52 Jones — Action of Carbon Dioxide 



moistened with water and allowed to stand sixty hours. The 

 contents of the crucible were then dried on a steam bath and 

 afterwards heated for thirty minutes in an air bath at 350° C. 

 The carbon dioxide remaining in the mixture was determined 

 and found to be 0-0844: grm. Total CO, in BaCOg taken, 

 0-1154 grm.; CO, liberated by B,03, O'OSIO grm. ; CO, dis- 

 placeable with formation of Bdi^OBfi^ by B^Og taken, 0-1210 

 grm. Therefore, 74-38 per cent of the boric acid taken, if 

 still unvolatilized, remains uncombined— at 350° C. 



From the foregoing experiments, then, it is obvious that 

 carbon dioxide decomposes the metaborate of barium in either 

 aqueous or alcoholic solutions, and a portion, at least, of this 

 boric acid liberated not only remains uncombined after evapo- 

 rating to dryness but even upon heating to a high temperature. 



Loss of horic acid hy volatilization. — It is scarcely conceiv- 

 able that a mixture of boric acid and barium carbonate in water 

 should not lose an appreciable amount of boric acid on evapo- 

 ration. Morse and Horn have found a detectable loss of boric 

 acid from treating aqueous mixtures of barium hydrate and 

 boric acid with carbon dioxide and evaporating. The carbon 

 dioxide was stopped shortly after the alkaline coloration with 

 phenolphthalein was destroyed. The quantity found by them 

 is given, and varies from 0-0001 grm. to 0-00016 grm.; in one 

 instance exactly 0-00012 on 0-0633 grm. of total boric acid 

 p,esent: | »-00CS6 + 0-02538 ^ ^3.^^ J ^ ^.^^^ ^ ^.^^33 ^^.^^^ 



The decrease in weight should be even more noticeable in the 

 presence of alcohol, though Morse and Horn did not detect 

 more than 0*0040 grm. B.Og [ (1/14200) X 50 = 0-0040] and 

 this only when the concentration of alcohol arose above 92 per 

 cent. Amounts below one part in 14,200 they were not able 

 to discover. 



The actual amount of boric acid volatilized on evaporating 

 such mixtures to dryness is, of course, small, but certainly 

 appreciable. Furthermore, under the analytical conditions 

 described by Morse and Burton, the greater loss of boric acid 

 doubtless occurs with the escape of water of combination 

 between the temperature 100° C. and that at which the boric 

 acid completely replaces its equivalent of carbon dioxide in 

 barium carbonate. This temperature I have shown by experi- 

 ment to be at least above 350° C. On the other hand, as was 

 shown in my original paper, under extreme conditions, by 

 the use of methyl alcohol and a continuous current of carbon 

 dioxide, it is possible to volatilize all the boric acid from a 

 mixture of barium hydrate and barium metaborate. 



The interaction at high temperatures of the carbonates and 

 borates of barium. — I have shown that the treatment recom- 



