494 BORACIC ACID. 



Boron 1 proportion, represented by the same number as oxygen, 

 namely 8, -{-2 prop, oxygen 1 6, forms dry boracic acid, having 24 

 for its equivalent ; the crystallized acid consists of dry acid 24 -j- 

 water 2 proportions, 18 =42 for the equivalent of the crystallized 

 acid; and for the 100 parts, 42 : 18 : : 100 : 43 nearly, being the 

 quantity of water in the 100 parts, of course there is 57 of dry acid. 

 According to Berzelius, crystallized boracic acid, contains .44 of 

 water, one half of which is expelled at a heat above 212, and the 

 other half when it combines with bases, but it cannot all be expelled 

 by heat alone, 



6, POLARITY. In the galvanic circuit, this acid goes to the posi- 

 tive pole, and is therefore, electro negative. 



7. USES. It melts very easily, and by acting as a flux, it favors 

 the fusion of minerals, with the blow pipe. It is used in the analysis 

 of stones, aiding their fusion in the crucible. After it is melted by 

 itself, it endures a white heat without volatilization, and as it cools 

 into a glass, it is called a glacial acid, being one of three that bear 

 that name, viz. the phosphoric, the arsenical, and the boracic. 



In the dry way, viz. with heat, the boracic acid displaces all the 

 acids except the phosphoric ; this arises from its great fixity and fusi- 

 bility by which it is able to vitrify the bases of the salts, even of the 

 earthy salts. 



BORON. 

 DECOMPOSITION OF BORACIC ACID. 



1. DISCOVERY OF BORON. 



(a.) The power of 500 pairs of galvanic plates extricates from 

 moistened boracic acid a peculiar olive colored combustible basis, first 

 ascertained by Davy, in 1807. 



2. PROCESS. 



(a.) Better obtained by heating very pure vitreous boracic acid 

 along with potassium, in tubes of green glass or copper, iron or 

 brass ; preferably the last. 



(b.) 12 or 14 grains of each substance were employed ; but 8 grains 

 of boracic acid will saturate 20 grains of potassium. At 302 Fahr. 

 ignition comes on, a little hydrogen appears, the potassium is con- 

 verted into potassa,* and boron is obtained. 



* See Recherches Physico-Chimiques, Vol. I. Berzelius employs the fluo-borate 

 of potassa with potassium in a crucible ; the boron is to be washed with sal-ammoniac, 

 and lastly with alcohol ; as water carries some of it through the filter. This process 

 is said to be less expensive in potassium than the other. 



