BORON AND FLUORINE. 5 



BORIC ACID. 



Several courses were open for the preparation of borax. It is 

 doubtful whether the impurities (such as silica, lime, organic mat- 

 ter, etc.) in commercial borax can easily be removed by recrystal- 

 lization. Hence for the purposes of this investigation the synthe- 

 sis of the salt from its acid and basic components in purest form, 

 though laborious, was preferred. The further purification of the 

 product could easily be completed by recrystallization. 



Pure boric acid was prepared as follows: A good "C. P." 

 grade was crystallized three times from water, the crystals being 

 drained and washed centrifugally each time. The product was 

 then dehydrated and fused to a clear glass in platinum. Approx- 

 imately 500 grams of this anhydrous acid were covered with 

 2 liters of redistilled and almost anhydrous methyl alcohol, which 

 contained only a trace of acetone. The mixture was boiled under 

 a reflux condenser in an all-glass apparatus until solution was 

 complete. In this reaction part of the boric acid forms the methyl 

 ester, whereas the remainder probably does not react at all, or 

 serves as a dehydrating agent and separates out on cooling in 

 crystalline crusts on the sides of the flask. The clear liquid, con- 

 taining the methyl borate, was decanted and distilled from an 

 apparatus constructed entirely of glass. Evidently the ester was 

 partly hydrolyzed during this process, for a considerable portion 

 of boric acid remained in the flask. 



The clear, colorless distillate, containing the methyl borate, 

 was mixed with an equal volume of boiling water, agitated from 

 time to time, and allowed to stand, when crystals of boric acid 

 separated out on cooling. The product was drained and washed 

 centrifugally and crystallized once from water. As was expected, 

 the method gave a poor yield in the end, but the boric acid thus 

 obtained was of great purity. 



SODIUM CARBONATE. 



A very pure commercial grade of sodium carbonate was fused 

 in a platinum dish in portions of 100 grams each with a small 

 quantity of pure, precipitated calcium carbonate. 7 After dis- 

 integration of the melt in water the cold liquid was decanted and 



7 Smith and Exner, Proc. Am. Philos. Soc. 43, No. 176, p. 134 (1904). 



