trodes. Being free from silica and low in sulphur, it makes an ideal reducer for such metals as aluminum, magnesium, etc., in the electrolytic reduction processes.

Of recent years the Mexican asphalt base crudes have been playing an ever increasingly important role. light top fractions are taken off in a similar manner to the paraffine crude. The topped residue may be distilled up to 700 deg. F. and sold for fuel oil. If flux oil is desired, the residue is blown with air to dehydrogenate and polymerize the oil hydrocarbons into asphalt. If the air is applied for a sufficient period, the highest grades of asphalt may be produced of any desired melting point or penetration.

THE BURTON PROCESS

Many unsuccessful destructive distillation inventions have left their only trace in the files of the Patent Office, thus giving evidence that they grew to be no bigger than an original idea. James Young, Benton, and Dewar & Redwood, all have their supporters as being the real inventors of the destructive distillation of oil, though it is perfectly well known that they could not work the process commercially on account of their lack of equipment facilities. While the original Burton process was eventually operated successfully, it fell to the part of Clark, Hopkins and Humphreys to furnish several much needed improvements. A view of the battery of old horizontal direct-heated stills is given.

HIGH PRESSURE VERTICAL BURTON PROCESS STILLS

Coke deposit formation, with resulting overheating of the still in spots, made it necessary to drop the pressure of the vapors lower than desirable. Clark evolved the vertical boiler tube heater in conjunction with the tall vertical still towers. Boiler tube cleaners are used to cut out the coke layers at the beginning of each run, and in this way a pressure of 100 lb. can readily be obtained, with a corresponding high yield of cracked gasoline. The gases obtained are stored in regular gas holders and used for fuel within the works.

come well inoculated with bacteria. The latter act on the embedding skin cells around the hair roots in such manner that when the hide is immersed in fresh lime solution for several days, ammonia is formed, the hides float up and the hair roots become disengaged. After passing the hides through rollers mounted with spiral scrapers to remove all the hair, they are delimed by soaking several days in oropon solution (ammonium chloride and dry hog pancreas). The soluble salts are then washed out, leaving a very porous skin structure saturated with neutral wash water. The hair obtained is graded, the different qualities being used in weaving rugs and carpets, making harness pads and reinforcing plaster.

The two-bath chrome process used for tanning the skins consists of soaking the skins for several hours in a solution of sodium bichromate and muriatic acid in the proportion of 6 and 3 lb. each per hundred of skins. The reaction is:

Na,Cr,O,+ 2HCl = 2NaCl + 2CrO, + H2O After the skins have become well yellowed with chromic oxide all the way through, they are greened by soaking in a reducing solution of hypo. This reaction is in three stages:

2CrO,+6HCl + 3Na,S,O, = 3Na,SO, +3S+ Cr,Cl + 3H,0

2

Cr,Cl, Na,S,0, + H,O= Cr, (OH),Cl, + SO2 + S + 2NaCl

The basic chloride is then converted to Cr,(OH), by washing in sodium bicarbonate.

The skins are now dyed, fat-liquored, dressed and glazed, finally being measured in an ingenious segment roller machine, inspected, graded and shipped.

The coated leather department was not visited, though fine specimens of this modern type of leather were exhibited at the office of the company.

The Electric Storage Battery Co.

The plant located at Nineteenth and Allegheny Sts., Philadelphia, is said to be one of the largest of its kind in operation today. The raw materials consist chiefly of pure lead, antimony lead in pigs, sulphuric acid, litharge, red lead, lumber and packing materials. Finished products such as glass jars for small batteries and rubber jars in all sizes are purchased from other manufacturers.

The visitor is immediately impressed with the extent of the lead-working activities, which embrace the larger part of the manufacturing establishment. All battery plates and fittings, terminals, busbars, connections, lugs, etc., are cast in hand-operated molds especially designed and built by the company.

The frames and sections of the plates which will be subjected to stress or strain in operation are cast from antimony lead wherever feasible, to give proper strength. This is particularly practiced in the larger sizes. The small plates and parts adjoining or carrying the activated material in the large plates are made from pure commercial lead, which is later burned to the antimony lead supports in assembling.

A noteworthy item in connection with the lead burning is the type of flame used. It was found unnecessary to employ the intense heat of the oxy-acetylene flame in this work, and the company therefore installed its own water gas plant. Water gas and oxygen are ignited in the torches. Other chemical plants having a considerable amount of lead burning to do might effect a saving through this feature.

