Gooch and Phelps—Determination of Carbon Dioxide. 101 
Art. X.—The Precipitation and Gravimetric Determination 
of Carbon Dioxide; by F: A. GoocH and I. K. PHELps. 
[Contributions from the Kent Chemical Laboratory of Yale College—XLI.]} 
THE method upon which reliance is most confidently placed 
for the determination of carbon dioxide in solid carbonates, 
involving as it does the liberation of that gas by the action of 
a strong acid and its absorbtion in weighed potash-bulbs, 
demands as conditions of the attainment of good results the 
careful observance of precautions and the expenditure of much 
time and attention. In the method described below we have 
sought to secure equal accuracy with greater economy of time 
and care. Our plan is to effect the rapid absorbtion of the 
carbon dioxide, evolved by the action of acids upon carbon- 
ates, in barium hydroxide contained in a specially devised 
apparatus, to filter and wash the pre- _ 
cipitated barium carbonate under a 
protecting layer of xylene, to dissolve 
in hydrochloric acid the washed car- 
bonate upon the filter or adhering to 
the receiver, to convert the barium 
chloride thus obtained into the form 
of the sulphate, and from the weight 
of the last to caleulate the carbon 
dioxide originally liberated by acid 
from the carbonate. 
The apparatus which we use, and 
which is shown in the figure, consists 
of a flask for the evolution of the car- 
bon dioxide, properly connected with 
a receiver in which the gas is retained 
until absorbtion is perfect. It isa form 
of a similar device employed hy one of 
us* for the absorbtion of ammonia in 
hydrochloric acid and the complete 
retention of the ammonium salt thus formed, but so modified 
as to avoid the danger of diffusion of carbon ‘dioxide through 
the rubber balloon—a source of error which we have found 
by experiment to be considerable when large amounts of the 
gas are handled. 
The evolution flask (F) has a capacity of about 50 cm’, and 
is fitted with a rubber stopper through which passes a ‘tube 
(A) wide enough (about 0°7°™ in interior diameter) to prevent 
the formation of bubbles, and expanded just above the stop- 
* Amer, Chem. Jour., i, 450. 
