The drum is provided with an opening for filling and emptying it, which is made tight by rubber. The drum is slowly revolved, at most two turns per minute. In the interior of the drum lies a massive cast-iron roller, 434 inches in diameter, of the same length as the drum. In 12 hours an apparatus of this size will pulverize in the finest manner about 55 lbs. of boneblack. The quantity of bone-black used does not exceed 3 per cent. by weight, and the paraffine retained by it amounts to about the same weight. This mixture of bone-black and paraffine is first collected in a double-walled kettle heated by waste steam, whereby the greater portion of the paraffine is separated

as a clear fluid, which is scooped up with shallow ladles and placed directly upon the paper filter. The mixture, which is now thin, is brought into a large iron kettle in which it is vigorously boiled with at least six to eight times the quantity of water and the occasional use of a jet of steam. By the cooling of the mass nearly all the paraffine separates upon the surface of the water as a solid layer of a gray color, which is lifted off, melted and filtered through paper, together with the other product. A repeated boiling of the mixture of bone-black and paraffine is seldom necessary; the paraffine obtained in such second operation scarcely ever covers the cost of the fuel used. However, the bone-black retains a small percentage of paraffine so tenaciously that it has to be driven off by heating the boneblack if the latter is to be again used as a decolorizer, or even if

it is to be employed in the preparation of fertilizers-superphosphate.

The dried bone-black is heated in a horizontal cast-iron retort about 71⁄2 feet long and 311⁄2 inches in diameter with a nearly elliptic cross section, and provided with a suitable receiver for the condensation of the paraffine vapors. However, even with the lowest possible melting temperature, these vapors never consist of undecomposed paraffine but of paraffine with a lower melting point and of oils as products of decomposition. The bone-black in shallow wrought iron boxes each about 3 feet long and 1.47 inches wide is brought into the retort and after the evaporation of all the paraffine, is allowed to partially cool off for four to six hours. The boxes are then taken from the retort, covered immediately with suitable lids, which are luted with clay, and allowed to become cold.

The paraffine in the filtering box is occasionally drawn off into moulds or boxes of various sizes and allowed to cool slowly.

Paraffine is a colorless, waxy, or foliated crystalline, alabaster-like, semi-transparent mass without odor or taste, and resembles spermaceti. It is slippery but not greasy to the touch, and is softened by the warmth of the hand so that it can be kneaded.

American paraffine occurs in commerce chiefly in three qualities A, B, C-paraffine, melting at 135°, 128° and 125° F. Paraffines from Pennsylvania and Rangoon petroleum have an average specific gravity of 0.869 to 0.873. Hot absolute alcohol dissolves about 3 per cent. of paraffine; it is readily soluble in ether, bisulphide of carbon, chloroform, benzine and volatile oils. From ether and photogene it separates in the form of a jelly, and from the other fluids as a crystalline mass. By heating paraffine for some time in the air to 302° F., it assumes a brown color by the absorption of oxygen.

The oil obtained after the crystallization of the paraffine from the heavy petroleum by pressure and decolorization is known as paraffine oil or liquid paraffine and is officinal. It is a clear oily

liquid, having a specific gravity of not less than 0.840 and boiling not below 680° F. It should be free from colored, fluorescing and odorous compounds. When heated for a day with sulphuric acid by means of a water bath, it should not become dark colored, and the sulphuric acid should become only slightly brownish. Metallic sodium placed in the oil should retain its metallic lustre; if it becomes tarnished it is an indication of the presence of combinations of sulphur or oxygen. Alcohol boiled with officinal liquid paraffine should not have an acid reaction.

Fossil paraffine or ozocerite occurs generally in fissures and cavities in the neighborhood of coal fields and deposits of rock salt, or under sandstone pervaded with bitumen. The principal deposits are in

AFRICA: Egypt.

AMERICA: Texas, Arizona, Utah, Canada.

