26-i HISTORY OF CHEMISTRY. 



be, served so well to express many chemical facts, that it kept its ground. 

 It is found, for instance, in Lemery's Chemistry, which was one of 

 those in most general use before the introduction of the phlogistic 

 theory. In this work (which was translated into English by Keill, in 

 1698) we find alkalies defined by their effervescing with acids. 4 They 

 were distinguished as the mineral alkali (soda), the vegetable alkali 

 (potassa), and the volatile alkali (ammonia). Again, in Macquer's 

 Chemistry, which was long the text-book in Europe during the reign 

 of phlogiston, we find acids and alkalies, and their union, in which 

 they rob each other of their characteristic properties, and form neutral 

 salts, stated among the leading principles of the science. 6 



In truth, the mutual relation of acids to alkalies was the most essen- 

 tial' part of the knowledge which chemists possessed concerning them. 

 The importance of this relation arose from its being the first distinct 

 form in which the notion of chemical attraction or affinity appeared. 

 For the acrid or caustic character of acids and alkalies is, in fact, a 

 tendency to alter the bodies they touch, and thus to alter themselves ; 

 and the neutral character of the compounds in the absence of any such 

 proclivity to change. Acids and alkalies have a strong disposition to 

 unite. They combine, often with vehemence, and produce neutral 

 salts ; they exhibit, in short, a prominent example of the chemical 

 attraction, or affinity, by which two ingredients are formed into a com- 

 pound. The relation of acid and base in a salt is, to this day, one of 

 the main grounds of all theoretical reasonings. 



o o 



The more distinct development of the notion of such chemical 

 attraction, gradually made its way among the chemists of the latter 

 part of the seventeenth and the beginning of the eighteenth century, 

 as we may see in the writings of Boyle, Newton, and their followers. 

 Beecher speaks of this attraction as a magnetism y but I do not know 

 that any writer in particular, can be pointed out as the person who 

 firmly established the general notion of chemical attraction. 



But this idea of chemical attraction became both more clear and 

 jiore extensively applicable, when it assumed the form of the doctrine 

 of elective attractions, in which shape we must now speak of it. 



Lemery, p. 25. 5 Macqner, p. 19. 



