292 



Messrs. C. H. Burgess and A. Holt, Junr. [Oct. 27, 



for boric anhydride, for, if the crystals had been due to a separation of 

 a borate from its solution in boric anhydride, this should have left the 

 compound pure. As a matter of fact we found that the methyl 

 alcohol decomposed both the crystals and glass, giving methyl borate, 

 boracic acid, and sodium methylate. Both glass and crystals were 

 decomposed at the same rate. 



Attempts to use water as a means of separation were also failures, 

 since the solubility of both glass and crystals is about the same. 



The results of our analyses are as follows : 



(i) Mixture of Composition about Na 2 O.2B 2 O 3 . This mixture crys- 

 tallised completely in a few hours, giving a hard, white, completely 

 crystalline mass. When about two-thirds had crystallised the glass 

 and crystals were separated, and gave on analysis : 



Glass = 30-9 per cent. Na 2 ; crystals = 31 -0 per cent. Na 2 0. 



(ii) Mixture of Composition about 3Na 2 O.8B2O 3 . This crystallised 

 completely, and had the same characters as (i). 

 On analysis obtained : 



Glass = 25-86 per cent. Na 2 ; crystals = 25-81 per cent. Na 2 0. 



(iii) Mixture of Composition about Na 2 O.4B 2 3 . This crystallised 

 completely, and had the same characters as (i). 

 On analysis obtained : 



Glass = 18-70 per cent. Na 2 O; crystals = 18-67 per cent. Na 2 O. 



(iv) Mixture of Composition about Na 2 0.6B 2 O 3 . This crystallised 

 very nearly completely, but seemed to contain small translucent glass- 

 like fragments. 



On analysis obtained : 



Glass =11-5 per cent. Na 2 0; crystals = 13*7 per cent. Na 2 0. 

 ^ (v) Mixture of Composition about Na 2 0.8B 2 O 3 . This did not crystal- 

 lise completely. After very prolonged heating it nearly all changed 

 to a crystalline mass with an almost waxy lustre, but which was not 

 really wholly crystalline. There was always in addition a portion of 

 the mass which remained a glass. 

 On analysis obtained : 



Glass = 10-06 per cent. Na 2 ; crystals = 11-90 per cent. Na 2 0. 



(vi) Mixture of Composition about Na 2 O.12B 2 O 3 . Only about half 

 would crystallise, and this took a very long time. 

 On analysis obtained : 



Glass = 2-1 per cent. Na 2 O; crystals = 12'2 per cent. Na 2 0, 

 (vii) Mixture of Composition about Ka 2 O.16B 2 O 3 . After heating this 

 mixture for several days only a very small amount crystallised. ^ 



