SPECIAL MANURES. 321 



instance, more phosphoric acid than other crops, and for these a 

 manure rich in phosphoric acid was provided. Others contained a 

 largo proportion of potash, and these were called ' potash crops,' 

 and the manure prescribed for them was rich in potash. And so 

 with the other ingredients of plants." 



" I recollect it well," said the Doctor, " and, in truth, for several 

 years I had much faith in the idea. It was advocated with con- 

 summate ability by the lamented Liebig, and in fact a patent was 

 taken out by the Musgraves, of Liverpool, for the manufacture of 

 Liebig's Special Manures, based on this theory. But the manures, 

 though extensively used by the leading farmers of England, and 

 endorsed by the highest authorities, did not in the end stand the 

 test of actual farm practice, and their manufacture was abandoned. 

 And I do not know of any experienced agricultural chemist who 

 now advocates this doctrine of special manures. 



"Dr. Vcelcker says: * The ash-analyses of plants do not afford 

 a sufficiently trustworthy guide to the practical farmer in selecting 

 the kind of manure which is best applied to each crop.' " 



" Never mind the authorities," said the Deacon ; " what we want 

 are facts." 



" Well," replied the Doctor, u take the wheat and turnip crop as 

 an illustration. 



" We will suppose that there is twice the weight of wheat-straw 

 as of grain ; and that to 10 tons of bulbs there is 3 tons of turnip- 

 tops. Now, 100 Ibs. each of the ash of these two crops contain : 



Wheat crop. Turnip crop. 



Phosphoric acid 11.44 7.33 



Potash 15.44 32.75 



Sulphuric acid 2.44 11.25 



Lime 5.09 19.28 



Magnesia 3.33 1.56 



" There are other ingredients," continued the Doctor, " but these 

 are the most important. 



" Now, if you were going to compound a manure for wheat, say 

 100 Ibs., consisting of potash and phosphoric acid, what would be 

 the proportions ? " 



The Deacon figured for a few moments, and then produced the 

 following table: 



100 LBS. SPECIAL MANURE FOB WHEAT AND TURNIPS. 



Wheat manure. Turnip manure. 



Phosphoric acid 42i Ibs. 18* Ibs. 



Potash 57* " 811 " 



100 Ibs. 100 Ibs. 



"Exactly," said the Doctor, " and yet the experiments of Lawea 



