in the fixed principles of the egg during incubation. 385 
merits with different yelks were made, in which lime and ni- 
trate of lime were substituted for the bicarbonate and nitrate 
of potash. 
With respect to the modes in which the different fixed 
principles originally exist in the egg, it is very probable, as 
Berzelius lias remarked, that the sulphuric acid obtained from 
albumen is a product of combustion, and exists in it naturally 
as sulphur. The same also appears to be the case, to a great 
extent at least, with respect to the phosphoric acid, especially 
that obtained from the yelk. The chlorine seems to exist 
originally in union with sodium, forming common salt. As 
to the earthy principles, Berzelius is of opinion that their 
metallic bases are probably to be considered as constituent 
principles of the primary animal compounds. These circum- 
stances have induced me to state the quantities of the acids 
obtained separately from the bases. 
It may be also remarked here, that as the following experi- 
ments were made almost entirely with the view of comparison 
only, my object was rather to conduct them in some general 
and uniform manner, than to enter into any very minute dis- 
criminations, which did not appear to be immediately neces- 
sary to my purpose. For this reason, the proportion of the 
potash to the soda, and the exact quantity of carbonic acid 
combined with them, were not attempted to be determined. 
With the same view also, the proportion of the lime to the 
magnesia, though ascertained, was not expressed, but the 
united weights of both introduced into the column. Lastly, 
every one acquainted with chemistry will perceive, that from 
the mode of operating, the weights of the different principles 
will be somewhat underrated. 
3 d 
MDCCCXXII. 
