BORACIC ACID 427 



by a diagonal movement. A few turns of a fly-wheel, worked cither by hand or 

 steam-power, bring the heavy pressure of an iron bar upon the pile of books when 

 thus brought into their proper position under the guillotine, by which the pile is 

 squeezed into a firm compact mass, upon which, and simultaneously, the knife-edge 

 is by the same power brought down, and the rough and superfluous fore-edges are at 

 one stroke severed from the rest, leaving a smooth and polished surface on the fore- 

 edges of the books, instead of the rough and uneven one before presented. The posi- 

 tion of the pile is then carefully shifted so as to bring in succession the tops and the 

 tails of the pile of books to the like action of the guillotine, and in a very short space 

 of time (varying according to the size and thickness of the volumes operated on) the 

 edges of many hundreds of books are cut smooth and in readiness for the sprinkler, 

 the colourer, the marbler, or the gilder. 



BOOK.THVI WOOD. An Indian wood, used for dyeing rod, the produce of the 

 Sappan tree, Ccesalpinia Sappan. 



BORACIC ACID, or BORIC ACID. (Acide boriquc, Fr. ; Borstiure, Ger.) 

 Composition of the anhydride, BO 3 (B 2 O 3 ) ; of the crystallised acid, BO S , 3HO 

 (B-O 3 , 3H 2 0). 



The chief sources of this acid and its salts the borates are the hot vapours, or 

 soffioni, which issue from the ground in certain parts of Tuscany, and are utilised by 

 a process fully described below. In addition to its occurrence in these vapours, 

 boracic acid is found native in a solid state, forming the mineral Sassoline or Sassolite, 

 so called from Sasso, in Tuscany, the locality in which it was originally discovered by 

 Mascagni. Sassoline is usually found in the form of small white pearly scales, 

 with a soapy feel. Theoretically, the pure mineral should contain 56 f 4 per cent, of 

 boracic acid (anhydride) and 43 - 6 of water. Klaproth, in examining the Sassoline of 

 Sasso, found 80 per cent, of boracic hydrate, with 1 1 per cent, of protosulphate of 

 manganese, and 3 per cent, of sulphate of lime, together with silica, carbonate of lime, 

 and other mechanically-mixed impurities. Sassolino also occurs abundantly in the crater 

 of Vulcano, one of the Lipari Islands, forming a layer on the sulphur and around the 

 fumaroles, or exits of the sulphurous exhalations. 



Among the numerous compounds of boracic acid occurring ready formed in nature, 

 the most important are native borax, or biborate of soda, and tincal, or crude borax : 

 substances fully described under the head of BORAX. Of the other native boratos, 

 the following are the more interesting species : 



Boracite, a borate of magnesia with chloride of magnesium, containing when pure 

 62'5 per cent, of boracic acid (anhydride). It crystallises in the cubic system, often 

 in hemihedral or tetrahedral forms, and is remarkable for being pyro-electric that 

 is, for exhibiting electrical polarity when exposed to a change of temperature. The 

 mineral is further notable for its anomalous optical properties ; thus, a ray of light 

 in passing through a crystal of boracite Buffers double refraction, contrary to the 

 general rule that crystals belonging to the cubic system are not capable of thus 

 affecting light. The probable explanation of this anomalous behaviour on the part of 

 boracite is beyond the scope of this article. 



Boracite is usually found in association with deposits of rock-salt and gypsum. 

 The mineral occurs crystallised at Luneburg in Hanover, and at Stassfurt near 

 Magdeburg ; the latter locality also yields a massive boracite called Stassfurtite. 



Ulexite or Boronatrocalcite is a hydrous borate of lime and soda, occurring in white 

 reniform masses, from the size of a hazel-nut to that of a potato, scattered over the 

 dry plains of Iquique, in Southern Peru, and in the Province of Tarapaca, where it is 

 called tiza. It is also found in Nova Scotia and in Nevada. A specimen from Peru 

 yielded boracic acid, 45'46 ; lime 14'32; soda, 8'22; potash, 0'51 ; sulphuric acid, 

 1-10 ; chloride of sodium, 2'65 ; sand, 0'32. This analysis was made by Mr. A Dick, 

 in the metallurgical laboratory of the Museum of Practical Geology. The term 

 Hayesine was formerly applied to this mineral, but some confusion has arisen in the 

 application of this name. According to Hayes the pure species contained no soda, 

 and was simply a hydrous borate of lime. Mr. David Forbes discovered a borato of 

 lime in the form of white silky flakes suspended in the waters of the hot springs 

 called the Bafios del Toro, in the Cordilleras of Coquimbo. The formation of this 

 substance was instructive, as throwing light upon the probable origin of the same 

 compound elsewhere. When the hot vapours, emanating from the neighbouring 

 volcanoes, passed into springs of water highly charged with carbonate of lime, the 

 boracic acid of the vapours combined with the lime to form borato of lime, whilst 

 carbonic acid gas was set free. The term BechUile has been applied by Dana to a 

 borate of lime from Tuscany. 



Howlite or Silicoborocalcite is a hydrous boro-silicate of lime, containing about 43 per 

 cent, of boracic acid, and occurring in nodular forms in gypsum and anhydrite in Nova 

 Scotia, 



