80 ^ Anal^ts tf the Tfaity of the Mtri of Dip. 



[The water, and other fubftances defcribed in the foregoing letter, were delivered to Mr. 

 Hatchett, who had been previoufly requefted, by the Prefident and Council, to examine 

 them. The refult of his examination is related in the following letter to the Prefident.] 



AnaJyfis of the Water of the Mere of Difsy by Charles HatcHETT, Efq. 

 Dear Sir, Hammerfmith, September 14th, 179!. 



In confequence of the requeft which you and the Council of the Royal Society have done 

 me the honour to maice, that I would examine the water of Difs Mere, and the other fub- 

 ftances fent by Mr. Wifemau, I now haften to acquaint you with the refult of my experi- 

 ments. 



The fubftances fent by Mr. Wifeman are as follows : Some copper-wire, with a blackifli- 

 grey incruftation. Water from Difs Mere (marked No. i.^ Copper-cuttings, covered with 

 a blackifti cruft, fimilar to that on the copper-wire (marked No. 2.) Some cuttings fimilar 

 to thofe above mentioned (marked No. 3.) The paper, No. 4, contained fome of the black 

 cruft, detached from the cuttings. No. 5, a quart bottle, containing fome water from the 

 lower part of the town of Difs, and called, by Mr. Wifeman, a chalybeate water. No. 6, 

 fome flints, taken from the SE. fide of the Mere, where the water is fhallow, and having, as 

 Mr. Wifeman terms it, a metallic ftain. 



My firft experiments were made on the incruftation of the copper-wire, mentioned in Mr. 

 Wifeman's firft letter. This incruftation was eafily detached from the wire, and being 

 reduced to powder, was digcfted with nitro-muriatic acid, in a gentle heat : a green folution 

 was formed, and there remained a refiduum, of a pale yellow, which proved to be fulphur. 



The folution being diluted with two parts of diftilleJ water, was fuperfatu rated with pure 

 ammoniac, by which a few brown flocculi of iron were precipitated. The fupernatant 

 liquor was blue ; and, being evaporated, and re-diffolved by fulphuric acid, the whole was 

 precipitated by a plate of polifhed iron, in the ftate of metallic copper. The component parts 

 of this coating were, therefore, copper, and a very fmall portion of iron combined with 

 fulphur. I could not extend thefe experiments, as the whole quantity of the coating that I 

 was able to collect, amounted only to three grains and a half*. 



The next experiments were made on the black cruft of Nos. 2, 3, and 4. This I found 

 to be exadly the fame as that formed on the copper-wire, viz, it confifted of copper 

 combined with fulphur, and a very fmall portion of iron. 



■'* The copper-wire, when the coating was removed, was perfe£\ly flexible, and the furface did not appear 



unequal or corroded : this is commonly the cafe under fuch circumftanccs ; for, when i'ulphur has combined 



fuperfitially with a metal, the compound-is obfervcd to feparate eafily, fo as to leave the metal underneath not 



injured in quality, and very little, if at all, affected in appearance. Thofe who diminilh filver coin, make ufe of 



the following method : They expofe the coin to the fumes of burning fulphur, by which a black cruft of 



fulphurated filver is foon formed, which, by a flight but quick blow, comes off like a fcalc, leaving the coin fo 



little affected, that the operation may foroetiroes be repeated twice or thrice, without much hazard of detection, 



f the coiohas a bold impreflioB. 



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