass scale divided into inches and fractions of an inch, placed upon a stand which is brought exactly into the vertical position by adjusting screws at the bottom. On this scale there is placed a sliding telescope sight, exactly at right angles to the vertical, which carries a vernier capable of measuring to fractions of an inch, each one hundredth part of the former. By fixing this telescope sight successively at the points A and B, as seen in the figure, we obtain by means of the graduated scale the exact distance between these two points. Now by loading the scale-pan with weights, and again measuring the distance between the points A and B, we ascertain the amount of elongation or extension arising from the traction of the weights. By experiments conducted in this manner, it has been found so long as the limit of elasticity has not been exceeded, that the traction or extension of rods and wires is regulated by the three following laws : 1st. Metal rods and wires have their elasticity of extension perfect; that is, they resume exactly their original length as soon as the force of traction ceases. 2nd. In the same substance, and having the same diameter, the extension or elongation is proportional to the force of traction and to the length. 3rd. In rods or wires of the same length and of the same material, but of unequal diameter, the extensions or elongations are in the inverse ratio of the squares of the diameters. Both calculation and experiment prove, that when bodies are extended by traction, their volume or bulk is increased. Elasticity of Torsion.-The laws of the torsion of metal wires and threads of various substances were first ascertained by M. Coulomb, a French philosopher, who died in 1806. In his researches on this subject he employed an apparatus called the balance of torsion; this is composed of a fine metallic wire or thread, fastened to a stand at its upper extremity, and stretched vertically by a weight, to the centre of which is attached a horizontal pointer or index. Below this is placed a graduated circle or dial-plate, attached to the stand by a sliding piece and tangent-screw; the centre of this circle, which is exactly under the centre of the index, is so adjusted as to be exactly under the direction of the wire or thread produced when it is in the vertical position. Now, if the index be turned round, out of its position of equilibrium, by the amount of a certain angle, which is called the angle of torsion, the force necessary to put the index in this new position is called the force of torsion. When this turning round of the indes takes place, the particles of the wire or thread which were before situated in the straight line parallel to its length or axis, are now situated in a spiral round it. If the limit of elasticity has not been exceeded, the particles have a tendency to return to their original position, and this tendency is verified by their actual return to it, as soon as the force of torsion is removed; but they do not remain in this position. For, in consequence of their acquired velocity, they pass this position, and produce torsion in a contrary direction; thus the equilibrium is again disturbed, and the wire revolving now on itself, the index does not point to zero on the dial-plate until after a certain number of oscillations on both sides of this point. By means of this apparatus Coulomb proved that when the amplitudes of the oscillations do not exceed a certain number of degrees, these oscillations are regulated by the following laws: 1st. They are very sensibly isochronous, that is, performed in equal times. 2nd. In the same wire the angle of torsion is proportional to the force of torsion. 3rd. In wires of the same diameter, and with the same force of torsion, the angle of torsion is proportional to their length. 4th. In wires of the same length, and with the same force, the angle of torsion is inversely proportional to the fourth powers of the diameters. Elasticity of Flexure.-All solids cut into thin lamina or plates, and fixed at one of their extremities, when more or less bent from their natural position, return to that position as soon as the force which bent them is removed. This property is very evident in tempered steel, caoutchouc, wood, and paper. Cerbe extended to a very great length, or be made extremely tain bodies can be bent only at a very small angle, unless they thin. For example, glass cannot be bent unless it be formed of very thin lamina about a foot in length, or be reduced to a very fine thread. In the latter state it becomes so flexible, that it can be formed into waving plumes, or woven into cloth. Numerous applications of the elasticity of torsion are to be seen in the construction of bows, cross-bows, watch-springs, carriage-springs, spring-balances, and