Chap. 32.] Detonation of Copper. 199 



that each plate may reft on and be covered with layers 

 of ftalks. The pots are covered with lids, and the 

 copper is thus left expoled to the aclion of the vinegar 

 for three or four days or more, in which time the 

 plates become covered with verdigris. The plates 

 are then taken out of the pots, and left in the cellar 

 three or four days, at the end of which time they are 

 to be moiftened with water, or forne of the weak vine- 

 gar above mentioned, and left to dry. When this 

 moiftening and drying of the plates has been repeated 

 three times, the verdigris will be found to have in- 

 creafed confiderably in quantity, and it may then be 

 fcraped off for fale. 



A folution or erofion of cop'per may be obtained by 

 employing ordinary vinegar inftead of wine^ as is di- 

 rected in the above procefs. It would not, however, 

 have the un&uofity of the bed verdigris, which quality 

 is necefTary for painting. Good verdigris cannot be 

 prepared, except with a vinous acid, or a folvent partly 

 acid and partly fpirituous. Accordingly the fuccefs 

 of the operation depends chiefly on the degree of 

 acetous fermentation to which the wine has been 

 carried. 



By diftilling verdigris, the acetous acid may be fe- 

 parated in a concentrated flate, and of a ftrength equal, 

 or perhaps fuperior, to the muriatic acid. 



Copper is capable of a very flight detonation ,with^ 

 nitre. It decompofes fal ammoniac, and at the fame 

 time the volatile alkali is in fome meafure refolyed into 

 its conftituent parts, azote and hydrogen. 



Sulphur and pholphorus may be united to copper; 

 they deprive it of its metallic Iplendor, and change it 

 to a black colour. If plates of copper are ftratified 

 in a crucible with fulphur, they unite, and form a 

 compound which is ufed in the dying and painting of 

 O 4 calicoes; 



