GRAMMAT1TE. 



1091 



For economical purposes Grasses are often of much importance. 

 The strong stems of the bamboo are employed instead of timber and 

 cordage. The cuticle of some species contains silex, which occurs in 

 large masses after the burning of a heap of corn or a stack of hay in 

 the shape of a colourless glass mass. 



For an account of the diseases of this tribe of plants see ENTOPHYTA 

 ERGOT, and FUNGI. The uses of various species are described under 

 ANATHERUM, COLK, DOXAX, ELECSIJJE, CYNODOJJ, GYNERIUH, ARUNDO, 

 and ELYMCS. 



(Lindley, Vegetable Kingdom ; Babington. Manual of British Botany.) 

 GRAMMATITE. [HORNBLENDE.] 

 GRAMMATOPHORA. [DRACONINA.] 

 GRAMPUS. [CETACEA.] 

 illANADILLA. [PASSIFLORA.] 



GRANAT E^E, a natural order of Plants separated by David Don 

 from Myrtacea [MYRTACEJ;], and containing only the species of the 

 genus Punica. [PumcA.] It differs from Myrtacetz in the leaves being 

 destitute of glands, and in being without the intramarginal vein, as 

 also in the nature of its fruit, its pulpy seeds, and convolute cotyledons. 

 (G. Don, DiMamydeous Planli.) 

 liltAXATCM. [PuxiCA.] 



GRANITE, one of the most abundant rocks seen at or near the 

 surface of the earth, and, from the variety of discussions to which it 

 has given rise, one of the most celebrated. Wherever the stratified 

 rocks, which were deposited by water, are seen to their very base, 

 tli. v are in all quarters of the world observed to rest on other unstra- 

 tified rocks of the nature of granite. This rock appears in many 

 instances to have been in a fluid state since the deposition of those 

 strata which cover it, for it is seen to penetrate into their cracks and 

 fissures, just as iron enters in veins the cracks of the sandstone which 

 forms the sides or bed of the furnace. The fluidity of granitic rocks 

 is now almost universally attributed, and with sufficient reason, to 

 the effect of great heat analogous in its origin to that which supplies 

 the energies of volcanoes, but probably more general in its distribution 

 and more uniform in its action. 



It is impossible to say how much of the mass of the earth is 

 composed of granitic rocks, though from the matter thrown up by 

 volcanoes we see that mineral compounds in some degree analogous 

 exiat to considerable depths. To what extent it can be demonstrated 

 that the sedimentary stratified rocks have been derived from disinte- 

 grated granites is yet uncertain, and Sir Charles Lyell has recently 

 introduced the consideration of the more difficult question, whether 

 granite haa not been produced and may not still be forming by the 

 remelting of such sedimentary aggregates into the general mass of the 

 interior of the globe. The bare mention of such expanded views 

 shows the high interest which attaches to the contemplation of 

 granite. [GEOLOGY.] 



Granite is one of the most beautiful of rocks, and viewed mineralo- 

 gically its composition is remarkable. Mica, felspar, and quartz, in 

 distinct crystals, or else filling interstices between crystals, constitute 

 the typical varieties, and the most abundant masses of granite ; but 

 it in impossible so to limit the signification of the term. Hornblende 

 must be included among the legitimate constituents of granite, if we 

 are to use the term in a manner at all consistent with geological 

 experience or the variations of granitic compounds. Other minerals, 

 especially actiuolite, chlorite, talc, compact felspar, steatite, garnet, 

 zircon, 4c., enter into and sometimes considerably modify the aspect 

 of granite. The colours vary : the felspar is red, gray, yellow, white, 

 green; the quartz is usually clear white or gray; the mica is black, 

 gray, white, brown, and in various degrees eilvery ; the hornblende is 

 dark green or black. The mica and felspar are invariably, and often 

 (especially in cavities) beautifully crystallised ; the quartz commonly 

 fills the interstitial spaces left by these minerals, but small pyramidal 

 crystals of quartz in great perfection may be sometimes seen imbedded 

 in the faces of the prismatic felspar crystals, which are also sometimes 

 penetrated by the filmy plates of mica. 



Except in the veins which ramify into stratified rocks, and there 

 grow fine-grained and even compact (like the base of some porphyries), 

 granite, as its name implies, shows the grains of its component parts : 

 the size of these varies extremely. The mica in the granite of Rubies- 

 law, near Aberdeen, forms himimc some inches across ; but in that of 

 Cornwall, Skiddaw, &c., it exists in small plates ; the felspar in 



Granite of three ingredients (the typical varieties) : 



Quartz, felspar, and mica, uniformly blended, or with distinct 



additional crystals of felspar, then called Porphyritic Granite. 

 Quartz, felspar, and hornblende. (Syenite of authors.) 

 Quartz, felspar, and mica. (Instead of the mica, chlorite or talo 



sometimes appears.) 

 Granite of four ingredients : 



Quartz, felspar, mica, and hornblende, or actinolite. (Syenite of 



some authors.) 



Quartz, felspar, mica, and compact felspar, or porcelain clay. 

 Quartz, felspar, hornblende, and chlorite, or steatite. 

 GRAPE-HYACINTH. [MuscARi.1 

 GRAPE-VINE. [ViTis.] 

 GRAPHIDACE.E. [LICHENS 1 

 GRAPHIS. [LICHENS.] 



