304 Chittenden and W hitehouse— Metallic 
by Harnack. Further, Rose* found that the serum of ox blood 
yielded a similar compound with cupric sulphate, which contained 
only 1:14 per cent. of CuO or 0°88 per cent. of Cu. Hence there 
would seem to be little in these earlier investigations to substantiate 
the results obtained by Harnack. Mérner,+ however, working with 
alkali-albuminate, found that on precipitating a solution of alkali-al- 
buminate with cupric sulphate, in the presence of an excess of alkali, 
he obtained a copper albuminate containing a percentage of cupric 
oxide corresponding closely with that found by Lieberkiibn. When, 
on the other hand, he precipitated a nearly neutral solution of alkali- 
albuminate with cupric sulphate, then the percentage of copper in the 
copper albuminate amounted to only one-third that found by Lieber- 
kiihn, or an amount about equivalent to that found by Harnack in his 
lowest copper compounds. Moérner further found that by precipitat- 
ing a calcium albuminate solution with cupric chloride, the albumin- 
ate combined on an average with 2°33 per cent. of CuO, or just one- 
half the amount required by Lieberkiihn’s formula, and considerably 
less than the amount contained in Harnack’s largest copper com- 
pounds. . 
Preparation of the albumin solution.—In our experiments it was 
thought best, as far as possible, to avoid exposing the albuminate to 
the action of alkalies, hence especial care was taken to prepare 
the egg-albumin as free from salts as possible, so that it would not 
be necessary to purify the albuminate by reprecipitation. The whites 
of a large number of eggs were finely divided by scissors and by 
shaking with glass, then mixed with an equal volume of water and 
thoroughly shaken with air, after which the solution was strained 
through cloth. Globulin was then precipitated by the addition 
of dilute acetic acid (the acid added as long as a precipitate 
formed), the solution finally filtered through paper, after which the 
filtrate was made exactly neutral with sodium carbonate and again 
filtered. The fluid so obtained was then dialyzed in running water 
for many days, a little thymol being added to prevent putrifaction. 
The fluid finally obtained was perfectly neutral, clear and contained 
but a small amount of inorganic salts. 
In forming the albuminate we employed both cupric acetate and 
cupric sulphate, using in each case the same volume of albumin solu- 
tion, but varying the amount of copper salt. The copper salt was 
generally added as long as a precipitate formed. The albumin- 
* Loc. cit., p. 139. + Jahresbericht fiir Thierchemie, 1877, p. 8. 
