a premium for every unit above and a dockage for every unit below that figure. The settlement is made on the combined assay of zinc and lead. If the lead assays check and the zinc assays are far enough apart for umpire, both lead and zinc are umpired, and the settlement made on the sum of the umpire assays.

The ore is unloaded from the car into a 10" X 15" Blake crusher which discharges into a Gates elevator by which the ore is carried to the top of the building. Here it is discharged into a revolving screen having 5-inch openings, the oversize going to a set of rolls on the second floor. These rolls are 18 in. X 36 in. and are equipped with locomotive tire-steel shells. The 5-inch material is discharged into a second trommel the openings in which are 4 inch. The oversize from this screen goes to another set of 18" X 36" rolls, on the first floor, and after passing these rolls is elevated and discharged into the set of rolls on the second floor, which discharge. into the 14-inch trommel.

The ore after passing the 14-inch trommel is elevated to a mixing drum. which discharges into a Vezin sampler which cuts out one-fifth. This onefifth is discharged into a Bridgeman automatic sampler which cuts out a sample weighing about 500 pounds. The discharge from the samplers is elevated to the bins. The crushing machinery is driven by a 50-horsepower motor.

There are 18 bins arranged so that the ore may be drawn from beneath into the cars.

The roasting is done in two, five-hearth McDougal furnaces which are driven by a 30-horsepower motor. They are fired by gas, ordinary 1" X 2" mixers being used for burners. These furnaces have a capacity of from

20 to 25 tons each in 24 hours.

The ore is taken from the bins in cars which have a capacity of 2 tons. They are provided with bottom gates through which the ore is discharged into the elevator boot at the McDougall furnaces. The elevator carries it to the top of the furnaces where it is discharged into two large hoppers, one on each furnace. From these hoppers it is fed automatically to the roasting hearths.

The roasted ore, which now carries 3 per cent sulphur, is discharged into cars with bottom gates which are pulled up an incline over the cooling bins and discharged. After cooling the ore is shoveled into cars which are weighed, elevated to the furnace track and distributed to the oxidizing furnaces.

There are two blocks of oxidizing furnaces each containing 18 furnaces. The furnaces are 6 ft. X 12 ft. the bottom being made of grates 11⁄2 in. X 8 in. X 72 in. These grates are perforated with conical holes 11⁄2 inches apart, the holes being inch at the top and 3/4 inch at the bottom. The blast enters the charge through these holes.

In charging, the grates are first covered with a layer of coal. When this is burning freely the charge of ore and coal is thrown in and distributed evenly over the grate. While burning the charge is raked as required.

The blast is furnished by two fans driven by a 30-horsepower motor. The blast is carried to the furnaces by a large underground conduit and is

discharged under the grates through holes in the bridge wall. The air for each furnace is controlled independently by a draft grate.

The fumes are drawn from the furnaces by a large exhaust fan which is located at the bag room. This fan is driven by a 40-horsepower motor and has water-cooled bearings. The fume first enters the combustion chamber where the carbon is all burned out, and the dirt allowed to settle. It then passes through too feet of cooling pipe by which means the temperature is lowered so that it will not burn the bags in the bag house. It then enters another large chamber where there is an additional settling. From this chamber it enters the fan and is driven into the bag room.

The bag room is 90 ft. X 140 ft. The fume first enters a lateral pipe a called the breech from which it is distributed to 18 pipes b, each of which has 17 hoppers below shown by dotted circles in the plan Fig. 1, and marked

c in Fig. 2. On these hoppers are tied short bags d reaching to the floor. In the top of the pipes are two rows of thimbles, 25 in a row, on which are tied the 30-foot bags e, which do the sifting. Both long and short bags are 24 inches in diameter. This makes a total of 900 long, and 306 short bags. The oxide accumulating in the long bags is shaken down into the short bags which are removed every 24 hours. These bags are dumped into a conveyer which carries the oxide to the packing room. There are two packers driven by a 20-horsepower motor. The oxide is packed 400 pounds in a barrel and loaded to the market.

Electric power is used in this plant. The boiler room is 50 feet square and contains two 180-horsepower boilers fired by gas. Zimmerman burners are used, there are six burners to each boiler.

The engine room is also 50 feet square there being room for two engines and generators. The engine is a 250-horsepower Allis-Corliss which

drives a 150-kilowatt Bullock generator, from which the power is distributed to the different departments. The switchboard is provided with Weston direct-reading voltmeter, ammeter and wattmeters, and circuit breakers of the most improved pattern.

The coal used is nearly all Arkansas semianthracite and all goes through the coal crusher. It is unloaded from the cars into a hopper at the bottom of which is a pair of toothed rolls. After passing through these it discharged into a pair of rolls which reduce it to about 1⁄2 inch. It is then discharged into an elevator which carries it to a large hopper at the top of the building. From this it is drawn off into cars, which run on the same distributing track as the ore cars, and is carried to the furnaces or storage yard. The coal crusher is driven by a 30-horsepower motor.

Fig. 2.

This smelter has the best laboratory in the State of Kansas so a word about it will not be out of place.

The building is 30 ft. X 40 ft., containing a chemical laboratory 20 ft. X 30 ft., an assay room 20 ft. X 20 ft., a weighing room 9 ft. X 13 ft., which opens into both the laboratory and assay room, and a toilet room opening off the weighing room.

The laboratory is equipped with a hood 8 ft. X 4 ft. which is large enough for four chemists to work at once. Around the sides of the room are work tables equipped with funnel racks, burette stands, and other necessary apparatus. A sink with hot and cold water and ample drain boards is conveniently placed between the ends of the two main work tables.

The assay room is equipped with a gas-fired furnace. This furnace has a large melting chamber below, heated by a 1" X 2" mixer, and two 9" X 15" muffles above heated by two 1" X2" mixers. At the side of the furnace is a boiler-iron table 3 ft. X 6 ft. supported by brick pillars, and the table and furnace are both covered by a sheet-iron hood which serves to carry off the gases.

The weighing room has a balance table made of three-ply cypress supported on three concrete pillars which do not touch the floor and are therefore free from vibrations of the building. A Thompson analytical balance occupies this table and it is the intention of the company to add other balances when needed.

Composition of the Earth's Crust.

The average composition of the earth's crust has been approximately estimated as follows:

Per cent.

Copper, lead, zinc, tin, silver and gold, although metals of great importance to man, constitute so small a part that their percentages are expressed by four to eight decimals, that is, between hundred thousandths and billionths of a per cent. In some eruptive rocks, however, the percentage is much higher, and has been determined to be in the thousandths of a per cent in the case of copper, lead and zine, and one-tenth to one-hundredth as much of silver and gold.