62 



AGRICULTURAL CHEMISTRY. 



and those from beech the most serviceable. 

 The asiies of oak-wood contain only traces 

 of phosphates, those of beech the fifth part 

 of their weight, and those of the pine and fir 

 from 9 to 15 per cent. The ashes of pines 

 from Norway contain an exceedingly small 

 quantity of phosphates, namely, only 1-8 

 per cent, of phosphoric acid. (Berthier.) 



With every 100 Ibs. of the lixiviated ashes 

 of the beech which we spread over a soil, 

 we furnish as much phosphates as 460 Ibs. 

 of fresh human excrements could yield. 

 Again, according to the analysis of De 

 Saussure, 100 parts of the ashes of the grain 

 of wheat contain 32 parts of soluble, and 

 44-5 of insoluble phosphates, in all 76'5 

 parts. Now the ashes of wheat straw con- 

 tain 11-5 per cent, of the same salts ; hence 

 with every 100 Ibs. of the ashes of the beech, 

 we supply a field with phosphoric acid suf- 

 ficient for the production of 3820 Ibs. of 

 straw (its ashes being calculated at 4-3 per 

 cent., De Saussure,) or for 15-18000 Ibs. of 

 corn, the ashes of which amount, according 

 to De Saussnre, to 1-3 per cent. 



Bone manure possesses a still greater im- 

 portance in this respect. The primary 

 sources from which the bones of animals 

 are derived are, the hay, straw, or other 

 substances which they take as food. Now, 

 if we admit that bones contain 55 per 

 cent, of the phosphates of lime and magne- 

 sia fBerzelius,) and that hay contains as 

 much of them as wheat-straw, it will follow 

 that 8 Ibs. of bones contain as much phos- 

 phate of lime as 1000 Ibs. of hay or wheat- 

 straw, and 2 Ibs. of it as much as 1000 Ibs. 

 of the grain of wheat or oats. These num- 

 bers express pretty nearly the quantity of 

 phosphates which a soil yields annually on 

 the growth of hay and corn. Now the ma- 

 nure of an acre of land with 40 Ibs. of bone 

 dust is sufficient to supply three crops of 

 wheat, clover, potatoes, turnips, &c., with 

 phosphates. But the form in which they 

 are restored to a soil does not appear to be a 

 matter of indifference. For the more finely 

 the bones are reduced to powder, and the 

 more intimately they are mixed with the 

 soil, the more easily are they assimilated. 

 The most easy and practical mode of effect- 

 ing their division is to pour over the bones, 

 in a state of fine powder, half of their weight 

 of sulphuric acid diluted with three or four 

 parts of water, and after they have been di - 

 gested for some time, to add one hundred 

 parts of water, and sprinkle this mixture 

 over the field before the plough. In a few 

 seconds, the free acids unite with the bases 

 contained in the earth, and a neutral salt is 

 formed in a very fine state of division. Ex- 

 periments instituted on a soil formed from 

 grauwacke, for the purpose of ascertaining 

 the action of manure thus prepared, have 

 distinctly shown that neither corn,, nor 

 kitchen-garden plants, surfer injurious ef- 

 fects in consequence, but that on the con- 

 trary they thrive with much more vigour. 



It has also been found that bones act 



| more speedily and efficaciously after oeing 

 ' boiled. This is probably owing to the re- 

 moval of fatty matter, the presence of which 

 impedes the putrefaction of the gelatin con- 

 tained in them. 



In the manufactories of glue, many hun- 

 dred tons of a solution of phosphates in mu- 

 riatic acid are yearly thrown away as being 

 useless. It would be important to examine 

 whether this solution might not be substi- 

 tuted for the bones. The free acid wo jld 

 combine with the alkalies in the soil, espe- 

 cially with the lime, and a soluble salt 

 would thus be produced, which is known 

 to possess a favourable action upon the 

 growth of plants. This salt, muriate of 

 lime (or chloride of calcium,) is one of 

 those compounds which attracts water from 

 the atmosphere with great avidity, and in 

 dry lands might advantageously supply the 

 place of gypsum in decomposing carbonate 

 of ammonia, with the formation of sal-am 

 moniac and carbonate of lime. A solution 

 of bones in muriatic acid placed on land in 

 autumn or in winter would, therefore, not 

 only restore a necessary constituent of the 

 soil, and attract moisture to it, but would 

 also give it the power to retain all the am- 

 monia which fell upon it dissolved in the 

 rain during the period of six months.* 



The ashes of brown coal and peat often 

 contain silicate of potash, so that it is evi- 

 dent that these might completely replace one 

 of the principal constituents of the dung 

 of the cow and horse, and they contain also 

 some phosphates. Indeed they are much 

 esteemed in the Wetterau as manure for 

 meadows and moist land. 



It is of much importance to the agricul 

 turist that he should not deceive himself re- 

 specting the causes which give the- peculiar 

 action to the substances just mentioned. It 

 is known that they possess a very favour- 

 able influence on vegetation ; and it is like- 

 wise certain that the cause of this is their 

 containing a body, which, independently of 

 the influence which it exerts by virtue of its 

 form, porosity, and capability of attracting 

 and retaining moisture, also assists in main- 

 taining the vital processes in plants. If it be 

 treated as an unfathomable mystery, the na- 

 ture of this aid will never be known. 



In medicine, for many centuries, the mode 

 of action of all remedies was supposed to be 

 concealed by the mystic veil of Isis, but 

 now these secrets have been explained in a 



* Immense quantities of bran are used in all 

 print-works, for the purpose of clearing printed 

 goods. After having served this purpose, it is 

 thrown away. But the insoluble part of bran 

 contains much phosphates of magnesia and soda ; 

 it would, therefore, be useful to preserve it as a 

 manure. This has been done for some years in a 

 farm with which I am connected, and its value as 

 a manure has been found so great that it is much 

 preferred to cow-dung. In some works this waste 

 bran is heaped up into little hillocks, which might 

 be disposed of as a manure, instead of being an 

 annoyance on account of the space which it occu- 

 pies. ED. 