There are two general types of grids made: The pasted grid, made up with a sort of mesh into which the red lead is plastered by hand to form a smooth surface, and the button or Manchester grid, which consists of an antimony lead plate punched with holes about in. in diameter. These holes then receive a button or roll of pure lead corrugated ribbon forced into place by hydraulic presses. This ribbon is made by extruding lead from the cold ingot at a pressure of 300 tons, resulting in a dense product. Large rolls similar to those employed in steel mills make the sheet lead from the pig for use as battery box linings. The department for the making of wood separators used between plates covers considerable space and consists mainly of chemical processes. Cypress, cedar or California redwood is used and is first placed in a bath of hot alkali for several hours. From this it is taken through tanks involving about 20 operations which were not revealed to the visitors. The purpose of the process is to make the wood resistant to deterioration in the sulphuric acid bath of the battery.

The pasting of red lead on the grids is carried on by hand with a large number of workmen. The material is damp so there is little dust to cause lead poisoning. The men are required to have special suits of clothes furnished by the company and are forced to take at least one shower bath each week.

There is a large wood working plant which turns out boxes for the wood type storage cells. This shop makes only special sizes, as the company has found it cheaper to buy the others on the outside. The machine shop is large, due to the fact that the company makes its own factory equipment as well as the small metal parts, other than lead, for the battery outfits. The steel and copper parts are lead lead plated before assembling.

A variety of operations are carried on in the assembling departments. The individual plates are gathered in small racks where the busbars connecting a set for each cell are put on by the lead burners. The busbars are cast in hand molds in the same department: The sets thus formed are placed in the boxes which have been previously constructed and painted with asphaltum paint, in case of wooden containers, and the covers put on. The mechanical part of the cell thus completed is taken to the charging or activating department.

Several large rooms are in continuous operation where the acid is placed in the cell and the charging is carried on. Other large batteries of tanks are subjected to current for activating unassembled plates. The current for this work is supplied from a 2000-kw. steam-power plant supplemented by three substations receiving an additional 2500 kw. in power from the Philadelphia Electric Co.

The visitors witnessed the complete process of manufacture of several types of storage cells. One of these was the lighting set made for the Cadillac automobile, said to be one of the best turned out by the company. Another was a glass jar, 16 cell, farm lighting set built with the view of being assembled and put in operation by the layman. This set contains a pilot cell with a depression molded in the glass side about an inch in width and extending vertically along a part of the height. When the battery is in operation a composition ball of proper specific gravity floats in this slot, forming a hydrometer. When the ball is near the bottom of the slot the operator knows it is time to start his generator and when near the top the completion of the charge is thereby indicated.

The cell most worthy of mention, however, is that manufactured for submarine boat propulsion in the U. S. Navy. This cell is made with extreme care under the vigilant supervision of Government inspectors, who carry on exhaustive tests to determine its performance on completion. The large units are assembled in rubber jars, the completed cell weighing 2200 lb. Each battery for the new S type submarine is made up of 120 of these cells arranged in two equal groups for either independent or combined operation in propelling the boat.

The laboratories include a chemical laboratory, in which all raw materials are analyzed; a process laboratory, in which manufacturing methods are perfected; a research laboratory, for development work; a commercial laboratory, in which batteries are tested to determine their characteristics and life, and an engineering laboratory, in which auxiliary apparatus is developed and tested.

A thorough study of the work done in this plant would be well worth the time of anyone interested in either mechanical operations or electrochemical work relating to the operation of the storage battery.

Cedar Hollow Limekilns

Three types of limekilns are operated in the Cedar Hollow plant of the Charles Warner Co. at Devault, Pa., the visit to which proved to be very instructive as well as a delightful excursion of 30 miles up the Chester Valley. For the benefit of those who think of the burning of limestone in the simplified symbols of CaCO, less CO, produces CaO with a little thermo and equilibrium chemistry thrown in, these few notes are designed to furnish somewhat of an appendix to their knowledge.

The decarbonating process of the dolomitic limestones begins as low as 660 deg. F. After all the CO, has been removed, which is around 2100 deg., the lime begins to harden. Only about 1 per cent of acid fluxes (SiO,, R,O,) are present in the raw stone, which reduces the tendency to sinter, but the lime structure apparently changes, becoming less porous, at a rate increase proportional to the magnesia content. The stone at the Cedar Hollow quarry is dolomitic, the ratio of lime (CaO) to magnesia (MgO) being very close to 3 to 2. This is very important in connection with the slaking properties of the product. Pure calcium oxide, as is well known, has to be added to its slaking water, because it is so porous, and thus reactive, that it will "burn" itself with the heat of reaction of the hydration. Probably this so-called "burned slaked lime" is a lower hydrate; at any rate, it is non-plastic, gritty, and cannot be used for plaster.

