the Mere of Diss, upon various Substances. 56$ 
spersed with very hard shining particles. The wire was evi- 
dently eroded, and this substance deposited in the place of the 
copper that was decomposed, somewhat similar to the decom- 
position of iron in cupreous waters. 
By repeated chemical analysis of this substance, one hundred 
grains contain, of copper, 70; of sulphur, 1 6.6; of iron 13.3 
grains. 
I have never met with an account of the decomposition of 
copper, in waters impregnated with iron, in any chemical 
work; and, as iron appears to have a greater affinity to the 
vitriolic acid than copper has, (as is constantly evinced in the 
neighbourhood of copper mines,) it appears an anomaly in 
chemistry, that I am not adept enough in the science to ac- 
count for. 
[The President and Council, thinking the effects of the 
water of Diss Mere deserving of further inquiry, desired 
Mr. Wiseman would send some of the said water, for 
the purpose of examination. Mr. Wiseman accordingly 
sent a quantity of the water, accompanied by the other 
substances described in the following letter to the Pre- 
sident.]] 
4D 
MDCCXCVIIJ. 
