496 BORATES. 



BORATES OF ALKALIES AND EARTHS. 



General properties, 



1. In the humid way, decomposed by all acids except the car- 

 bonic. 



2. In the dry way, the action is often reversed, especially where 

 the acid of the other body has a tendency to become gaseous. 



3. Boracic acid attracts the earths more forcibly than the alkalies. 



4. Alkaline borates are very soluble in water ; the earthy the re- 

 verse. 



5. The boracic acid being feeble, it neutralizes the alkaline bases 

 imperfectly, and hence the borates of the alkalies have alkaline char- 

 acters. 



6. Borates are very fusible. 



7. Digested with strong sulphuric acid, the residue imparts to al- 

 cohol the power of burning with a green flame. 



BORATE OF POTASSA. 



1. PROCESS. 



(a.) Boil boracic acid in caustic potash, either to saturation or so 

 as to leave a slight excess of alkali. 



(b.) In the latter case, it crystallizes in pretty large four sided 

 prisms taste sub-alkaline. 



2. PROPERTIES. 



(a.) Not altered by the air by heat, swells, foams, and runs into 

 a clear glass. 



(6.) Decomposed by lime, baryta, and magnesia. 



BORAX. 



BI-BORATE OF SODA, formerly called sub-borate. 



1. PREPARATION. It can be formed synthetically, but this is un- 

 necessary, as it is abundant in commerce. 



2. PROPERTIES. 



(a.) Turns vegetable blues green; taste, cool, sweetish, and sub- 

 alkaline. 



(b.) Soluble in 12* parts of cold water, and in 6 of boiling ; slight- 

 ly efflorescent ; deposits crystals by cooling ; prisms with 6 irregular 

 sides. Phosphoresces by collision of its crystals. 



(c.) Suffers the aqueous fusion, is very much inflated, and at igni- 

 tion becomes a pellucid glass ; soluble again in water. f 



t Provided it were melted in a silver crucible or hastily in one of earth, for it H 

 prone to corrode earthen crucibles. 



