XX [ ADVERTISEMENT. 



4. Three, four, &c. atoms of the acid are denoted by 

 prefixing the Latin numerals, ter, quater,* &c. Three, 

 four, &c. atoms of the base, by prefixing the Greek nume- 

 rals, tris, tetrakis, &c. 



5. When a metal is combined with oxygen in the pro- 

 portion of two atoms metal to one atom oxygen, the com- 

 pound is called a suboxide. Thus, suboxide of manganese 

 is a compound of two atoms manganese and one atom 

 oxygen, or, of one atom manganese and a half atom 

 oxygen. 



All the other terms employed will be understood with- 

 out any farther explanation. 



* The affix quadro having been already applied for this purpose by Dr, 

 Wollaston, and having come into general use, I have thought it better to con- 

 tinue it than to use guater. 



