1()4 



liAT Gt'AXO IX KHOJ)KSIA. 



Lab. jVTo. 125 G. — Average sample of the siiiface layer 

 to a depth of 15 inches, near centre of cave. 



Lab. No. 120 G. — Average sample of the surface layer 

 to a depth of 12 feet, near centre of cave. 



Lab. No. 120 liG. — Average sample of the portion of the 

 deposit lying 12 to 14 feet from the surface. 



The samples were air-dried, and sifted through a 

 quarter-inch sieve to remove stones, etc. The following are 

 tlie results of analysis of the air-dried material after tlie 

 samples had been passed through a one-millimetre sieve : — 



Tlie classification of the above samples is as folhnvs : — 

 Nitrogenous bat guano — Lab. Nos. 124 G and 125 G. 

 Phosphatic bat guano — Lab. Nos. 120 G and 120 BG. 



I would draw attention to the high solubility of the 

 phosphoric oxide in samples Nos. 124 G and 125 G, as against 

 the low amounts in samples Nos. 120 G and 120 BG. Samples 

 Nos. 124 G and 125 G were of a fine, uniform dry texture. 



Extent of Deposits. 



AVhilst it is impossible to give any idea of tlie amount 

 of material in these caves owing to their irregular nature, 

 one, however, is justified in saying that many thousands of 

 tons exist, and the material as found in the Umniati Cave 

 No. 1 and the N'gondoma Cave is of considerable value. 



Gexekal Nature of Bat Guano Deposits. 



It is in the upper layers of the deposit that most of the 

 nitrogen occurs, with a fair amount of phosphoric oxide. 

 After the top layers are removed, the percentage of nitrogen 

 decreases, with an increased amount of phosphoric oxide. 

 The amount of phosphoric oxide soluble in a weak acid 

 solution, such as a 2 per cent, citric acid, varies considerably, 



