492 BORACIC ACID. 



is brought to Europe from the East Indies, under the name of tin- 

 ea], and is obtained from Boutan and Thibet ; sometimes in small 

 crystalline masses, found two yards under ground ; it is procured 

 also from natural lakes, whose waters, containing the salt in solution, 

 yield it it by evaporation, and deposit it in the solid form, at the bot- 

 tom or in artificial reservoirs. In Europe, the salt goes through re- 

 fining processes, formerly confined to Holland but now practised in 

 England. 



(6.) In the free state, found in the hot springs of Lipari and 

 , and in the hot waters of Lake Cherchiago, and Castlenuovo, 

 in Italy. By evaporating 120 Ib. of the water, 3 oz. of the concrete 

 acid are obtained ; 12280 grs. of the water of Lake Castlenuovo 

 yielded 120 grains of acid. 



Boracic acid is also found in the vicinity of these lakes, adhering to 

 the rocks in crystals. 



The boracic acid is now obtained in such quantities from Tuscany 

 that it forms an important article of commerce, and is used to form 

 borax by a direct combination with soda. 



(c.) In minerals. Found in the Boracite of Luneberg, a hard 

 cubical stone, imbedded in gypsum, and containing magnesia as the 

 basis ; also in the Datholite and in Tourmalines, &c. 



3. PREPARATION. Obtained from borax, both by sublimation 

 and by precipitation. 



(a.) By sublimation. A solution of 2 Ibs. calcined sulphate of 

 iton, and 2 oz. of borax, is filtered, evaporated to a pellicle, and sub- 

 limed in an alembic or retort ; the boracic acid, in crystals, lines the 

 upper cavity, and may be swept out with a feather.* 



(b.) Or, the acid may be obtained of a beautiful whiteness, by ad- 

 ding to the borate of soda J its weight of sulphuric acid, and sub- 

 liming.^ 



(c*) The usual process is to dissolve borax 2 parts, in water 6 

 or 8; and to add Ij of sulphuric acid diluted with 1 of water, a gen- 

 tle heat being continued for a short time ; it is set by, and on cool- 

 ing, crystals of boracic acid, in white shining plates or scales, or mi- 

 nute prisms, will be abundantly precipitated. They must be washed 

 with cold distilled water, to remove any adhering sulphuric acid, or 

 sulphate of soda, and dried on blotting paper. The remaining fluid 

 is a solution of sulphate of soda. The crystals obtained in this man- 

 ner are still contaminated by a little of the base of the borax, and of 

 the acid used to decompose it. It is said to be obtained purer by 

 using the muriatic or the nitric acid, instead of the sulphuric. Gay- 



* Chaptal, Vol. I, p. 265. 



t The product by sublimation is much less than by precipitation Id. 



