-Chap. 8.] &orax. 45 



have loft much of its weight. By incre'afe of heat, ic 

 undergoes a proper fufion, and aflumes the appearance 

 of glafs; but is diftinguiflied from that fubitauce, by 

 diflblving and cryftaHizing again. 



Borax may be decompofed by means of the muri- 

 atic acid. It appears furprizingj but the fact is cer- 

 tain, that a quantity of acid of borax, though fo weak 

 an acid in its more obvious properties, will diflodge, 

 when heat is applied, both the nitrous and muriatic 

 acids, and unite itfelf to their alkali. The reafon 

 feems to be, that the attraction of different fubftances 

 for the fame body is different in different degrees of 

 heat. This again is to be attributed to a double 

 elective attraction, in confluence of the addition of 

 the matter of heat. The cohefion of ihe nitrous and 

 muriatic acids to their bafes is fo much weakened by 

 their affinity wkh heat, or in other words, their ten- 

 dency to aiTbme the gaffecus {bun, that the attraction 

 of the boracic acid, which is more fixed, becomes fu- 

 perior, and difplaces them. 



Borax, as imported from the Eaft Indies, is very 

 impure. When purified, it has a very regular form. 

 Its cryftals are fix fid ed prifms, two of the fides being 

 commonly larger than the others, terminated by tri- 

 hedral pyramids. Its cryftallization is, however fub- 

 ject to confiderable varieties. It is ftyptic, and acts 

 ftrongly on the tongue, and like alkalies it converts the 

 fyrup of violets to a green. Borax, expofed to the 

 air, lofes a fmall part of its water of cryitallization, and 

 (lightly efflorefces. It is foluble in twelve parts of 

 cold and fix of hot water. Its cryftals may therefore 

 be obtained by cooling , but the fined and moft regular 

 are formed by fuffering the cold faturated ibluticn to 

 evaporate fpontaneouOy in the ordinary temperature 

 of the atmofphere. 



Borax 



