Carbon Dioxide in Relation to Incubation. 

 By C. C. Thom, Demostrator in Physics. 



Carbon dioxide is a colorless gas with an acid (sour) taste, and a 

 more or less pungent odor. It is formed largely by the oxidation of car- 

 bonaceous organic matter, and is given off in considerable quantities by 

 the lungs of the living animal during respiration. It is not a poisonous 

 gas, although in an atmosphere containing large quantities of carbon 

 dioxide death might result from suffocation or from want of oxygen. 

 While carbon dioxide is not of itself injurious, yet it is a product of com- 

 bustion and respiration usually accompanied with other injurious pro- 

 ducts, and the amount of it present in the atmosphere is taken as a stan- 

 dard by which we can judge of the quality or purity of the air. It is 

 everywhere found in small quantities, from 3 to 4 parts in 10,000 in the 

 atmosphere of the country. 



Taking the atmosphere of the country as a standard of purity neces- 

 sary to the proper maintenance of animal life, it was thought that pos- 

 sibly the air in the egg chamber of the incubator, during incubation, be- 

 came so highly impregnated with carbon dioxide as to impair the healthy 

 and normal development of the embryo chick. To test this theory it was 

 decided to analyze the air in the egg chambers of a number of incubators 

 for carbon dioxide. For this purpose a special apparatus was fitted up 

 consisting (see Fig. 6) of a large aspirator, bottle A, so fitted and gradu- 

 ated that a definite volume of water could be drawn from it by opening 

 the pinch-cock P, necessitating the same volume of air being drawn into 

 the bottle to replace the water taken out. The air drawn in was taken 

 from the egg chamber of the incubator by inserting the end of the rubber 

 tube T through a small hole in the door of the incubator. The air drawn 

 from the egg chamber was not allowed to pass directly into the large 

 aspirator bottle, but was first made to pass through a known volume of 

 a standard solution of potassium hydrate contained in the small bottle K, 

 and in so doing all the carbon dioxide in the air was absorbed by the 

 potassium hydrate uniting with it to form a potassium carbonate. In 

 testing the solution in the small bottle K for potassium carbonate the 

 following method was used : 



To an aliquot portion of the solution was added a few drops of phe- 

 nolphthalein indicator, and the excessive alkali neutralized with one- 

 hundredth normal sulphuric acid, care being taken to keep the tip of the 

 burette immersed in the solution to prevent the escape of any carbon 

 dioxide. To the clear solution was then added a few drops of methyl 

 orange indicator, and the solution again titrated with one one-hundredth 

 normal sulphuric acid, until all the carbonate present had been broken 

 up, as indicated by the change in color of the solution. From the amount 

 of one one-hundredth normal acid used in the last titration, the volume 

 of carbon dioxide in the volume of air taken from the incubator was de- 

 termined. In figuring the results of these analyses no correction was 



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