Agricultural Cliemistry. 
This comment we had made in reference to a sentence in 
Baron Liebip;'s ' Letters,' wherein, speaking of the exhaustion of 
phosphate of lime and alkaline phosphates, bj the sale of flour, 
cattle, &c., he says : — 
" It is certain tliat this incessant removal of the phosi>hates must tend to 
exhaust the land and diminish its capability of producing grain. The fields 
of Great Britain are in a state of progressive exhaustion froni this cause, as is 
proved by the rapid extension of the cultivation of turnips and mangold 
wuvzel — plants which contain the least amount of the jihosphatcs, and 
THEREFOKK REQUIRE THE SMALLEST QUANTITY FOR THEIB DEVELOPMENT." — 
Letln-s, 3rd Edition, p. 522. 
On this sentence we further commented thus : — 
" Now, we do not hesitate to say that, however small the quantity of phos- 
phates contained in the turnip, the successful cultivation of it is more de- 
pendent upon a large supply of phosphoric acid in the manure than that of any 
©thor crop." 
Baron Liebig thus meets these comments, — 
" No one surely can believe that my statement as to the very small pro- 
portion of phosjihates in turnips is vmtrue, because Mr. Lawes has misunder- 
stood the meaning of the sentences above quoted from my work. My remarks 
had no reference whatever to the manuring of turnips, but were designed to 
direct attention to the difference between turnips and other cro]is which require 
in certain periods of their growth more phosphates than tuniips do. With 
reference to the cultivation of grain, I wished to show that the growth of 
turnips had acquired so vast an extension [the italics are Baron Liebig's 
©■wii], for this reason, namely, because the soil loses so little of the iihosphates 
In/ the cultimtion of the latter crop. Turnips are so advantageous in a rotation, 
only because, whatever be the quantity of phosphates conlained in the soil, or 
added to it in the manure, they leave in the soil so large an amoiuit of these 
indispensable salts for other crops, which require a larger supply of them." 
— Priaciples, p. 131. 
Farther on, Baron Liebig refers the reader to the letter in 
question, to justify the meaning which he has now given to his 
sentence, and to convince him that we do not do him justice. 
Now we must say, that we have carefully re-perused that 
letter ; and still maintain, not only that if language has any 
meaning at all, we liave done Baron Liebig entire justice in the 
interpretation of his sentences which we liave given of them, 
but that, by no interpretation of language, can the meaning which 
he now claims be given to his argument as formerly put forth. 
Certainly nowhere have we previously been told by Baron Liebig 
that— 
" Turnips are so advantageous in a rotation only becaufc whatever be the 
quantity of phosphates contained in the soil, or added to it in the inunnre, they 
leave in the soil so large an amount of these indispensahle salts for other crops 
which require a larger supply of them." 
Baron Liebig's statement was, not only that turnips were 
"plants which contain the least amount of the phosphates," but 
that they " f/<r7r/b?-c require the smallest quantity ior their develop- 
