Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/58

Rh by M. Constantin, a landscape painter of some reputation who lived in the town. In 1793 Granet followed the volunteers of Aix to the siege of Toulon, at the close of which he obtained employment as a decorator in the arsenal. Whilst yet a lad he had, at Aix, made the acquaintance of the young Comte de Forbin, and it was upon his invitation that Granet, in the course of the year 1797, proceeded to Paris. De Forbin was one of the pupils of David, and Granet entered the same studio. Later on he got posses sion of a coll in the convent of Capuchins, which, having served for a manufactory of assignats during the Revolution, was afterwards inhabited almost exclusively by artists. In the changing lights and shadows of the corridors of the Capuchins, Granet found the materials for that one picture to the painting of which, with varying success, he devoted his life. In 1802 he left Paris for Rome, where he remained until 1819, when he returned to Paris, bringing with him besides various other works one of fourteen repetitions of his celebrated Choeur des Capucins, executed in 1811. The figures of the monks celebrating mass are taken in this subject as a substantive part of the architectural effect, and this is the case with all Granet s works, even with those in which the figure subject would seem to assert its import ance, and its historical or romantic interest. Stella painting a Madonna on his Prison Wall, 1810 (Leuchtenberg collec tion) ; Sodoma a 1 Hopital, 1815 (Louvre); Basilique basse de St FranQois d Assise, 1823 (Louvre) ; Rachat de Prison- niers, 1831 (Louvre) ; Mort de Poussin, 1834 (Villa Demidoff, Florence), are among his principal works ; all are marked by the same peculiarities, everything is sacrificed to tone. In 1819 Louis Philippe decorated Granet, and afterwards named him Chevalier de 1 Ordre St Michel, and Conservateur des tableaux de Versailles (1826). He be came member of the Institute in 1830; but in spite of these honours, and the ties which bound him to M. de Forbin, then director of the Louvre, Granet constantly returned to Rome. After 1848, he retired to Aix, immediately lost his wife, and died himself on the 21st November 1849. He bequeathed to his native town the greater part of his fortune and all his collections; these are now exhibited in the Muse s, together with a very fine portrait of the donor painted by Ingres in 1811. M. Dele cluze, in Louis David et son temps, devotes a few pages to Granet and his friend the Comte de Forbin.

 GRANITE, a rock so named from the Latin granum, a grain, in allusion to the granular texture of many of its varieties. The term appears to have been introduced by the early Italian antiquaries, and it is believed that the first recorded use of the word occurs in a description of Rome by Flaminius Vacca, an Italian sculptor of the IGth century. This description was published by Montfaucon in his Diarium Italicum, where we read of certain columns &quot; ex marmore granito yEgyptio &quot; (cap. xvii. ), and of others &quot;ex marmore granito /Ethalhe insulae&quot; (cap. xviii.), showing that the Romans of Vacca s day were acquainted with granite from Egypt and from Elba. Granite is also referred to by Csesalpinus in his treatise De Metallids (1596), and by Tournefort in his Relation d un Voyage au Levant (1698); indeed the latter has been cited by Emmerling (Lehrb. &amp;lt;J. Mineral, ) as the first author who uses the term. By these early writers, however, the name was loosely applied to several distinct kinds of granular rock, and it remained for Werner to give it that precise meaning which it at present possesses as the specific designation of a rock. Granite is a crystalline-granular rock consisting, in its typical varieties, of orthoclase, quartz, and mica, to which a plagioclastic felspar is usually added. These minerals are aggregated together without the presence of any matrix or connecting medium. Thin sections of a true granite, examined under the microscope by transmitted light, show no trace of any amorphous or crypto-orystalline ground- mass. The chemical composition of the rock will, of course, vary with its mineralogical constitution. For an average analysis see GEOLOGY, vol. x. p. 233. The proportion of silica varies fiom 62 to 81 per cent. Granite belongs therefore to Buusen s class of acid recks, or those which contain more than 60 per cent, of silica. Dr Haughton has found an exceptionally low proportion of this oxide in some of the Irish granites (58 - 44 per cent., e.g., in some Donegal granite, Quart. Journ. Geol. Soc., xviii., 1862, p. 408). The specific gravity of granite varies from 2 59 to 2 73. Orthoclase, or potash felspar, is the principal constituent of most granites. This mineral occurs either in simple crystals, or in twins formed on what is known as the &quot; Carlsbad type,&quot; such crystals being common at Carlsbad in Bohemia, In porphyritic granites, such as those of Cornwall and Devon, the orthoclase crystals may attain to a length of several inches, and the twinning is marked on the fractured crystals by a line running longitudinally down the middle, and dividing the crystal into two halves. In colour the orthoclase generally varies between snow-white and flesh-red. The green felspar known as Amazon stone, which occurs in certain granites, has lately been shown by Des Cloiseaux to belong to the species microdine, and not, as previously supposed, to orthoclase (Annab sd. Ck., 5ser., ix., 1876, p. 433). The plagioclastic, anorthic, or triclinic felspar of granite occurs in crystals which are generally smaller than those of the orthoclase, and which exhibit, even to the naked eye, their characteristic twin striation. Moreover the lustre is frequently resinous or fatty, while that of the orthoclase is pearly on the cleavage-planes. In most cases the plagioclase is the soda-lime felspar called oligodase ; but in some granites it is albite or soda felspar, as shown by Haughton in many of the Irish and Cornish granites (Proc. Roy. Soc., xvii., 1869, p. 209). When a granite becomes weathered, the felspar may decompose into kaolin or china-clay ; the commencement of this alteration is indicated under the microscope by the turbidity of the felspar, by the ill-defined edges of the crystals, and in the case of plagioclase by disappearance of the characteristic stria?. The quartz of granite occurs generally in irregularly- shaped angular grains ; but occasionally in distinct crystals which are double hexagonal pyramids with or without the corresponding prism. Colourless quartz is most common, but grey, brown, or bluish varieties also occur. Whatever its colour, it is as a rule transparent in microscopic sections, though sometimes rendered milky by the presence of vast numbers of minute cavities containing liquid (see GEOLOGY, ut supra, and for Sorby s original researches Quart. Journ. Geol. Soc., xiv. p. 453). In many granites the quartz fills up the spaces between the crystals of felspar and of mica, and receives impressions from these minerals. This fact has been advanced against the view that granite has existed in a state of fusion; since it is assumed that, as the quartz is the most infusible of the three component minerals, it would have been the first to solidify on the cooling of the magma, whereas the relation of the quartz to the associated minerals in most cases shows that it must have solidified after the crystallization of the felspar and mica. In some granites, however, the quartz is developed in free crystals, thus pointing to an early solidification of this mineral. The mica, which is usually the least abundaat constituent of the granite, occurs in thin scales of irregular shape or in hexagonal plates. It is either a white biaxial potash mica (rnuscovite) or a dark-brown magnesian mica, generally uniaxial (biotite). Both species may occur in the same granite. Haughton has shown that some of the white mica of the Cornish granites is lepidolite, or lithia mica ; while some of the black mica in the same rocks is the iron- 