261 



BONE-BLACK. 



BONES. 



262 



substance is manufactured by heating bones in vessels so contrived as 

 to prevent any access of atmospheric air. The bones having been 

 freed from fatty and fleshy matter by long boiling, are heated in a 

 large still or retort made of cast iron or Welsh bricks ; it is usually 

 two to three feet square, from fifteen to twenty feet high, and sur- 

 rounded by a furnace of brick-work. The bones are introduced 

 through an opening at the top, which may be closed by an iron 

 plate ; and a steady ignition is kept up for a proper time, convenient 

 arrangements being made for conveying away the volatile products of 

 decomposition. The carbonaceous residue is received through a double 

 trap-door at the bottom of the furnace into cast-iron canisters, which 

 are immediately closed and set aside, that the bone-black may cool. 

 It is then sent into commerce, in a coarsely granulated condition. 

 During the operation the bones lose an average weight of 50 per 

 cent.; some of the matters driven off by the heat are, however, con- 

 densed and utilised. [BONE LIQUOR.] 



Bone-black necessarily varies somewhat in its quantitative compo- 

 sition ; but the following analysis is probably a near approximation to 

 the average amount of its several constituents : 



Parts. 



Phosphate of lime . . 

 Carbonate of lime . 

 Charcoal . i 



Carbide or silicicle of iron 

 Sulphide of calcium or iron 



80-0 



5-0 



14-0 



1-0 



traces 



100-0 



Nearly the whole of the inorganic ingredients may be removed by 

 digesting the bone-black in hydrochloric acid, which dissolves thorn ; 

 the residue well washed with water is nearly pure carbon, and is 

 known in commerce as purified animal charcoal. 



Bone-black is chiefly used as a decolorising agent in various che- 

 mical and pharmaceutical processes ; but more especially in the 

 refining of sugar, for depriving the crude syrup of its colouring matter, 

 which is thus better effected than by any other process. M. Bussy, 

 who has paid much attention to this subject, has drawn up the 

 following table, showing the power possessed by various kinds of 

 charcoal of decolorising solutions of indigo and molasses. The 

 indigo solution contained one-thousandth part of its weight of indigo ; 

 the molasses was mixed with twenty times its weight of water. The 

 amount of charcoal employed in each experiment was one gramme 

 (= 15'34 grains). The third and fourth columns contain numbers 

 showing the relative decolorising values of the various charcoals, 

 when compared with common bone-black. 



An attempt has been made to substitute bone-black by common 

 wood-charcoal, artificially impregnated with alumina, phosphate of 

 Ac., but without practical success. An excellent decolorising 

 charcoal may also be made by calcining pitch, tar, resin, Ac., with 

 hydrate of lime, removing the latter with hydrochloric acid, washing, 

 and drying at a hot-water temperature; .but, unlike bone-black, this 

 charcoal, when saturated with colouring matter, cannot have ita de- 

 colorising power restored by re-ignition. 



According to Dr. Stenhouse, decolorising charcoals act either by 

 virtue of their porosity (e. g., purified animal charcoal), by the mor- 

 danU they contain (t.y., the artificially prepared phosphate of lime or 

 almniniseJ charcoal), or in both ways, like ordinary bone-black. The 

 inorganic ingredients also fulfil another office; namely, that of separating 

 the particles of charcoal from each other, and thus preventing them 

 from agglutinating, which always takes place when the charcoal is 

 heated alone. 



Animal charcoal not only absorbs colouring matters, but to a cortair 



extent deprives infusions of most of the active medicinal herbs, &c., of 

 heir active principles, and even takes from solution certain metallic 

 wits. 



Ivory-dust, when calcined in the same manner as directed for bones, 

 yields when finely ground a charcoal of a rich velvety-black colour, 

 extensively used as a pigment. The article used largely by blacking 

 manufacturers, and known as ivory-black, is merely finely ground bone- 

 >laek. 



