Phosphatic Materials used for Agricultural Purposes. 17 



in this rock is as high as in good samples of South American 

 bone-ash. 



Phosphatic rocks similar in composition to the Sombrero Rock 

 have lately been discovered in the Anguilla Isles, forming part 

 of the Leeward Islands.* 



7. KOORIA MOORIA GUANO. 



A considerable portion of the Kooria Mooria guano imported 

 into England is bought up by manure manufacturers, and by 

 means of sulphuric acid converted into useful turnip-manures. 



Although this guano may be used by itself as a manure for 

 turnips or Swedes, it is better to add to it some sulphuric acid 

 (say one-third of its weight), with a view to changing a portion 

 of the insoluble phosphates, in which it is rich, into the more 

 efficacious form of a soluble phosphate. 



Kooria Mooria guano varies considerably in composition, as 

 the following analysis made in my laboratory will show : 



Composition of Kooria Mooria Guano. 



Kooria Mooria guano, it will be seen, contains but little 

 organic matter, and hardly any ammonia. It is generally met 

 with in commerce in a tolerably fine powder, offering its phos- 

 phates in that finely divided state which enables plants to assimi- 

 late them more readily than those found in coprolites or other 

 like substances which have become completely fossilized. 



8. OTHER PHOSPHATIC GUANOS. 



There are several species of African and West Indian guanos 

 which at present are occasionally used in the manufacture of 



* Vide Communication by Sir Roderick Murchison, in Journal, vol. xx. p. 31. 



C 



