1 54 MEMOIR OF DR. DALTON, AND 



will remain unshaken. Let then the methods be exactly 

 decided on, and no fallacy is to be feared." * 



ON ELECTIVE ATTRACTIONS. 



" Simple elective attractions.! Let A be the substance to 

 which a, b, c, &c., are drawn ; further, let A be added to c to 

 saturation, this we shall call Ac, when again b is added, let 

 the union take place to the exclusion of c ; then A is said to 

 attract b more than c, or b has a stronger elective attraction 

 than c; then Ab, when a is added, gives up b, and a is united 

 instead, then it is understood that a excels b in attractive 

 force, and the order of the efficacy of the attraction forms 

 a series «, b, c. What we here call attractions, others 

 call affinity; we use either term promiscuously in future, 

 although the latter being more a metaphorical expression 

 does not appear so suitable in physics. 



* * * * Page 3 18. " It has not escaped me, that some 

 chemists have considered, as entirely without foundation, the 

 doctrine which asserts that neutral or middle salts can receive a 

 distinct excess of acid. That this sometimes takes place the 

 experiments to be related most clearly shew, although naturally 

 it (the excess) adheres with far less tenacity than that por- 

 tion which is necessary to effect saturation. 



* * * * Page 325. " From all that has been brought 

 forward, I consider it clear, not only that the doctrine of a 

 decided superfluity of either ingredient is not absurd, but that 

 in reality this result is found in many cases. Certainly this 

 superfluity attaches itself much more loosely than the portion 

 necessary for saturation, so that frequently it is easily driven 

 off, but this in no way causes it to be less real." 



Here we find Bergman endeavouring to obtain the amount 

 of oxygen in metallic oxides, or phlogiston in metals. He 

 finds that the amount in equal quantities of metals is not the 

 same. This could only be the case if the atomic weights of 

 all metals were the same. 



♦ Page 396. f Vol. III., page 294. 