dynamometers, or instruments for measuring the intensity of forces, chiefly of animal power. The elasticity of hair, wool, and feathers is employed in the construction of mattresses, cushions, and other pieces of domestic furniture. Whatever may be the species of elasticity under consideration, as we have formerly remarked, there is always a limit to its action; that is, a degree of molecular displacement beyond which the elastic bodies are fractured, or rendered incapable of reassuming their original form. Owing to several causes, this limit is variable. For instance, the elasticity of several metals is increased by hardening them; that is, by bringing their particles more closely together, as in wire-drawing, plate-rolling, or hammering. Some substances, as steel, cast iron, glass, &c., become more elastic and at the same time harder by the process of tempering, which consists in cooling a metal suddenly after it has been raised to a high tempera ture. Elasticity, on the contrary, is diminished by the process of annealing, which consists in bringing bodies to a lower temperature than that required for tempering, and then slowly cooling them. It is by this process that the elasticity of springs is graduated at pleasure. In the operation of tempering, steel and cast iron acquire a great degree of hardness, and it is chiefly for this purpose that tempering is employed. All cutting instruments are made of tempered steel. But there are some bodies upon which tempering produces an entirely opposite effect. Thus the combination of metals called tam-tam, which is composed of one part of tin to four parts of copper, becomes ductile and malleable when it is suddenly cooled; on the contrary it becomes hard and brittle like glass when slowly cooled. Sulphur exhibits the same phenomenon; when cooled slowly, it is hard and brittle; but when cooled suddenly, it becomes soft and ductile like wax; but it does not continue in this state. Glass presents a curious phenomenon of tempering in what are called Dutch tears or Prince Rupert's drops, names given to small globules of glass, in the shape of tears, which in a state of fusion are dropped into cold water. Glass being a bad conductor of heat, the central parts of these globules are still in a state of fusion when the parts in contact with the water have become solid. From this, it follows that their molecular forces being unable to resume the state of stable equilibrium, the globules become so brittle that fracture at a single point of their surface is sufficient to make them burst in pieces with a loud noise, and at once fall into powder. As glass undergoes the real process of tempering when too suddenly cooled, the brittleness of newly-made articles is diminished by annealing them over a fire, from which they are very slowly withdrawn. Tenacity is the resistance which bodies oppose to their extension by traction. In order to determine the amount of this force in different bodies, they are formed into cylindric or prismatic rods, and subjected, in the direction of their length, to the traction of a weight of so many pounds as are sufficient to determine the force of rupture or separation of their particles. Tenacity is directly proportional to the force which produces transverse section of the rods or prisms employed in resisting the rupture, and inversely proportional to the area of the the strain. According to numerous experiments upon metals, the force necessary to produce rupture is nearly triple of that which corresponds to the limit of elasticity. Tenacity `diminishes with the duration of traction. It is found that, after a certain period, metallic and other rods give way under smaller loads than those which would produce immediate rupture; and in all cases, the resistance of bodies to traction is less than their resistance to pressure. Tenacity varies not only in different bodies, but also in those which are composed of the same matter, and in equal quantity according to their difference in form. In rods of equal sectional area, the prismatic form possesses less power of resistance than the cylindric. In a given quantity of matter, the hollow cylinder possesses a greater power of resistance than the solid cylinder; and the maximum of tenacity in the former takes place when the outer diameter is to the inner one in the ratio of 11 to 5. In the same body, the form has the same influence on the resistance to pressure that it has on the resistance to traction. Hence, a hollow cylinder, of equal matter and altitude, has a greater power of resistance to pressure than a solid one; whence it follows that the bones of animals, the feathers of birds, the stalks of grass and of a great number of plants, being hollow, present a greater resistance to rupture by pressure or traction than