VOL. 6, No. 3
THE CHEMISTRY STUDENT
541
Rayon through the Microscope Rayon (with the possible exception of Bemberg) can readily be distinguished from silk hy means of the microscope because of the fact that the fibers are larger and present a peculiar texture of outline with which one becomes familiar by careful study. The Bemberg fiber is so fine that it requires considerable practice to be able to distinguish it microscopically. Cross-section views reveal the fact that the fibers are not quite as regular as they appear when looked a t longitudinally. These irregularities occur as the liquid is squeezed out through the orifices of the spinneret. These do not interfere with the luster of the fiber, however, since the fibers still present an excellent mirror-like surface for the reflection of light rays in parallel lines. Identifying Rayon Chemically The following simple qualitative procedure, based either on comparative solubilities, or upon comparative dyeing qualities will form a satisfactory method of distinguishing the four types of rayon chemically: Reagcnt
viscose
Acetone no change ljl, Carminic acid. Allow fibers pink to remain in soln. 5 min., then dip in distilled water pink Ruthenium red 0.1 g. in 10 cc. water
Tubire
Bemberg
no change deep pink
no change no change or slightly colored light blue
red-violet
Celsnese
dissolves no change
yellow
New Wrinkles in the Rayon Industry Hollow rayon fibers have recently been produced by application of sodium carbonate, or a similar substance, to the digested liquor. This generates carbon dioxide when the filament hits the acid-hardening bath, which causes the production of a channel through the tube. This hollow tube will then collapse somewhat into a ribbon-like fiber, which has increased elasticity and improved drying qualities because of the in-
* This article is an elaborated revision of a paper read before the Institute of Chemistry at State College, Pennsylvania, July 26, 1927. The original paper was published in the Chemistry Lea,#& 1, No. 14 (Jan. 14, 1928).
crease in interior and exterior surface. La Compagnie Nouvelle des Applications de la Cellulose, of Gouchy, France, is marketing a tubular fiber made with bubbles, under the trade name of Celta. Among other new developments in the rayon industry, we find the introduction of delusterized rayon. No sooner had the human race produced a fiber that surpassed all previous fibers in luster, than a clamor was set up to remove some of the luster. This has been done, and lusterless rayon (produced by precipitating barium sulfate or some other similar compound in the fiber) is on the market. Another new wrinkle in rayon manufacture is the production of immunized rayon. Immunized rayon can be made in such a way that it is immune to all dyes, or it can be made to resist some dyes and take on others. This product is being used with non-immunized rayon in the production of fancy two- or three-color patterns on fabrics. The modem tendency in rayon manufacture is toward the production of threads with a larger number of fibers per thread. Ordinarily 24 filaments are combined together and twisted into one thread. The modern so-called super extra yams have 60 or more filaments in the thread. This gives a softer, finer appearing thread with an excellent covering power and a more subdued sheen. Cornstalks and Cane
A few years ago attention began to be drawn to the advisability of finding out how to utilize farm wastes as a means of helping to improve the status of agriculture in this country. Congress appropriated $50,000 for research in this field, and designated the Bureau of Standards as the agency for carrying out this program. Dr. Warren E. Emley, Chief of the Organic and Fibrous Materials Division of the Bureau, entered into a cooperative agreement with Iowa State College, a t Ames, whereby the Chemical Engineering Laboratory a t this college (under the direction of Professor 0. R. Sweeney) should conduct a piece of research on the utilization of cornstalks. The first work done a t Ames has been the production of an insulating and building board from the cellulose fibers of cornstalks. Boards suitable for serving as the raw material in the rayon and other cellulose industries will be worked on in their turn in this laboratory. An Indiana Company has already been capitalized for the exploitation of the cellulose of cornstalks. Rayon is the chief product which the members of this company hope to make when they pass from an experimental to a commercial basis. A German syndicate proposes to establish a rayon plant in Jamaica which will attempt to develop a process for the utilization of fibers from waste cane, as a raw material for their industry.
VOL. 6. NO.3
THE CHEMISTRY STUDENT
543
The Natural and the Synthetic Combined One of the chief uses of rayon is in combination with other fibers. Rayon has really been an inspiration to the cotton goods manufacturer. It has enabled him to create many new designs and new patterns by combining rayon with his less interesting cotton fabrics. Rayon has been artistically combined with wool in "silvertone" and striped materials, and with silk in many novelty cloths. Silk-plated rayon hose, in which silk is superimposed on rayon gives one of the sheerest kinds of hosiery to be desired. Far from being a competitor of silk, rayon has rather worked out a new field for itself and is no longer called or looked upon as "artificial silk." Hot Dogs and Hats The production of synthetic clothing has not been restricted to the human race. Hot dogs, once trimly clad in shirts made of intestines, are now more conveniently dressed in tight-fitting jackets of Visking, a synthetic cellulose product. A recent practice in this connection is to encase sausage and '
