86 PROCEEDINGS OF THE AMERICAN ACADEMY 



A sample of Schweinfurt green was then obtained from Messrs. 

 Folsom & Co. of this city. This sample was said to be perfectly 

 pure, and was made in their works. It was of a much brighter shade 

 than the preceding, and gave on analysis : — 



Analysis No. II. 



99.82 



This is very nearly the same as the preceding sample, calculated 



as pure copper aceto-arsenite. It corresponds quite nearly to the 



formula, 



2 (CuOCJip,) 3 (CuOAs^Og), 



which calculated to percentages is thus : — 



Per cents. Atomic Ratios. 



Copper oxide, 33.19 5. 



Arsenic trioxide, 49.73 3 



Acetic anhydride, 17.08 2. 



100. 



It will be seen by comparing the percentages that both samples 

 analyzed contain more arsenious acid than is called for by the formula: 

 this is most probably due to the difficulty of washing out the excess 

 of arsenic in process of manufacture. 



The foi-mula given in the books for Schweinfurt green is, — 



100. 



This analysis was made by E. Ehrmann in the laboratory of Pro- 

 fessor Von Liebig, and the results were published in " Der Annalen 

 der Pharmacie," * in 1834, in which paper Ehrmann, after giving the 



* Der Annalen der Pharmacie, Band XII., 1831, Seite 72. 



