82 E. V. d'iNVILLIERS PHOSPHATE DEPOSITS OF NAVASSA. 



Tliis sample, which came from the "diggings" August 13, 1890, was ana- 

 lyzed by Dr. W. J. Gascoyne, chemist. 



A sample of the red variety (dried) taken by myself from the drying 

 house in July, 1890, gave the following results upon analysis in the labora- 

 tory of the University of Pennsylvania : 



Analysis of Red Navassa Phosphate. 



Per cent. 



Loss on ignition 14.228 



Lime 23.090 



Magnesia (Trace) 



Sesquioxide of iron 9.796 



Alumina 18.425 



Phosphoric acid 29.779 



Sulphuric acid 1.160 



Carbonic acid (by difference) 3.527 



Bone phosphate _' 65.037 



Numerous partial analyses of the red variety have shown moisture from 

 6.71 per cent, to 9.10 per cent., and bone phosphate from 49.69 per cent, to 

 55.84 per cent. ; but such samples were not thoroughly dried. 



Moisture. — In addition to the somewhat varying percentage of phosphoric 

 acid, iron and alumina, another qualifying feature of the Navassa phosphate 

 is its moisture. A shower of short duration soon converts it into a sticky 

 mass, difficult to dig, handle and transport. 



Experience has demonstrated the fact that the phosphate earth cannot be 

 dried properly under cover, and hence the practice prevails of piling the 

 newly dug material in long heaps about 10 feet high, when exposure to wind 

 and sun brings about such a reduction in moisture as enables it to be con- 

 veyed to storage houses near the wharf, there to await shipment. Once put 

 under cover dry, it can be kept dry. Of course the water of composition is 

 chemically combined and cannot be decreased by such means ; but owing to 

 the great swelling which ensues while the material is moist it becomes abso- 

 lutely necessary to thoroughly wind-dry it before storing or loading into 

 vessels. 



To determine the real effect of moisture more definitely I took three sam- 

 ples of the red phosphate from approximately the same locality, measured 

 them into a box 1 cubic foot in capacity, and weighed with the following 

 results : 



No. 1. Freshly dug phosphate earth from near surface — weight, 63 pounds. 



No. 2. Phosphate from edge of exposed drying pile — weight, 68 pounds. 



No. 3. Phosphate from dried pile in storage-house — weight, 89 pounds. 



Therefore a cubic yard of the same materials would show w^eights respect- 

 ively as follows : 1,701 pounds, 1,836 pounds and 2,403 pounds, making a 

 difference of 411 per cent, between the freshly dug and thoroughly dried 



