6 Chemical Composition and Commercial Value of 



men renders available for the use of farmers the discoveries of 

 phosphatic deposits in Norway, Spain, America, and other 

 countries. The composition of most of the phosphatic materials 

 which are used at the present time by manure-manufacturers in 

 England has been carefully ascertained ; but many of the analyses 

 are scattered in scientific journals, and not readily accessible to 

 the agriculturist or manufacturer. Several phosphatic materials 

 again have only recently been imported into England, and of 

 these no trustworthy analyses have been as yet published. Of 

 others we possess careful analyses made from picked specimens, 

 but no published account of the composition of the materials in 

 the state in which they actually occur in commerce. I propose, 

 therefore, to give an account of all the more important phos- 

 phatic materials now in use, and briefly to describe their general 

 appearance and more characteristic physical properties, stating 

 the localities where they are found, their composition as ascer- 

 tained by me, and some particulars which may be of interest or 

 practical importance either to the farmer or to the maker of 

 artificial manures. The following is a list of the substances of 

 which I shall treat : 



1. Norwegian apatite. 



2. Spanish phosphorite. 



3. Cambridgeshire coprolites. 



4. Suffolk coprolites. 



5. American phosphate (Maracaibo guano). 



6. Sombrero, or Crust-guano. 



7. Kooria Mooria guano. 



8. Other phosphatic guanos. 



9. South-American bone-ash. 



10. Animal-black, or bone-charcoal. 



11. Bones. 



There are a few other phosphatic materials which now and 

 then find their way into commerce, but to these 1 shall either not 

 refer at all or only incidentally. 



1. NORWEGIAN APATITE. 



Apatite, a hard and often well-crystallised mineral, chiefly 

 composed of phosphoric acid and lime, is found in this country 

 in Devonshire, Cornwall, and Scotland, but not as yet in sufficient 

 quantity to allow of its being collected for technical purposes. 

 In America it is found imbedded in granite at Baltimore, in 

 gneiss at Germantown, in mica-slate in West Greenland ; in 

 granite at Milford Mills, near Newhaven, Connecticut ; at 

 Topsham, in Maine, in granite, and in various other localities 

 mentioned in detail in Dana's * Mineralogie.' On the Continent 