if they were solid, the mass of matter being the same. num. Ductility. This is a property which many bodies possess, and it consists in their power to change their form under various degrees of pressure or traction. In some bodies, as clay and wax, a very slight force is sufficient to produce a change in their form; in others, as glass and rosin, it is necessary to add heat; but in metals, strong force is required, as in hammering, wiredenominated malleability when it is produced by the operation drawing, and laminating or reducing to plates. Ductility is of the hammer. The most malleable metal is lead; the most ductile in laminating is gold; and in wire-drawing, is platiproduce wires of this metal not exceeding the thirty-thouThe great ductility of platinum enabled Wallaston to sandth part of an inch in diameter. This was effected by covering a platinum wire of about one-hundredth of an inch in diameter with a coating of silver until the diameter of the compound wire was about of an inch in thickness; then by drawing this wire until its diameter was as fine as possible, the two metals were equally extended by the process; and lastly, by dipping the wire in nitric acid, the silver was dissolved and the platinum wire remained, exhibiting the extraordinary degree of fineness above mentioned. A thousand yards of this wire would weigh only about three-quarters of a grain; and a quantity equal in bulk to a common die would reach from London to Vienna. Tenacity, as well as elasticity, varies in the same body according to the direction in which force is applied. In wood, for example, the tenacity and elasticity are greater in the direction of the fibres than in any crossing direction. This difference is, in general, manifested in all bodies whose contexture is not the same in all directions. Yet M. Savart discovered, by means of ingenious experiments on the sonorous vibrations of bodies, that a difference in this respect existed in a number of bodies whose contexture was completely homogeneous; such as zinc, lead, brass, glass, resinous bodies, &c. He also discovered this difference in certain directions perpendicular to each other, which he called axes of stronger and weaker elasticity. M. Savart attributed this modification of these properties to a symmetrical arrangement which the particles of bodies tend always to assume when they are slowly cooled. It is of the greatest importance, in the arts of construction, to take into consideration the limits of the tenacity and compressibility of materials. In suspension-bridges, for instance, the stability of the structure chiefly depends on the tenacity of the rods which support the road-way. The follow-bodies, but cannot be scratched by any. After the diamond ing table exhibits the weights in tons on the square inch which certain bodies can support in vertical traction before rupture, or in other words, the limit of direct cohesion or tenacity. Hardness.-This property of matter is the resistance which bodies present to scratching or abrasion by other bodies. This property is only relative, that is, a substance may be hard with reference to one body and soft with regard to another. The relative hardness then consists in this, that one body can be made to scratch or abrade another without being itself capable of being scratched or abraded by the other. The hardest of all bodies is the diamond, for it will scratch all in hardness follow the sapphire, the ruby, the rock-crystal, the flint, the stone, &c. Metals in a state of purity are generally soft. Lead can be scratched with the nail. The processes which increase their elasticity also increase their hardness; such as tempering, annealing, &c. Alloys or mixtures are harder than metals. Thus in jewellery and in coining, the hardness of gold and silver is increased by alloying them with copper. The hardness of bodies does not increase in proportion to their resistance to pressure. Glass and the diamond are much harder than wood, but they present less resistance to the blow of a hammer. The hardness of bodies is usefully employed in polishing-powders, such as emery, pumice-stone, and tripoli. The diamond, which is the hardest of all bodies, can only be ground or polished by means of a powder which is merely pulverized diamond. CASE-HARDENING is a process by which the surface of articles made of wrought iron is converted into steel. The articles to be case-hardened having been prepared in wrought iron, they are placed in an iron box in layers, in order to receive that degree of hardening on the surface which will prepare them for receiving a final polish. A layer of animal carbon (horns, hoofs, skins, or leather), at first so burned as to be capable of reduction to powder, is spread over each; the box, then carefully covered and luted