Chemical Work in Connection With Incubation Problems. 



By R. Harcourt, Professor of Chemistry, and H. L. Fulmer, 



Demonstrator in Chemistry. 



The chemical work herein reported was undertaken with the object 

 of gaining some definite information regarding the distribution of the 

 mineral constituents in the different parts of the egg, and to determine 

 the effect of different methods of incubation on the amount of these con- 

 stituents absorbed by the chick. Previous investigations carried on in 

 the department of Physics of this institution demonstrated the fact that 

 there was a large quantity of carbon dioxide gas around the eggs during 

 incubation by the hen. It is well known that carbon dioxide in the pre- 

 sence of moisture will dissolve calcium carbonate and that the shell of 

 the egg is composed largely of this substance ; consequently, the question 

 naturally arises, has the presence of this gas anything to do with the 

 greater vitality of the chicks incubated by the hen? This hypothesis was 

 further strengthened by the observed fact that, although the percentage 

 of eggs hatched was small, the chicks obtained from incubators in which 

 lamp fumes were present were generally strong and vigorous. It was 

 hardly thought that the humidity of the air under the hen or in the incu- 

 bator was sufficient to allow the carbon dioxide to dissolve any appreciable 

 amount of the lime, yet it was thought that the point was worth investi- 

 gating. 



The plan of our investigation was to determine the amount of lime 

 (CaO) and phosphoric acid (P2O5) in a number of eggs from several hens, 

 and then to ascertain the amount of these constituents in the chicks got 

 by different methods of incubation from the eggs of the same hens. As 

 it would, obviously, be impossible to analyze an egg and to get a chick 

 from the same egg, we had to analyze a number of eggs from each of 

 several hens and thus obtain figures that would be approximately correct 

 for comparison in the after work. 



Method of Analysis. 



An outline of the methods employed in separating the different parts 

 of the egg and of making the analysis is as follows : 



Proportion of Shell, White, and Yolk. This part of the work re- 

 quired no special skill, since the different parts were separated in a 

 strictly mechanical way. The egg was first freed of all adhering foreign 

 matter as completely as possible, and then weighed. The parts were next 

 separated and placed in tarred dishes and weighed, their total weight being 

 checked with the original weight obtained. 



As our object in studying the composition of the original egg was 

 to obtain figures with which to compare the composition of the chick 



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