PHYSIOGRAPHY. 81 



Borax Bornite. 



Cleavage parallel to M and M' perfect, also to both the 

 diagonals of the primary form. Fracture conchoidal. 



Lustre resinous. Color white, inclining to grey and 

 green. Streak white. Transparent . . . translucent. 



Rather brittle. Hardness = 2-0 . . . 2-5. Sp. gr. = 

 1'716. Taste sweetish alkaline, feeble. 



1. It is soluble in water; the solution changes vegetable blues to 

 green. It intumesces before the blow-pipe, and then melts into a trans- 

 parent globule. 



2. Analysis. 

 Soda 167 



Boracic acid . . ' . . . 36-4 

 Water 46 9 



3. Borax occurs in different districts of Persia and Thibet, where it is 

 found on the surface of the soil, in the vicinity, and sometimes at the bot- 

 tom, of several lakes, and in a state of solution in the waters of mineral 

 wells. It is found also in Ceylon and at Potosi. 



4. The natural salt is employed in manufacturing the artificial one by 

 the addition of a greater quantity of soda. The artificial salt is made use 

 of as a flux, in the production of imitation gems, and in the process of sol- 

 dering. 



5. The natural historical properties above described apply to the 

 manufactured salt : concerning the natural salt but little is known, al- 

 though perfect crystals of the form here figured are sometimes found 

 among it. In general, it is understood, that it is found mingled up with 

 Common Salt and some excess of boracic acid. The locality in Thibet, 

 which is 15 days from Tisvolumbo, the capital, is a lake supplied by 

 springs, the waters of which contain both borax and common salt. The 

 edges and shallows of this lake are covered with a stratum of Borax, 

 which is dug up from time to time, and the holes thus made are gradu- 

 ally filled by a fresh deposition. 



BORNITE. Bismuthic Poly po ion e -Glance , 

 Primary form. Rhomboid. Angles not determined. 

 Cleavage perfect parallel with the primary form. 

 Lustre metallic. Color pale steel-grey. 

 Elastic. Not particularly sectile. Soft. Sp. gr. =8-0, 



