LECTURE XXIX. 



CHEMISTRY. 



SALTS. 



THE objects of chemistry are commonly divided 

 into salts, earths, combustibles, metals, waters, and 

 vegetable and animal substances. By taking them 

 in this order, we shall find that those of a simi- 

 lar nature, and which have most qualities in 

 common, are united together. 



Salts are commonly defined to be substances 

 which are fusible, volatile, soluble in water, not 

 inflammable, and sapid when applied to the 

 tongue. These qualities are united to distin- 

 guish them from other bodies which will be af- 

 terwards mentioned. The first objection that 

 has been made to this definition is, that their 

 fusibility or volatility are not distinguishing cha- 

 racters, as we have reason to conclude there is 

 no species of matter incapable of both : but what 

 is meant here is, that they are easily melted and 

 converted into vapour with a moderate heat. 

 Another objection is, that the absence of inflam- 

 mability is mentioned as a characteristic ; whereas 

 many salts by a vigorous test show signs of in- 

 flammability. 



