HISTORY OF THE ATuMit iiihuitY. 159 



investigating the quantity of attraction which each acid bears 

 to the several bases to which it is capable of uniting ; for it 

 was impossible not to perceive, first, that the quantity of real 

 acid, necessary to saturate a given quantity of basis, is in- 

 versely as the affinity of each basis to each acid. 2ndly. 

 That the quantity of each basis, requisite to saturate a given 

 quantity of each acid, is directly as the affinity of such acid to 

 each basis. Thus 100 grains of each of the acids require for 

 their saturation a greater quantity of fixed alkali than of 

 calcareous earths, more of this earth than of volatile alkali, 

 more of this alkali than magnesia, and more of magnesia than 

 of earth or alum, as may be seen in the following table. 



Quantity of Basis taken up ty 100 grs. of each of the Mineral Acids. 



" As these numbers agree with what common experience 

 teaches us concerning the affinity of these acids with their 

 respective bases, they may be considered as adequate expres- 

 sions of the quantity of that affinity, and I shall in future use 

 them as such. Thus the affinity of vitriolic acid to fixed 

 vegetable alkali, that is, the force with which they unite, or 

 tend to unite, to each other, is to the affinity with which that 

 same acid unites to calcareous earth, as 215 grs. to 110 ; and 

 to that which the nitrous acid bears to calcareous earth as 215 

 grs. to 96," &c.* He adds a similar table of metals and acids. 

 Kirwan gives here what would lead to the atomic weights 

 of the bodies had he known the law which appears to have 

 been first published by Richter; one obtained the atomic 

 weights as the measure of affinities, the other reciprocal 



• Philosophical Transactions Abridged. Vol. XV., p. 386-6, year 1783. 

 This was read, I believe, in 176M. 



