Acids. 159 



2. Chloric acid. 3. Perchloric, or oxychloric 

 acid. 



There are also other acids derived from the 

 mineral kingdom : as the arsenic, tungstic, mo- 

 lybdic, &c. which are only metals oxidized, and 

 their properties as acids not important. 



ithly, The boracic (formerly called sedative 

 salt, from its supposed medicinal power, and 

 which, with soda, constitutes the well-known 

 salt borax) is perhaps more properly entitled to 

 the name of a mineral acid. It is obtained only 

 from borax, which is imported from the East 

 Indies, and of the origin of which we have very 

 little account. The method by which it is ex- 

 tracted is such, that it has no other form than 

 crystals, which are composed of very fine small 

 flakes adhering slightly together; they feel 

 smooth and slippery, and are remarkably light. 

 From some experiments we might conclude that 

 some part of the salt is volatile, and some fixed : 

 but in reality none sublimes, but what is carried 

 oft' with the particles of water. If to the crystals 

 we apply heat, the first effect is an exhalation of 

 a little water with a quantity of salt, which sub- 

 limes in crystals of thin platen much finer and 

 thinner than before ; what remains endures any 

 degree of heat without being volatilized. When 

 red-hot it melts into a mass like glass ; it has the 

 same sort of transparency, and preserves it when 

 cool : it may be again dissolved by pouring cold 



