Sharpies.] 250 [March 21, 



Moisture 30.60 



Bone phosphate of lime . . 33.35 



Sulphate of lime .... 21.80 



Organic matter .... 9.98 



Silica . . . . . . 1.00 



Potash 0.32 



Soda . .•'■'. . . . 0.14 



Chlorine, Alumina iron, Carbonic acid, etc. 



The question naturally arises, what is this deposit and .whence 

 does it come ? Dr. Liebig, of Baltimore, who visited the island 

 shortly after I did, says of it 3 " It is a strictly organic deposit of 

 recent origin." He seems to think that it has been thrown up in 

 some manner by the waves and that it consists of the remains of 

 " the organic matter so abundant in the surrounding ocean." 



The evidence in support of this view is, however, very slight ; 

 the remains in it are very few and can readily be accounted for 

 on other suppositions. 



The deposit differs from most deposits of the kind in the fact 

 that it is in the form of a fine moist powder ; there was a deposit 

 somewhat similar at Navassa, but it was mostly in the form of 

 a rock, while I have not seen any of this too hard to be crushed 

 by the hand. Some samples of guano, from Jarvis Island in the 

 Pacific Ocean, have almost exactly the same composition as this 

 deposit. That from Jarvis Island is an undoubted bird deposit. 

 There are a number of caves in Texas which contain large 

 deposits of bat guano. The bat guanoes are always easy to 

 identify since they consist mainly of the hard parts of insects, 

 which the bat has been unable to digest. In exploring these 

 caves a bat was occasionally encountered and small piles of their 

 droppings were seen, but these were few and far between. The 

 occasional remains that are found are not such as would be 

 deposited by bats, but are small fragments of fish bones. 



A sample of guano from a neighboring Cay serves to throw 

 some light on the subject. In this we find much organic matter, 

 consisting largely of fragments of bone ; in some cases these are 

 so well preserved that the part of the body from which they 

 came can readily be identified ; the vertebra, of small fish are 

 common among them. 



