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3. C-petroleum-naphtha (petroleum-benzine, safety oil, Danforth oil). Boiling point: 176° to 2120 F. Density: 0.667 to 0.707. Use: For the removal of stains, for the adulteration of petroleum, in large quantities for firing purposes, and as an illuminant in lamps of special construction.

4. B-petroleum-naphtha (ligroine). Boiling point: 176° to 248° F. Density: 0.707 to 0.722. Use: For burning in lamps of special construction, in the preparation of illuminating gas, in painting in place of oil of turpentine, it drying more rapidly than the latter.

5. A-petroleum-naphtha (Putzoel, polishing oil). Boiling point: 258° to 3020 F. Density: 0.722 to 0.737. Use: For cleaning parts of machinery, as a substitute for oil of turpentine, for thinning oil-paints, varnishes, etc.

The fractions mentioned under 3, 4, and 5 are sometimes comprised under the term petroleum-spirit. Density: 0.667 to

0.737. Boiling point: 176° F. to 302° F.

The division given above is a modification of that originally complied by R. Wagner, in order to make it more generally acceptable by taking into consideration the division into gasolene, C-, B- andA-naphthas customary in Pennsylvania. Besides the boiling points are at nearly equal graduations.

II. Illuminating oil (petroleum, kerosene). Boiling point: 302° to 572° F. Density: 0.753 to 0.864. To make it a commercial article, it is treated with sulphuric acid and an excess of the latter neutralized with soda. Its use is well known. III. Residuum (tar). Boiling point: 572° F. or above: Density varying, over 0.83. By a further increase in the temperature are obtained:

1. Heavy oils, which pass over with continued distillation, and, according to their density, are divided into.

a. Lubricating oil. Density: 0.7446 to 0.8588.

b. Paraffin oil. Density: 0.8588 to 0.959.

Paraffin is separated in scales from the heavy oils, especially from the last named. It is used for candles, as an insulating material, etc. The use of lubricating oil is indicated by the word.

2. Coke. This remains as a solid body in the still, and is used for firing.

In consideration of its technical importance, the salve-like product known as cosmoline, vaseline, petrolina, etc., which may be separated from the residuum of some oils, may here be mentioned. R. Wagner' declared it a mixture of paraffins with the fluid member heptane, while Moss considered it a mixture of readily fusible paraffins. Miller agrees with Wagner, he having shown it to be a mixture of paraffin with volatile oils. Engler and M. Bōhm* arrive at the same conclusion in regard to the Galician and American products.

Cosmoline serves as a vehicle for salves, for the preparation of pomades, rouges, etc., as well as for a protection against rust and oxidation for all metals and their alloys, for oiling machines, etc.

The relative proportions of the separate fractions vary ac cording to the different localities, even oil of the same well yielding different results, according to whether fresh oil or oil stored for some time has been used for analysis. The result of the latter is also influenced by the manner in which it is executed, and especially by heating.

It remains to be mentioned that the density of distillates of the same temperature from different crude oils may vary; those, for instance, of Baku oil being throughout specifically heavier than those from Pennsylvania oil, because in the one there is a preponderance of hydrocarbons of entirely different series from the other. Generally speaking, the Pennsylvania petroleum is the generic type, the Baku oil forming an exception.

According to S. F. Peckham, the average percentage of commercial products obtained from crude petroleum (specific gravity = 0.800) from Pennsylvania, New York, Ohio and West Virginia is a follows:

1 Dingl. pol. Jour., 233, 515.

2 Jahrb. f. reine Chemie, 1876, 471. 3 Deutsch. Ind. Ztg., 1875, 18. Dingl. pol. Jour., 262, 468. 5 Report on Petroleum, p. 165.

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To avoid confusion, it may here be mentioned that in working on a large scale the yield of illuminating oil from Pennsylvania crude oil amounts to about 75 per cent.

To Dr. Kraemer we are indebted for an examination of the petroleum of most regions, whereby the fractions above 482° F. passed over under a decreased air-pressure. The results of the analyses were as follows:

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In the lighter oils, like those from Tegernsee and Pennsylvania, considerable quantities of dissolved non-condensed gases of the methane series were established.

In more recent times, Engler also examined various varieties. of oil; a few of his analyses are given below:

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A. Nawratil has rendered great service in making us acquainted with the crude oils of West Galicia, he having determined, commencing with 104° F., the fractions of 18 different samples comprising most localities of this region. From this valuable series of investigations, the two crude oils differing most in specific gravity and the limits of value found will here be given:

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Hence the differences in the specific gravities of the fractions at the same temperature of the two most extreme varieties of Galician oil vary as much as the fractions of Baku oil compared with those of Pennsylvania oil. These comparisons lead to the following proposition, which is valid, however, in a general way only: The denser the crude oil, the denser its fractions.

Calorific Value of Petroleum.

Dr. H. Gintl gives for various districts the calorific values (the absolute heating effects) of petroleum. Since the quantitative composition of the oils, even of one and the same region, varies, these calorific values give only a general idea, which is, however, of some importance, as the values quite agree. For a better comparison the combustion-heat of methane and ethylene, which has been determined by the calorimetric method, is added:

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The calorific value of crude oils is, therefore, nearly three times as large as that of dry wood substance, about four times as large as that of air-dry pine, or nearly 1.5 times as large as that of excellent Moravian coal (with 8.28 per cent. ash). Massive coal being, however, about 1.5 times denser than crude oil, both fuels occupy about the same volume, but in consequence of comminution, coal requires more space than crude oil, which might be of importance as regards steamships, etc.

The steamers running on the Caspian Sea and the Volga, as well as the refineries of Baku and the railroad from Baku to Batoum, have for some time used for firing the very cheap. residuum remaining in the distillation of crude oil. Its calorific value is given as nearly twice that of good coal.

Gases accompanying Petroleum.

Gases which burn when ignited always occur together with petroleum, and hence, special precautions against the dangers of explosion and fire have to be taken in the immediate neigh

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