446 Jones — Action of Carbon Dioxide on Soluble Borates. 



carbonic acid falls tinder the principle of mass action, and if 

 the boric acid is taken in sufficient excess over the barium hy- 

 droxide, the action of the carbonic acid should be inappreciable. 

 This idea is sustained by an experiment in which about 1 grm. 

 of boric acid was dissolved with 0*15 grm. of barium hydroxide. 

 No precipitate could be obtained by passing carbon dioxide 

 and boiling. In fact, in the French process of borax manu- 

 facture just this action of an excess of boric acid upon a boil- 

 ing solution of sodium carbonate is used. On the other hand 

 to prevent the formation of a carbonate this excess of boric acid 

 must be considerable if the action of carbon dioxide is pro- 

 longed. Thus in an experiment in which a current of carbon 

 dioxide was passed into a solution containing 0*1219 grm. of 

 boric anhydride and one-half the amount of barium needed 

 to form a metaborate, the solution (60 cm ) deposited on boiling 

 ninety per cent of the barium present in the form of the car- 

 bonate. 



In view of the facts which I have described, it is diffi- 

 cult to see under what conditions Morse and Burton pre- 

 vented the excessive action of carbon dioxide and obtained in 

 their analytical method the excellent results which they record. 



I wish to express my thanks to Professor Gooch, whose advice 

 has been constantly sought and freely given. 



