ELECTIVE AFFINITY. 
37 
water, the camphor will be set free, because the al- 
cohol combines with the water. So, also, all the 
gum resins which are insoluble in water are libera- 
ted in the same manner. Sulphuric acid has an 
affinity for the following substances, in the order in 
which they are arranged. 
Sulphuric acid will be separated from any of these 
bodies by adding any one above. For example, it is 
separated from magnesia by ammonia, from am- 
monia by lime, &c., but none can withdraw it from 
baryta. Geological phenomena furnish numerous 
instances of simple and compound elective affinity, 
which we shall hereafter find occasion to notice ; 
in the mean time, we must pass on to other sub- 
jects. There are numerous other points of great 
interest connected with chemistry, which it Inight 
be profitable to dwell upon did our limits permit. 
We have only alluded, and that in a very cursory 
manner, to such laws and principles as are abso- 
lutely essential to an intelligible comprehension of 
geological phenomena ; and the more thoroughly 
these principles are studied and understood, the 
more attractive and interesting will the science of 
geology appear. 
Baryta. 
Strontia. 
Potassa. 
Soda. 
Lime. 
Ammonia. 
Magnesia. 
D 
