lOb AGRICLLTUIIAL MUSEUM 



Sweden, discovered that arsenioiis acid (white arsenic 

 oftlie shops) when combined with copper in the state oi' 

 oxid, afforded a green pigment, designated by the name 

 of Scheelc's green ; the j)Z'ocess has been employed in 

 this city with much advantage (in the manulacLure ol some 

 hun(h-ed weight) and sold under the name of iKitent 

 grtcn. 



Seheele's green is usuaHy prepared by niixii^g tclile 

 arsenic, with a sohilion of potash, and adding thereto a 

 solution of blue vitrioK The pigment when washed, to 

 free it of soiphate of potash whtch isfuimcd, is of a bf-au- 

 <iful color, and wciy durable in all kinds of painting. 

 ]5runswiek green, a j^aint formerly in much esteem in 

 Kurope, is, it is said, far inlerior 4o Scheelc's green ; 

 which is also prepared of copper 



Having stated these few facts, which arc connected in 

 some measure with the subject u;ulcr consideration, we 

 shall proceed to consider some ciicumstances relative to 

 a process of preparing verdigrease in this countr}-, where 

 the stalk or the refuse matter of the grape cannot be had 

 in suflicient quantity. 



Copper may either be carroded by the action of vine- 

 gar, and thus form verdigrease, by long boiling and frc 

 quent exposure to air ; or it nuiy be converted into i\\\F 

 substance by exposing it in the same manner, and in 

 similar circumstances, a&that of corroding plates of lead 

 in the forming of white lead. For the latter purpose^ 

 copper plate? (oM sheathing copper, or any old copper) 

 are io be relied spirally, so that the space of an inch shall 

 be left between each circumvokition ; which must be pla- 

 ced vertically in earthen pots of a proper size, containing 

 good vinegar. These copper rolls ought to be support' 

 cd in the pots, that they may not be in contact with the 

 vinegar ; but that tho acid vapor may circulate freely, 

 between tlie circumvolutions. 



The pots are to be covered and placed in abed ofdun^, 

 'The vinegar being thus exposed to the constant and uni- 

 form temperature of a dung heap, suffers a slow, though 

 cpntiiiual evaporation, and attaches itself to the surface 



