380 HISTORY OF SCIENCE. 



His name deserves always to be remembered in connection with two 

 great chemical industries he may be said to have created ; for he was 

 not only the first to propose (1785) the application of chlorine to 

 bleaching, by which that operation is now accomplished in as many 

 hours as it formerly took weeks, but he was also the first to reduce to 

 a system and explain by scientific laws the operations of the dyer. 

 His contributions to the theory of chemistry were numerous and im- 

 portant, as his profound treatises on the " Laws of Chemical Affinity " 

 and on " Chemical Statics " sufficiently testify. He points out that the 

 tendency to chemical combination is possessed by bodies in different 

 degrees, and that it is influenced and modified by the various physical 

 forces, such as elasticity and cohesion. He proves that when solutions 

 of two salts are mixed together, two new salts are formed by the parti- 

 tion of each base between the two acids, and by this exchange of acids 

 and bases four salts co-exist in the solution. The decomposition of 

 the original salts proceeds only until a certain condition of equilibrium 

 among the contending forces is reached. But if one of the four salts 

 be by any means removed from the liquid mixture, the state of equi- 

 librium is destroyed, and fresh portions of the original salts are decom- 

 posed. The removal of one of the salts occurs if it is a substance 

 insoluble in the liquid, in which case it is precipitated \h&\. is to say, 

 it falls to the bottom in a solid form ; or, if it be volatilized by a suffi- 

 ciently high temperature. Berthollet held, however, that definite pro- 

 portion was not the essential law of chemical combinations, but merely 

 an accidental result determined by the equilibrium of opposing//^wV#/ 

 forces. 



