114 



THE FARMER'S MONTHLY VISITOR. 



tiou, to have become jiositively electric, but the 

 electricity is preserved ouly for a moment. 



Pure quaitz consists of 48.05 per cent of a 

 brown metalloid substance called siliciuni, and 

 51.95 per cent of oxigen. 



Common sand is composed of quartz or silex. 



It also enters into the composition of a great 

 number of minerals, and is even found to consti- 

 tute a certain proportion of all plants. 



Quartz is used in the arts for various purposes. 

 Pure and transparent crystals are frequently cut 

 by lapidaries and opticians into ornaments and 

 into lenses for spectacles. The spectacles called 

 Scotch ])ebble are made of transparent quartz. 



Some colored varieties of quartz are highly 

 valued in jewelry, those of a dark, smoky yellow 

 being sold for toj)az. The fine transparent vari- 

 eties, when cut and painted on the back, resem- 

 ble precious stones. 



Quartz is used for making glass, for when it 

 is ground into a powder, and is mixed with prop- 

 er proportions of potash and red lead, it melts 

 at a white heat into flint glass, and where no red 

 lead is need, but lime is substituted, it forjns a 

 white and hard glass, w hich withstands the ac- 

 tion of tire and of chemical reageiits much bet- 

 ter than flint glass. 



In common plate glass, for the manufacture 

 of mirrors, soda is used instead of potash as a 

 flux. 



If too large a portion of alkali is introduced 

 into glass, it is liable to dissolve in water, and ad- 

 vantage is taken of this property to form a sol- 

 uble compound which has the property of pre- 

 venting the combustion of wood, which is im- 

 pregnated, or covered wirh a crust of it ; for the 

 soluble glass melting when the wood is heated, 

 coats_ its fibres and prevents their contact with 

 the air ; so that they cannot burn. 



Granular quartz is very usefid for the manu- 

 facture of sand-paper, and it is largely employed 

 for this purpose in New HampsJiire. It is also 

 converted into glass at the New Hampshire Glass 

 Works in Keene. Pulverized granular quartz is 

 also mixed with white lend, and is found to be 

 useful for painting exposed parts of buildings, 

 for the wood-work will not readily ^ield to the 

 penknife when encrusted with quartz. 



The white substance found beneatli peat bogs 

 and in swampy places, which is frequently mis- 

 taken for marl, consists generally of silex com- 

 bined with waterand some vegetable juices from 

 the peat. This silicious substance is composed 

 of collections of minute infusorial animalculoe, 

 which originally lived in the stagnant waters. 

 They have been fully described by Count Erhen- 

 berg and by Prolessor Bailey. Silicious rocks a- 

 bound in New Hampshire, and the soils partake 

 largely of the nature of the rocks. 



FELSPAR. 



This mineral is not so brilliant as quartz, nor 

 is it so hard. It is generally of a white or red- 

 dish color, the hues being due to the jwesence 

 of metallic oxides, which are accidental admix- 

 tures. 



Felspar is divided into two varieties, which 

 are distinguished by the alkalies contained in 

 them. 



That containing Potash is called Orthose, and 

 the variety called Albite contains soda. Orthose 

 is the common felspar. Its characters are as fol- 

 lows : The primary form of llie ciystal is a doub- 

 ly oblique firism, whose angles are 120deg. and 

 60deg. on the sides, and the inclination of the 

 planes on the baseis 1 i2df-g. and 68deg. Its specif- 

 ic gravity is from 2.39 to 2.58. It scratches glass, 

 but yields to the knife. When heated to white- 

 ness before the blow-pipe, it melrs into a white 

 enamel. 



