'6 A SYSTEM OF 
if I may be allowed that expreffion ; and this 
again to be confidered as a different method. 
Another way, and which in our tmes is much 
favoured, is that of deflruflion partly by very 
violent means, fuch as fubterranean fires, and 
partly by more mild ones, fuch as the weather- 
ing, wafting, or decompounding away *, and by 
this way we have innumerable varieties, and 
new compofitions. The vitriolic and muriatic 
acids do not lie dormant *, and being once let ^ 
loofe by the faid way of weathering or deftruc- 
tion, they do not flop till they are faturated with 
fomething. Where thefe acids cannot penetrate 
by themfelves, they are forwarded by the water, 
which, according to the laws of nature, is almoft 
in a conftant motion : but the effedls of thefe falts 
ought again carefully to be diftinguiflied from 
thofc of the water alone, becaufe this latter a6ls 
both as a menftruum, for inftance, upon the cal- 
careous earth •, and at the fame time by its vis in- 
ertia^., heavinefs and motion, wears off or abrades 
fome partjcles from folid bodies, carries them 
along, and depofits them in other places, where 
thefe particles often acquire a different pofition 
from what they had before. Are the Bog-ores 
produced of decayed mundics, although no vi- 
triolic matter is found in the waters or trads 
around the,m ? or. Are they to be reckoned a fe- 
diment of martial earth diffolved in water alone ? 
Would it be amifs to fuppofe, that a vegetable 
mould may of itfelf be changed into iron, fince 
it is found to yield from a grain to about half of 
|ts weight of the faid metal, as the experiments 
The original has, “ OF c3efi:ro^l:ion that a£ts privative,” 
which I have omitted, as it is quite uninteiligible to me. 
demon- 
