No. 10. 



Animal Offals. 



3pl 



ceive the different conditions under which 

 this residuum, apparently the same, produced 

 three sets of phenomena so distinct. 



Bones treated by the process in question 

 leave a variable residuum ; I have sometimes 

 met with it containing from eighty to ninety- 

 five per cent, of the azotic, organic, decom- 

 posable matter of the bones, sometimes con- 

 taining from twenty-five to thirty-three, but 

 more usually one or two percent.; finally, 

 it sometimes contains scarcely a few thou- 

 sandths. The following are the causes and 

 eflfects of these various proportions: the tem- 

 perature is almost always high in these ope- 

 rations, to the degree of rendering the great- 

 est part of the net-work soluble, and conse- 

 quently the bones are disaggregated and 

 easily broken. But, although soluble, the 

 organic alterable matter can still be held in 

 the interstices, either because the washings 

 proper to draw it out have been operated in- 

 sufficiently, or ill-directed; or further, be- 

 cause the steam may have been chiefly con- 

 densed upon the sides of the digesters. This 

 matter soluble in the proportion of 0.8 or 0.9 

 of the contents of the bones, will act more 

 rapidly as a manure, since its dissolution and 

 decomposition will be more rapid under the 

 same influences; but, instead of being pro- 

 longed four or five years, its action will be 

 almost exhausted in one season — practice 

 has always confirmed this deduction of the- 

 ory. A washing better conducted but in- 

 complete, easily accounts for the presence 

 and solubility of 0.25 to 0.33 of gelatinous 

 matter in the residuum ; whence, also, we 

 deduce the prompt action, but less and less 

 durable efiect than in the preceding case. 

 As to the reduction of 0.01 or 0.02 at the 

 most in the proportion of the azotic decom- 

 posable substance, it evidently makes the 

 residuum inefficacious as a manure. But 

 this state of the case results, as I have 

 proved, from one of the two following cir- 

 cumstances or their concurrence : 



When the bones operated upon in the 

 large way have been cut only in the cellu- 

 lar parts and the grease extracted, the divis- 

 ion not being sufficiently thorough, the wash- 

 ing or maceration not being sufficient, only 

 from thirteen to fifteen per cent, of dry ge- 

 latine is obtained ; there should, therefore, 

 remain about fifteen per cent, of fibrous ti& 

 sue, or the products of its decomposition; 

 but these dregs are scarcely thrown into a 

 heap before a brisk fermentation is developed 

 and ammoniacal vapors are disengaged ; thus, 

 the greatest part of the organic matter dis' 

 appears. 



The second circumstance which equally 

 produces a very poor residuum, is when a 

 well-conducted treatment is applied to bones 



sufficiently divided, and finally, when they 

 are exhausted by continued maceration, as 

 in the processes of the hospitals. 



We must not therefore generally expect 

 to find in the manufactories of glue any but 

 impoverished residuums and valueless as 

 manures. 



Hence the use of them has been abandon- 

 ed by those cultivators, even who at first ob- 

 tained beneficial results; the diSerences, 

 however, are now easily explained, and a 

 simple analysis, consisting in the exhaustion 

 by boiling water of a portion dried and pow- 

 dered, will suffice to test them, a, priori; 

 then drying and weighing anew the pow- 

 dered exhausted substance, we shall find 

 how much the boiling water has diminished 

 the total weight, and consequently the pro- 

 portion of soluble organic matter, all the 

 rest being almost entirely inert as a manure, 

 and able to act only as a calcareous amend- 

 ment. 



The application of bones to agriculture. — 

 In their natural state bones reduced to pow- 

 der are an excellent manure, which is spread 

 in the average proportion of fifteen hundred 

 pounds to the acre, and the influence of which 

 is felt in a diminishing degree from three to 

 five successive years, according to the soil 

 and the seasons; all sorts of bones moreover 

 are fit for this application, when the distance 

 or want of communications does not permit 

 the better part to be used for the arts which 

 we shall speak of in a future division of the 

 work;* and when, moreover, a machine can 

 be procured to grind them, which is quite ex- 

 pensive in its first cost and requires a large 

 expenditure of motive power. 



However, in the absence of this machine, 

 we shall often employ with advantage, espe- 

 cially in the intervals of field labour, the 

 processes of breaking by hand, first cleaving 

 the bones with an axe and then powdering 

 them with a heavy mallet or sledge. 



I have remarked that it is much easier to 

 break bones when thoroughly dried and 

 heated than when fresh; it will be best 

 therefore to put them in the oven immedi- 

 ately after baking bread, and break them 

 afterwards while they are warm. 



In France broken bones are used as a ma- 

 nure in the department of Puy de Dome; in 

 Germany the practice is very extensive. 

 Twelve bushels are there substituted for 

 thirty-five loads of dung for an acre. But 



* The bones used for the manufacture of animal 

 black are not lost for agriculture, for we shall see that 

 after having, in the state of powdered charcoal, served 

 to refine sugar, they conceal a portion of coagulated 

 blood, which conduces to render their effect as a ma- 

 nure very remarkable. 



