210 



BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



marls, which generally find only local application. Under mineral 

 phosphates we have the crystalline varieties or apatites and the foliated 

 amorphous varieties or phosphorites. Under rock phosphates we have 

 various nodular varieties, as the river phosphates of South Carolina, 

 phosphatic limestones, guanos, and bone deposits. 



Besides these phosphates of lime there are two, known as Eedonda 

 and Alta Veta phosphates, which are phosphates of iron and alumina. 



The principal application of phosphates is for the manufacture of fer- 

 tilizers, for which purpose they are sometimes simply ground very fine 

 and applied directly to the land, but it is more frequent to treat them 

 with sulphuric acid in order to render the phosphoric acid more easily 

 available to vegetation. Besides the native phosj>hate8, the highly 

 phosphatic slag produced in the basic steel process is generally used 

 for a fertilizer. It is simply ground very fine for use. 



The native phosphates of lime used in the manufacture of fertilizers 

 are illustrated by a series of mineral phosphates, apatites, and phos- 

 phorites; a series of the river phosphates of North and South Carolina; 

 and three guanos. To these are added a sample of basic slag ground 

 very fine. 



APATITES. 



Apatite occurs iu a variety of rocks, but especially in crystalline 

 limestone and granitic rocks, and iu metallic veins. While it is a 

 mineral of very common occurrence, yet large deposits of it have been 

 found in only three countries, Canada, Norway, and Spain. Seven 

 characteristic specimens of apatite are shown : 



(1) Rough crystals. Nortli Burgess, Ontario, Canada. (3073.5.) 



(2) Massive, three characteristic specimens. North Burgess, Ontario, Canada. 

 (30754.) 



(3) Massive. High Rock Mine, Buckingham, Province of Quebec, Canada; 100 feet 

 deep. (64012.) 



(4) Massive. High Rock Mine, Buckingham, Province of Quebec, Canada; 120 

 feet deep. ((54013.) 



(5) Massive. Canada (44278), of the following composition : 



Per cent. Per cent, 



Moisture at 212° (H^O) 



Water of combination (HjO) . 



Phosphoric acid* (P2O5) 



Lime (CaO) 



Oxide of iron and alumina ((FeAl^jOj) 

 Magnesia, etc., not determined (MgO) 



Carbonic acidt (CO2) 



Insoluble matter 



0.60 

 0.59 

 38.37 

 49.84 

 1.14 

 6.54 

 0.64 

 2.28 



0.66 



0.13 



37.52 



52.23 



a 100. 00 & 100. 00 



* Equal to tiibasic phosphate of lime, 83.76 and 81.91 per cent. 



1 Equal to carbonate of lime, 1.45 per cent. 



a Analyst, G. H. Ogaton. 



6 Analyst, l)r. Augn-stus Voelcker. 



