The Phosphates of America. 53 



tinue for this reason to maintain a leading position as a raw 

 material. 



Before the land rock can be made available for industrial pur- 

 poses, it is made to pass through three distinct and successive 

 operations. 



1. Mining or excavating. 



2. Washing it free from sand and other impurities. 



3. Kilning, to free it from moisture. 



Taking these in their order, it is customary to establish a main 

 trunk railroad, starting at the river front or on the bank of some 

 convenient stream, and passing right through the centre of the 

 property to be exploited. 



Alternate laterals can be run off at right angles from any por- 

 tion of this main line, at distances of, say, 500 feet, in conformity 

 with the % nature of the ground. Between and parallel to these 

 laterals a ditch or drain is dug to a depth extending 4 to 5 feet 

 below the phosphate strata. From this main drain the excava- 

 tors start their lines at right angles to the laterals, commencing 

 at one end of the field and digging trenches 15 feet wide and 

 500 feet long, the work being so arranged that the men are stationed 

 at intervals of 6 feet. Every man is supposed to dig out, daily, 

 a "pit" 6 feet long, 15 feet wide, and down to the phosphate 

 rock. The overlying material is thrown out to the left-hand side 

 of the trench. The phosphate itself is thrown out to the right and 

 taken in wheelbarrows to the railroad cars which pass at either 

 end of the trench. The water drains from the trenches into the 

 underlying ditch, and is thence pumped out by means of a steam- 

 pump worked by a locomotive engine. The pump and the engine 

 are secured to connected railway platforms, and run along the rail- 

 road track from one ditch to another as occasion requires. 



The cars, loaded with the crude phosphatic material dug out of 

 the pits, are run down to the washing apparatus, constructed at an 

 elevation of some 30 feet from the ground, and generally consist- 

 ing of a series of semi-circular troughs 20 to 30 feet long, set in 

 an iron framework at an incline of some 20 inches rise in their 

 length. Through every trough passes an octagonal iron-cased 

 shaft provided with blades so arranged and distributed as to form 

 a screw with a twist of one foot in six, which forces the washed 

 material upwards and projects the fragments against each other. 

 The phosphate-laden cars are hauled up an incline and their con- 

 tents dumped into the bottom trough, where the phosphate en- 