On the other hand, a dolomitic burned lime, being of a denser structure, can safely be slaked by adding water to it. This is a very desirable feature in the building trade, as it makes it easier to regulate the consistency and quality of the lime paste.

However, another peculiarity should be noted, and that is that if hard burned dolomite is added to a large bulk of water, the slaking reaction is very slow, because sufficient heat is not spontaneously generated to give the temperature required for the high-velocity reaction throughout the mass. Variations in the degree of burning, soft, medium and hard burned, depend on the period of firing, and, in turn, the size of the rock and the type of kiln.

The terms dead, hard, medium, and soft burned, as applied to calcined dolomite and magnesite products, are primarily descriptive from a chemical activity point of view. Neither pure CaO nor MgO is fusible at atmospheric pressure, for their boiling points are below their melting points. However, on the same physical principle as exhibited in the case of alloys, etc., their

melting points, or better, softening and cohering temperatures, are lowered by the association with foreign materials. In the case of magnesite, it has been found necessary to have several per cent of ferric oxide present to produce a dead burned refractory of dense The enough structure to withstand slag corrosion. same reasoning is applied in using a soft burned pure CaO for fluxing ores, for it has a porous structure, the pores being the space occupied by the CO, burned off, and offers a maximum reaction area to the silica, phosphate, etc., to be slagged. Thus it will be seen that the physical structure of these materials is of primary importance and that it is dependent on the chemical constitution together with the heat treatment given.

CEDAR HOLLOW QUARRY

The quarry has been worked on a 40-ft. face over an area of about 25 acres. Recently a drainage tunnel about 800 ft. long was cut in so as to carry off the water from the second level, which will be 50 ft. lower than the floor of the original quarry. Better quarrying conditions cannot be conceived, as a floor of several million tons of virgin rock has been stripped of overburden and drained of surface water at what might be called a cost too negligible to take into account.

In the run-of-quarry blasted rock, all gradations of sizes are produced. Stone for lump lime, known as "one-man stone," i.e., pieces that can conveniently

be handled by one man, are hand picked in the quarry and loaded upon quarry cars for transportation to the kilns. For best results in burning, a kiln charge must be fairly uniformly sized so as not to get too hard a burn with smaller pieces and at the same time leave no carbonate centers in the larger ones. The large rocks are broken up into "one-man stones" and graded to size.

The smaller pieces of stone, known as spalls, are crushed in a gyratory to pass a 3-in. mesh screen. The material running less than in. goes to the pulverized stone plant, where it is dried in a direct-fired rotary drier, pulverized in a Fuller-Lehigh mill and bagged through automatic packers. Over 85 per cent will pass 100 mesh. The pulverized stone is used in agriculture to counteract soil acids and to increase the porosity of heavy clay land. Of recent years great amounts have been used in filling tar and asphalt pavements. The -in. stone is burned in a rotary kiln and slaked at the hydrating plant.

TYPES OF KILNS

The present equipment consists of seven 10-ton vertical brick, two 25-ton vertical brick, seven 15-ton steel jacketed kilns with direct coal firing, also one 50-ton vertical steel jacketed, and one 100-ton rotary kiln, each fired with producer gas. A vertical Mount kiln with rotating base is now in the course of erection, which is expected to increase the output 100 tons per 24 hr. of firing, thus giving a daily production of about 450 tons per day of burned lime.

The rotary kiln is used to burn the smaller sizes of stone, making the conversion in 24 hr. Due to the short time of firing, the product is very soft and slakes quite rapidly, not having had time for the magnesialime condensation reaction referred to previously. It is pulverized and then slaked in a machine which proportions the correct amount of powdered lime and water conditions most favorable to give a high quality of product-called by the trade name of "Limoid."

Surplus burned lime product from the vertical kilns is mixed with the rotary product and the resulting mixture is used in making "Limoid" (hydrated lime). All Warner hydrated lime is seasoned in steel tanks for at least three days before finishing and shipping.

To produce a super quality of hydrate, the burned lime is specially hydrated and then finished in an air pulverizer, so that there are no tailings in the finished

BATTERY OF SEVEN 10-TON VERTICAL KILNS

material. This is called "Kreme-Kote" and is used for high grade finishing plaster.

