60 



Prof. S. U. Pickering on 



almost infinite number of groups of compounds which might 

 be constructed out of the 300 quantities given in Thomsen's 

 2nd volume. Similarly, also, the number of comparable reac- 

 tions (Class C) which might be collected in the same field 

 would certainly afford sufficient chances for the existence of 

 the two coincidences shown in Nos. 13 and 14. 



In the Berichte, v. p. 170, and vi. p. 239, Thomsen drew 

 attention to the (supposed) existence of a common constant 

 of affinity, of which the following are considered as proofs : — 



s,o 2 ... 



. = 4x17,768 



S0 2 , 0, aq. . . 



= 4x17,837 



*S0 4 H 2 ,aq. . . 



. = 1x17,848 



S0 2 ,0,H 8 . 



. = 3x17,834 



*S,0 3 ,H 2 0. . 



. = 7x17,796 



*S,0 3 ,aq. . . 



= 8x17,803 



N 2 ,0 . . . 



= 1x18,316 



*N 2 4 aq.,0 . . 



= 1x18,300 



N 2 2 , O, aq. . 



= 2x18,170 



*N 2 2 , 2 ,aq. . 



= 3x18,214 



^A, 3 , aq. . . 



= 4x18,235 



Cu,0,S0 3 ,aq. 



, = 3x18,070 



Pb, O, S0 3; aq. 



= 4x18,888 



Fe,0,S0 3 ,aq. 



= 5x18,772 



Cd, 0, S0 3 , aq. 



= 3x18,994 



Zn, 0, S0 3 , aq. 



= 6x18,077 



Mg,0,S0 3 ,aq. 



= 10x18,092 



Cu, S, 4 , aq. . . 



= 11x18,058 



Pb,S,0 4 ,aq. . . 



= 12x18,163 



Ee, S, 4 , aq. . . 



= 13x18,176 



Cd,S,0 4 ,aq. . . 



= 11x17,882 



Zn, S, 4 , aq. . 



= 14x17,920 



Mg,S,0 4 ,aq. . . 



= 18x17,963 



Br 2 aq., H 2 . . . 



= 3x18,551 



Cl 2 aq., H 2 . . . 



= 4x18,441 



H 2 2 aq., H 2 . . 



= 5x18,335 



* These are not fundamental quantities, but depend on the other 

 accompanying quantities. 



