1864.] CHEMISTRY OF 3IANURES. 103 



to the circumstances in each case ; or to maceration in water ; or 

 to torrefaction by fire ; or to digestion, at low or high pressure, 

 sometimes in moist, sometimes in dry or super-heated steam. 



Several of the patents include recipes for mixing the products 

 thus obtained with each other, or with products of a different 

 origin, to adapt them (as the inventors allege) for special crops or 

 for paculiar soils. Many of these proposals possess merit ; though 

 a still larger number exhibit ignorance on the projectors' part ; 

 while a certain percentage almost seem to have been concocted with 

 a view to profit by the ignorance of others. 



Superphosphate op Lime Manufacture. — First in impor- 

 tance, and nearly first also in chronological order, among the 

 manure-patents enrolled since the publication of Liebig's book in 

 1840, stands the celebrated patent granted in 1842 to Mr. J. B. 

 Lawes,* for converting tricalcic into monocalcic phosphate by 

 means of sulphuric acid. The invention of this process, so far as 

 it applies to the treatment of recent bones, is not claimed by Mr. 

 Lawes, but belongs to Justus Liebig, who suggef=ted it in his 

 great work already quoted. As this suggestion has become the 

 foundation of the modern industry of manures, and its authorship 

 has been the subject of controversy, the Reporter feels bound to 

 record, in the foot-note below, Liebig's own words on the subject. f 



The great merit of Mr. Lawes consists, first, in his having ex- 

 tended the application of sulphuric acid to phosphates of mineral 



* Lawes (J. B.), Patent No. 9353, May 23, 1842. 



t " The form in which they [bones] are restored to a soil does not ap- 

 pear to be a matter of indiflFerence. 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 effecting 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 digested for some time to add 

 100 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. 

 Experiments 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 suffer injurious effects 

 in consequence, but that, on the contrary, they thrive with much more 

 vigor." — " Organic Chemistry in its Application to Agriculture and 

 Physiology," pp. 184, 185. 



