SELECT REFERENCES ON AGRICULTURE

BY NELSON ANTRIM CRAWFORD

DIRECTOR OF INFORMATION, U. S. DEPARTMENT OF AGRICULTURE

EATON, G. D.-Backfurrow.
Putnam.

WILLIAMS, Ben

HARLAN, R.-A New Day for the
Country Church. Cokesbury Press.
ROADMAN,

E. A.-The Country Hind. N. Y., Dutton.

Church and its Program. Metho- BOYD, Thomas.-Samuel Drummond.

N. Y., Scribner.
Anonymous.-The
BOJER, Joban.-The Emigrants. N. Y.,
Harper.
Century.

DIVISION XIX

MINERAL INDUSTRIES

MINING AND ORE DRESSING

BY CHARLES E. LOCKE

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Good business conditions in gen- | per long ton in 1925, making an eral in America with a closer ap- average higher than in 1924. Other proach to normalcy following the war metals and metallic products had and its after effects, and also a fur- their various ups and downs during ther recovery of Europe, have been the year with perhaps more on the reflected in the mining industry dur- up side than on the down side. Aring 1925 and have made it a satis-senic showed a most decided slump factory year without any of the fea- because of a decreased demand. On tures of a boom period. A good the whole, the whole metal situation criterion is the iron ore shipments showed an encouraging tendency tofrom Lake Superior ports, which, upward higher prices as the year came to November first, amounted to 49,- to a close. Gold mining continues 816,469 long tons. While this figure to suffer under the handicap of a is not up to the high tonnages of fixed price in terms of a dollar which some previous years it shows a has a lower value in terms of commarked improvement over 1924 with modities. its 40,558,525 long tons over a similar period.

Labor conditions have been excep tionally peaceful, the only major strike being that of the anthracite coal miners. Wages held at a sat

Prices.-Ranges in average monthly prices for the major metals have been 66.9 to 71.1 cents per ounce for sil-isfactory level and while slight labor ver; 13.3 to 14.7 cents per pound for shortage existed in some districts the copper; 8.0 to 10.2 for lead; 7.0 to supply in general about equalled the 8.3 for zinc; and 51.4 to 60.5 for tin. demand. The effect of a decreased All of these will show averages higher supply of labor has been to force the than in 1924. Lead stands out at the operators to adopt more and more highest price for years, due to the labor-saving machinery with the uncertainty of a future lead supply rather unexpected but pleasing result sufficient to meet the demand. Cop- that the operators have found that per has not kept up with the proces-efficiency was increased and costs resion and many mines are operating at duced by the forced change. Other little or no profit on account of in-contributing factors to this improvecreased costs of labor and supplies ment have been the various studies and the overdevelopment of copper in standardization of apparatus and mines to a point where curtailment operations and the broad investigaalone prevents an excess of production over consumption. The possibility of a further increase in the output of low-cost copper from the Katanga district in Africa is another big adverse factor. The price of basic pig iron ranged from $19.76 to $23.76

tions of the U. S. Bureau of Mines in the many phases of mine work. Without gains such as these, many mines could not exist under the burden of heavy taxes from which they are suffering and for which they are begging relief.

Consolidation of the Industry.- Invention and use of the Gilman The whole mining industry is under- automatic heat-treating machine to going a revolution. The day of the insure proper uniform tempering of small mine is past. The number of drill-steel bits for maximum cutting mines is decreasing and new mines effect and minimum wear. Successare discovered less frequently. Pro- ful development of liquid oxygen as duction to-day is coming more and a commercial explosive for mining more from large, low-grade deposits and general use of low freezing dynaand the tendency is to consolidate mites to avoid the necessity of thawinto big units. Anaconda, in the ing in cold weather. The advent of copper industry, has come to hold a electrical shovels of the revolving place similar to the U. S. Steel in type with long booms and mounted the iron industry. Mining is becom- on caterpillar tractors in place of the ing more like a manufacturing busi-old steam shovel on rails which had ness. Increased production results lower efficiency and higher operating not from new mines as much as from cost. Machine loading underground expansion of producing properties and by various types of mechanical from the ability to reopen and operate shovels and scrapers to replace hand old mines at a profit under the stimu- shoveling and thus speed up opera lation of increased prices of metals tions and reduce costs. The general and improvements in methods of use of electric locomotives of both treatment such as are referred to the trolley and storage battery type later under ore dressing and metal-in mine haulage with an increase in lurgy. The only important discov- size of the storage battery type to ery of new mines of recent date is put it more nearly on a par with that of the gold-copper deposits of the trolley type, and the greater field the Rouyn district in Quebec. for gasoline locomotives in work on Mining Technic.-Outstanding de- the surface where the exhaust fumes velopments in present day mining are not serious as is the case in the technic may be summarized as fol- mine. The general adoption of eleclows:-Greater use of electrical power trical pumps of either the plunger generated in central station units and or turbine types with the latter type for these central stations the Diesel gaining in favor. Electricity also engine is finding a place as the prime coming more and more into vogue mover. Successful application of vari- for hoists and supplanting steam and ous methods of electrical prospecting a beginning made in the installation and the adaptation of a sectional of automatic hoists electrically drill-rod system to the ordinary rock operated without manual attention. drill to enable it to penetrate up A constantly widening field for systo 100 feet for prospecting purposes. tematic ventilation in metalliferous Some installations of turbo compres- mines following the lead of coal sors where. the need of large units mines. Electric lighting systems for operating uniformly at full load al- the much-traveled underground places lows their use, and an increased em- with the replacement of candles and ployment of small portable compres- open oil lights by the individual sors driven by electricity underground acetylene lamp at the working faces or by either electricity or gasoline in all except the gassy coal mines engine on the surface. The almost where electric cap lamps are complete replacement of old style for safety. A general improvement piston drills by the modern hammer in living conditions together with drills with greater cutting speed up more attention paid to the miner's to a record of thirty-one inches per welfare, safety, education and recreaminute in granite under test condi- tion. tions for one of the latest Gilman Ore Dressing.-Just as the applicadrills, and the limit is not set by tion of the flotation process revoluthe drill but by the ability of the tionized ore dressing ten years ago, manufacturers of drill steel to fur- so now the discovery of organic flonish a steel which will stand up un-tation reagents is revolutionizing floder the powerful blows of the drill. tation plants. The general tendency

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