OP ARTS AND SCIENCES. 11 



II. 



SCHEELE'S GREEN, 



ITS COMPOSITION AS USUALLY PREPARED, AND SOxME EX- 

 PERIMENTS UPON ARSENITE OF COPPER. 



By S. p. Sharples, SB. 



Presented, June 14, 1876. 



In 1778, the eminent Swedish chemist, Charles William Scheele, com- 

 municated to the Academy of Sciences at Stockholm the method of 

 preparing the green pigment which has since borne his name. He, 

 however, says, that it was discovered three years previously. 



This piument is of a yellowish green color, and has been long used 

 in the arts under various names ; such as, mountain green, mineral 

 green, and Swedish green. At the time of its discovery, it was the 

 most brilliant green obtainable. 



The discovery, in. 1814, of the copper aceto-arsenite, known as 

 Schweinfurth green, Paris green, English green, and sometimes wrongly 

 called Scheele's green, has, however, almost entirely tlirown Scheele's 

 green out of the market ; and it is at the present day an unknown sub- 

 stance, so far as its use as a pigment is concerned ; although it may be 

 still found on the price lists of manufacturing chemists, and the receipts 

 for its manufacture are found in works on dyeing and calico-printing. 

 But its covering power is very low, and it is far inferior in brilliancy 

 to its successful rival, Paris green. 



Having had occasion to examine some samples of this pigment some 

 time ago, I became convinced that the composition of Scheele's green, 

 as laid down in the books, was altogether a matter of conjecture ; since 

 I could find no record of any analysis that had ever been made of the 

 substance prepared according to Scheele's directions, which have been 

 copied without change for the last hundred years. 



The formula given varies with the date ; Scheele himself, of course, 

 neither made a quantitative analj'sis nor gave a formula. Succeeding 

 writers seem to have followed him in the first respect, but have given 

 formulas to correspond with their ideas of the composition that the salt 

 should have. 



