102 THE CANADIAN NATURALIST. [April, 



during upwards of twenty years, Justus Liebig has unquestionably 

 shed upon his all-important theme a flood of light, as copious and 

 brilliant to the full as that which it successively received, in former 

 days, from the luminous minds of Lavoisier and Davy. Indeed, 

 of the affiliation of his labors to those of his immediate predeces- 

 sor, Liebia: himself, in the dedication of his work to the British 

 Association, speaks with becoming humility and justifiable pride : — 



" I have endeavored," he says, "to follow the path marked out 

 by Sir Humphrey Davy, who based his conclusions only on that 

 which was capable of examination and proof. This is the path of 

 true philosophical inquiry which promises to lead us to truth, 

 the proper object of our research." 



Of Licbig's views, and of the rapid and profound revolution of 

 opinion they brought about, occasion will arise to speak in a sub- 

 sequent page. Meanwhile, it may suffice to remark that, amongst 

 other things, they completely overthrew the conceptions previously 

 entertained as to the nature and operation of manures. 



[Here referring again to the history of patent manures in England, 

 the author remarks, that, as a result of the newly-awakened interest 

 in the subject of scientific agriculture, no less than ninety-six patents 

 for manures were registered between 1850 and 1855 ; and he esti- 

 mates that the whole number of such patents registered from 1842 

 to 1862 was at least 200.] 



This long series of inventions comprises plans and processesfor 

 turning to account, as manure, almost all the known forms of 

 animal waste and ejeeta : such as, for example, the night-soil and 

 sewage of towns ; the rags of woollen, silken, and leathern clothing ; 

 the debris of manufactures in which horn, bone, hides, bristles, 

 gut, and other organic and nitrogenous materials are used; the 

 spent animal or bone charcoal of the sugar refineries, and other 

 phosphatic residua; the ammoniacal liqu')rs of gas-works ; the 

 alkaline wash- waters of soap, dye, bleach, and many other factories ; 

 — in a word, several hundred forms of residua, — nitrogenous, phos- 

 phatic, and alkaline, — formerly cast away as worthless rubbish. 



These, the respective patentees propose to subject to various 

 processes, mechanical, physical, and chemical : such as, for example, 

 in the case of liquors, to concentration by boiling down, or pre- 

 cipitation by chemical agency ; in the case of solid residua, of 

 crushing, grinding, or other process of comminution ; or to chemi- 

 cal disintegration by powerful solvents, acid or alkaline according 



