the Attractive Powers of Mineral Acids. 3 - 
but many very eminent chymiffs have been induced to doubt, 
whether any general law whatfoever could be traced. But, as 
the judicious bergman well obferves, it were much more rea- 
fonable to examine the circumftances of thefe exceptions, which 
undoubtedly arife from the introduction of new powers, and 
lay down rules qualified with luch reftri&ions as are obferved in 
the aCtion of thefe antagonift powers. This is the plan I have 
followed ; but before I proceed to explain myfelf, I mull open 
the iubjeCt in a more general way. 
Chymical affinity or attraction is that power bv which the 
inviiible particles of different bodies intermix and unite with 
each other fo intimately as to be infeparable by mere mecha- 
nical means. In this refpeCt it differs from magnetic and 
eleCtrical attraction. It alio differs from attraction of cohelion 
in this, that the latter takes place betwixt particles of almoft 
all forts of bodies whofe furfaces are brought into immediate 
contaCt with each other ; for chymical attraction does not aCt 
with that degree of indifference, but caufes a body already 
united to another to quit that other and unite with a third, and 
hence it is called elective attraction. Hence attraction of cohe- 
fion often takes place betwixt bodies that have no chymical 
attraction to each other ; thus regulus of cobalt and wilmuth 
have no chymical attraction to each other, for they will not 
unite in fufion, yet they cohere with each other fo ffrongly. 
that they can be feparated only by a ffroke of a hammer. 
Hence bodies, which refufe to unite to each other chymically 
when they are molt minutely divided, as when both are in a 
vaporous or aerial ffate, or when both are in a liquid ffate, may 
be judged, in the hrit cafe, to have none ; or in the fecond cafe, 
to have at heft but a very lmall affinity to each other. But 
thofe that unite, when one ot them only is in a liquid ffate, 
F 2 may 
