302 Chittenden and W hitehouse— Metallic 
I. Ea@e-aALBuMIN. 
(a) Copper Compounds. 
In looking over the literature of the subject, it becomes evident at 
once that the older investigators, owing either to the nature of the 
compound, to adherent impurities or to faulty methods, were not 
able to obtain concordant results, since the copper compound of egg- 
albumin, as prepared and analyzed by six distinct investigators, was 
found to contain from 1°50 to 5°19 per cent. of CuO. In all of these 
cases the preparation of the copper compound was essentially the 
same; a solution of egg-albumin was precipitated with a solution of a 
copper salt, the precipitate collected, washed thoroughly with water, 
dried, and the copper determined by simple ignition. Naturally this 
method, as suggested by Harnack, might be expected to give too 
high results, since the copper precipitate would unquestionably re- 
tain considerable of the inorganic matter of the albumin. Treated in 
this manner, however, F. Rose,* as already stated, found the copper 
compound to contain from 1°50 to 1°69 per cent. of CuO. Mitscher- 
lich,t who held that the copper precipitate was a compound of egg- 
albumin with the copper salt, found in his preparations 2°8—3°3 per cent. 
CuO, while Bielitzki,t who demonstrated that the precipitate was an. 
actual compound of albumin with cupric oxide, found in his preparations 
4°75—5'20 per cent. of CuO. Lassaigne, as quoted by Harnack, found 
4°95 per cent. of CuO, Mulder§ 4:44 per cent., while Lieberktihn’s|| 
preparation contained 4°6 per cent. of CuO. Further, Ritthausen’s 
copper compounds of the vegetable albumins were found to contain 
from 11°5 to 17°0 per cent. of CuO. These results collectively, would 
therefore seem to indicate that when egg-albumin is precipitated by 
a soluble copper salt, the resulting compound does not contain a defi- 
nite proportion of albumin and cupric oxide, or else that there are a 
large number of albumin-copper compounds. More recently, how- 
ever, E. Harnack,§ from analysis of fifteen separate preparations, 
comes to the conclusion that there are two distinct compounds of 
albumin with copper; one containing 1°35 per cent. of Cu, the other 
2°64 per cent. of Cu, indicating as Harnack suggests, a copper albu- 
minate in the first case of the formula C,,,H,,,N,,0,,5,Cu, in which Cu 
replaces two atoms of hydrogen in the albumin molecule, and in the 
second case, an albuminate of the formula C,,,H,,,N,,0,,5,Cu,, in 
* Pogeendorff’s Annalen, vol. xxviii, 1833. + Miller’s Archiv. for 1837, p. 91. 
{ Dissertation, Dorpat, 1853. § Physiologische Chemie, 1844-51. 
|| Poggendorff’s Annalen, vol. Ixxxvi, 1852. f Loc. cit. 