A pure crystalized specimen, analyzed by 

 Berlhier, yielded in 100 |)arts — 



Silex 94.20 



Alumina 18.40 



Potash 16.95 



Lime traces 



99.55 

 Flesh colored felspar, analyzed by Rose, was 

 found to contain — 



Silex 66.75 



Alumma 17.50 



Potash 12.00 



Lime 1.35 



Oxide of Iron 0.75 



W.25 



Felspar undergoes a gradual decomposition 

 when exposed to the action of air, water, and to 

 vegetable rootlets, and the mould of soils. The 

 carbonic acid gas of mineral waters and of the 

 atmosphere acts upon it, so that tlie alkali is 

 gradually removed, and the mineral crumbles to 

 a fine powder. 



When the mineral is moist, this action is quite 

 manifest; but the dry rock is not liable to rabid 

 decomposition, but endures for ages untarnished 

 in its lustre. 



Felspar is the principal source vvlience plants 



obtain the potash which exists in tin 



r juices ! 



solid substance, and their opei-ations are the only 

 economical methods known of eliminating this 

 alkali. 



Felspar forms by its decomposition a very fine 

 unctuous clay, known under the name of Kaolin. 

 It is highly valued for making Porcelain or China 

 ware. 



The mineral in its undecomposed state is also 

 employed for this purpose, and is known iu Chi- 

 na under the name Petuntze. In order to ren- 

 der the felspar suitable for this purpose it must 

 be heated red hot, then it is to be thrown into 

 water, after which it crushes readily and may be 

 ground into a fine powder, which will tbrin a 

 paste suitable lor the potter's wheel. It is gen- 

 erally allowed to remain for two or more years 

 in a moist cellar, in order to become thoroughly 

 deromposed, and then it is more plastic and duc- 

 tile. 



When formed into the shape desired, the paste 

 is first dried slowly and then is baked into ware 

 called biscuit, after which it is painted, glazed, 

 burnt or semi-fused into fine porcelain ware. 



ALBITE. 



This variety of felspar is generally of a pure 

 white color, and is less transparent than the or- 

 those. It crystalizes in the form of an oblique 

 prism, the base being an oblique angled parallel- 

 ogram, having three cleavages whose angles are 

 liSdeg. 62deg. 93deg. 30m. aiid 86deg. 30iit. 

 llOdeg. and tJom. the most brilliant of which is 

 parallel with the base. 



Sp. gr.— 2.61. It scratches glass, but yields to 

 the knife. It contains no water. Before the 

 blow-pipe it fuses into a white enamel. 



The albite of Finland analyzed by Tengstrom 

 consists of 



Silex 67.99 



Alumina 19.61 



Soda 11.12 



Lime 0.66 



Oxide of Manganese 0.47 



Oxide of Iron 0.23 



Cleavelaiidite,Bo named in honor of ProfCleav- 



land of Bowdoin College, is a variety of albite 



containing less soda than exists in the specimen 



above mentioned] 



The Cleavelan'dite of Chestei-field, Ma.ss., yiel- 

 ded, according to the analysis of Stroymeryer, 

 Silex 70.68 



Alumina 19.80 



Soda 9.06 



Lime 0.23 



Ox. Mang. ai>d Iron 0.11 



Another variety of felspar has also been de- 

 scribed under the name of perciline, owing to 

 its ready cleavage on all the planes of the crys- 

 tal. It contains both alkalies, potash and soda. 



According to an analysis by Gmelin, it con- 

 sists of 



Silex 67.94 



Alumina 18.93 



Soda 9.98 



Potash 2.4] 



Lime 0.15 



The soda felspars have not yet been used lo 

 any extent in the arts. They abound in New- 

 Hampshire, where the purest kinds may be ob- 

 tained in any quantities desired. Felspar has 

 been artificially produced iu the furnace, and 

 there is every reason to believe that it originated 

 as before mentioned from crystallization in the 

 molten mass, which formed the granite rocks by 

 crystallization. 



Mica. This mineral is also an essential con- 

 stituent of granite. It is easily recognized by 

 its brilliant laniinse, which split readily into thin 

 leaves, when tried by the penknife. It is easily 

 distinguished from talc by its elasticity and its 

 want of an unctuous feel when ruhbcll by the 

 fingers, the latter characters belonging to talc. 

