HALDANE GAS-ANALYSIS APPARATUS. 



77 



comparable. I am much indebted to Miss Alice Johnson and Miss 

 Grace A. Dunning for assistance in the alterations in the apparatus and 

 for very painstaking work in making the analyses. As an illustration 

 of the adaptability of the apparatus, it may be mentioned that the 

 latter analyst had had no experience with it previous to June 1912. 



Table 10. — Comparison of 'potassium pyrogallate and phosphorus as absorbents 

 for oxygen with Haldane gas-analysis apparatus {laboratory form) . 



Results inclosed in braces were obtained from one sample of the gas. 

 Cake of the Apparatus. 



The burette should always be kept thoroughly clean to insure correct 

 results. If a poor grade of rubber tubing is used for the connections 

 this may cause trouble in several ways. The mercury may become 

 dirty from the sulphur and other material in the rubber tubing and 

 thus require frequent cleaning. Also, if tubing containing much free 

 sulphur is used on the connections of the potash pipette it may cause 

 error in the determination of carbon dioxide. The best grade of pure- 

 gum rubber tubing should be employed for practically all of the con- 

 nections, and for the connection between the leveling bulb and burette 

 a heavy-walled tubing must be used. The joints of the apparatus 

 should fit as closely as possible, i. e., glass to glass, thus minimizing the 



