XXXV 



A s it was not enough to know the ashes of a particular plant grown 

 in a particular region, but was desirable to get them from as many- 

 different plants, fields, and regions as possible, so Liebig procured ashes 

 from all possible localities. Just as a merchant writes letters of busi- 

 ness to all parts, so Liebig sent about letters everywhere for analyses of 

 ashes. 



In order to make the work of analysis as easy as possible, his pupils Will 

 and Eresenius had worked out and published an excellent method of ash 

 analysis ; and in a short time thousands of analyses were made of the 

 most different plants and parts of plants in very different localities. He 

 found that each plant takes an exact quantity of mineral matter and in 

 an exact proportion, which may be recovered again from its ashes ; and 

 he concluded that whatever else the plant requires for the formation of 

 its combustible constituents is derived from the carbonic acid, water, 

 and ammonia of the air. From these views Liebig laid down the rule 

 that to keep a wheat or corn-field fertile one has only to return to it the 

 mineral constituents which have been taken out by the crops, and in the 

 proportions in which those minerals are present in the ashes of each 

 crop. 



Liebig induced the distinguished alkali manufacturer Muspratt, in 

 Liverpool, to prepare mineral manures for wheat, rye, oats, clover, 

 potato, and other fields. The different manures were manufactured 

 according to a method invented by Liebig, which consisted in melting- 

 together the necessary substances, so that salts easily soluble in water 

 were brought into an almost insoluble form that the rain might not carry 

 them off out of reach of the germinating seed. Liebig was as much 

 convinced of the soundness of his mineral theories as of the working 

 power of his mineral manure. Eut matters turned out differently from 

 what he anticipated, and a heavy trial was in store for his great genius. 



The English agriculturists saw no result from his artificial manure, 

 ceased to buy it, and again had recourse to dung and other substances, 

 and the factory in Liverpool ceased to work. Nay, even Liebig was 

 himself convinced by his unsuccessful experiments in agriculture in 

 Griessen that his mineral manure could not make a barren soil more 

 fertile. One single ray of hope came to cheer him after years of failure. 

 It turned out that after a length of time those fields when no longer 

 manured at length became more fertile. But here again was a new 

 riddle for him. 



Meanwhile adversaries rose up, not merely to expose the uselessness 

 of his manure, but also to show that new methods must be adopted 

 in order to reach a practical end. 



In the foreground stood an English agriculturist, Lawes, who soon 

 joined with an excellent chemist, Gilbert, and made on one of his estates 

 experiments with all sorts of manures, which they manufactured and 

 tried in many different ways. It was shown that the more soluble a 



