INDUSTRIAL A N D ENGINEERING CHEMISTRY
624
the amounts of barium and calcium coming through from the amounts going in gave the amounts remaining in the zeolite by reason of the exchange reactions. Since each atom of barium and calcium remaining in the zeolite replaced two atoms of sodium, it was possible to calculate the sodium replaced by each metal. CONCLUSIONS
A large excess of the replacing metallic ion is necessary. A large number of treatments or saturations with the solution of the replacing metal are required, the number being entirely dependent upon the particular exchange reaction involved. Barium showed approximately four and one-half times the replacing power of calcium when both were present in chemically equivalent amounts. The particular significance of this fact is not yet entirely clear. It is evident that these reactions can hardly be mere adsorption phenomena. If they were, it is not a t all probable that the chemically equivalent ratios found could exist between replacing and replaced metals. The exchange reactions of replacing metals in dilute solutions, which are more highly ionized, are more nearly com-
Ethylene Glycol-Its
Vol. 16, No. 6
plete than with concentrated solutions. This fact would tend to prove that the exchange reactions are ionic. The point of equilibrium reached in any particular reaction would be determined by the relative ionization of the replacing solution, of the resulting solution, and of the zeolites. Since all these zeolites are practically insoluble in neutral solutions, no data are available regarding their possible ionization. There was enough variation in the composition of the zeolite to make impossible any definite statements regarding the exact chemical constitution of this particular kind of zeolite. Not quite all the sodium present in a sodium zeolite could be replaced, the unreplaceable portion being a constituent of some of the impurities inherent in the zeolite. Of that portion of a metal which may be replaced, all can be actually replaced by another metal. It is expected that further work will be done in the future along lines here presented and it is hoped that more data can be secured. ACKNOWLEDGMENT The authors desire to express appreciation of the courtesy of the Permutit Company, of New York City, which furnished samples of Permutit and certain publications.
Properties and Uses'
By Henry C. Fuller INSTITUTE O F INDUSTRIAL RESEARCH, WASHINGTON,D. C .
THYLENE glycol has been transferred from the status of a comparatively rare, or a t least an uncommon, chemical individual, to that of an easily obtainable commercial product. The possibilities for its use in various lines of industry have created a demand for it, and as some of these applications are connected with industries in the food and medicine fields, it has been deemed desirable to study the action of the substance on the animal economy. The glycols are dihydroxy derivatives of the paraffins. Ethylene glycol, CzHd(OH)z, is the simplest glycol, and may be considered as standing between ethyl alcohol, C2HbOH, on the one hand, and glycerol, C3Hs(OH)3, on the other. It is a colorless liquid, with a sweetish taste. It has no odor. It is heavier than water, its specific gravity being about 1.116, and is miscible with it in all proportions. It i s less viscous than glycerol, though in physical properties it bears a considerable resemblance to that substance. The product as now made commercially is of high purity. For industry, ethylene glycol offers itself as a solvent and preservative, and its competition with other solvents will depend, of course, upon any superior qualities that it may possess, and the comparative cost entailed by its use. I n these days the search for substitutes for alcohol in the food and drug industries makes the advent of any new possibility a welcome circumstance, and it is the purpose of this paper to note some of the uses that have suggested themselves for ethylene glycol, and to set forth the results of a research on its physiological properties and its action on microorganisms in comparison with glycerol and alcohol. When it became evident that alcohol was to be legislated against, no matter what the use of this time-honored solvent and preservative was to be-and in the food and drug industries pure, rectified grain alcohol is looked upon only as a
E
1 Received
November 13, 1923.
