654 poisons : their effects and detection. [§ 834. 
The formation of copper compounds with the fatty acids takes place 
so readily that Jeannel 1 has proposed the green colouring of fats by 
copper as a test for the presence of copper ; and Bottger 2 recommends a 
brandy holding copper to be shaken up with olive oil to free it from copper. 
Lehmann has made some useful researches on the amount of copper 
taken up by fats under different conditions. 100 c.c. of strongly rancid 
fat dissolved in fourteen days 8-7 mgr ms. of copper ; but when heated to 
160° for one hour, and then allowed to stand, a similar amount was 
found. Some rancid butter was rubbed into a brass bowl of 90 c.c. 
capacity, and then allowed to stand for twenty-four hours ; the butter 
became of a blue-green colour. Into this dish, thus partially attacked 
by fatty acids, 50 c.c. of rancid butter was poured in a melted con¬ 
dition, and allowed to stand for twenty-four hours. The amount taken 
up was found to be equal to 10 mgrms. of copper for every 100 c.c. of 
fluid butter. 
Hilger found a fatty soup, which had stood twelve hours in a clean 
copper vessel, to contain 0-163 per cent, copper. According to Tschirch, 
the easiest fatty salt to form is the oleate, hydrated copper oxide dissolv¬ 
ing in oleic acid with great ease, and even copper oxide dissolving to 
some extent ; the palmitate and the stearate are not so readily produced 
—hence the amount of copper dissolved is greater in the case of olive oil 
and butter (both rich in oleic acids) than in the case of the firmer animal 
fats. Copper oleate, according to H. Baum and B. Seeliger ( Zeit . 
offentl. Chem., iv. 181-210), is more poisonous than either the acetate 
or sulphate. Acid solutions, such as clarets, acetic acid, vinegars, and 
so forth, as might be expected, dissolve more or less copper. The 
amount likely to be dissolved in practice has been investigated by 
Lehmann. He steeped 600 square metres of copper sheeting or brass 
sheeting in vessels holding 2 litres each of acid claret ; the sheets were 
in some of the experiments wholly immersed, in others partly so. More 
copper was dissolved by the wine when the copper was partly immersed 
than when it was wholly immersed ; and more copper was dissolved 
from brass sheeting than from pure copper sheeting. With a sheet of 
copper, partly immersed, claret may contain as much as 56 mgrms. 
per litre. Lehmann also investigated the amount of copper, as acetate, 
which could be dissolved in wine before the taste betrayed its presence : 
with 50 mgrms. per litre no copper taste ; with 100 mgrms. there was a 
weak after-taste ; with 150 mgrms. it was scarcely drinkable, and there 
was a strong after-taste ; with 200 mgrms. per litre it was quite undrink¬ 
able, and the colour was changed to bluish-green. Vinegar, acting under 
the most favourable circumstances on sheet brass or copper, dissolved, in 
seven days, 195 mgrms. of copper per litre from the copper sheet, 195 
from the brass sheet. 
1 L? Union pharmac., xvii. 81. 2 Arch, de Phann., 1853, cxxvi. 67. 
