Cork: Its Origin and Industrial Uses Part 2

Yellow and red coloring matter.

Quercitannic acid.

Gallic acid.

A brown nitrogenous substance.

Salts of vegetable acids.

Calcium.

Water.

Suberic acid.

Suberin (cellulose).

I am inclined to think that Chevruel selected a poor grade of cork, full of stone cells and Jasperado, as his findings include much that would indicate that was the case.

In further defining the various substances which go to make up the body of corkwood the one that is most impressive is that substance that is peculiar to cork itself, the others being readily known, but suberic acid is the one of interest, and this is described by Fownes as a product of the oxidation of cork by nitric acid; is a white crystalline powder, sparingly soluble in cold water, fusible and volatile by heat, the chemical formula given being (C_{4}H_{14}O_{4}). Suberic acid is also described as a dibasic acid which forms small granular crystals very soluble in boiling water, alcohol and ether. It fuses at 300 degrees Fahrenheit and sublimes in acidular crystals. It is also produced when nitric acid acts on stearic, margaric or oleic acid. The chemical a.n.a.lysis is given as (C_{8}H_{14}O_{4}) and I am inclined to believe it is the truer one, as it is much later than Fownes'.

This suberic acid has been further broken up to ascertain its fundamental characteristics and it was found to partake of the two compounds suberone and suberate.

Suberone (C_{14}H_{24}O_{2}) being regarded as the ketone of suberic acid, an aromatic liquid compound obtained when suberic acid is distilled with an excess of lime.[24] Also described as a colorless oil with an odor of peppermint and a boiling point of 179 to 181 degrees Centigrade, chemical formula, Suberone-Cycloheptanone-

CH_{2} . CH_{2} . CH_{2} / CO CH_{2} . CH_{2} . CH_{2}

[24] "Standard Dictionary."

Suberate (C_{8}H_{12}M_{2}O_{4}) is known as the salt of suberic acid having a metal cast,[25] and Suberin or cellulose[26]-is that portion remaining after nitration and is chemically expressed by the formula (C_{6}H_{10}O_{5}). Dr. Robert K. Duncan, Prof. of Industrial Chemistry in the University of Kansas, informs us that this material is the commonest of common things[27] and when dry, forms one third of all the vegetable matter in the world. This mysterious substance is the structural basis of the wood, but with all its prominence and use, we know nothing more about it than that which is expressed in the formula.

[25] "Watt's Dictionary" ("M" signifying metal).

[26] "Century Dictionary."

[27] _Review of Reviews_, September, 1906.

The presence of this cellulose is only a natural fact, as the greater part of plant life is cellulose; nor is the list of elements that go to make up the solid matter so strange and unaccountable, but the quality that makes it a wonderful growth and so popular above its fellows is its lightness-this is its commendable feature and it is light indeed.

Ure puts the specific gravity at .24 and this is concurred in by Brisbane.

TEST OF CORKWOOD FOR ASCERTAINING THE POSSIBLE PRESENCE OF AN ESSENTIAL OIL, BY STEAM DISTILLATION

Two tests were made on this material to ascertain the presence of an essential oil. The first showed the presence of an oily film, resplendent in colorings, opalescent, variegated and beautiful, but odorless and of such small quant.i.ty that it may safely be said "No Oil."

The second proved the same as the first, and although the strong odor of cork or suberic acid was present, no oil appeared.

The results of these tests indicate that there is no essential oil in corkwood obtainable by steam distillation.

TEST NO. 1

4-4-1913.

A copper still, supported on two trunnions, fitted with a dome and goose-neck, which terminated in a tin coil (water cooled), and with a perforated bottom through which the steam pa.s.sed, was used.

This measured two inches in diameter and two inches high, from the perforated plate to the top of the pot, the dome being about one foot higher.

Into this still was placed 41 pounds of corkwood, as it comes from the cutters and punchers (sc.r.a.p pieces), no preliminary washing or preparing being done; this 41 pounds filled the pot or the still.

All things made tight, using an asbestos packing, the steam was turned on at 70 pounds and run for one hour.

TEST NO. 2

4-15-1913.

Same still used as in Test No. 1, thirty pounds of a clean, good grade Granulated Cork, of a fineness to pa.s.s a 1/16? mesh, was put into the still-this half filling same.

