LECTURE III.] HISTORY OF CHEMISTRY. 37 



Berthollet, however, is the first to point out the error to 

 which chemists had committed themselves in drawing up these 

 tables. He destroys their significance by advancing the doc- 

 trine that the effective action of a substance is related to its 

 mass. 



Berthollet illustrates, especially by reference to salts, the 

 laws in accordance with which chemical compounds are formed. 

 He assumes that the same chemical effect is always connected 

 with the neutralisation of any given quantity of a particular base 

 (or acid). He represents this effect as the product of the 

 affinity A, and the saturating capacity S (that is, for example, 

 the quantity of acid necessary to neutralise a unit of weight of 

 alkali). This gives 



AS= Constant 

 A Constant 

 ~~S~ 



that is, the affinities of two acids are inversely proportional to 

 their saturating capacities, 11 or just the reverse of what Berg- 

 man had regarded as correct. 12 



But, according to Berthollet, the quantity Q of any sub- 

 stance present exercises, quite generally, an influence upon the 

 chemical action, which he considers to be proportional to the 

 product of Q into the affinity of the substance. He calls this 

 product the chemical mass. 13 In the case of acids, the chemi- 

 cal mass may also be stated as proportional to the product of 

 the saturating capacity S into <2, the quantity present, as 

 Berthollet likewise points out. 14 



The effects produced by affinity do not, however, depend 

 exclusively upon the chemical mass : they are varied besides 

 by the state of condensation of the substance concerned, and 

 are subject, therefore, to the physical conditions of the experi- 

 ment (to the pressure, temperature, etc.). As regards the state 

 of condensation of matter, it is, according to Berthollet, a con- 



11 Berthollet, Statique Chimique. I, 71 ; E. I, 45. 12 Kopp, Ges- 

 chichte. 2, 314. I3 StaL Chim. I, 72 : E. I, 45. 14 Ibid. I, 16 ; 

 E. I, xxiv. 



