Intelligence and Miscellaneous Articles. 4? 19 



PREPARATION OF BORON. BY DR. R. D. THOMSON. 



" In the process for obtaining boron by the action of potassium 

 on boracic acid, a considerable loss has been generally experienced 

 in consequence of an explosion which usually accompanies the 

 combination. A more oeconomical method has therefore been pro- 

 posed, viz. to decompose an alkaline fluoborate by potassium. It 

 appears to me that there can be only two causes which can produce 

 the explosion in the first mode of preparation — either the presence 

 of water in the boracic acid (as suggested by Dr. Thomson of Glas- 

 gow), or the existence of this fluid either in the potassium itself, or 

 in connexion with the same metal. I believe [says Dr.R. D. T.] 

 the latter circumstance to be the cause of the failure of the 

 experiment in most cases. I have succeeded [he continues] in 

 forming pure boron readily by the following plan; — A portion 

 of Tuscan boracic acid was fused in a red heat in a plati- 

 num crucible till it became perfectly white ; it was then taken out 

 of the crucible and reduced to a granular powder ; two parts of 

 potassium were then introduced into a common test-tube. Care 

 should be taken to remove the white crust which usually covers 

 potassium, as it occurs in the country ; this coating is hydrate of 

 potash generated by the action of water contained in English naphtha. 

 If German naphtha is employed to preserve the potassium there 

 is little or no hydrate of potash formed. The quantity of water in 

 English naphtha is sometimes so considerable, that I have actually- 

 seen potassium take fire when introduced into it. For the speci- 

 men of potassium with which the present experiments were made, 

 I am indebted to the kindness of Mr. Graham of Glasgow. To pro- 

 ceed with the process : the potassium, cut into minute fragments, 

 was mixed with one part of the granular boracic acid described ; 

 the tube was then cautiously exposed to the flame of a spirit lamp; 

 scanty white fumes began to be discharged; as soon as they ceased 

 to be formed, the mixture was heated to redness, and the process 

 continued for ten minutes; when the tube had cooled, a drop of 

 water was introduced in contact with this mixture by means of a 

 glass rod; no action occurred, showing that no potassium was pre- 

 sent ; a quantity of water was then introduced into the tube, mixed 

 with some muriatic acid ; the tube was washed out, and the con- 

 tents thrown upon a filter ; the boron was well washed and dried ; 

 it possessed a fine deep brown colour, and was entirely converted 

 into boracic acid by ignition with nitrate of potash. 



The improvements, therefore, in the process for preparing boron 

 now described, consist, 1st, in pointing out the probable cause of 

 former failures, viz. the employment of potassium containing water; 

 and 2nd, the use of boracic acid in a granular or rough state, which 

 enables the decomposition to go on slowly, and thus prevents the 

 rapid union of elements either foreign or essential to the process. 

 We are thus enabled to witness the whole operation ; no violent 

 action occurring to prevent the performance of the experiment in 

 a glass tube." British Annals of Medicine ^ Feb. 1837. 



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