From the crude petroleums are obtained products that are indispensable, one of these being lubricating oil and another is kerosene, needed for the lighting of isolated houses and all buildings that can not obtain gas or electricity at reasonable cost.

Gasoline, another product, is almost universally used in this country as motor fuel and may be regarded as necessary, though numerous efficient substitutes are available at higher prices. The Diesel type of engine, which burns either vegetable or mineral oils, also suggests how a scarcity of gasoline may be met.

Some unnecessary and wasteful uses of petroleum are as follows: Burning it under steam boilers, the most obviously unnecessary use; oiling roads, coal-tar residues being equally efficient; and making oil asphalt. The last use, though desirable, is unnecessary, because deposits of native bitumen and asphaltic rocks are available in Utah, California, Texas, Oklahoma, and elsewhere.

The growth of the petroleum industry in the United States has been accompanied by the invention of new processes and devices and the improvement of old ones, making the industry notable for the introduction and development of distinctly American features. Some of these features are the perfecting of the cable rig, a chisel-shaped bit suspended by a rope, that has probably been tried in every oil field in the world, the rotary rig developed in the Gulf field and since used in California, Roumania, and Russia; the construction of pipe lines hundreds of miles long, connecting the wells with refineries and shipping ports; the invention of processes for refining oils of unusual composition; the perfecting of processes by which the percentage of gasoline obtainable from a crude oil is greatly increased; the production of gasoline from natural gas; and the manufacture of toluol and benzol from petroleum.

Some of the wastes in the petroleum industry are enumerated here: Careless methods of drilling and casing wells, whereby oil and gas are wasted, wells get beyond control or run "wild," and productive sands are ruined by water; production in excess of immediate marketing facilities and demand; storage in earthen sumps or open tanks, with resulting loss by seepage or evaporation; fires from lightning or other causes, which have caused enormous losses of stored oil or oil from flowing wells.

Some of the substitutes for petroleum are as follows: For illuminating purposes; acetylene gas, water gas, coal gas, animal fat or vegetable oil, or alcohol from grain, potatoes, and waste products; for motor fuel; alcohol, benzol, or vegetable oils in Diesel engine; for fuel oil; coal, coke, lignite, wood, and charcoal; and for lubricating oil; no efficient substitute known.

NATURAL GAS.

The quantity of natural gas commercially utilized in the United States in 1914 is estimated to have amounted to 592,000,000,000 cubic feet, valued at more than $94,000,000. In 1885 the value of the natural gas utilized in this country was estimated at $4,857,000.

Productive areas correspond fairly closely in distribution with the petroleum fields, except in California, where the commercially utilized production is obtained mainly from the Buena Vista Hills division of the Midway field in Kern County.

Probable areas lie in extensions of the present productive fields either areally or deeper. Natural gas resources far in excess of present demand within the limits of transport are known to exist in the Healdton, Loco, and Duncan fields in southwestern Oklahoma, in the Buena Vista and Elk Hills in Kern County, Cal.; in Buffalo Basin, Park County, Wyo.; and in Zapata and San Patricio Counties in southern Texas.

Natural gas is an ideal fuel that has been grossly wasted, but it can be replaced, though at an increased cost, by manufactured substitutes. Substitutes for natural gas, which can be prepared from raw materials abundant in the United States, include coal gas, water gas, producer gas, and for illuminating purposes, acetylene gas, gasoline, and petroleum derivatives.

Natural gas can be used in place of any other fuel, experiments having demonstrated that natural gas compressed in cylinders can even be applied as a motive power for automobile propulsion.

Epoch-making features in the natural gas industry are the development of the internal-combustion engine for the economic consumption of natural gas, whereby a saving of 90 per cent of fuel may be effected as compared with burning natural gas under a steam boiler with only 10 per cent efficiency. Other features are the development of the mud-laden process for stopping the flow of gas and conserving the supply underground until needed, and the development of the process for extracting gasoline from casing-head gas.

Some of the losses due to waste of gas may be grouped as follows: (1) The unexpected encountering of large volumes of gas under great pressure and attendant loss of control, as at White Point, San Patricio County, Tex.; and in lack of skill or indifference of the operator in permitting wells, which could be capped at a little additional cost, to run wild.

(2) Underground leakage from a gas sand to another permeable stratum through improperly cased wells.

(3) Where the quantity of gas in individual oil wells is not great, though great in the aggregate, the gas is often conveyed to a safe distance from the well and burned. Increased recognition of the

gasoline extractable from such natural gas has caused operators to greatly reduce this form of waste.

(4) Waste in consumption includes the use of natural gas under power-plant boilers where the same power could be generated in an internal combustion engine by using about one-tenth the volume of gas; in burning, in open air, residual gas after gasoline extraction, and in burning natural gas for the manufacture of carbon black, the latter form of consumption being an unnecessary use rather than a waste, as the carbon-black industry has grown up only in localities where a large gas production is not tributary to markets where the gas might be better utilized. The remedy for most wastes lies in conserving the natural gas underground until it can be utilized to best advantage.

In the past there has been enormous waste and the total waste is still discreditable to the Nation. In the Appalachian field the loss of gas from oil wells, flambeaux, from leaking pipe lines, and many other methods of waste was not less than 1,000,000,000 cubic feet daily and probably much more. The heating value of 1,000,000,000 cubic feet of natural gas is roughly equivalent to that of 1,000,000 bushels of coal.

