﻿466 Dr. E. J. Mills on Statical and 



lower oxide) or salts as a case may require. These views, it may be 

 added, were fully retained by their author when (two years later) 

 he wrote his celebrated f Essai. ; 



3. The preceding historical survey is sufficient to show that 

 some of the inadvertencies of chemical thinking have been for 

 hundreds of years precisely the same as those of ordinary think- 

 ing, and consequently abundantly exemplified in our daily life. 

 In our habitual (and for the most part uncritical) mood the mind 

 is in a fixed attitude, and its object is a sedentary image ; it re- 

 sembles a mirror in an unoccupied apartment. If not purely 

 receptive, it either postpones inquiry, or soon bounds that in- 

 quiry with the kind of limit that is known as belief. In this 

 manner statical ideas arise. On the other hand, a mind in which 

 every event is criticised on its occurrence, by the sum total of its 

 predecessors, can only evolve dynamical ideas. Doubt is the 

 popular representation of such a condition. Now neither of these 

 states is ever exclusively realized ; but history and common ex- 

 perience show that, of the two, the former accurately describes 

 the greater part of our intellectual existence, the latter designates 

 its occasional or unsystematic life. Nevertheless it is this which 

 it is advantageous to make uniform ; the abandonment of sta- 

 tical ideas necessarily follows from the criterion of motion. 



Acid, alkali, and salt have had, it appears, very varying but 

 kindred significations. They all at first were names for one con- 

 crete substance respectively. They were all at times generically 

 used for bodies whose properties were explained by universals ; 

 of which the "universal acid" of Stahl,, the "aciduin pingue" 

 of Meyer, and the " igneous particles " of Lemery are examples, 

 and from which the ' ' acidifying principle " of Lavoisier only 

 differed by being isolated. These universals were supposed really 

 to exist in bodies and to constitute part of them. The finest 

 conception of this kind was the primitive acid of Stahl, supposed 

 to be common to acids, alkalies, and salts ; few men have so 

 closely approached a dynamical theory as he did and yet failed 

 to reach it. 



Tachenius was undoubtedly the first to give a clear statement 

 of the dualistic doctrine respecting salts. But if, as Freind as- 

 serted, his doctrine led to this result, namely, that acids and 

 alkalies have only a relative existence, Tachenius deserves a 

 nobler monument than obscurity; for he must be credited with 

 one of the first dynamical theories in chemistry. The transition 

 from this to certain later views is easy. Davy's experiments in 

 electrolysis suggested to Avogrado the idea of a chemical force 

 polar at the moment of action, and presiding not only over the 

 union of acid with alkali, but over every chemical change. Ber- 

 zelius afterwards announced that salts are electrochemically in- 



