126 TRANSACTIONS OF THE [ FEB. 13, 
every 12 revolutions of the bit. The blasting is done with dy- 
namite, of which 80 to 100 boxes, each containing 100 lbs., are 
used every month, say on an average 150 lbs. daily. 
After blasting down 40 feet, the salt is broken by sledges, 
placed in small hand-carts, and hoisted on a platform to the sur- 
face by steam power. About one hundred men are employed by the 
company, of whom fifty work below the surface. ‘They workon 
ten-hours time. 
The rock mass is quite dry, but, owing to bad management 
in the early history of the mine, water from the surface runs 
into it through seams and openings; to remove this, two pumps, 
capable of throwing out 100 gallons per minute, are run about 
ten hours out of the twenty-four. The brine pumped out is 
allowed to waste. 
Ventilation is necessitated by the great quantity of dynamite 
exploded daily. Air is supplied by a fan 8 feet in diameter, 
4 feet wide, driven at about 250 revolutions per minute. ‘This, 
it is estimated, supplies about 600,000 cubic feet of air per hour. 
Pockets of an inflammable gas have been repeatedly struck, 
and on a recent occasion the issuing gas waslitand burnt for an 
hour or more. Perhaps this phenomenon is connected with the 
underlying lignite. 
The engines used for running the blower, the fan, reels, 
breakers, etc., are three in number, and aggregate 250 horse- 
power. 
The salt brought to the surface is crushed between corrugated 
rollers driven at high speed; one set breaks it into lumps from two 
to three inches in diameter, and another into lumps one-half 
inch in diameter and finer. It is then ground into various 
grades by six buhr-stone mills, each capable of grinding 50 tons 
in ten hours. The salt is sorted by jigs, revolving reels, and 
blowers, the fine dust being blown out by a horizontal current 
of air striking against a column of falling salt. 
The salt is sent into market in eight grades: (1) Rock-salt in 
lumps from 100 to 300 pounds, used by farmers, it being placed 
under sheds for cattle to lick. (2) Crushed salt that passes 
over 4-inch screens and through #-inch screens. (3) ‘‘ Fish 
salt,” including all which passes through a }-inch screen. 
(4) Coarse ground. (5) Medium ground. (6) Fine ground. 
(7) For sack and barrel salt the coarser particles of grade 6 are 
screened out with a wire screen of ten meshes to the inch, and 
the fine dust is blown out. (8) The fine dust thus blown out 
divides itself by gravity into an impalpable part (which is 
thrown away, being a small percentage) and a coarser part, 
which forms table salt. The salt is shipped to market in sacks 
and barrels. 
