37^ Dr. Prout's experiments on the changes which take place 
Preliminary experiments on the egg in its recent and unaltered 
state. 
The specific gravity of new laid eggs has been found to 
vary from 1.080 to 1.090. When kept for some time, eggs, 
as is well known, rapidly lose weight, and become so spe- 
cifically light as to swim in water. This diminution of spe- 
cific gravity, however, is only apparent, and depends on the 
substitution of air for a portion of the water of the egg which 
escapes ; for it is obvious, that the specific gravity of the con- 
stituent principles of the egg must be rather increased than 
diminished by the escape of water. The following table 
shows the gradual loss of weight of an egg during a period 
of two years. 
The original weight on the 19th May, 1820, the day it 
was laid, was 907.5 grains. 
Grains. 
Loss 
per day. 
jGrains. 
Loss 
per day. 
19 May, 1820. 
20 . . . 
24 „ . . 
31 . . . 
8 June . . 
17 . . . 
27 . . . 
19 July . . 
7 August . 
2 6 .. . 
30 September 
907-5 
9 o6 -5 
901.3 
894.2 
886.6 
879 3 
870.7 
848.5 
829.6 
810.8 
778-5 
1.00 
1.30 
1.01 
•95 
.81 
.86 
1.01 
•99 
•99 
.92 
5 May, 1821. 
6 
5 December 
7 • • • 
si March, 1822. 
25 April 
26 
17 May . . 
18 
19 
Total Loss 
648.7 
647.8 
488.2 
486.6 
4*3 5 
384.6 
3 8 3-7 
3 ^ 5 - 2 
3%3 
363.2 
•59 
.90 
•75 
.80 
• 7 ° 
.82 
.90 
.84 
.90 
1.10 
544-3 
•744 
Mean 
Hence we learn, that a moderately sized egg loses on an 
average about .75 grain in twenty-four hours, and that 