BONE-LIQUOR. When bones are submitted to destructive distil- 

 ation for the purpose of manufacturing bone-black, liquid products of 

 most intensely offensive odour distil over. This distillate separates 

 nto two layers : one forming a heavy, black, tar-like fluid, which 

 constitutes what is known as bone-oil (consisting of a complex mixture 

 of hydrocarbons, organic bases, &c.) ; and another and lighter one, 

 consisting chiefly of a solution of carbonate of ammonia in water. The 

 atter is commonly known as bone-liquor, and is much employed for the 

 manufacture of the salts of ammonia, especially the carbonate, sulphate, 

 and hydrochlorate. [AMMONIA.] 



BONES have long been extensively used as manure, especially on 

 3oor and dry sands and gravels. They have thus become a consider- 

 ible article of commerce with Gerniany, Belgium, and Holland, in 

 Europe, and with the chief parts of South America. 



Experiments on bones as a manure were made long before their use 

 was extensively adopted, and these, in general, were not attended with 

 i very favourable result, in consequence of the bones not being broken 

 into sufficiently small pieces, or being put upon the land in too fresh a 

 state. But since mills have been erected to crush them to a small size, 

 and the proper use of them has been ascertained, the advantage of this 

 manure in distant and uncultivated spots, where the carriage of com- 

 mon stvble or yard manure would have been too expensive, and where 

 it could not be made for want of food for cattle, is incalculable. By 

 means of bones, large tracts of barren sands and heaths have been 

 converted into fertile fields. 



The bruising or grinding of bones soon became a distinct business. 

 They were broken into different sizes, accordingly called inch bone,half- 

 'nii-li liniies, and iliist. Most of the bones procured from London and 

 the manufacturing towns have undergone the process of boiling, by 

 which the oil and a great part of the gelatine which they contain have 

 been extracted. The bones imported from South America have been 

 burned, and are properly bone-ash, the mineral part alone remaining. 



At first sight we should be led to imagine, that having lost much of 

 the rich animal matter which they contained, they would be propor- 

 tionably less effective in the soil. This however does not seem to be 

 the case from the comparative experiments made with bones which 

 have been subjected to either burning or boiling, and those which are 

 quite fresh. All those who have used bones extensively report, that 

 little difference can be observed between them ; some even give the 

 preference to those from which the glue has been extracted. But glue 

 forms excellent manure. How is this to be explained ? It appears, 

 from the result of many experiments, that bones do not furnish much 

 nourishment to the roots of plants until they have undergone a certain 

 degree of decomposition. The fat and the gelatine, being intimately 

 blended with the bony matter, and contained in cavities or cells, may 

 remain a long time in the earth without decomposition. As a proof of 

 this, it has been found that bones which had lain in the earth for many 

 centuries, on spots where ancient battles were fought,' afforded, on 

 analysis, nearly as much gelatinous matter, by the abstraction of the 

 earthy parts, as fresh bones would have done. Bones analysed by 

 Fourcroy and Vauquelin were found to consist of 



Parts. 



Solid cartilage, gelatine, and oil . . . .51 

 Phosphate of lime . . . . , . . 87-7 

 Carbonate of lime . . , . . . .10 

 Phosphate of magnesia 1-3 



100-0 



The more recent analyses of the bones of the sheep and ox by 

 Berzelius and others are as follow : 



Thomson. Berzelius. 



Bones of Ox. 

 33-3 

 55-45 



3-85 



Phosphate of 



Magnesia. 



2-05 



2-45 



2-90 



99-8 100-3 100-00 



It is obvious from these, that bones must vary greatly, according to 

 their age and other circumstances. 



It would seem, then, that the great effect of bones, as a manure, 

 must depend on the phosphate of lime ; and the effect of bone-ashes 

 seems to strengthen this opinion. As to the boiled bones, the more 

 the lione has undergone fermentation, the more soluble its gelatine will 



