84 NOMENCLATUEE. 



formed of the same constituents, were formerly divided into 

 neutral-, super-, and swZ-salts. They were called neutral if 

 the acid and alkali were in proportion for neutralising one 

 another ; super-salts, if the acid prevails ; and sub-salts, if 

 the alkali is in excess. The name is now regulated by the 

 atomic constitution of the salt. If it be a compound of one 

 equivalent of the acid, to one equivalent of the alkali, the 

 generic name of the salt is employed without any other 

 addition; but if two or more equivalents of the acid be 

 attached to one of the base, or two or more equivalents of 

 the base to one of the acid, a numeral is prefixed so as to 

 indicate its composition. The two salts of sulphuric acid 

 and potash are called sulphate and bi-sulphate ; the first 

 containing one equivalent of the alkali, and the second, two 

 of the former to one of the latter. The three salts of oxalic 

 acid and potash are termed the oxalate, "Jm-oxalate, and 

 #?m^r0-oxalate, because one equivalent of the alkali is united 

 with one equivalent of the acid in the first, with two in the 

 second, and four in the third salt. As the numerals which 

 denote the equivalents of a super-salt are derived from the 

 Latin language, Dr. Thomson proposes to employ the Greek 

 numerals dis, tris, tetrakis, to signify the equivalents of an 

 alkali in a sub-salt." 



The above account of the present system of nomenclature 

 explains the nature of the compound substances, termed 

 acids, oxides, sulphurets, and carburets ; and we will now 

 offer a slight explanation of the distinguishing properties of 

 acids and alkalis. Acids are compounds, capable of uniting, 

 in definite properties, with alkaline and earthy bases ; and 

 when in a state of solution, they either have a sour taste, or 

 redden litmus paper. Most acids contain oxygen as one of 

 their elements, which was therefore supposed, at one time, 

 to be the acidifying principle ; but acids exist which have 

 no trace of oxygen; and there are bodies for instance, 

 water which contain a large proportion of oxygen, with- 

 out possessing acid properties. Alkalis have a peculiarly 

 pungent taste ; neutralise acids ; turn vegetable blues to 

 green ; change to a reddish brown the yellow colour of paper 

 stained with turmeric ; and restore the blue colour of litmus 

 paper, reddened by the action of acids. 



Minerals may be discriminated by their external and their 



