260 NITROCALCITE. 



Brit. Mus., Case 52. 



JNitre is employed in medicine, the arts, 

 and in metallurgy. 



Its principal use, however, is in the ma- 

 nufacture of gunpowder, lucifer matches, 

 detonating powder, &c. 



" In India, Spain, and, as some say, in 

 Persia and China, it germinates in certain 

 seasons out of the earth, and what is more 

 singular, this earth, accumulated in large 

 heaps, and thus exposing a larger surface to 

 the atmosphere, is found to reproduce it 

 annually." * * * « But the most cele- 

 brated discovery of native nitre was that 

 made by Abbe Fortis, in Apulia, in the 

 Pulo or cavit}' of Molfetta, In this hollow, 

 which is about one hundred feet deep, there 

 are several natural grottos, in the interior 

 part of which, between strata of compact 

 limestone, nitre is found irregularly crj^stal- 

 lized. The stone itself is so richly impreg- 

 nated with it, that it bursts it in many 

 places, and forms white efflorescences and 

 crusts resembling Canary Sugar, mixed 

 with g3'psum on its surface; when these 

 efflorescences are scraped off, more is gene- 

 rated in the space of about a month, but 

 more quickly in summer than in winter." 

 {Kirwan, vol. ii. pp. 25, 26.) Similar 

 efflorescences cover the surface of some beds 

 of Portland stone, shooting out in the form 

 of colourless acicular crystals, even after the 

 stone has been painted for the purpose of 

 preventing their appearance. 



NiTROCALciTB, Shepard. Occurs in efflo- 

 rescent silky tufts and coatings of a white 

 or grey colour. Taste sharp and bitter. 



Comp. Ca N + 4H = lime 23-73, nitric 

 acid 45-76, water 30-51 = 100. 



On burning coals fuses slowly with slight 

 detonation, and dries : deliquesces very ra- 

 pidly in the air before being dried. 



Dissolves in one- fourth its weight of water. 



This salt is found on old walls, in lime- 

 stone caverns, and on calcareous rocks. 



NiTRO-MAGNRSiTE, Shepard. Occurs 

 with Nitro-calcite, with vrhich it agrees in 

 colour and other characters. 



Comp. Mg N + H, or magnesia 24, nitric 

 acid 65, water 11 = 100. 



Noble Hornblende. See Pargasite. 



Noble Metals. The name given to 

 those metals which can be separated from 

 oxygen by heat alone. They are Mercury, 

 Gold, Silver, Platinum, Palladium, Rhodium, 

 Iridium and Osmium. 



Noble Opal. See Precious Opal. 



Noble Tourmaline. The name given 



NOSEAN. 

 to the finest transparent varieties of Tour- 

 maline. 



Nontronite, Berthier. Occurs massive, 

 with an opal-like appearance, and earthy. 

 Colour varying from siskin-green to straw- 

 yellow. Lustre dull or glimmering. Opaque 

 to translucent. Immersed in water, gives 

 off bubbles and becomes transparent. Frac- 

 ture splintery or earthy. Unctuous to the 

 touch. Streak resinous. H. 2 to 3. S.G. 

 2 to 2-3. 



Comp. Hydrated tersilicate of iron, 



or #e Si3 + 6H = peroxide of iron 36-11, 

 silica 43-06, water 20-83 = 100. 



Analysis, from Montmort 



Silica 

 Peroxide of ii*on 

 Alumina 

 Lime . 

 Oxide of copper 

 Oxide of zinc 

 Water . 



by Jacquelain 



41-31 



35-69 



3-31 



0-19 



0-90 



trace 



18-63 



100-00 

 BB decrepitates, turns yellow, then 

 brown, then black, and becomes magnetic, 

 but does not fuse. 



Insoluble in cold acid, but dissolves in 

 hot sulphuric, muriatic, or nitric acid, with 

 separation of gelatinous silica. 



Localities. France, at Nontron, Dept. of 

 the Dordogne, in small kidney-shaped 

 masses, among manganese. Montmort, 

 Dept. du Marne. Andreasberg, in the Harz. 

 In amorphous and kidney-formed masses, 

 generally very small (rarely as large as a 

 fist) in masses of manganese worked near 

 the village of Saint-Pardoux, near Nontron. 

 Nontronite is known in commerce as 

 Manganese de Perigueux. 

 Brit. Mus., Case 26. 



Normal Ophiolite. The name adopted 

 by T. Sterry Hunt for the purer Serpentine 

 rocks, when free fi-om foreign admixtures. 



Nosean, Nosiane, Nosin, Leonhard. 

 NosiNB, Beudant. Cubical. Occurs in 

 rhombic dodecahedrons, with an indistinct 

 cleavage parallel to the faces of that solid. 

 Colour grey, brown, bluish; sometimes 

 black. Lustre vitreous to resinous. Trans- 

 lucent to nearly opaque. Very brittle. H. 

 5-5. S.G. 2-25 to 2 28. 



Comp. Na3 Si + 3AI Si + Na S = silica 36-3, 

 alumina 30*9, soda 24-8, sulphuric acid 

 8-0 = 100. 



Analysis, by Bergemann : 



Silica ..... 37-00 

 Alumina . . . , 27-50 