GRAPHITE, Plumbago, Slack Lead. This substance occurs crystal- 

 lised and massive. Primary form a rhomboid. Occurs in imbedded 

 hexagonal prisms. Cleavage parallel to the terminal planes of the 

 prism, very distinct, and the lamina; flexible. Fracture granular and 

 uneven. Hardness I'O to 2'0. Colour steel or blackish-gray. Streak 

 black, shining. Lustre metallic and glistening. Unctuous to the 

 touch. Opaque. Specific gravity 2 P 08 to 2'45. 



Found in Greenland and in the neighbourhood of Philadelphia in 

 the United States. 



The massive varieties occur amorphous, in reniform masses and 

 irregular nodules. Structure foliated, granular, compact. 



Found in various parts of the world. That of Borrowdale in 

 Cumberland is of the best quality for what are called black-lead 

 pencils ; while the commoner sorts are used for making melting-pots, 

 for diminishing the friction of machinery, and for protecting iron from 

 rusting. That which is imported from the East Indies is remarkably 

 soft. Plumbago conducts electricity, is infusible, and very difficult 

 of combustion. 



Professor Vanuxem has analysed several varieties of Graphite. 

 No. 1 was a pure specimen from Borrowdale, and No. 2 from Bustle- 

 town, Pennsylvania. 



Carbon 88'37 



Silica 

 Alumina . 



Water 



Oxides of Iron and Manganese . 



5-10 

 1-00 

 1-23 

 3-60 



99-30 



No. 2. 

 94-4 

 2-6 



0-6 



1-4 



99-0 



graphic granite is almost cue huge crystallised mass ; large detached 

 crystals in the granites of Snap and Ben Nevis make those rocks 

 porphyritic, but in gome of the building granites of Aberdeen all the 

 ingredients are in small grains. 



The proportion of the ingredients in typical granite varies greatly : 

 tin: mica is sometimes absent, or replaced by hornblende. The fol- 

 lowing is a general view of the most remarkable granitic mixture*, to 

 wljiuh some authors apply distinctive names, but we think with little 

 advantage to geology, borne of these, mineralogically speaking, are 

 :';al with rocks of the trap family [SYKNITE], but certainly occur as 

 parts of a granitic series, viewed geologically. (M'Culloch, 'On Rocks.') 

 Binary Granite, composed of two ingredients : as felspar and 

 mica, quartz and felspar, either equally blended (as in Muncaster 

 Fell, Cumberland), or in segregated portions (as the graphic 

 granite); quartz and hornblende (M'Culloch); felspar and 

 hornblende. 



It was at one time supposed that Graphite was a carburet of iron, 

 but, in the opinion of Berzelius, the experiments of Karsteu have 

 proved that it is a peculiar form of carbon, and that the substances 

 which it contains are in a state of mixture merely and not of chemical 

 combination. 



According to Dr. Thomson, Graphite is found usually in primary or 

 transition rocks. At Borrowdale it occurs in nests in a greenstone 

 rock, which constitutes a bed in clay-slate. In Inverness-shire it 

 occurs in gneiss; at Arendal in Norway, in quartz-rock; and in the 

 United States, in felspar and mica-slate, but always in primary rocks. 



The material for lead-pencils, when of the finest quality, is first cal- 

 cined and then sawn up into strips of the requisite size, and commonly 

 set in wood (usually cedar) as they appear in the market. It is much used 

 now in small cylinders, without wood, for ever-pointed pencil-cases. Gra- 

 phite that cannot be thus used for pencils is reduced to a powder, and 

 on being submitted to pressure it is made to adhere into a solid mass, 

 which is subsequently cut up in the way referred to above. Graphite 

 is also added to clay for making a kind of pottery. It is also exten- 

 sively employed for diminishing the friction of machinery, also for 

 the manufacture of crucibles and furnaces, which withstand a great 

 heat. For this purpose it is mixed with half its weight of clay. It 

 is also employed as a wash forgiving a gloss to iron-stoves and railings. 



GRAPSIDyE, Grapsoidians, a tribe of Brachyurous Crustaceans 

 belonging to the family of Catametopes, placed by M. Milne-Edwards 

 between the Gouoplaciaus and the family of the Oxystomes,and approach- 

 ing in his opinion nearer to the tribe of Gonoplacians than to the Ocypo- 

 diaus. He gives the following as the characters of the Grapsoidians : 



Carapace in general less regularly quadrilateral thau in the Gono- 

 placians and Ocypodiaus : its lateral borders are nearly always slightly 



curved, and its fronto-orbital border frequently does not occupy more 

 than about two-thirds of its transversal diameter. The body is nearly 

 always compressed, and the sternal plastron but little or not at all 

 curved from before backwards. The front is nearly always strongly 

 recurved, or rather bent down, and very wide, occupying about the 

 half of the anterior border of the carapace, and exceeding on each 

 side the edge of the lateral borders of the buccal frame. The orbits 

 are oval-shaped and of moderate size ; and the lateral borders of the 

 carapace are slightly curved and nearly always trenchant. The ocular 

 pedicles are large and short ; their insertion is below the front, and 

 the cornea occupies one-half of their length. The internal antennae 

 are sometimes vertical and lodged in distinct pits (fossettes), which 

 are open at the upper surface of the carapace ; but in the great 

 majority of instances these organs are entirely transversal and com- 

 pletely covered above by the front ; their terminal stem is nearly 