In one State not less than 250,000,000 cubic feet of gas has been wasted daily, and possibly more than double that quantity, 80 per cent of which might have been easily and cheaply preventable. In the Caddo (La.) natural-gas field at least 400,000,000 cubic feet of gas was wasted daily, practically all the waste being preventable. Two wells in this field having an estimated volume of 20,000,000 or 30,000,000 cubic feet per day blew out and burned for one or two years.

All flowing oil wells are also gas wells of more or less volume, not uncommonly an oil well producing 50 to 100 barrels of oil produces 5,000,000 to 10,000,000 cubic feet of gas, the latter having fuel value at a very low figure per 1,000 feet of many times the value of the oil. The oil producer, if in need of power, has used what gas he required for power purposes and turned the balance loose, looking on any surplus gas as a nuisance to be gotten rid of, claiming the right to do as he pleased with his own product.

Through the investigations of the United States Geological Survey and the efforts of the Bureau of Mines to interest drillers and well owners in methods of lessening waste, conditions in some fields are improving, and State officials are having better success in bringing about the enactment and enforcement of practicable and adequate legislation to conserve natural gas. But there is need of much more investigation to ascertain the conditions that cause waste in different fields and to devise methods by which waste may be minimized or prevented.

STRUCTURAL MATERIALS.

CLAY AND CLAY PRODUCTS.

Clay that is suitable and available for the manufacture of clay products is one of the most widely distributed minerals, and there are clay-working plants in every State and Territory. In 1913 the clay produced in the United States was 2,648,000 tons, valued at $4,180,000. These figures refer only to clay not manufactured by the miner but sold as clay, which is only a small part of the total production. In the same year the imports, chiefly higher grade clay, were 338,000 tons, valued at $2,000,000. The United States is practically independent of the rest of the world as regards the coarser clay wares, and its production of these is greater than its consumption.

The output of clay products in the United States in 1913 was valued at $181,000,000, compared with $42,000,000 in 1880, an increase of over 300 per cent. Large as this increase is, it is not so great as was the improvement in the character and quality of the wares produced.

The higher grades of clay are used for making the better classes of pottery, tile, and refractory products, and for filling paper, and the developed deposits of white-burning clays in the United States are along the Atlantic seaboard from New England to Florida. Besides these deposits there are clay beds in Alabama, Arkansas, Missouri, Texas, Utah, and other Western States that can be drawn on for large supplies of white-burning clay when commercial conditions warrant. There seems to be no reason why, with proper preparation and technical control, they can not entirely supplant the imported clays.

Ball clay, also used in the manufacture of high-grade pottery, occurs in Florida, Kentucky, Missouri, New Jersey, and Tennessee in sufficient quantity and of suitable quality to make this country entirely independent of foreign supplies.

The greatest demand since the beginning of the European war has been for a high-grade fire clay to replace that imported from Germany for use in the manufacture of glasshouse supplies. Such clay is found in the United States and is now being used. Fire clays occur in 28 States, the principal production coming from Pennsylvania, New Jersey, Ohio, Missouri, and Illinois. One obstacle to the use of clays otherwise suited to the manufacture of high-grade wares is the presence of iron. A process for eliminating the excess of iron has been devised and successfully used and may make some undeveloped clays available for higher uses.

Exports of clay are of minor importance, being valued in 1913 at $300,000, about one-fifth of which represents fire clay. Over half

of the fire clay exported went to Canada. Of the unclassified clay exported in 1913 Germany was the largest consumer, followed by Canada, Belgium, and England in the order named.

Investigations are being conducted regarding domestic clays to replace clays formerly imported from Europe. There should be a more comprehensive study of the clays of the United States, with especial reference to the uses for which they are adapted, in order that the public may have more exact information regarding supplies of clay for definite purposes. Interest centers especially around the kaolin or china clay industry. Investigations by the Bureau of Mines have shown the wastes at some kaolin mines and the ways by which they can be lessened or prevented.

It is gratifying to know that practically every variety of clay products is produced in the United States and that the absolute independence of the country as regards the great structural, engineering, and refractory wares industries is assured, the output of these wares being greater than the consumption. The United States is almost independent as regards pottery, over four-fifths of its consumption being homemade. So one can safely say that judging by the ever-increasing proportion of domestic wares used, and the constant improvement in these wares, that the United States will before long be as independent of foreign potters as it is already in many other industries that were only a few years ago entirely dependent on the European market.

The great achievements in the clay-working industries in the last half century were made possible by the use of American-made machinery, which has a world-wide reputation for superiority. The first successful brick-making machine was invented by an American about the middle of the last century. It was small and inefficient compared with the mammoth machines of to-day which have a capacity of 100,000 brick per day of 10 hours. Improved American machinery has also been an important factor in the development of the pottery industry, among the latest achievements being a machine for making oval-shaped pieces of all kinds. Wasteful American methods of manufacture have been prevalent, but these are being overcome in modern plants by improved kilns and more scientific methods in burning.

The establishment in this country of ceramic schools, the advertising campaigns carried on by manufacturers of clay products, and the improvement in the quality of wares, has had and will continue to have a marked influence on the development of the clay-working industries. The outlook for these industries is bright, and it seems almost certain that the opportunity presented by existing conditions will result in the higher grades of American wares making a name for themselves, capturing the home market and gaining such a foot