116 THE CANADIAN NATURALIST. [April, 



material, in the superpliosphate manufacture, reference has already 

 been made ; and in the section on potash, the new means at our 

 disposal for extracting this fertilizer from the ocean and the 

 primitive rocks, have been set forth at length.* 



It is not necessary however to pursue these reasonings further ; 

 nor to trace, to a more distant future, the probable influence of 

 foregone and contemporary events on the course of the man urial in- 

 dustry. The Reporter will have accomplished his wish should the 

 attention of governments and individuals throughout the world be 

 directed by these cursory remarks to the double revolution, Sani- 

 tary and Agricultural, now taking place in England ; and to the 

 signal benefits likely to accrue therefrom to the British nation, and 

 ultimately to the whole human race. 



Modern Theory of Plant-Nutrition. Nature and 

 Operation of Manures. — Quitting the historical aspect of the 

 question, the Reporter proposes now to oflFer a few remarks on 

 the nature and modus operandi of manures, and on the grand and 

 simple laws which govern their relations to the soil and the crop. 

 For the clear apprehension of these it will be necessary, in the 

 first instance, briefly to direct attention to the nature and func- 

 tions of plants, and to the modern theory of their alimentation. 

 Growing as they do, with their leaves spread forth in the air, and 

 their roots radiating in the soil, plants necessarily draw from these 

 media the materials of which they consist. As fertile soils are 

 rich in the debris of previous vegetation, such as dead roots, leaves, 

 and the like, crumbl d to mould or h'tmus ; and as this humus is 

 slightly soluble in water, which is constantly supplied to the soil in 

 the form of rain and dew; it was formerly and not unnaturally 

 (believed, that the aqueous solution of organic matter thus formed 



* Reference is here made by the Reporter to a previous section of this 

 report, pp. 48-52. From this it appears thai the process for the economic 

 extraction of potash-salts from sea-water, as described by Mr. Sterry 

 Hunt (Canadian Naturalist, vol. iii, pp. 105-109), has been still further 

 perfected by Mr. Merle, who employs artificial cold to aid the process; 

 and has now established, in the south of France, very extensivr works 

 for the purpose of carrying out Mr. Balard's processes with this improve- 

 ment. As regards the extraction of potash from feldspathic rocks, the 

 late experiments of "Ward and Wynants, as noticed in the report, show 

 that by carefully calcining feldspar with proper proportions of lime or 

 chalk and fluor-spar, a frit is obtained from which nearly all the potash 

 may be removed in a caustic state by the action of water. — Editors. 



