Compounds of Albumin and Myosin. 311 
While the difference is not very great, it is a constant difference, 
and it is to be remembered that the last six compounds differ in no 
respects whatever from the first six, except in being subjected to the 
longer action of water. 
In comparing now these different results, it is seen that we have 
not been able to obtain a copper albuminate with a higher content 
of Cu than 2°19 per cent., and this only as a result of two reprecipi- 
tations ; a condition, which, from our experience, tends to alter mate- 
rially the composition of the original precipitate. The average of 
the results obtained by simple precipitation, show a content of 0°94 
per cent. of Cu. A study of the individual results, however, shows 
too great a variation to believe wholly in the existence of a single, 
stable copper albuminate. Either there are one or two definite com- 
pounds, which, being more or less unstable, are prone to change under 
varying conditions and thus give rise to the variations in the content 
of copper noticed, or else there are a number of definite compounds 
liable to be formed as the conditions are varied, all of which, how- 
~ ever, must be more or less unstable. Glancing over the individual 
results, it is plain that an amount of Cu approximating to 0°96 per 
cent. is found altogether too frequently to be the result of chance. 
Doubtless this figure represents most closely the content of copper in 
the ordinary copper albuminate obtained by simple precipitation, 
while the majority of the variations from this figure are due mainly 
to dissociation. 
Taking Lieberkiihn’s formula of albumin, the following copper 
albuminates would be possible: 
(Cr2Hi12NisSOe2)3 +Cu— H2=1'29 per cent. Cu. 
(CrsH2N1eSOn2).+Cu—H.=0'96 “ 
(CroH112N1e8Oo2)5+Cu—Hy=0-77 
For the first, in which Lieberkiihn’s formula for albumin is treb- 
led, the percentage of copper corresponds nearly to the lowest results 
obtained by Harnack, while in the second formula the percentage of 
copper accords closely with the average of our results. Whether 
the weight of the albumin molecule is represented more nearly 
by the second formula than by the first we have not sufficient data to 
determine, but certainly our results with the copper albuminate show 
a lower percentage of copper than would correspond with the first 
formula. , Further, it would appear that the copper albuminates are 
readily prone to change under slight provocation and that this point, 
in part, undoubtedly explains the reason for the great variation in 
the results obtained by so many workers. 
