4 
f i»3 ] 
Experiment i. 
Into fome of this water, taken out of the ftream 
above the pits where the iron bars are placed, I pour’d 
a folution of an alkaline fait, which raifed a ftrong 
effervefcence, and precipitated a large quantity of a 
dark-brown fubftance. 
Corollary.. This experiment fliew’d, that the wa- 
ter contain’d a ftrong acid, with a folution of the 
fubftance precipitated. 
Experiment 2. 
Iput fome aqua-fortis, orfpirit of nitre, into fome 
water taken out of the fame place; and obferved, 
that the ftrong acid immediately deftroy’d the blue 
colour. 
Corollary . From this experiment we may con- 
clude, that the fubftance, which was precipitated by 
the alkali, in the firft experiment, was fo perfectly 
diffolved by the acid'fpirit in the fecond, as to trans- 
mit all the rays of light. 
Experiment 3. 
Some fmall iron nails put into this water were in' 
four minutes fo clofely cover’d with fome fubftance 
of a copper colour, that, with a magnifier of half an; 
inch focus, I could not difcern the iron through it. 
In that time the nails gained four grains. The water 
had the fame effed on filver and tin, but not on gold. 
Corollary. The colour and increafe of weight were 
owing to the adhefion of the particles of the matter 
diffolved in the water by an acid, that could not ps* 
netrate gold. 
Experiment- 
