HOB 



HOR 



of making horn to imitate tortoise-shell, 

 see COMB. 



HORN is also a musical instrument of 

 the wind kind, chiefly used in hunting, 

 to animate the hunters and the dogs, and 

 to call the latter together. 



The French horn is bent into a circle, 

 and goes two or three times round, grow- 

 ing gradually bigger and wider towards 

 the end, which in some horns is nine or 

 ten inches over. 



HORNS of insects, the slender oblong 

 bodies projected from the heads of those 

 animals, and otherwise called antennx, 

 or feelers. The horns of insects are ex- 

 tremely 'various; some being forked, 

 others plumose or feathered, cylindrical, 

 tapering, articulated, &c. As to the use 

 of these parts, some have imagined that 

 they served as feelers, lest the creature 

 should run against any thing that might 

 hurt it; and others there are, who think 

 them the -organs of hearing. See ENTO- 

 MOLOGY. 



HORN ore, in mineralogy, is one of the 

 Species of silver ore; its most frequent 

 colour is pearl-gray, of all degrees of in- 

 tensity, which borders sometimes on milk- 

 white, and sometimes approaches to laven- 

 der and violet-blue. It passes also, 

 though but rarely, into green. It is found 

 massive, disseminated in thick mem- 

 branes, in roundish hollow balls; also 

 crystallized: specific gravity 4.8. When 

 heated on charcoal before the blow-pipe, 

 it melts quickly, and leaves a globule of 

 silver; it is even fusible by the flame of 

 a candle; it takes a polish by friction; 

 and its constituent parts, according to 

 Klaproth, are 



Silver ... 67.75 



Muriatic acid - - 21. 



Sulphuric acid - - 6.25 



Oxide of iron - - 6.0 



Alumina - - - 1.75 



Lime - - - 0.25- 



Loss 



97.00 

 3.00 



100,00 



It occurs in veins, and generally in 

 their upper parts, and is usually accom- 

 panied with brown iron ocre, and with 

 silver glance, but seldom with native sil- 

 ver and red silver ore. It occurs in con- 

 siderable abundance in the mines of 

 South America, in some parts of France, 



and in Hungary. It derives its name from 

 its property of cutting like horn; and is, 

 of course, soft, flexible, and ductile, when 

 obtained in thin plates. 



HORN stone, or HORN steen, in minera- 

 logy, a species of the flint genus, divided 

 by Werner into three sub-species: the 

 splintery, the conchoidal, and the wood- 

 stone. The most common colour of the 

 splintery horn stone is gray ; it is found 

 in veins, in the shape of balls, in lime- 

 stone, and forming the basis of porphyry, 

 in several parts of Germany, and also 

 in the Shetland islands. It appears to 

 differ from quartz in containing a greater 

 proportion of alumina; when it contains 

 a very large quantity, it passes into 

 jasper. It sometimes borders pn chalce- 

 dony and flint. The best millstone, called 

 French burr, is cellular-splinter horn- 

 stone. Conchoidal hornstone occurs in 

 beds, accompanied with agate; and is 

 distinguished from the splintery by the 

 lightness of its colours, its fracture, 

 and its inferior translucency ' and hard- 

 ness. 



In the woodstone several colours occur 

 together, and it commonly exhibits co- 

 loured delineations, as clouded and strip- 

 ed, and these arrange themselves in the 

 direction of the original woody texture. 

 Its shape is exactly conformable to its for- 

 mer woody shape, so that it occurs in the 

 form of trunk, brandies, and roots. It is 

 found in sandy loam, in Germany, and in 

 Ireland. It receives a good polish, and 

 serves the purpose of agate. 



Mr. Jameson observes, on this mineral, 

 that, " at first sight it may appear incon- 

 sistent, to consider a petrifaction as a par- 

 ticular fossil species; when we reflect, 

 however, that woodstone differs in its ex- 

 ternal characters from all other fossils, 

 the justness of the Wernerian method 

 will become evident. Many other fossils 

 occur in the shape of petrifactions, but 

 they are almost always identical with some 

 known species, and therefore are to be 

 considered only as varieties of the exter- 

 nal sfiape of the particular fossil to which 

 they belong. 



HORN work, in fortification, an out-work 

 composed of two demi-bastions, joined by 

 a curtin. 



HORN geld, a tax paid for feeding 

 of horned beasts in the forest. See FO- 

 REST. 



HORNBLENDE, in mineralogy, a spe- 

 cies of the clay genus, of which there 

 are four sub-species; viz. the common 





