46 Ufa of Borax. [Book VI. 



Borax is exceedingly ufeful in many manufactures. 

 It is employed as an excellent flux in the art of glafs- 

 making, as well as in affays. It is advantageoufly em- 

 ployed in foldering, which it affifts by promoting the 

 fufion of the folder, by foftening the fur faces of the 

 metals, and by defending them from the action of the 

 air. 



Very little is known of the combinations of the acid 

 of borax with the vegetable and volatile alkalies. 



The phofphoric acid, and the acid x>f amber, are ca- 

 pable of combination with the alkalies j but the refults 

 of thefe combinations are fo little known, that I lhall 

 pafs them over in filence, and haften to the confidera- 

 tion of the earthy and ftony fubftances. 



Some falirre, earthy, and metallic fubftances, have 

 fuch a relation to each other, that they are feparated 

 with great difficulty, and adhere after repeated folutions 

 and cryftallizations. This circumftance has given rife 

 to another divifion of falts, which are denominated 

 triple, as they do not, however, appear of fufficient 

 confequence to be treated of under a feparate fecTion, 

 J fhall merely enumerate them at the conclufion of the 

 prefent. The moft remarkable examples of this kind 

 are, mineral alkali with calcareous earth ; common ialt 

 with magnefia ; vitriolated magnefia with iron.; alum 

 with iron ; vitriolated copper with iron ; vitriolated 

 copper with iron and zinc ; vitriolated iron with cop- 

 per ; vitriolated iron with zinc ; vitriolated iron with 

 nickel. 



