104 



A RESPIRATION CALORIMETER. 



in another ; consequently it is to be expected that the average of two or 

 three periods would be much more accurate than any single period. 

 On the other hand, if periods of 10 or 12 hours in length are consid- 

 ered, the possible error in determination of residual amounts becomes 

 quite insignificant. It would seem from the experiment here reported 

 that the determination of carbon dioxide by this apparatus, even in 

 short periods, is extremely satisfactory. 



DETERMINATION OF WATER. 



The computations for the determination of water in the alcohol check 

 experiments are made in a manner quite similar to those for carbon diox- 

 ide, the details for this particular experiment being given in Table 2. 



The column headings are self-explanatory, and it is seen that the 

 percentage error in the determination of water is, relatively speaking, 

 small. When it is considered that one of the most difficult determina- 

 tions in elementary organic analysis or with large respiration apparatus 

 has been the accurate determination of water, it is seen that the accu- 

 racy here obtained is much greater than would be ordinarily expected. 

 Indeed, the accuracy of the water determination would justify the use of 

 the ' ' closed circuit ' ' were the determination of oxygen (its chief object) 

 not practicable. 



TABLE 2. Record of Water in Ventilating Air Current. 

 Alcohol check experiment, April 6-7, 1905. 



THE COMPUTATIONS FOR OXYGEN. 



Inasmuch as carbon dioxide and water have been determined by other 

 methods with apparatus as large as this with great accuracy, 1 especial 

 interest in this particular form of apparatus lies in its power for deter- 



1 U. S. Dept. of Agr., Office of Experiment Stations Bull. 136, pp. 37, 38. 



