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346 Miscellanies. 



als, and in immediate sequence to their own metallic bases, which 

 cannot be procured without previously obtaining, describing and de- 

 composing the very alkalies and earths,* which are, immediately af- 

 ter, to be placed again in the rear of those metals, which have been 



extracted from them. 



Nor, is this all. Ammonia, connected by every chemical and elec- 

 trical affinity, with the other alkalies, and with the earths, is severed 

 from them, and left behind, in an earlier part of the arrangement 



in connexion with hydrogen and nitrogen, its parent gases, where it 

 certainly belongs, and where most writers now place it. So far from 

 objecting to this position of ammonia, I leave it there, and bring up 

 the other alkalies and the earths into the same connexion. 



In my judgment, the teacher, who postpones the history of the fix- 

 ed alkalies and earths, until he can introduce them in connexion with 

 the metals, subjects himself and his pupils, to much embarrassment; 

 for, it is scarcely possible to proceed, more than a few steps, in the his- 

 tory of particular bodies, and in practical chemistry generally, with- 

 out calling in the aid of the alkalies, and of some of the earths, 

 is true, that the fixed alkalies and the earths graduate, by almost in- 

 sensible shades, into the other metallic oxides ; but, the class ot me- 

 tallic oxides, (using the phrase in the most general sense) is so exten- 

 sive, that there can be no logical impropriety, and there certainly is 

 reat advantage, in breaking it up into natural orders, of alkalies, 

 earths and oxides, (proper) distinguished, as they are, by striking di- 

 versity of properties. It appears also very desirable to maintain, m 

 the mind of the student, a clear apprehension of the distinct exist- 

 ence of alkalies, and of earths, and not to oblige him to look tor 

 them, one by one, among the subordinate compounds of metals, 

 studied in that manner, he will not see them grouped and describe 

 together, although they are connected by strong natural affinities. 

 is a very sensible remark of Dr. Ure— that, " Whatever may be the 

 revolutions of chemical nomenclature, mankind will never ceas 

 consider as earths, those solid bodies, composing the mineral stra a, 

 which are incombustible, colorless, not convertible into metals by 

 the ordinary methods of reduction, or when reduced by scientific r 

 finements, possessing but an evanescent metallic existence, an > 









* This order, in the case of some of the common metals, creates no embaria 

 ment. 