Steam turned on at 70 pounds and run for one hour.

Tests made at A. J. Crombie & Co., Brooklyn, N. Y.

Anderson, Ure, Chevruel, Fownes, Watts, Brisbane, men of science; to these we are indebted for the little that is known of corkwood, and although perhaps much more could be said by elaboration, it will suffice to record the facts in this monograph for the purpose involved.

But to the data a.s.sembled may be added much in commentation, for the material becomes more interesting the more it is studied, and most naturally excites comparison with other materials and subst.i.tutes, as well as calling forth a discussion as to the dangers involved by its presence in the places where, by skill of hand and machinery, it is transformed into the many commercial forms, noted in this article. We comment upon its growth, which is truly wonderful and all-absorbing in its many interesting phases; it takes us to the romance of the East and the enchantment of the Moorish occupation; through which these forests of cork-producing trees pa.s.sed and yet remain to furnish the present generation. We comment upon its lightness and buoyancy, due to the presence of air and excess of hydrogen, known to be lighter than air; and the small percentage of other matter which, being of less importance, make its other quality so renowned as to make it the most wonderful growth of its kind. Its imperviousness to water and other liquids have given us moments of reflection, upon this phenomenon, but now known to be because of the cellulose composing the cell walls and which, when the substance is under compression, practically is all that remains, except for the small quant.i.ty of resin, etc., to resist the pa.s.sage of liquids or gases. But heretofore when these commentations have reached the burning point, its physical nature was entirely eliminated from the conjecturing and the important part neglected, that as the cork contained fifty-three per cent of air, heat of 450 degrees expands to the point of explosion, the contents of those cells nearest the surface, which giving up their oxygen feed the flames and in their pa.s.sage help to disintegrate the cell walls and make them more easily ignited. Thus causing a rapid burning, flash fire which, in its fury, Pluto could not rival, only racing over the surface of the cork, burning but slightly, yet helped by other conditions, resulting in a fire destructive and fierce. This rapid burning leaves the outer surface of the cork charred and flaky and causes a discoloration beneath it attributed to the dissolving of the resins, etc. Of course where there is a large quant.i.ty of corkwood the extent of the burning must necessarily be greater and the depth of the char increased. But it appears that the first flash burning produces a sort of protection coat of carbon around the remaining unburned portions which a subsequent flame penetrates with difficulty.[28]

[28] In the making of insulation material, the carbonization of the cork is accomplished without destruction of fibre and stands a high flame test.

A simple experiment to show this depth of burning, and one that is easy to do, is the flash and flame test which was found of interest.

Two pieces of cork were taken, having the following measurements-8/16?

7/16? 11/16?-and the first piece held so that the flame of a gas jet would cause a flash over its surface; then the second piece is taken and held within the flame for a minute.

It will be found that the corkwood has expanded and the dimensions increased to the following:

Flash Flame 8/16? 13/16? 11/16? 10/16? 14/16? 11/16?

showing the effects of the heat upon the tissue and contents of the cells.

Now in sc.r.a.ping these samples clean of all char the dimensions will return to the following:

Flash Flame 6/16? 11/16? 11/16? 8/16? 10/16? 11/16?

clearly setting forth the fact that the char is comparatively light in both cases, ranging from 1/8? to 1/4?.

To this cause is ascribed the burnability of cork having by careful observation and experiment, extending over a period of two years, studied the results of numerous fires in premises where cork was being worked and also conducted heat applications on various grades of cork[29] resulting in the foregoing findings.[30] Thus it is found that cork contains sufficient air to supply any fire in it and precludes the necessity of free access to any outside supply which makes it a material worthy to be watched. To its many qualities of great service to man, giving him a material which from the ages past, till now, has proven of such value, must be added this one, no less important than others, which heretofore have been its commendable features.

[29] Using ordinary gla.s.s (armoured) thermometer for ascertaining degrees.

[30] One thousand degrees Fahrenheit, causing no greater combustion than the lower degree, other than the increased burning of remaining substance after the flash, due to the higher temperature.

Rather than attend the "cork" through the many pa.s.sages of commerce and manufacture, it is deemed propitious to deviate a little from a natural course, i.e., from the growing to manufacture and rather advance to a knowledge of the many uses to which this material is put and its application to the innumerable arts, and then take up the manufacture.