280 MANtJi'AOTTTRE OF NITRATE OF SODA. 



6 inches to 12 feet, beneath a covering of from 1 foot to 10 feet 

 of conglomerate or pudding stone, or hard rock, principally por- 

 phyry, but varying also in character to foliated gneiss, greenstone 

 and syenite. No caliche beds are known to exist nearer than 15 

 miles from the sea coast, and the furthest, those in the district 

 of Atacama, are distant about 90 miles. The Ramirez caliche 

 beds, or raw nitrate deposits, comprise 3,270 acres, or nearly 6 

 square miles, and are situated on the border of the Tamarugal 

 Pampa, 59 miles from the port of Iquique by the line of the 

 Nitrate Kailway Company, and 42 miles by direct mule road. 



The caliche is plentiful and easy of extraction ; its chemical 

 analysis is, nitrate of soda, 51 per cent.; common salt, 26 per 

 cent.; sulphate of soda, 6 per cent.; sulphate of magnesia, 3 per 

 cent.; and insolubles, 14 per cent. 



In order to provide caliche sufficient to meet the require- 

 ments of so large a system of machinery, at least two hundred 

 and fifty mules and forty carts would be required ; to avoid this 

 expense the Author introduced the innovation of a portable rail- 

 way with two locomotive engines and eighty side-tip cars, thus 

 precluding the necessity of employing more than thirty mules 

 and five carts for taking the caliche to the side of the line which 

 runs out 1^ mile in the caliche quarries. This has proved a 

 most efficient and economical mode of carriage. 



The locomotives are four-wheel coupled side-tank engines, 

 with two-wheel trailing bogie and outside cylinders 8 inches in 

 diameter, and having 12 ins. length of stroke. The driving- 

 wheels are wrought iron with steel tires 2 feet 6 inches in 

 diameter, and 4-feet wheel base ; the trailing-wheels are cast- 

 steel, 1 foot 6 inches in diameter ; the weight of the engine in 

 working order is 6 tons 15 cwt., and it carries 250 gallons of 

 water and 5 cwt. of coal. The locomotives, as well as the cars, 

 were designed by Mr. David Greig, M. Inst. O.E. The line has 

 a 2-feet gauge, with steel rails and steel sleepers, known as 

 Greig's Patent Portable Eailway. The sharpest curve on the 

 line is 60-feet radius, and the steepest gradient 3" 15 in 100. The 

 rails weigh 16 lbs. to the yard. The cars with frames and 

 wheels weigh 5 cwt. each, and carry 1 ton 10 cwt. of caliche. 

 The ordinary load for an engine is fifteen cars, or from 22 to 23 

 tons per trip. 