 MicH splits into laminae pf extiems de)i<-arv, the 



thinnest of which are but 1-10000 of an inch in 

 thickness. It is, when pure, jierfectly transpa- 

 rent and colorless, but there are varieties which 

 arc colored by met;illic oxides, and possess vari- 

 ous shades of red, green, brown and black col- 

 ors. When in a state of decomposition, it fre- 

 quently presents a rich yellow color, and is some- 

 times mistaken by those who are unacquainted 

 with minerals, for native gold. 



On examining blocks of granite of various 

 shapes, it will be found generally, that the col- 

 ors are produced by the diflliirent tints and pro- 

 portions of the mica, which they contain. In 

 some varieties, however, the felspar is strongly 

 colored, and in the red granites is the predomi- 

 nant mineral and coloring ingredient. Ourcoin- 

 nion granites liowever.inore frequently owe their 

 colors to the mica. 

 Berzelius divides mica into three species, viz: 

 1st. Mica with a Mairnesian base. 

 2d. « " " Potash base. *• 



3d. " " " Potash and Lilhia base. 

 There are many varieties of mica in New- 

 Hampshire, some of which are different from 

 those which have been analyzed and described. 

 They will be examined and noticed hereafter. 



The late Doct. Turner of London, analyzed 

 two varieties ol inica from Cornwall, and obtain- 

 ed the follow ing results : 



Brown Mica. Grey Mica. 

 Silex 40.06 50.82 



Alumina 39.90 21.33 



Protoxide of Iron 27.0(i 9.08 



Plot Ox. of Manganese 1.79 

 Fluoric acid 2.71 4.81 



Potash 4.30 8.86 



Lithia 2.00 4.05 



100.82 99.95 



A common variety of granite consisting of 

 three-sixths felspar, two-sixths quartz an<l one 

 sixth mica, according to De la Beche, will con 

 sist of 



Silica 73.04 



Alumina 18.83 



Potash 8.51 



Magnesia 0.83 



Lime 0.44 



Oxide of Iron 1.73 



Oxide Manganese 0.10 



Fluoric acid 0.18 



A more common variety of granite, consisting 

 of two fifths quartz, two-fifths felspar and one 

 fifth mica, will consist of the following ingre- 

 dients : 



Silica 74.84 



Alumina 12.80 



Potash 7.48 



Magnesia 0.99 



Lime '0.37 



Oxide of Iron 1.93 



Oxide of Manganese 0.12 



Fluoric acid 0.21 



To which a small proportion of lithia may be 

 added, when the mica contains that alkali. 



On comparing the composition of the granite 

 soils with the above analysis, a remarkable re- 

 Bemblance in composition will be noted. 



It will be observed, however, that some o.f the 

 ingredients are exhausted from long cultivated 

 soils, especially the alkaline and earthy ingredi- 

 ents which form soluble combinations with the 

 vegetable acids of soils, and are thus taken up by 

 the rootlets of plants. A large proportion of ox- 

 ide of iron is also found in soils, and this may 

 ha^■e been derived from the oxidation of iron 

 pyrites, (or the bi-sulphuret of iron.) 



In many cases we are enabled to replenish the 

 soil with the ingredients that have been removed 

 from them by this process. 



Wood ashes contains a large proportion of 

 potash and lime ; hence this substance is found to 

 be very useful on old worn out sandy soils. 



May not pulverized felspar also answer a use- 

 ful purpose, since it contains, generall.v, more 

 than twelve per cent, of alkali, and a small pro- 

 portion of lime.' Its action would necessarily 

 he slow, for time would be required for its com- 

 plete decomposition. 



We have now described the essential ingredi- 

 ents of granite rocks, and may devote a few lines 

 to a description of some of the more common 

 accidental minerals which it contains. 



GHi-nets, black tourmalinH, bervl» anH iron 



