Jones — Action of Carbon Dioxide on Soluble Borates. 445 



Ba(OH) 2 taken. 



Calculated as 



BaC0 3 . 



B 2 3 

 taken. 



Weight of residue after 

 ignition. 



B 3 O a 



found. 



Error. 



grm. 



grm. 



grm. 



grm. 



grm. 



. 0*6073 



0-1573 



1st wt., 0-6820 



0-201.1 



+ 0-0438 







2d " 0-6783 



0-1911 



+ 0-0338 







3d " 0-6720 



0-1742 



+ 0-0169 







4th " 0-6700 



0-1688 



+ 0-0115 







5th " 0-6655 



0-1567 



— 0-0006 







6th " 0-6630 



0-1499 



— 0-0074 







7th " 0-6609 



0-1443 



— 0-0130 



This result is manifestly an improvement over those obtained 

 without the careful restriction of the supply of carbon dioxide. 

 A similar experiment, differing only in the single point that 

 the carbon dioxide was made to act upon a boiling solution, 

 resulted in like manner. 



In the light of these observations it is plain that a suffi- 

 ciently prolonged action of carbon dioxide should result in the 

 displacement of all the boric acid if that acid can be removed 

 from the field of action as fast as it is liberated. Experiments 

 were made which clearly demonstrate the truth of this hypoth- 

 esis. A small side-necked flask was charged with a solution 

 of boric acid (0-1143 grm.) and barium hydroxide (0*3227 grm.) 

 in proportion to form the metaborate. The mass was brought 

 nearly to dryness by distillation and methyl alcohol (15 cm8 ) 

 added. Through this flask, in which the alcohol was kept boil- 

 ing by a Bun sen burner, was passed the vapor of methyl 

 alcohol, while carbon dioxide, purified by a neutral solution of 

 silver nitrate, bubbled continually through the entire system. 

 The methyl alcohol vapor coming from the side-neck flask was 

 kept lighted by contact with the flame of a Bunsen burner 

 and the distillation continued for two hours until the flame 

 showed not the slightest tinge of green. The residue in the 

 flask originally containing barium metaborate was brought to 

 dryness and tested for boric acid. Only a trace was found and 

 this was thought to be due to inclusion by the insoluble barium 

 carbonate. In a similar experiment in which borax was used 

 instead of barium borate, no trace of boric acid was found in 

 the residue of sodium carbonate, either by tumeric or the 

 flame test, while the distillation was continued only one-half 

 the time of the preceding experiment. This result is quite in 

 harmony with the views of P. Georgevic* to the effect that 

 the large absorption of carbon dioxide in solutions of borax 

 indicates that the boric acid is displaced from its union with 

 the base. 



Obviously, the division of the base between boric acid and 



* Jour. Prac. Chim., xxxviii, 118. 



