1822.] Royal Society. t) ae 
lost nearly two-thirds of its weight. Experiments were next 
related, the object of which was to attempt to ascertain the rela- 
tive weights of the shell, albumen, and yolk. For this purpose 
the eggs were boiled hard in distilled water, and the different 
parts weighed in their movs¢ state. The average of 10 experiments 
gave for the shell 106°9, albumen 604-2, and yolk 288:9, on the 
supposition that each egg originally weighed 1000 grs. to 
which standard the weights of all the eggs were reduced. 
These experiments show that the relative weights of these 
different portions of the egg differ very considerably, particu- 
larly the shells, the weights of which were found to vary from 
77-6 to 108, on the supposition that the original weights of the 
two egos were equal. An egg, when boiled, and cooled in the 
air, always lost considerably in weight; and the water was 
found to contain traces of most of the saline contents of the 
ege. 
PA fier these remarks on the recent egg, the author proceeded 
to relate the results of his analysis of the egg at the end of the 
first, second, and third week of incubation, and arrived at con- 
clusions of which the following may be considered as an onte-. 
line: 
1. That an egg loses about one-sixth of its weight during 
incubation—a quantity amounting to eight times as much as it 
loses in the same time under ordinary circumstances. 
2. That in the earlier stages of incubation, an interchange of 
pzinciples apparently takes place between the yolk and a portion 
of the albumen ; that this interchange is confined on the part of 
the yolk to a portion of its oily matter, which is found mixed with 
a portion of the above-mentioned albumen. That this portion of 
albumen undergoes some remarkable changes, and is converted 
into a substance analogous in its appearance, as well as some of 
its properties, to the curd of milk; and, lastly, that a portion of 
the watery parts of the albumen is found mixed with the yolk, 
which becomes thus apparently increased in size. 
3. That as incubation proceeds, the saline and watery matters: 
again appear to quit the yolk, which is thus reduced to its origi- 
nal bulk, or even becomes less than natural; and that in the last 
week of the process, the greater portion of the phosphorus quits 
the yolk likewise, and is found chiefly in the animal, where it 
exists as phosphoric’acid, and in union with /ime, constituting, its 
bony skeleton, which lime amounting to about three grains, does 
not pre-exist in the recent egg, but makes its appearance, in some 
unaccountable manner, during the process. 
The author then proceeded to make a few remarks on the 
source of the earthy matter, which, he observed, must be either 
derived from the shell, or from the transmutation of other prinet- 
ples. The great difference existing among the shells of different 
eggs rendered it impossible to determine by chemical means, 
and the application of averages, whether it was derived from the 
New Series, vou. 1v. F 
