448 :;ffect of boiling upon bones. 



the little success which has attended the use of bones in Mecklenburg 

 and North Germany. Others, again, attribute the whole of their in- 

 fluence to the organic part — the gelatine — which bones contain. 

 Neither of these views is strictly correct. Plants, as we have seen, 

 require a certain quantity of phosphoric acid, limej and magnesia, 

 which are present in the inorganic part of bones, and so far, therefore, 

 are capable of deriving inorganic food from bone-dust. But the or- 

 ganic part of bones will decompose, and therefore will act nearly in 

 the same way as skin, wool, hair, and horn do — which substances it 

 resembles in ultimate composition.* It cannot be doubted, therefore, 

 that a considerable part of the effect of bones upon all crops must be 

 due to the gelatine which they contain. 



The principal facts, now known in regard to the action of bones, 

 may be thus stated : — 



1°. The organic matter of bones acts like that of skin, woollen rags, 

 horn shavings, &c., but-as bone-dust contains only about one-third of 

 the organic matter which is present in an equal weight of either of the 

 above substances, its total effect, in so far as it depends upon the or- 

 ganic matter, will be less in an equal proportion. 



2°. But as the organic matter of bones contains more water than 

 horn or wool, (p. 446,) it will decay more rapidly than these substan- 

 ces when mixed with the soil, and will therefore be more immediate in 

 its action. Hence the reason why woollen rags and horn shavings must 

 be ploughed in in the preceding winter, if they are to benefit the subse- 

 quent wheat or turnip crops, while bone-dust can be beneficially ap- 

 plied at the sowing of the seed. 



3*^. When bones are boiled the oil will be separated, and a p^Ttion of 

 the gelatine will at the same time be dissolved out.j The bones, 

 therefore, will be in reality rendered less rich as a manure. But us 

 they at the same time take up a considerable quantity of water, boiled 

 bones will decompose more rapidly when mixed with the soil, and 

 thus will appear to act as beneficially as unboiled bones. Hence the 

 reason why in Cheshire, where boiled bones are used to a considerable 

 extent, many practical men are of opinion that their action upon the 

 crops is not inferior to that of bones from which the oil has not been 

 extracted by boihng. The immediate effect may indeed be equal, or 

 even greater, than that of unboiled bones, but the total effect must 

 be less in proportion to the quantity of organic matter which has 

 been removed by boiling. Cases, however, may occur in which the 



' The main difference is in the quantity of sulphur contained in hair. An analysis of 

 human hair, by Van Laer {Annalen dcr Pharmacie, xiv.. p. 168,) which has reached me 

 since the preceding sheet went to press, shows the proportion of sulphur more accurately 

 than that which is given at page 445. lie found human hair of various colors to leave froih 

 one-third to nearly two per cent, of ash when burned, and to consist besides of Carbon^ 

 50-65— Hydrogen, 6 36— Nitrogen, 17-l4-Oxygcn, 20-85— Sulphur, 500— Total, 100— and 

 nearly half a per cent, of Phosphorus. 



t The prolonged boiling of bones, so as to dissolve a portion of the gelatine, is practised 

 to a considerable extent as a mode of manufacturing size or glue. In the large dyeing es- 

 tablishments in Manchester, the bones are boiled in open pans for 24 hours, the fat skim- 

 med off and sold to the candle-makers, and the size afterwards boiled down in another 

 vessel till it is of sufficient strength for stiffening the thick goods for which it is intended. 

 The size liquor, when exhausted, or no longer of sufficient strength for stiffening, is applied 

 with much benefit as a manure to the adjacent pasture and artificial grass lands, and the 

 bones are readily bought up by the Lancashire and Cheshire farmers. The boiled bones 

 must evidently lose all the fertilizing*virtue which the size liquor acquires. 



