BORACIC ACID. 495 



3. PROPERTIES. 



(a.) An opake, pulverulent, olive colored mass, does not scratch 

 glass, does not conduct electricity, is tasteless, inodorous, insoluble in 

 water, ether, alcohol and oils, and does not affect blue colors. 



(b.) Burns in atmospheric air, at a heat below that of boiling 

 olive oil, or at about 600, with a red light, sparkles like charcoal, 

 and produces boracic acid, the coating of which, on the boron, soon 

 stops the combustion. 



(c.) Not fused or volatilized by a white heat, in close vessels, but 

 becomes dense enough to sink in sulphuric acid of the sp. gr. 1.844, 

 hence its sp. gr. must be nearly 2. 



(d.) The heat of a spirit lamp makes it burn brilliantly in oxygen 

 gas, and boracic acid sublimes.* 



(e.) It burns spontaneously in chlorine gas, and forms a new gas, 

 which when brought into contact with atmospheric air, smokes as 

 much as fluoboric gas. Freed from excess of chlorine, by standing 

 over mercury it becomes colorless, and is rapidly absorbed by water ; 

 its composition is chlorine, 90.743, boron, 9.257 = 100. Berzelius. 



(jf.) Niti'ic acid converts it into boracic acid, while nitric oxide 

 gas is liberated. 



(g.) It dissolves in hot sulphuric acid with effervescence, and pot- 

 ash throws down a black precipitate. 



(h.) Muriatic acid acquires a green color, but its action is feeble, 

 and there is no solution. 



(i.) With fixed alkalies, it forms pale olive-colored compounds, 

 from which muriatic acid throws down dark precipitates. 



(j.) Sulphur dissolves it by long fusion, and acquires an olive tint 

 little action with phosphorus, none with mercury. 



(k.) It burns vividly, when mixed with chlorate or nitrate of potash, 

 and thrown into a red hot crucible. 



(I.) Boron heated in the vapor of sulphur, unites with it, with the 

 appearance of combustion producing a sulphuret, which is white and 

 opake, and which, when thrown into water, gives off sulphuretted 

 hydrogen and forms boracic acid. 



4. EQUIVALENT NUMBER AND POLARITY. 



The equivalent of boron is 8, as already stated. In the galvanic 

 circuit, it goes to the negative pole. 



5. NATIVE BORON. 



Boron is to be regarded as a peculiar combustible ; a little resem- 

 bling carbon in fixity in the fire, but it is unlike it in being a non-con- 

 ductor of electricity. 



* There is a black residuum which produces more boracic acid by being heated 

 again in oxygen gas. 



