78 Accsunt of the Mire of Dip in 



On the Effect of the Mere of Difs upon various Subjlances, 

 01>lerving feveral years ago, that flint ftones taken out of the Mere of Difs were incrudcJ 

 with a metallic ftaiii, I was induced to make fome experiments, in order to difcover the 

 nature or coT.pOlition of this metallic fubftance. Nitrous acid readily removes it, diffolviiig 

 a part, and leaving a yellovyifh powder, which, vvafhed and filtered, was found to W. 

 fulphur. Vegetable fixed alkali precipitated from the nitrous acid a ferruginous coloured 

 powder, which was iron. 



With a view to determine what length of time was neccfiary fur the formation of this 

 metallic llain upon flint ftones, or other fubftances, I inclofed in a brafs-wire net the follow- 

 ing articles : flint ftones, cakareous fpar, common writing flate, a piece of common white 

 fiono ware, and likewife a piece of black Wedgwood-pottery. After remaining in the water 

 from the fummer of 1792, to Auguft, 1795, the flints and Wedgwood-ware had acquired 

 tl« metallic ftain in a flight degree, and the flate had affumed a ruft colour ; the other 

 fubftances appeared not to be at all altered. I was greatly furprifed to find the copper wire 

 that held the net,, furroundcd with a metallic coating of a confiderabis thickuefs; it was 

 of a deep lead colour, and of a granulated texture. When taken from the wire, and ground 

 in a mortar, it had a black appearance, interfperfed with very hard fliining particles. The 

 wire was evidently eroded, and this fubftance depofited in the place of the copper that 

 was decompofed, fomewhat fimilar to the decompofition of iron in cupreous waters. By 

 repeated chemical analyfis of this fubftance, one hundred grains contain, of copper, 709 

 of fulphur, 16.6; of iron, 13.3 grains. 



I have never met with an account of the decompofition of copper, in waters impreg- 

 nated with iron, in any chemical work ; and, as iron appears to have a greater affinity to the 

 vitriolic acid than copper has (as is conftantly evinced in the neighbourhood of copper 

 mines), it appears an anomaly in chemiftry, that I am not adept enough in the fcience to 

 account for. 



[The Prefident and Council of the Royal Society thinking the efFe(5ls of the water of Difs 

 Mere deferving of further inquiry, defired Mr. Wifeman would fend fome of the faid water, 

 for the purpofe of examination. Mr. Wifeman accordingly fent a quantity of the water, 

 accompanied by the other fubftances defcribed in the following letter to the Prefident.] 



Sir, Difs, May 29, i7(,S. 



As the Society have exprefled a wifh, through Mr. Frere, to have fome of the water in 

 which the copper wire was depofited, which Mr. Frere, at my requeft, laid before the Society, 

 I have fent two gallons of the water of Difs Mere (No. i), with a fmall quantity of copper 

 cuttings (No. 2), which laid in the fame water, a few feet from the fide, and fix feet in 

 depth, from the 7th of February, 1797, to the 20th of the prefent month. May, 1798. The 

 pieces of copper, when laid in, weighed 3051 grains ; when they were taken out, and walhed 

 from the mud that lightly adhered to them, preferving and weighing the fcaly matter that 

 came off, they weighed 2944 grains, indicating a lofs of 107 grains. Examining the pieces 



of 



