Cryjlallifed Verdigrifei 1 7^ 



2ci, I took a large earthen jar of Provence, well glazed, 

 capable of containing iwo hundred (French) pints of water, 

 buried it one half in a ftratum of very warm dung in full 

 decompofition, and having put fome manganefe in the bot- 

 tom of it, and adapted to it a ftraight glafs tube which 

 reached from the mouth to the bottom, I filled the jar with 

 plates of copper (lightly rolled, in order that they might not 

 touch each other but in fome points. I then made to pafs 

 into the bottom of the jar, by means of the tube, the necef- 

 fary quantity of the muriatic acid, and immediately clofed 

 the upper aperture with a luted covering. Two days after 

 thefe plates were entirely crufted over with a greenifh oxyd, 

 ' which detached itfelf in duft and in fcales : I feparated of it 

 two pounds ten ounces. This oxyd, lefs lively than that of 

 the common verdigrife, is foluble in vinegar : and this me- 

 thod may then be employed, with fome advantage, to form 

 the acetat of copper ; but it cannot fupply the place of the 

 acetous verdigrife either in painting or dyeing. 



3d, I formed fulphat of copper by pouring, upon plates oi 

 copper brought to a red heat in a crucibk, about a third in 

 weight of pounded fulphur. This fulphure, exceedingly fri- 

 able, pulverifed and expofed to a pretty violent heat for four 

 or five hours, left a grey powder, eafily attacked by the ace- 

 tous acid. That which I drgefted at a heat above a gentle 

 temperature, gave, by evaporation, a confiderable quantity 

 of very blue and beautiful crj'ftals of acetat af copper, and a 

 ftratum of true fulphat of copper of a pale blue and without 

 cryftals. 



4th, I faturated diftillcd acetous acid with oxygenated 

 muriatic acid gas. This acid, digefied cold on the copper, 

 diflolvcd it in part;, but it formed a beautiful micaceous fcaly 

 ' liite, which had no relation with the acetat. Copper cx- 

 pofud to the vapour of tliis acetous acid, liituratcd with oxy- 

 genated muriatic acid gas, becomes covered with very bril- 

 liant fmall cryftals of a bright-blue colour, fome of whicW 

 are tranfparent and white, Thefe cryftals prcfcnted lonjj; 



fquar*' 



