material is so hard that it requires to be broken, and contains about 20 per cent bitumen.

The transportation problem has been solved by first crushing the sand by specially devised machinery, and conveying it to a large vat, where it is treated with a form of gasolene specially prepared for the purpose from crude petroleum. The gasolene dissolves the bitumen and, carrying it in solution, overflows the vat, runs down a pipe-line 27 miles to the shore, where it is distilled off and the asphalt reduced to the desired penetration and put up in barrels. The gasolene is then pumped back to the mine with very little loss and used again. The sand after the bitumen has been extracted is raised by means of a screw, being sprayed all the time with gasolene to make sure that it is entirely free from bitumen, and deposited outside as waste.

The entire apparatus and process are protected by letters patent. The system has not been in operation a sufficient length of time to demonstrate what will be its ultimate economy and capacity, but long enough to insure its complete success.

oil.

In several places asphalt is produced from the crude petroleum

The ordinary method is to pump the oil and accompanying water from the wells into tanks where it is heated by steam-coils to a temperature of about 220° F. This lessens the weight of the oil, which rises, allowing the greater portion of the water to be drawn off from below. The remaining moisture is then evaporated by increasing the heat.

The oil is then conducted to the refining-kettles, where it is kept heated with open lid till it will stand a temperature of 300° F. without foaming. The lid is then screwed down and the temperature gradually increased to 550° F. The vapors given off are withdrawn by suction. The process is continued, the heat being increased towards the end to 700° F. till a sample of the material poured into water forms a hard black substance that bends slightly and breaks under moderate pressure. The crude oil from the Sunset Oil Works in Kern County yields about 50 per cent distillates of a specific gravity of 20° Beaumé.

The average of 100 barrels of mixed crude oils from Ventura County was as follows:

In the western part of Kern County there are important deposits of asphalt. In some localities it is found on the surface, and in others as veins of asphalt in the mountain rock. The surface material was used at first with good results. In appearance it is very similar to that found near Santa Barbara. It lies in beds of from 6 inches to several feet in thickness, the purer material being on the top. In some places the deposit rests upon clean sand, and in others upon sand that is saturated with oil.

The vein of asphalt is found in a dike and consequently runs parallel with the mountain range, is covered with a soft brown rock which can be traced for several miles, indicating the existence of asphalt to that extent. The vein is from 3 to 15 feet in width, and is easily worked from shafts or by drifting.

The Southern Pacific Railroad has built a spur track from Bakersfield to this deposit, a distance of about 50 miles. The terminal has been given the name Asphalto.

The crude material being analyzed shows:

The asphalt is refined in Asphalto in much the same manner as that already described, except that a little heavy oil is added to

assist in melting. Dry asphalt and the refuse material are used for fuel. When it is to be refined to 90 per cent bitumen, the entire operation of charging, boiling, and emptying requires about twenty-four hours. The process is continued till the asphalt becomes hard enough to retain its form at ordinary temperatures. The material is then drawn off into boxes or barrels for shipment. It is not ready for use in pavements until it has been fluxed with maltha, when it is called paving cement.

When, however, the asphalt is sold for paving purposes, this fluxing is generally done at the plant, as the maltha, on account of its consistency, is not conveniently handled. A small quantity, however, is generally kept at the plant where the paving mixture is made, if by chance the cement should require some modification.

Besides the asphalt, maltha is found in Asphalto.

In Santa Cruz, San Luis Obispo, and Monterey counties asphalt occurs of an entirely different nature. It is called bituminous rock, and consists of a natural mixture of bituminous oil and sand. It is found in large quantities with much variation in amount of contained bitumen. The sand is of all grades of fineness, sometimes mixed with clay and so hard as to be almost a sandstone. It makes a good pavement in its natural state when properly treated. The early asphalt pavements of California were laid with this material, and when the variation in amount of bitumen, as well as the ignorance of the industry at that time, is considered, the wonder is that so many good results were obtained, rather than that there were some failures. The material was simply softened by heating on the street sufficiently to allow it to be smoothly and evenly rolled when it was laid on the slightly prepared surface. Doubtless a lack of proper foundation often caused a failure in an otherwise fairly good pavement.

The larger portions of the present California asphalt pavements were laid with this material, and the experience with these has unjustly given a bad name to California asphalt as a whole.

The first street east of the Rocky Mountains paved with material from California was in South Omaha, Neb., in 1891.

European Asphalt.

The asphalts from Europe from which pavements are made are found in France, Germany, Switzerland, and in the island of Sicily. (In a pamphlet issued by a Greek professor in 1721 he says he discovered ten years before a mine of asphalt in the Val de Travers Canton, Neuchatel, Switzerland, similar to that existing in the valley of Siddim near Babylon.) Although somewhat widely separated, these asphalts are practically of the same nature, differing somewhat in amount of bitumen contained.

They are all bituminous limestones.

They occur in strata

of varying depths, from 6 to 23 feet in thickness, separated by impermeable beds of stone.

The theory of the formation is that at an early geological period bitumen must have been vaporized by extreme heat, that certain strata of the limestone were softer than others, and that this bituminous vapor was forced through and along the soft strata, as subterranean water follows any previous stratum confined by beds of clay or rock, and that fissures in the overlying

strata have allowed the vapor to pass to other strata above. In passing, the vapor impregnated the particles of the soft limestone to a greater or less extent, and the geological changes in the subsequent years produced the rock asphalt as it exists to-day. Fig. 1 illustrates this formation.

Its composition is almost entirely carbonate of lime and bitumen. To make a good pavement, the rock should contain from 9 to 11 per cent bitumen. While this amount may not be found in just the required proportions in nature, it can be obtained by mixing a rock that is rich in bitumen with one containing less, so that the compound shall contain the percentage desired.

Published analyses of the same mine differ considerably, perhaps on account of the solvents or methods used by the examining chemists, or possibly from an actual variation in samples from the same deposit.

The following are some analyses collected from various authorities, the bitumen and calcium carbonate only being considered:

In the State of Vera Cruz, Mexico, there are fifteen separate deposits of asphalt; that is, there are fifteen places where asphalt is found at the surface.