320 SALTS. 



6. The genera are derived from the acids ; the species from the 

 bases, thus all that contain sulphuric acid are sulphates ; all that con- 

 tain nitric acid are nitrates, &ic. 



7. The bases are the oxides* of which there are three divisions ; the 

 alkalies, the earths, and the other metallic oxides. 



8* Every base that combines with acids, furnishes a species ; thus 

 sulphuric acid with potassa, soda, and ammonia forms a sulphate of 

 each of those bases. 



9. The termination ate, corresponds with the acid, whose termina- 

 tion is in ic, and the termination ite, with the acid whose termination is in 

 ous ; thus, sulphuric acid gives sulphates ; sulphurous acid sulphites. 



10. There are some acids containing less oxygen than those that 

 terminate in ous ; in such case, the word hypo is prefixed ; thus we 

 have hypo-sulphurous acid, hypo-nitrous acid, giving also salts that 

 are called hypo-sulphites, and hypo-nitrites. 



11. It was formerly supposed, that there is sometimes an excess of 

 acid in a salt, in which case, the preposition super or hyper was pre- 

 fixed ; and on the other hand, that there is, in particular cases, a de- 

 ficiency of acid or an excess of base, and then the preposition sub 

 was prefixed ; thus, there was a super-sulphate of potassa. and a sub- 

 carbonate of potassa. 



Now, salts with excess of acid are distinguished by the prefix, 

 bis or bi; thus we have fo'-sulphate and 6i-carbonate of potas- 

 sa ; because in these salts, there is just twice as much acid as in 

 the carbonates of the same base. In some salts, the double propor- 

 tion is again doubled, and then the word quadro is prefixed ; thus 

 there is oxalate, 5w-oxalate and quadr-oxalate of potash, implying 

 one, two, and four equivalents of the acid to one of the base. The 

 word super is now banished from the nomenclature of salts ;f but 

 sub is still retained by some, where there are two or more propor- 

 tions of the base. But, Dr. Thomsonf has proposed to use the 

 Greek numeral words, dis, tris, tetrakis, to denote the proportions of 

 base in a sub-salt ; thus, 6?i-sulphate of alumina contains one propor- 

 tion of acid and two of the earth, but this nomenclature has not yet 

 obtained general currency. 



12. Salts are generally, but not always sapid. The first idea was 

 derived from common salt ; but many earthy salts are insipid, e. g. 

 sulphate of lime, carbonate of lime, &c. and such salts are generally 

 insoluble. 



13. Salts are generally, but not universally soluble in water ; the 

 alkaline salts are all soluble, but earthy and metallic salts have some- 

 times one character and sometimes the other. A salt is said to be 



* Ammonia excepted. 



i It may be, and often is still used in a vague and popular sense. 

 } Dr. Thomson has introduced the word sesqui, where there is supposed to be a 

 half of an equivalent. 



