PKINCIPAL PHOSPHATE DEPOSITS. 



47 



TABLE XXXIX.— ANALYSIS OF MEJILLONES GUANO. 



Water ..... 

 Carbonate of lime 

 Sulphate of lime . 

 Phosphate of lime basic 

 Phosphate of lime monacid . 

 Phosphate of magnesia monaciil 

 Oxide of iron a id alumina 

 Silica ..... 

 Sodium chloride . . 

 Organic matter . 



Per cent. 



9-14 



0-32 



3-26 



33-64 



26-44 



10-35 



1-35 



0-89 



7-32 



7-29 



100-00 



As will be seen from these analyses, about one-fourth of the 

 phosphoric acid is combined with magnesia. And if the phosphate of 

 magnesia is in itself more soluble than phosphate of lime, it 

 is so to a still greater extent in the case of monacid phosphate of 

 magnesia.^ 



Clipperton Island Guano. — The discovery of guano deposits in 

 Clipperton Island is more recent. This island is situated in the 

 open sea off the coast of Brazil. The coral chain surrounds a fresh- 

 water lake in mid ocean and has served as a refuge to sea birds 

 for thousands of years. Whilst the nitrogen of the excrement was 

 carried away by rain water the phosphoric acid combined with the 

 hme of the coral. The whole of the isle is covered with phosphate 

 to a depth of six feet. The average analyses of thirteen samples 

 taken in different sections, has given 83 to 86 per cent of tribasic 

 phosphate and 0-03 of oxide of iron and alumina. In the dry state 

 the phospho guano is a yellowish sandy powder. Dr. Gilbert gives 

 the following analysis : — 



TABLE XL.— ANALYSIS OF CLIPPEKTON ISLAND GUANO. 



Water 



Tribasic phosphate of lime 



Phosphate of magnesia 



Carbonate of lime 



Quicklime . 



Sulphate of lime 



Sodium chloride 



SiOj 



Organic matter . 



Oxide of iron and alumina 



Undetermined . 



Per cent. 

 3-80 

 78-09 

 0-55 

 6-73 

 2-S4 

 0-78 

 0-15 

 0-28 

 4-83 

 0-04 

 1-91 



100-00 



^ The translator dissents ; no superphosphate made from material con- 

 taining organic matter to the extent to which phospho guano does, approaches 

 a bone ash superphosphate in this respect. For whiteness free from a yellow 



