Compounds of Albumin and Myosin. 303 
which two atoms of Cu replace four of hydrogen. The results ob- 
tained by this investigator would certainly seem to warrant this con- 
clusion, for the analytical data of the different preparations show but 
slight variations ; 1°34-1°37 per cent. in the one case, and 2°48—2°74 
per cent. in the other. Further, Harnack worked with nearly ash-free 
preparations, the compounds after their first precipitation and wash- 
ing being dissolved in sodium carbonate and reprecipitated by care- 
ful addition of acid. By repeating this process several times, the ash 
of the preparation was almost entirely removed, while the relative 
proportion of copper and albumin was not affected. As to the condi- 
tions which determine the formation of one or the other compound, 
there seems to be little definite other than that in general, the com- 
pound with smaller content of copper was obtained when the precipi- 
tation took place in the presence of a slight excess of albumin, and 
the compound with larger content of copper when in the presence of 
an excess of the copper salt. In no case were the copper salt and albu- 
min solutions mixed in definite proportions, yet in every case one of 
the two compounds was formed; further, Harnack states that when 
an amount of copper salt exactly sufficient to form the albuminate 
is added to a given quantity of albumin, no precipitate results; in 
other words an excess of the copper salt is necessary to insure a 
separation of the compound. 
Harnack’s results, therefore, differ from those of the preceding in- 
vestigators in that definite compounds appear to have been formed in 
every case, and further, in that the compounds contain a lower per- 
centage of copper than found by any other investigators aside from 
F. Rose. This latter, it will be remembered, found 1°50-1°69 per 
cent. of CuO ; 1°69 per cent. being equal to 1°34 per cent. of Cu, one of 
the percentages found by Harnack. Harnack further states that the 
average of the analyses made by other investigators, aside from Rose, 
show about 4°4 per cent. of CuO, and assuming that the various prep- 
arations contained an amount of ash equivalent to about 1 per cent. 
(which amount Harnack found in his preparations before purification) 
the percentage amount of cupric oxide would be reduced to about 3:4 
=2°7 per cent. Cu, or the amount found by Harnack in his highest cop- 
per compound. But as Rose’s preparation was made by the simple ad- 
dition of an aqueous solution of egg-albumin to the copper salt and the 
copper determined as oxide by simple ignition, it would seem neces- 
sary to make the same deduction of 1 per cent. also in this case, 
which would make Rose’s compound contain far less CuO than found 
