METHOD FOR MEASURING CARBON DIOXIDE. IO9 



Sufficiently uniform manipulation in different determinations 

 is very easily attained as the results below will show. The 

 amount of CO 2 contained in the air in the bottle is determined 

 by titrating with n/ioo HC1, 15 c.c. of n/ioo Ba(OH) 2 in each 

 of two bottles. One of these samples of Ba(OH) 2 is titrated at 

 once and the other at the end of an hour. The difference in the 

 amounts of HC1 is equivalent to the CO 2 of the air in each of the 

 bottles at the beginning. To increase the accuracy three such 

 tests are made at the same time and the average of the three 

 taken as the true value. 



The following are typical examples of tests showing the degree 

 of uniformity. 



Three samples of 15 c.c. Ba(OH)2 each when titrated at once using one drop of 

 phenolphthalein took 



12.65 c.c. 

 12. "jo c.c. 

 12.65 c.c. 



Average 12.66 c.c. n/ioo HC1 



At the end of i 1/2 hours three other samples of 15 c.c. of the same Ba(OH)z 

 solution in each, took 



12.35 c -c- 

 12.32 c.c. 

 12.32 c.c. 



Average 12.33 c.c. w/ioo HC1. 



The amount of CO 2 absorbed was therefore equivalent to the 

 difference or .33 c.c. n/ioo HC1. 



Several days later another set of three samples of 10 c.c. each of Ba(OH)z solu- 

 tion titrated at once, took 



8.32 c.c. 



8.32 c.c. 

 8.35 c.c. 



Average 8.33 c.c. n/ioo HC1. 

 At the end of 2 1/2 hours three corresponding samples took 



8.15 

 8.13 

 8.14 



Average 8.14 w/ioo HC1. 



The amount of CO 2 absorbed from the air in the bottle and 

 during the manipulation on this day was therefore equivalent to 

 .19 c.c. n/ioo HC1. 



