the Mere of Diss, upon various Substances. 571 
The water in the higher parts of the town is good ; in the lower 
parts, it is a chalybeate, of which a specimen is sent, (No. 5.) 
No. 6 . contains a quantity of flint stones, taken from the SE 
side of the Mere, where the water is shallow ; many of which 
are strongly marked with the metallic stain, which they acquire 
by lying in this water a few years. 
The Mere contains about eight acres, and is of various depths, 
to twenty-four feet: from its situation with respect to the 
town, it may naturally be supposed to contain a vast quantity 
of mud, as it has received the silt of the streets for ages. In 
summer, the water turns green ; and the vegetable matter that 
swims on its surface, when exposed to the rays of the sun, af- 
fords vast quantities of oxygen gas. I cannot help considering 
this process as having a considerable agency in the. corrosion, 
and in the formation of the metallic crust upon the copper 
deposited in this water. Some of this vegetable matter will be 
found in the water sent to the Society. 
I intend to make some further experiments with different 
metallic substances, at different parts, and at various depths ; 
but, as the process is slow, if in the mean time you, Sir, or any 
of the members of the Society, will have the goodness to point 
out any experiment you or they may wish to have made, I 
shall be very glad to contribute all in my power towards the 
illustration of the subject. 
I have the honour to be, &c. 
* 
BENJ. WISEMAN. 
The Right Hon. Sir Joseph Banks, Bart. 
k.b.p.r.s. 
4 D 2 
