58 THE FERTILITY OF THE SOIL [ch. 



by no means universally adopted, and in many dis- 

 tricts medieval agriculture was still the rule. It is 

 impossible to determine how far the low yield was 

 due to this circumstance. But in many cases the 

 small supply of phosphates in the soil was now the 

 limiting factor, preventing the crop from rising. 



Then gradually bones came into use as manure and 

 produced such remarkable results that from the early 

 years of the nineteenth century considerable quantities 

 were imported from Europe. It would, perhaps, be 

 unkind to enquire too particularly where they came 

 from : Liebig roundly declared that " England is 

 robbing all other countries of their fertility. Already 

 in her eagerness for bones she has turned up the 

 battlefields of Leipsic, and Waterloo, and of the 

 Crimea: already from the catacombs of Sicily she 

 has carried away the skeletons of many successive 

 generations.... Like a vampire she hangs upon the 

 neck of Europe, nay, of the whole world, and sucks 

 the heart blood from nations without a thought of 

 justice towards them, without a shadow of lasting 

 advantage to herself." 



But even finely ground bones sometimes acted 

 only slowly and sometimes failed to act at all. This 

 was the case at Rothamsted: during the years 1836 — 

 1838 Lawes had used bone dust on turnips without 

 avail, although it was effective elsewhere. He there- 

 fore prepared the soluble calcium phosphate, then 



