On the Manufahlurt of Verdigrife. J 1 



4. Having found thefe tranfitlons, or any others, in feme 

 mountains, if they are not then found in other mountains, 

 you muft examine whether their abfence does not ariie from 

 their having been deftroycd ; veliiges of them are to bs 

 fought for; and if it appears that they never exifted, you muft 

 endeavour to difcover, in the nature and pofition of the 

 mountains, what may have been the caufe of tlieir abfence*. 



[To be continued.] 



XI. Obfervations on the Manufailure of the Acet'ttc of Copper 

 or Verdjgrf, Verdct, &c. By J. A. CHAPTAL.f 



A. H E acetite of copper is one of the preparations of that 

 metal moft frequently ufed in the arts. It is not or\]yone of 

 the principal refources of painting, but upon many occafions 

 is employed with great advantage in dyeing. Almoft all the 

 oxydes of copper obtained by the aft ion of faline fub fiances 

 have a blue colour, more or lefs inclining to green, and 

 almoft all the neutral falts corrode the metal, and produce 

 that oxyde which is called verdigrife. It is fufficient to 

 bring them into contaft with the copper, or to immerfe the 

 metallic plates in a faline folution, and afterwards to expofe 

 them to the air to dry. 



Thofe acids which oxydate the copper by their dccompo- 

 fition, produce an cffeft like that of neutral falts. The oxyde 

 is of a foft blucifli-grcen colour ; their aftion is fo fpccdy, 

 that if the copper be expofcd to the vapour of them for fome 

 minutes its furface will . be immediately oxydated. The 

 oxygenated nmriatic acid produces that effeft as well as the . 

 vapour of the nitric acid, and even thofe of the fulphuric 

 acid. A phcnomcnpn which cannot efcape the eye of au 



• The bcft mctlioil of obferving mountains, in order to acquire a tho- 

 rough knowledge of them, is, not to confine oncfelf merely to follow the 

 valleys, but to intcrfcft alfp, as much as polfible, the princip il chains and 

 the branches detached from them in the diretlion of their breadth. C. 



f From Annalts de Chimic, Ko. LXXV- 



|'4 pbfcrvcr, 



