the Attradl'ive Powers of Mineral Acids. . y 
As thefe numbers agree with what common experience 
teaches us concerning the affinity of thefe acids with their 
refpe&ive bafes, they may be conhdered as adequate expreffions 
of the quantity of that affinity, and I ffiall in future ufe them 
as inch. Thus the affinity of the vitriolic acid to fixed vege- 
table alkali, that is, the force with which they unite, or tend 
to unite, to each other, is to the affinity with which that fame 
acid unites to calcareous earth as 215 grs. to no ; and to that 
which the nitrous acid bears to calcareous earth as 215 grs. to 
9.6, &c. But before I proceed further in the comparifon of 
thele forces, it is neceffary to fay fomething of the nature of 
faturation 
A body is faid to be faturated with another, when it is fo, 
intimately combined with that other as to lofe fome peculiar 
characterise property, which it poffeffes when free from that 
other. Thus acids poffefs the property of changing the juice 
of turnfol, or infulion of litmus, red. According to Mr. 
BERGMAN one grain of the moft concentrated oil of vitriol will 
give a vihble rednefs to 172,300 grs. of this infulion, and one 
cubic inch of water, faturated with fixed air (the weakeft of 
all acids, as is generally thought) of which water takes up 
only about its own bulk, and confequently 2^3 grs. take up 
only about half a grain, reddens 50 cubic inches, that is,, 
about 1 2,650 grs. of the infufion. When acids lofe this pro- 
perty they are faid to be faturated : and if both bodies are fatu- 
rated, the compound is hid to be neutralized. 
If an acid be united to lefs of any bafis than is requilite for 
its faturation, its affinity to the deficient part of its bafis is as 
the ratio which that deficient part bears to the whole of what the 
acid Cdii iaturate. Thus if 100 grs. of vitriolic acid be united-' 
to 55 parts only of calcareous earth, its affinity to the deficient- 
55 parts. 