reagent, a solvent, a vehicle, not as a beverage-the various branches of trade affected began to look about for other agents to take its place, and a great deal of experimental work was conducted with the use of different substances offered as whole or partial substitutes. Acetone and glycerol as solvents, benzoic and salicylic acids and their salts as preservatives were the common substances usually employed in the researches, and many old-time formulas and types of products have been revamped with the aid of these substances. Substitutes are prone to objections and there has been no exception to this truism in the movement under present discussion. Acetone cannot replace alcohol in many classes of products, owing to its odor and taste. Glycerol alone is a poor solvent compared with alcohol, and its action in this particular often has to be augmented by other substances; while as a preservative its action is not uniform, and often so much of it is necessary to prevent spoilage that the original character of the product containing it is changed. Other objections, such as its taste and physiological effects, have militated against its more general application. I n a patent specification2 recently granted there are set forth certain applications of ethylene glycol to the food industry, in particular its use in the preparation of flavoring extracts. Mention is made of extracts of apricot, peach, apple, allspice, pear, celery, cassia, and anise, that have been successfully prepared with the solvent, either alone or in combinations with a certain percentage of ethyl alcohol. It is claimed that vanilla extract of a superior character can be made with ethylene glycol, and that the solutions are less viscous and heavy and of better color, clearer and more brilliant, than when prepared with glycerol, and are accordingly more nearly like the ethyl alcohol solution. The results of this investigation confirm the foregoing
* Smith and Eoff,U. S. Patent 1,384,681.
I N D CXTRIAL A N D EA-GINEERING CHEMIXTR Y
June, 1924
assertions, and in addition it has been found that almond, wintergreen, terpeneless lemon, and terpeneless orange extracts; root beer, sarsaparilla, and maple flavors; imitation peach, pear, apricot and other extracts of like character can be prepared with ethylene glycol as the vehicle. All these possess a degree of fluidity approaching that of flavoring extracts made with alcohol, and they are therefore easy to handle and are miscible without difficulty in ice cream, candy, beveragcs, and other food products. I n the drug and medicine field the possibilities of ethylene glycol are a t once apparent, especially in liquid products where it is desired to reduce or entirely eliminate the alcohol. There are so many different types of medicines that it is impossible to describe any general procedure for carrying out the subbtitution of the alcohol, but for simple mixtures of medicinal agents that are readily soluble, the customary manipulations may obtain, while for those of more complex character methods must be evolved to fit the cases. In some instances, where vegetable drugs require percolation or where resinous material must be dissolved out from the inert portions of the drug, the combination must be first brought into solution with alcohol, then the proper proportion of ethylene glycol added and the alcohol removed by evaporation, using proper precaution to avoid loss of valuable constituents or destruction of delicate principles by excessive heating. Each preparation usually becomes a special study by itself, but it is surprising how, with a little ingenuity, the substitution can be brought about in cases where a t first thought the difficulties seem hopeless to overcome. Having noted some of the possibilities of ethylene glycol as a solvent, let us consider how it acts as a preservative in comparison with alcohol and glycerol. Tests were run with a strain of Bacillus typhosus (Rawlings) grown on broth, adding increasing quantities of the substances under investigation, and noting the appearance or absence of growth in the original and in the subcultures. A graphic exhibition of both inhibitory and disinfectant phases of the test is shown herewith.
It is thus apparent that, as far as Bacillus typhosus is concerned, ethylene glycol shows inhibition a t a dilution of 1 to 10 and is disinfectant a t 14 to 100; glycerol shows inhibition at 3 to 10 and disinfectant a t 35 to 100; alcohol shows some inhibition a t 1 to 20, and is completely disinfectant at 8 to 100. Therefore, as a preservative agent toward bacterial growth, ethylene glycol shows a close approach to alcohol and is much superior to glycerol. COMPARATIVE INHIBITORY ACTIONAGAINST YEASTSOF ETHYLESE GLYCOL, GLYCEROL, AND ALCOHOL TEcHNIcPreparations in the following percentages of the Substances mixed with standard dextrose medium (beef extract 1.5 grams, beef peptone 5 grams, dextrose 5 grams, sodium and potassium phosphate 2.5 grams, water 500 cc.) were planted with wine yeast and incubated 72 hours at 36" C. Percentage Mixture
Quantity of Preparation Used cc 0.1 0.2
.
