424 
Agricultural Chemistry. 
" If it were possfblc to restore to the soil of England and Scotland the 
pliosi)hates which during the last fifty years have been carried to the sea by 
ilio Thames and the Clyde, it would be equivalent to manuring with millions 
of hundredweights of hones, and the produce of the land would increase one- 
third, or perhaps double itself, in five to ten years." — Ih., p. 523. 
" If a rich and cheap source of phosphate of lime and the alkaline phos- 
phates were o])en to England, there can be no question that the importation 
of foreign corn might be altogether dispensed with after a short time." — 
Ih., p. 524. 
" It has been mentioned in the preceding part of the chapter, that animal 
excrements may be replaced in agriculture by other materials containing their 
constituents. Now, as the principal action of the former depends upon their 
amount of 7«i«eraZ food so necessary for the growth of cultivated plants, it 
follows, that we might manure with the mineral food of wild jilants, or, in 
other words, with theie ashes ; for, these plants are governed by the same 
laws, in their nutrition and growth, as cultivated ])lants themselves. Thus, 
these ashesmight he substituted for animal excrements ; and if a proper selection 
were made of them, we might again furnish our fields with all the consti- 
tuents removed from them by crops of cultivated plants." — ^th Edition, 
p. 182, 183. 
Speaking of the exhaustion of alkalies by the growth of wheat 
and tobacco in Virginia, he sajs: — - 
" Almost all the cultivated land in Europe is in this condition.'" — ith Edition, 
p. 118. 
" It is also of importance to know, that the rule usually adopted in France 
and in Germany of estimating the value of a manure according to the amount 
of its nitrogen, is quite fallacious, and that its value does not stand in pro- 
portion to its nitrogen. 
" By an exact estimation of the quantity of ashes in cultivated plants, 
growing on various kinds of soils, and by their analysis, we will learn those 
constituents of the plants which are variable, and those which remain con- 
stant. Thus also we will attain a knowledge of the quantities of all the con- 
stituents removed from the soil by different crops. 
" The farmer will thus be enabled, like a systematic manufacturer, to have 
a book attached to each field, in which he will note the amount of the various 
ingredients removed from the land in the form of crops, and therefore how 
much he must restore to bring it to its original state of fertility. He will 
also be able to express in pounds weight, how much of one or of another 
ingredient of soils he must add to his own land, in order to increase its 
fertility for certain kinds of plants. 
" These investigations are a necessity of the times in which we live ; but 
in a few years, by the united diligence of chemists of all countries, we may 
expect to see the realisation of these views ; and by the aid of intelligent 
farmers, we may confidently expect to see established, on an immovable 
foundation, a rational system of farming for all countries and for all soils." — 
p. 212, 213. 
Speaking of the importation of phosphoric acid into Great 
Britain in the form of bones, in ten years, he says : — 
" To have increased the fertility of the fields in the right proportion, 
800,000 tons of potash ought to have been added to the 1,000,000 tons of 
Ixmes in a suitable form." — Address, p. 13. 
" The fabrication of a manure, equal in its composition and effects to the 
solid and fluid excrements of animals and men, seems to me one of the most 
essential demands of our time, more especially for a country like England, in 
