94 PROCEEDINGS OP THE ACADEMY OP 



The specimens from which the material for the above analyses were se- 

 lected, I received from Messrs. Richards & Miller, agents for the Philadelphia 

 Guano Company; there is doubt as to their exact locality; in appearance they 

 correspond exactly with that from Monk's Island, but the results of the analyses 

 are very different from those obtained from the specimens from this Island which I 

 received from Dr. Luther. 



That Alumina is present as a phosphate, in the Guano from Monk's Island, I 

 have proved, by treating 3.4023 grammes of an average sample of the cargo of 

 Schr. Trident from Monk's Island, with pure Caustic Potash in a silver dish, 

 and was found to contain 1.32 per cent, of Alumina. 



Specimens were given me from Monk's Island by Dr. Luther, the character- 

 istic appearance of which has already been described. 



1.5915 grammes were treated in a silver dish with Potash, but not a trace of 

 Alumina could be detected ; the residue dissolved in Hydrochloric Acid was 

 found to contain Lime, 39.08 per cent. 



The guano rock from Monk's Island when finely powdered and treated with 

 distilled water, gave an acid reaction with litmus paper. 



(V.) . 



1.70'76 gammes (organic matter and water not determined.) 

 " " 0.1993 gram. BaO, SO3 gave Sulphuric Acid, 4.00 per cent. 



" " 0.0780 " 2MgO, PO5 " Magnesia, 1.64 " " 



" " 1.1999 " CaO, CO2 " Lime, 39.34 " " 



" " 1.1461 " 2MgO, PO5 " Phosphoric Acid, 42.98 " " 



For the Oxygen of the Sulphuric Acid 2.39 there are required, 0.88 of the oxy- 

 gen of the lime, and if to the remainder be added the Oxygen of the Magnesia 

 we have 10.95, which is to the Oxygen of the Phosphoric Acid very nearly as 1 : 2 



(VI.) 



2.8678 grammes treated with distilled water gave : 



" " 2.7076 grams, residue, 94.41 per cent. 



" " 0.1287 " BaO, SO3 gave Sulphuric Acid, 1.49 " «' 



" " 0.0655 " CaO, CO2 " Lime, 1.27 " " 



«« « 0.0363 " 2MgO,P05 " Phosphoric Acid, 0.81 " " 



2.8420 grammes treated with distilled water gave: 



" « 0.0076 grams Ag gave Chlorine,' 0.09 " " 



■' " 0.0347 " 2MgO,P05 " Phosphoric Acid, 0.78 " " 



'« " 0.1099 " BaO, SO3 " Sulphuric Acid, 1.33 " " 



Guano Rock has been brought from another group of islands called Centinella, 

 consisting of peaks, which sometimes attain a height of 800 ft. The rock is 

 described as consisting of two layers, the upper of which is a dark-brown com- 

 pact rock, varying slightly from the lower layer. This so called lower layer 



[March, 



