sian oils cooled to the same temperature separate no paraffine, and only acquire gradually the consistency first of grease, next of butter, and finally of tallow. If this test leaves the question of derivation in doubt, it is advisable to execute a fractional distillation and to cool off the fractions 25° C. (77° F.) at a time, whereby American oils will be observed to separate paraffine. Galician oil and oil from Pechelbronn flowing wells, as well as oils from Scottish shale and Saxony coal, behave like American oils, while Oelheim and Pechelbronn pit oils correspond more with Caucasian oils. 2. The specific gravity of fractions boiling at the same temperature is higher with Caucasian than with American oils. 3. The refraction of light may also be used for distinguishing heavy mineral oils of different origin, as shown by the appended indices of refraction of separate fractions determined by Engler with an Abbe refractometer.

The method of distinguishing mineral oils by the absorption of iodine and their behavior towards nitric acid has proven not reliable.

CHAPTER XII.

USES AND PROPERTIES OF PETROLEUM.

Crude Oil.

IN localities where crude oil abounds and where coal and wood are scarce, it is used for fuel; otherwise it occupies but a secondary position in this respect, only such oil as cannot be employed for the production of illuminating and lubricating oils being utilized in this manner. For metallurgical purposes

it is advantageously used in some localities. A large number of processes have been invented and patented for employing crude oil in the manufacture of iron, amongst others the "Whipple and Dickerson," or "Ambler process' and the "Eames process." Of these the Eames process seems to have been most successful. It has been put in practical operation both in Titusville, Pa., and in Jersey City, opposite New York, and has been made the subject of a most careful and exhaustive examination by Professor Henry Wurtz and Professor R. H. Thurston.' The apparatus consists of an ordinary reheating furnace with "generator" and steam-boiler attached. The generator consists of a cast-iron vessel with alternate projecting shelves attached to its sides. The oil on entering the apparatus trickles over the shelves, from which it is swept by a jet of superheated steam. The amount of oil required for this furnace, which is capable of working charges of 3000 pounds, and making steam for the rollers besides, is a maximum of 30 gallons, or 200 pounds per hour. The trickling oil is met by a jet of steam moving in the opposite direction, and is at once completely vaporized under a pressure of about 10 pounds, and is carried into an adjoining furnace.

1S. F. Peckham. Report on Petroleum.

Air subsequently mingles with the steam and oil vapor previously described, and passes the furnace bridge, and burns within the furnace, and then runs beneath the boilers to the flue and stack.

The old bridge is completely bricked up, excepting a space which extends across the furnace closed only by fire-bricks placed on one end, and it is found that if this "combustion chamber" has a horizontal thickness of more than eighteen inches, the fire-bricks are fused.

Crude oil has been used as a remedial agent from the earliest times, it being mentioned by both Pliny and Vitruvius. François Arioste discovered, in 1416, on Mount Libio, in the duchy of Modena, Italy, a rock oil, with which he cured men and animals afflicted with itch. In America the Seneca Indians used crude oil as an external application, and in fact in olden times the therapeutical effect of crude oil was considered almost miraculous.

Throughout the oil regions of Pennsylvania petroleum bears a high reputation as an internal remedy in cases of consumption, and there is no doubt of its efficiency as an external application for muscular rheumatism.

Petroleum products.

Of much greater importance is the utilization of a series of products obtained from crude oil by distillation. From the primitive beginning of the utilization of crude oil as such, an industry has been gradually developed, partially by an increased demand and partially by competition, which insures the use and utilization of all the constituents of the crude oil. Although this industry is at present highly developed, it cannot be said that all products are utilized to the best advantage. Thus the intermediate oils between the actual illuminating and lubricating oils are not profitably disposed of, they having to be used either for heating or mixing purposes, and frequently also for the production of gas. The products of petroleum occurring in commerce are known by various names, accord

ing to their specifs grantes. A cassification of these products has been given on p. 74 but for the sake of convenience may here be repeated.

Besides the above-named products, there are found in commerce a considerable number of light, medium and heavy oils with special names, which will be mentioned further on.

Volatile oils (light essences).

The properties and uses of the volatile constituents of crude oil boiling below 302° F. have already been described on p. 74. They are at present employed to a limited extent only, but with the more general introduction of petroleum engines their use will be largely extended. According to the patented process of A. F. Bang and M. C. Ruffin it is claimed that petro

leum-ether may be used for rectifying crude spirits on account of its property of dissolving fusel oil and aldehyde and being itself insoluble in alcohol.

The properties of gasoline have been given on p. 74. It is one of the lightest products of the distillation of petroleum and it has not yet been applied to any important industrial use save the manufacture of illuminating and fuel gas. The quantity produced is increasing yearly, so that the cost of this product is decreasing and it is therefore very extensively used throughout the United States as well as Europe for isolated lighting of small towns, railroad stations, hotels, factories and private residences.

The subject of artificial light has become of great importance to all persons, especially to those out of reach of city gas. It may therefore be of interest to enter into the details of producing light from gasoline and to give a description of the most approved machine for the purpose.

The illuminating apparatuses mostly used are based upon the simple principle of allowing a current of atmospheric air to pass over, or come in contact with, a body of gasolene in socalled carburetters. It is a well known fact that the process of evaporation produces refrigeration, and as the process of making gasoline gas consists simply in the evaporation of gasoline by its coming in contact with the above mentioned current of air, it follows that there is a sensible loss of heat while the gas is burning, and unless this loss is restored, there would be, in the course of a few hours, a marked diminution in the quality of the light.

A typical machine for the manufacture of this quality of gas is the Improved Royal Gas Machine, manufactured by the Pennsylvania Globe Gas Light Company, of Philadelphia, who are the owners of the patents. Thousands of this machine are in daily use throughout the United States, and we are credibly informed that not a fire has occurred from one of them, nor a life been lost. The machine has been accepted and approved by the National Board of Underwriters, and in using it there is no increase in insurance rates.