BAR 



BAS 



evening, suddenly opening 1 , after remain- 

 ing closed all day. The other species, 

 B. polypetala, is" a perennial, growing 

 on gravelly hills, near the Grand Detour, 

 and flowers in August. 



BARTRAMIA, in botany, is a genus of 

 the Decandria Monogynia class of plants, 

 the calyx of which is a perianthium, cut 

 into five parts : the corolla consists of five 

 wedge-shaped petals ; the fruit is globu- 

 lar, and the seeds are four in number, 

 convex on one side, and angular on the 

 other. 



BARTSIA, in botany, so named from 

 Dr. Bartsch, the intimate friend of Lin- 

 nasus, a genus of the Didynamia Angios- 

 permia class of plants, whose flower con- 

 sists of one petal, having the upper lip 

 longest ; the seeds arc numerous, small, 

 angular, and inclosed in capsules. There 

 are five species, one called B. gymnan- 

 dria, grows within the arctic circle, on 

 the north side of the Frozen Ocean in 

 Kamtschatka, where there is no other 

 vegetation. The American species are six 

 in number, according to Pursh. 



BARUTII, an Indian measure, contain- 

 ing seventeen gantans : it ought to weigh 

 about three pounds and an half of Eng- 

 lish avoirdupois. 



BARYTES was discovered by Scheele 

 in 1774 ; and the first account of its pro- 

 perties published by him in his Disserta- 

 tion on Manganese. This is a very heavy 

 mineral, most frequently of a flesh colour, 

 of a foliated texture, and brittle, very 

 common in Britain and most other coun- 

 tries, especially in copper mines. It was 

 known by the name of ponderous spar, 

 and was supposed to be a compound of 

 sulphuric acid and lime. Gahn analyzed 

 this mineral in 1775, and found that it is 

 composed of sulphuric acid, and the new 

 earth discovered by Scheele. Scheele 

 published an account of the method of 

 obtaining this earth from ponderous spar. 

 The experiments of these chemists were 

 confirmed by Bergman, who gave the 

 earth the name of terra ponderosa. Mor- 

 veau gave it the name of barote, and Kir- 

 wan of barytes ; which last was approved 

 by Bergman, and is now universally adopt- 

 ed. Barytes may be obtained in a state 

 of purity, by the calcination of its carbo- 

 nate or nitrate. It exhibits, when pure, 

 the following properties : 1. Barytes, in 

 a pure form, has a sharp caustic taste, 

 changes vegetable blue colours to green, 

 and serves as the intermedium between 

 oil and water : in these respects it bears 

 a strong resemblance to alkalies. 2. When 

 exposed to the flame of the blow-pipe 

 on charcoal, it melts, boils violently, 



and forms small globules, which sink into 

 the charcoal. If perfectly free from wa- 

 ter, however, it is infusible. 3. If a small 

 quantity of water be added to recently 

 prepared barytes, it is absorbed with 

 great rapidity; prodigious heat is excit- 

 ed ; and the water is completely solidifi- 

 ed, a sort of hard cement being obtained. 

 A little more water converts this mass 

 into a light bulky powder; and when 

 completely covered with water, the ba- 

 rytes is dissolved. Boiling water shouldbe 

 employed for this purpose, unless suffi- 

 cient temperature has been produced by 

 the sudden addition of the whole quan- 

 tity necessary for solution. 4. When the 

 solution, prepared with boiling water, is 

 allowed to cool slowly, it shoots into re- 

 gular crystals. These have the form of 

 flattened hexagonal prisms, having two 

 broad sides, with two intervening narrow 

 ones; and terminated at each end by a 

 quadrangular pyramid. 5. The crystals 

 are so soluble as to be taken up when 

 heated, merely by their own water of 

 crystallization. When exposed to a strong- 

 er heat, they swell, foam, and leave a dry 

 white powder, amounting to about 47 

 parts from 100 of the crystals. This again 

 combines with water with great heat and 

 violence. At 60 of Fahrenheit, an ounce- 

 measure of water dissolves only 25 grains 

 of the crystals, i. e. they require for solu- 

 tion 17^ times their weight of water. 

 Exposed" to the atmosphere, they efflo- 

 resce, and become pulverulent. 6. When 

 added to spirit of wine, and heated in a 

 spoon over a lamp, they communicate a 

 yellowish colour to its flame. 7. The spe- 

 cific gravi'y of this earth, according to 

 Fourcroy. is 4, but Hassenfratz states it 

 at only 2374. The former account, how- 

 ever, is the more probable. All its com- 

 binations have considerable specific gra- 

 vity ; and hence its name is derived, viz. 

 from the Greek word j3eft$, signifying 

 heavy. 8. Barytes does not unite with 

 any of the alkalies. 



BASALT, in mineralogy, occurs mas- 

 sive, in blunt and rolled pieces, and some- 

 times vesicular: its common colour is 

 greyish black, of various degrees of in- 

 tensity ; from this it passes into ash-grey ; 

 sometimes to brown, and even in some 

 varieties to raven black. It is dull in- 

 ternally, and the fracture is commonly 

 coarse-grained and uneven. It occurs 

 almost always in distinct concretions, 

 which are usually columnar, and from a 

 few inches to several fathoms, and even 

 to upwards of 100 feet, in length. They 

 are sometimes straight, sometimes bent, 

 and either parallel OF diverging. In moun- 





