578 Mr. Hatchett’s Analysis of 
sively during formation,) has been deposited on bodies, such as 
the flints, when in contact with the mud. 
But an excess of sulphur appears to be present ; for, when 
copper is put into the Mere, the sulphur readily combines with 
it ; and, at the same time, a small portion of iron appears to 
unite with the compound of copper and sulphur, possibly by 
the mere mechanical act of precipitation. 
/ 
The incrustation on the copper wire and cuttings is, in every 
property, similar to that rare species of copper ore, called by the 
Germans Kupfer schwartze , ( Cuprum ochraceum nigrum ; ) and 
I consider it as absolutely the same. In respect to the martial 
pyrites on the flints, there can be no hesitation ; and, as in these 
two instances, there were evident proofs of the recent formation 
of ores in the humid way, I was desirous to ascertain the effect 
on silver. I therefore wrote to Mr. Wiseman, to request that 
he would take the trouble to make the experiment; and re- 
ceived from him the following answer, accompanied by the 
specimens. 
“ SIR, Diss, 8th September, 1798. 
44 Immediately upon the receipt of your letter, (27th July,) I 
laid some silver plate, and silver wire, into the Mere ; the whole 
weighed 235.6 gr. I took it out on Thursday last, (Sept. 6th) 
and, after cleaning it carefully from mud and weeds, I find it 
weighs 242.8 gr. ; an increase of 7.2 gr. 
“ The silver plate you will find much tarnished, in some parts 
almost black ; the wire is in many places fairly incrusted, 
which crust, upon the pressure of the fingers, comes off in thin 
scales. The whole appearance of the silver strongly indicates 