The vertical kilns are used for making lump lime and require from 24 to 72 hr. for conversion to medium burned lime having easily regulated slaking properties. The trade preference in some localities for lump lime was established in the days when the stone was burned directly with wood and coal fuel. Ancient practice was to sort out all the clean lumps, and sell the smaller pieces along with the fuel ashes for fertilizer. However, as a rule, small sizes usually indicated overburning with corresponding slaking trouble on the job and the trade now refuses to take time to investigate by running any slaking tests.

As long as there is an appreciable core of unburned stone, lumps in the kiln show dark spots against the incandescent mass. On cooling, lumps containing "core" (center of undecomposed stone) show a pink or salmon pink tint on the surface. Experienced lime men can make an infallible separation between properly burned and incompletely burned lime by this color test. This color test is applicable only to dolomitic lime.

of the difference in the length of time of heating. Of course the greater production of the latter in proportion to the overhead costs counteracts the difference in fuel cost considerably. However, the Mount kiln should have the heating advantages of the stationary producer gas fired vertical and the controlled feeding of the rotary kiln. Forced firing and fast lime burning go hand in hand, but exit gases over 400 deg. indicate an uneconomical heat leakage, unless greater production must be had because of market activity.

Large steel tanks having a combined storage capacity of several thousand tons act not only as an interdepartment regulator but as a seasonal reservoir. The plant is excellently equipped with conveyors, dump cars and machine car loaders. Fluctuations in shipping from none to 30 cars per day are thus readily provided for. A view is given of the first Manierre box car loader, installed in 1913, at work. The loader itself is an ingenious but simple belt conveyor, so carefully balanced on ball-bearings that one man can easily project it through the car door and into place. The end of the conveyor is raised or lowered so that the first lime charged into the car is deposited easily on the car floor with a minimum of breakage. As the pile builds up, the end of the conveyor is raised so that the drop of the lime is always a minimum.

The Barrett Company

The Frankford, Philadelphia, Works of the chemical department of the Barrett Company has grown out of the business originally started in 1884 by Dr. H. W. Jayne. In 1886 Dr. Jayne formed the partnership of Jayne & Chase, manufacturers of fine chemicals.

In 1887 the H. W. Jayne Chemical Co. was incorporated, specializing in refined coal-tar products such as naphthalene, carbolic acid, benzol and nitrobenzol.

In 1896 the H. W. Jayne Chemical Co. was one of the companies which formed the Barrett Manufacturing Co. Dr. Jayne was appointed manager of the Frankford plant, and held that position until his death, in 1910. The business in refined products from coal-tar has grown steadily along the lines originally laid down by Dr. Jayne. Many of the processes in use at the present time were worked out by him.

The plant has grown from a very small one, covering about three acres, to the present works, covering 17

acres.

An extensive research laboratory is maintained for the development of new products and the perfection of old processes. Practically the entire plant has been rebuilt during the last four years. To-day, with its up-to-date power plant, fire-fighting equipment, service buildings, dispensary, shops, etc., it is representative of the most modern type of chemical works.

The Frankford Works is essentially a refining plant and does not handle any crude-tar distillation. One of the principal processes is fractional distillation, the plant having an equipment of 35 column stills, varying in capacity from 1200 to 10,000 gallons.

In the distillation of coal tar several fractions are cut, the actual operation being somewhat different for different plants. In general the first cut obtained is known as light oil and contains all of the benzol, toluol and xylol in the tar and some of the tar acids, pyridine bases and naphthalene. The second fraction, or carbolic oil, contains almost all of the naphthalene and tar acids and the bulk of the pyridine bases. The naphthalene is sometimes allowed to crystallize out of this oil and separated by centrifuging as a crude naphthalene. The tar acids are also sometimes extracted with caustic soda and the carbolate so formed decomposed with carbon dioxide, giving crude carbolic acid. The fraction following the carbolic oil is known as creosote oil and is used largely for creosoting purposes. A fourth fraction, known as anthracene or heavy oil, is sometimes taken off, this fraction on cooling crystallizing out a crude anthracene.

The chemical department of the Barrett Company takes as its crudes, light oil and carbolic oil from other plants, crude naphthalene and crude carbolic acids already removed from the carbolic oil and crude anthracene obtained from the heavy oil. In addition to this there are worked up several miscellaneous oils from outside sources, such as drip oils from gas works, coke oven light oils, etc.

The following discussion attempts to take up the processes as carried out in the various buildings in as nearly as possible the order in which they take place.

Naphthalene Stills, Pan House

Packing

Benzol

Crude Carbolic

Power Machine Shops

Garage Administration Laboratory