with an equal mixture of clay and sand, is kept at a slight heat for half an hour, and its contents are then emptied into water. By this means, a surface of hardened steel is obtained over the whole of the article, of a thickness depending on the duration of the time in which heat has been applied. This process is particularly applicable to articles wanting external hardness and polish, as fire-irons; but it is not applicable to cutting instruments. In the direction of their bres. bahn-keeê-rai Concluded Ghiera gheeê-rah Ghiova gheeô-vah Ringhiare rin-gheeáh-rai Preghiera Singhiozzo Cinghia Unghie Ringhio tchín-gheeah English. Gravel, sand To grin Prayer, desire Sob, sigh, hiccough Girth Nails, hoofs Dirty, foul I catch or snap Royal palace A Roman coin, July 5. Gua, Gue, Gui, Guo, Qua, Que, Qui, Quo. English. A ford A Guelph, an ancient Leader, guide This I receipt The vowel before e, when both follow the consonant c, are pronounced as though the i was not there, and the whole combination only ce. The same remark, however, made with regard to the combinations cia, cio, and ciu-that in a more measured enunciation the vowel in these cases is slightly touchedholds good here also. The observation just made in the foregoing note with respect to cie is strictly applicable to the syllable gie. It is always pronounced as though the i was not there; unless slightly touched in measured pronunciation. § No observation has yet been made in reference to the pronunciation of the double c (cc). This depends, as well as the pronunciation of double g (gg), on the vowel that follows the latter c. If that vowel is a, o, or u, the cc is sounded like a double k (kk) or ck. For example, bocca (bók-kah), mouth; becco (bêk-ko), beak; accusare (ahk-koo-záh-rai), to accuse, If, however, that vowel which follows the latter e is e ori, the double c (cc) is sounded Igrin, grinding the teeth something like tch in the English word match, only perhaps stronger, and with vibration. On that account, I have tried to imitate the stronger sound of the co by the letters ttch, placing the first t in the first syllable, and tch at the beginning of the second, just as I have attempted to imitate the sound of the gg by placing d in one syllable, and 6 at the beginning of the next, in such words as paggi (pahd-jee), pages, attendants. The remark with respect to the pronunciation of the gg, however, holds good of o; the The remark made with respect to the syllable chi, fol- first e occurs, and glide as quickly as possible to the pronunciation voice must not pause too long on the t of the syllable where the lowed by any of the five vowels, is equally applicable to the of the second o, which must be very much vibrated. In this way syllable ghi followed by a vowel: here, likewise, the syllable ghi is, a more equal distribution of the sound tch between the two sylla as it were, squeezed, and the voice must slide into the pronunciables will be effected, which will produce the correct sound o tion of the vowels that follow ghi with great rapidity. I have explained the combination chi to be sounded like kee. When one of the five vowels follows this syllable, it is so intimately blended with the following vowel, that a kind of squeezed sound of CHI is the result, the voice sliding, as it were, from CHI to the next vowel with great rapidity. the co; and my imitation of that sound by ttch has no other object The double zz, as well as the single, may have the mild than to indicate to the reader the necessity of giving a stronger sound of the word adze (with which, by-the-bye, the ds in the word vibration to the cc. It is obvious that when oc is followed by con Windsor corresponds), or the hard sound of tz in Switzerland. sonants, it must be pronounced like k, just as the single c in the According to modern orthography, the letter z is generally doubled like case must be so pronounced. For example, acclamare (ahk in the middle of words between two vowels, and the pronunciation klah-máh-rai), to elect by acclamation, to applaud; accrescere (ahk of this a scarcely differs from that of the single z However, krái-shai-rai), to increase, &c. When between the cc and the before diphthongs,-as, for example, ia, ie, and io,-z must remain vowels e or the letter A is interposed, the cc is also sounded like k, single, and has always, in such a case, the sharp sound. For as well as the single c in such cases and for the same reasons, the example, ringraziare (rin-grah-tseeáh-rai), to thank; pigrizia (pee-h being a mere auxiliary letter to indicate that co before e and is grée-tseeah), idleness; inezie (ee-nê-tseeai), follies; Bonifazio (Bonee-fáh-tseeo), Boniface. not to have the sound of tich, but of kk, as in chicchera (kík-kai-rah), a tea-cup; chiacchiera (keeśhk-keeai-rah), chit-chat, |