244 SCIENCE PROGRESS 



carbon it contained from the humus in the soil. The researches 

 of Boussingault completed the demonstration on a large scale 

 that the plant drew its carbon from the atmosphere and this 

 point of view was driven home by Liebig's brilliant report to 

 the British Association in 1840. 



What we nowadays call artificial manures were practically 

 unknown. From very early times men had learned empirically 

 the value of materials like woollen rags, rape dust, soot and 

 bones but their specific action was unknown and the importa- 

 tions of nitrate of soda and guano and mineral phosphates had 

 not yet begun. Lawes became interested in the utilisation of 

 spent animal charcoal, then a waste product on the market and 

 he discovered that the efficacy as a manure of the phosphate it 

 contained was enormously increased if the material were treated 

 with sulphuric acid, this being also true of other phosphates of 

 a mineral character. His experiments were extended into the 

 fields and having convinced himself of the value of super- 

 phosphate as a turnip manure, in 1842 he took out a patent 

 for its manufacture. Liebig in 1840 had recommended that 

 bones should be so treated with acid to increase their solubility 

 but Lawes' experiments had already been successful and his 

 patent, which he confined to the treatment of mineral phos- 

 phates, owed nothing to Liebig. With characteristic energy, 

 Lawes set about the manufacture of superphosphate and rapidly 

 built up an industry which provided him with the fortune from 

 which he spent so lavishly in the conduct of the later experi- 

 ments on his estate. 



Lawes' early experiments had thus been of a somewhat 

 unsystematic nature but they had the very practical object of 

 ascertaining how phosphates can best be applied to the 

 nutrition of the turnip crop, which turned out to be particularly 

 dependent upon this element of plant food. Their value was 

 immediately recognised by the farming community, which 

 was then in very active condition and was entering upon 

 its great epoch of development, so that within ten years or 

 so the advantages of using superphosphates had become 

 thoroughly accepted by agriculturists. The importance of the 

 work that Lawes had done was recognised by a public 

 subscription in 1853 which was expended on the erection 

 of a laboratory for the use of the then young experimental 

 station. This latter may be said to have come into existence in 



