DI'ALOGUE, in literature, a compo sition or part of a composition in the form of a conversation between two or more persons. The dialogue was the form must generally adopted by the an cients for the conveyance of instruction. and was considered equally applicable to the most grave and philosophical, and to the most ludicrous and comical subjects. Thus it was adopted by Plato. Cicero, and Lucian, with equal success. Plato chose this form for the conveyance of his phi losophical sentiments ; because real con versation had been the mode by which his toaster, Socrates, (who left no writ ing,) gave instruction to the Athenians. In the Dialogues of Plate, Socrates is himself introduced as the chief interlocu tor. Among modern writers the philo sophical dialogue has been frequently employed for the same purpose, more es pecially by the French, to whose language and mode of thought it should seem to be peculiarly suited. Among other eminent persons of that country who have enriched its literature with this species of compo sition are, FeneIon; Paschal, in his Pro vincial Letters ; Bouhours, in his En ire Betsy d' A riste et d'Eug'ene ; Fontenelle, in his Dialogues of the Dead, and Plu rality of Worlds; Galiani, Suer le Com merce des Grains, &c. In England, this me thud of composition has been less fre quently practised; and, perhaps, with the exception of Berkeley and llurd, has rarely succeeded in the hands of those who attempted it. Both the Germans and Italians have attempted to impart a kmavledge of their different philosophical systems in this manner. Among the latter may be mentioned Machiavelli and Algarotti; and among the former, !tossing, Mendelssohn, Schelling, and Ilcrder ; though the labors of none of those distinguished persons in this de partment of literature are so important, as to require any particular notiee this place. The drama-tie dialogue differs free the philosophical, inasmuch as its subject is one of action. The whole of modern dramas is dialogue, with the exception of occasional monologue or soliloquy.
a mark or character, con sisting of two points placed over one of two vowels, as mosaic, to separate the diphthong, and show that they must be sounded distinctly.—In rhetoric, dialysis is a figure of speech in which several words are placed together, without the I aid of a conjunction, as reni, ridi, rich DrAMOND, the most valuable and I the hardest of gems. When pure, it is perfectly clear and pellucid, and is emi nently distinguished from all other sub stances, by its vivid splendor, and the brightness of its reflections. Though
found of different shapes, and sometimes accidentally tinged with several colors, yet it ever carries the same distinguish ing characters. Diamonds are generally very small ; but a few large ones have been found, for which incredible prices have been given. The largest ever known belonged to the king of Portugal ; it weighed 1680 carats, and was valued, although uncut, at 224,000,0001. sterling; the one in the sceptre of the emperor of Rossin. weighs 779 carats, and valued at upwards of .1,000,000/., but was bought by the empress Catharine for about 135,0001. The Pitt diamond, which, at that time was one of the largest, weighed 136 carats, and cost Louis XIV. 130,000/. The Mogul diamond, called Eoh-i-noor, or Mountain of Light, exhibited at the Great London Exposition of Industry in 1851, weighs nearly 280 carats, and was estimated by Tavernier at 469,9591., or according to the rule proposal by Jct. fries, it would be worth 622,0001. This diamond formed a part of the spoil taken in the Sikh war, on the defeat of Run jeet Singh, and was presented by the East India Company to Queen Victoria. The places whence diamonds are brought arc the island of Borneo, and the king dents of Visapour, Golconda, Bengal, in the East Indies; and the Brazils, in the West Indies. These gems consist of pure carbon, with a specific gravity of 3.5; and the hardest tools noticing no impression on them, they arc cut and ground by time power of their own substance. In the experiments of modern chemists, the diamond has been reduced to ashes by the power both of the furnace and the burning Diu ands are valuable for many purposes. Their powder is the best for the lapidary and gem engraver, and more economical than any other ma terial for cutting, engraving, and polish ing hard stones. Glaziers use them for cutting their glass; their diamcnd being sot in a steel socket, and attached to a smell wooden handle. It is very remark able, that only the point of a natural crystal can be used; cut or split dia monds scratch, but the glass will not break along the scratch, as it does when a natural crystal is used. The diamond has also of Lac years become an article of great value to engravers, particu larly in the drawing or ruling of lines, which are afterwards to be deepened by the use of aqua fortis; for which purpose steel points, called etching needles, were formerly used.