also made at an early date. Professor Benjamin Silliman, Sr., in 1833, wrote: "I have frequently distilled it in a glass retort, and the naphtha which collects in the receiver is of a light straw color and much lighter and more inflammable than petroleum. On the first distillation a little water rests in the receiver at the bottom of the naphtha, from which it is easily decanted, and a second distillation prepares it perfectly for preserving potassium and sodium, the object which has led me to distill it."

In 1862, Isaiah Warren and his father, being in the lard oil

and candle trade in Wheeling, West Virginia, commenced the distillation of West Virginia petroleum in three 15-barrel stills. The stills in general use at this time were made in three parts, bolted or riveted together, and consisted of a cylindrical cast iron body, to which were attached a boiler plate bottom, and a cast iron dome and goose neck. They held about 25 barrels, were heated from the bottom and bricked up on the sides, and were sometimes protected from the direct action of the fire by fire-brick. These stills were charged with crude oil, the charge run off, the still cooled, and the coke cut out, often with a cold chisel. When four-fifths of the oil had been run off, the remainder was, when cold, as thick as pitch. At this time some of the refiners introduced steam, which mechanically expanded

'Am. Jour. Science and Arts, (1) xxiii, 101.

and carried over the last volatile portions of the charge, leaving a compact coke, while others distilled to coke without steam. The use of superheated steam in the distillation of natural petroleums was, in 1860, introduced in this poemy by Mr. Wilson, a manufacturer of stearic acid. Steam moder moderate pressure was also frequently used throughout the entire distillation, both above the charge and injected through it In the latter case it becomes superheated, as the boiling point of the oils rises above that of water. It was, however, considered preferable with the dense paraffin oils to superheat the steam before it entered the oil. Sometimes, after the charge in the retort was partly run off, it was the practice to allow a stream of fresh oil to enter the still about as fast as the vapors were condensed. In this way about twice the ordinary charge could be distilled and the residue of the whole run down to coke. The light naphthas were first taken off and were used for fuel. The distillate was then run to illuminating oil until the specific gravity reached 36 Bé. = 0.843, and the remaining charge run down till the distillate became of a greenish color. turers redistilled the illuminating oil and refined it.

Crude Oil Stills.

Some manufac

Experience has narrowed the style of stills down to two, their competing merits being a source of much controversy among practical men. These are known as the cheese-box and cylinder stills.

The cheese-box still is shown in Figs. 76 and 77. It is 30 feet in diameter and 10 feet in height. It is supported by circular brickwork in which are built 17 fire places, all communicating with a central flue. The bottom has a double curvature. The discharge pipe of the still enters on the side; on the inside is a swing-joint suspended by a chain wound around a shaft which is operated from the outside of the still. From

Jour. Franklin Institute, 338, 1860.

2S. F. Peckham. Report on Petroleum.

the top of this still project three pipes, each connecting with a drum stretching across the whole diameter of the still. From this drum proceed 40 3-inch pipes leading into the condensing tanks. In some stills, at the point where the vapors pass into the drums, a perforated steam-pipe is placed. This is employed only during the "cracking" process, and is thought to greatly improve the quality of the oils, both in respect to color and gravity, although the arrangement is not to be found in many refineries.

The still is provided with man-holes, for the double purpose of allowing the workmen to enter and clean it, and occasionally to inspect its condition. One is placed upon the top of the still, a second near the bottom plate, which allows the refuse coke to be conveniently thrown out. The covers of these manholes are generally fastened in their places by means of screwbolts and nuts. Many of the most expert and careful refiners use pyrometers in their stills; they are often of great assistance both to the fireman and the distiller. Large size stills are built of the very best quality of boiler-iron, of or inch thickness, securely caulked. The bottoms are of steel of the same thickness. The increased expense in the use of steel for the bottoms is more than compensated for by their enhanced durability and safety.

The still is provided with steam-pipes both closed and perforated. The steam issuing in jets from the perforated pipe has been found to facilitate distillation by carrying over mechanically the oil vapors.

Cylinder stills. Diagrams of a cylinder still much used in this country are represented in Figs. 78 and 79. The stills are frequently set in banks of two or more, there being considerable economy in thus placing them. The still is a simple horizontal steel or wrought iron cylinder 121⁄2 feet or a little more in diameter and thirty feet or a little more in length.

A cylinder of this size holds about 600 barrels of crude oil, and is the size generally found at the seaboard works.

A circular dome about 5 feet in diameter and 4 or 5 feet

high is set on the top of the still in the centre as an outlet for the rising vapors, a wrought-iron gooseneck 15 inches in

FIG. 78.

78

Ground Lerel.

LONGITUDINAL VERTICAL SECTION OF CYLINDER-STILL.

diameter conducting them to the condensing apparatus to be described later on. The still rests on brick-work which sur

rounds the lower half, the upper half being left exposed to