ASIA: Caucasus: Caspian Sea near Darbent. Baku; the islands of Swjatoi, Ostrow and Tachalkäu; Ekaterinodon; Station Kalachinsky. Persia: Truchmenia.

EUROPE: England: Newcastle. Roumania: near Plajesti in Wallachia, and Stanik, on the mountain Zietriska in Moldavia. Austria: Lower Austria near Gaming; in East Galicia near Boryslaw, Drohobycz, Dzwiniarz, Starunia, and near Solotwina, besides on the northern slope of the Carpathians. Germany: Wettin on the Saale; East Friesland.

The deposit in East Galicia is the most interesting. The ozocerite occurs there in a saliferous clay belonging to the miocene of the more recent tertiary period, and forming a narrow, almost continuous, strip on the northern edge of the Carpathians, which runs from Silesia into Galicia and Bukowina, and from there can be traced into Moldavia and Wallachia. This miocene group of saliferous clay consists chiefly of bluish and variegated clays, sands and sandstone, with numerous occurrences of gypsum, rock salt and salt springs. In Boryslaw the strata of saliferous clay form a perceptible saddle as they sink on the south below the so-called menilite shales, which are

very bituminous and foliated, and form here the most northern of the Carpathians. The principal deposit of ozocerite converges with the axis of this saddle.

The ozocerite as obtained from the mines in Galicia is not a commercial article, being contaminated by adhering earthy and stony parts, and varying very much in appearance and consistency. The crude product is therefore subjected to several processes. The large pieces are picked out, while the small ones are recovered by washing with water, the particles of ozocerite floating on the surface and the specifically heavier contaminations sinking to the bottom. The two varieties of ozocerite called respectively "Claub- und Wasch-Wachs" (handpicked and wash ozocerite) are then melted with a little water in large open boilers over an open fire, so arranged that only the sides of the boilers are heated. The earthy portion called "Schmelzlep (smelted clay) forms a deposit on the bottom of the boiler, while the melted pure ozocerite is ladled into moulds of a capacity of 110 to 220 lbs. The "Schmelzlep❞ retains 6 to 12 per cent. of ozocerite so tenaciously that it can be obtained only by extraction. The moulds, generally of iron, have the shape of a truncated cone, the inside being painted with milk of lime to prevent the adhering of the block of ozocerite. The ozocerite thus obtained forms the commercial article; its melting point lies between 133° and 158° F. Its price is governed by the melting point, and also to some extent by the color, which should be quite pale, but varies from pale green to brown. A good commercial article should be plastic when kneaded between the fingers, and plainly show every pressure; when cut with a knife the surface should not show a smooth, cheese-like appearance, but some of the ozocerite should adhere to the knife-blade. Notwithstanding these general tests by which a good commercial article may be recognized, there still remains to be decided the question whether the ozocerite is best adapted for the manufacture of paraffine or ceresin; for the former the article with the lowest congealing point is the best.

The structure and melting point of ozocerite depend, according to E. Sauerlandt, on its principal constituents, paraffine and waxy resin," because with the distillation of ozocerite conducted with superheated steam and the avoidance of decomposition, he distinguishes the following constituents:

1. Liquid hydrocarbons with a low boiling point.

2. Paraffines, chiefly with a melting point of from 140° to 158° F.

3. Resinous bodies called "waxy resins."

4. Bituminous resins.

5. Coke.

Paraffine and waxy resins are solid bodies, the latter, however, having a higher melting point than the former.

Ozocerite was first worked on a large scale in Galicia, in about 1860, and up to about 1875, was extensively used for the manufacture of paraffine. Distillation was at first carried on only over an open fire. To prevent too strong heating and the vapors of paraffine from rising too high, a still with quite a flat helmet, Fig. 117, similar to a tar-still, was used. The product

of distillation was about 5 per cent. of benzine, 15 to 20 per cent. of illuminating oil, 15 per cent. of "blue oil," and 50 per cent, of paraffine mass or paraffine butter.

The paraffine mass obtained by distillation over any open fire has a melting point of from 113° to 122° F., and is treated