BOR 



BOR 



posited in those lakes; whence, in sum- 

 mer, when the water is shallow, it is ex- 

 tracted, and carried off in large lumps. 

 Sometimes the water in these lakes is ad- 

 mitted into reservoirs, at the bottom of 

 which, when the water is exhaled by the 

 summer's heat, this salt is found. Hence 

 it is carried to the East Indies, where it 

 is in some measure purified and crystal- 

 lized ; in this state it comes to Europe, 

 and is called tineal. In other parts of 

 Thibet, it seems, by accounts received 

 from China, they dig it out of the ground 

 at the depth of about two yards, where 

 they find it in smaller crystalline masses. 



Borax, or sub-borate of soda. This salt, 

 the only one of the borates which has 

 been accurately examined, is supposed to 

 have been known to the ancients, and to 

 be the substance denominated chrysocol- 

 la by Pliny. At any rate, it is mentioned 

 by Geber as early as the ninth century, 

 under the name of borax. Its composi- 

 tion was first pointed out by Geoffrey, in 

 1732, and Baron, in 1748. Bergman de- 

 monstrated that it has an excess of base, 

 and is therefore in the state of a sub-bo- 

 rate. 



Borax, purified, may be obtained crys- 

 tallized in hexangular prisms, of which 

 two sides are much broader than the re- 

 mainder, and terminated by triangular 

 pyramids ; it is of a white colour : its spe- 

 cific gravity is 1.740 : it converts vegeta- 

 ble blues to green : its taste is styptic 

 and alkaline ; it is soluble in twenty times 

 its weight of water, of the temperature of 

 60, and six times its weight of boiling 

 water : when exposed to the air it efflo- 

 resces slowly and slightly : when heated, 

 it swells, loses about four-tenths of its 

 weight, becomes repy, and then assumes 

 the form of a light, porous, and very fria- 

 ble mass, known by the name of calcined 

 borax ; in a strong heat it melts into a 

 transparent glass, still soluble in water. 

 When two pieces of borax are struck to- 

 gether in the dark, a flash of light is emit- 

 ted. This salt, according to Bergman, is 

 composed of 



Acid 

 Soda 

 Water 



39 

 17 



44 



Too 



Though borax has been in common use 

 for nearly three centuries, it was only in 

 1702 that Homberg, by distilling a mix- 

 ture of borax and green vitriol, discover- 

 ed the boracic acid. He called it narco- 

 tic or sedative salt, from a notion of his 



that it possessed the properties indicated 

 by these names. Geoffrey afterwards dis- 

 covered, that borax contained soda ; and, 

 at last, Baron proved, by a number of ex- 

 periments, that borax is composed of bo- 

 racic acid and soda ; that it may be re- 

 produced by combining these two sub- 

 stances ; and that therefore the boracic 

 acid is not formed during the decompo- 

 sition of borax, as former chemists had 

 imagined, but is a peculiar substance, 

 which pre-existed in that salt. This acid, 

 for purposes of experiment, is obtained 

 from the purified borax of commerce, by 

 one of the following processes : 1. To a 

 solution of borax in boiling water, add 

 half its weight of sulphuric acid, previ- 

 ously diluted with an equal quantity of 

 water. Evaporate the solution a little ; 

 and on cooling, shining, scaly crystals 

 will appear, which consist of boracic acid. 

 Let them be well washed with distilled 

 water, and dried on filtering paper. 2. 

 Let any quantity of borax be put into a 

 retort, with half its weight of sulphuric 

 acid, and half its weight of water. Bo- 

 racic acid may be obtained by distillation, 

 and may be purified by washing in water, 

 &c. as before. Boracic acid has the fol- 

 lowing qualities : 1. It has a solid form, 

 is destitute of smell, and nearly so of 

 taste : 2. It fuses, when heated, and loses 

 its water of crystallization. If the heat 

 be increased suddenly, before it has lost 

 its water of crystallization, it sublimes ; 

 but, otherwise, it melts into a glass, which 

 is permanent in the strongest fire : 3. It 

 is soluble in twelve parts of cold water, 

 and in three or four of boiling' water : 4. 

 This solution reddens vegetable blue co- 

 lours, and effervesces with alkaline car- 

 bonates : 5. It is soluble in alcohol, and 

 the solution burns with a beautiful green 

 flame : 6. It combines with alkalies and 

 earths ; but the only important combina- 

 tion which it forms is with soda. 



BORBONIA, in botany, so called from 

 Gaston Bourbon; a genus of the Diadel- 

 phia Decandria class and order. Natural 

 order of Papilionaceae or Leguminosje. 

 Essential character : calyx acuminate, 

 spiny ; stigma emarginate ; legume mu- 

 cronate. There are six species. B. eri- 

 cifolia, is a small subvillose shrub, with 

 small ovate linear leaves, nerveless, 

 smooth above, villose beneath, revolute ;. 

 heads sessile, with small flowers. These 

 plants grow naturally at the Cape of 

 Good Hope, where they rise to the height 

 of ten or twelve feet ; but they are sel- 

 dom more than four or five in Europe. 



BORDURE, in heraldry, a cutting off 

 from within the escutcheon, all round it, 





