L A 



[251 ] 



LEG 



opaque and beautifully white ena- 

 mel. Specific gravity 2 '23. Lau- 

 monite consists of silica 52, alumina 

 21-20, lime 10-50, and water about 

 14. It occurs in secondary trap- 

 rocks in France, Scotland, Iceland, 

 and America. 



LA'ZULITE. A mineral of a light blue 

 colour, supposed by some mineralo- 

 gists to be a sub-species of lapis lazuli. 



LEAD, (lad, Sax.) Lead is of a bluish- 

 grey colour, with considerable lus- 

 tre, but soon tarnishes by exposure 

 to the atmosphere. By friction, 

 this metal exhales a peculiar, and 

 somewhat disagreeable odour. Its 

 specific gravity is 1T35, or nearly 

 eleven and a-half times heavier than 

 water. It is soft and easily melted, 

 being fusible at about 600 Fahren- 

 heit. It is the softest of all the 

 durable metals; it can be scratched 

 by the nail, and is easily cut by a 

 knife. Its elasticity, ductility, and 

 tenacity are comparatively low ; it 

 cannot be drawn into wire thinner 

 than a line in diameter. Lead is 

 very malleable, and can be beaten 

 into thin leaves; but these, from 

 its imperfect tenacity, are easily 

 torn. All the salts of this metal 

 are highly poisonous ; they are, 

 however, most shamefully employed 

 by unprincipled persons to correct 

 or conceal the acidity of cider and 

 wines. The presence of lead in 

 these liquors may be detected by 

 the following means. Dissolve 120 

 grains of sulphuret of lime, and 

 180 grains of supertartrate of po- 

 tash in 16 ounces of distilled water, 

 by repeatedly shaking the mixture; 

 when perfectly dissolved, leave the 

 mixture to settle, and pour off the 

 clear liquid into clean phials, adding 

 about twenty drops of hydrochloric 

 acid to each. A small quantity of 

 this poured into a wine-glass of the 

 suspected wine, will detect the 

 smallest quantity of lead, if any be 

 present, by producing a black pre- 

 cipitate. 



Several instances of the occur- 

 rence of native lead have been 

 mentioned, though in few of them 

 does the fact appear to be well 

 established. In the island of Ma- 

 deira, it is found in small masses, 

 in lava, and has undoubtedly been 

 reduced to its present state by vol- 

 canic fire. Next to iron, lead may 

 be considered the most abundantly 

 diffused of all the metals; it has 

 been known from the earliest ages. 

 The lead of our mines is in a state 

 of combination with sulphur, form- 

 ing a sulphuret of lead; this is 

 called galena, or lead-glance. By 

 exposure to a strong heat, the sul- 

 phur is driven off and pure lead is 

 obtained: the average produce of 

 metal from the Derbyshire ore is 

 about 66 per cent. The present 

 annual produce of lead in the "Uni- 

 ted Kingdom may be computed at 

 from 47,000 to 50,000 tons. 



LEE'LITE. (thus named after Dr. Lee, 

 of Cambridge.) An earthy mineral, 

 first noticed by Dr. Clarke, is found 

 at Gryphitta, in Sweden. It is 

 compact and massive, of a deep 

 flesh-red colour. Texture wax-like, 

 with the lustre and transparency of 

 horn. Fracture resembling that of 

 flint. Specific gravity 2- 71. Its 

 constituents are silica 75, alumina 

 22, manganese 3, or manganese 

 2-50, and water 0-50. Phillips. 



LEGU'ME. flegumen, Lat. legume, Fr. 

 legume, It.) A species of fruit; 

 a pod; a seed vessel peculiar to 

 leguminous plants, formed of two 

 oblong valves having no longitu- 

 dinal partition; the seeds are at- 

 tached to one of its margins only ; 

 the bean, pea, vetch, and all the 

 natural order of Ieguminosa3 furnish 

 examples. 



LEGUMINO'S^J. An order of plants, 

 calyx five -toothed, inferior, the odd 

 segment anterior, or farthest from 

 the axis; corolla papilionaceous, 

 rarely regular ; stamens definite or 

 indefinite, perigynous, either dis- 