0 ,3 0.4 0.5 0.6
0.7 0.8 0.9 1.0 1. 1. 1.2 1 3 1 . 4:
.
1 .5
1.6
1.7 1 , P# 1.9 2.0 2.2 2.4 2.8
2.8 3.0 3.2
3.4
3.6
c
+
Key: trol culrure.
Ethylene Glycol I S
I
Glycerol S
Ethyl Alcohol I S
Ethylene Glycol Glycerol
Ethyl Alcohol
++ ++ +15 --20 + 25 +-30 35 Control + + + Key: + indicates gas production; - indicates no gas production. 10
COMPARATIVE INHIBITORY ACTIONAGAINST MOLDOF ETHYLENE GLYCOL,GLYCEROL, AND ALCOHOL TECHNIC-PreparatiOnS in the following quantities were mixed w i t h 10 cc. of standard mold medium (maltose 4 grams, peptone 1 gram, agar 1.5 grams, water 100 cc.) inoculated with mixed mold culture and allowed t o remain under observation at room temperature. Records were made at the end of 2 weeks. Quantity of Preuaration 'Used cc. 1.0 1.1 1.2
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
2.1
COMPARATIVE INHIBITORY AND DISINFECTAXT ACTIONOF ETHYLENEGLYCOLWITH GLYCEROL AND ALCOHOL TECHNIC--PreparatiOnS in the following quantities were mixed with 10 cc. of standard extract broth, inoculated with one standard (4-mm.) loop of a vigorous 24-hour broth culture of Bacdlus typhosus (Rawlings); cultured a t 37.5" C. for 48 hours and observed for inhibition ( I ); subcultured on agar to determine disinfectant strength (S).
625
2.2
2.3 2.4 2.5 2.6
2.7
2.8 2.9 3.0
Key:
Ethylene Glycol Glycerol
+ 5+ +
+
T-
-----
++ +
++ ++ ++ ++ + ++ ++ +++ ++
Ethyl Alcohol
--
-------
+ indicates mold growth; - indicates no mold growth.
FOOD TECHNOLOGY The author's investigations instituted within the year show that ethylene glycol is a satisfactory agent for the preservation of natural and concentrated fruit juices, soda water concentrates, ice cream flavors, pie fillers, coffee, and many other similar commodities. The results of these researches are to be made the subject of a special report. It may be stated in brief that when fresh fruits are crushed, the pulp and juice treated with glycol, and heated, there is obtained an extract possessing qualities closely resembling those of the fresh fruit, permanent in character and color, and not subject to spoilage by microorganisms. Extracts have been prepared from strawberries, raspberries, blackberries, and other small fruits, pineapples, grapes, apples, and peaches, which show, after shelf tests of many weeks, no changes in organoleptic properties or chemical composition. Juices that have been properly concentrated to retain their characteristic tastes and aroma can be preserved by the same means. Satisfactory concentrated extracts of coffee and miscellaneous concentrated flavors for popular beverages have been prepared with glycol, and various fruit pulps have been packed successfully with it.
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TESTS3 The physiological tests were made with rabbits. They were large, gray specimens of the Belgian hare type, averaging in weight about 4 pounds. Careful attention was given to their health and none but sound, vigorous, adult specimens were employed. They were kept in a large, airy room under normal temperature conditions, and were plentifully supplied with water and wholesome food. In nearly all cases the animals were chloroformed at the expiration of the test period, the carcass autopsied, the gross pathology noted, and then the various organs were preserved in formaldehyde solution and later sectioned and examined microscopically. In certain exceptional cases, subjects were allowed to survive in order to determine whether or not there was a recovery from any abnormal manifestations, should any such phenomena have been noted in those animals examined a t the end of the test, and whose pathology may have resulted from the substance ingested. When the dosage of ethylene glycol administered to the subjects is compared with the quantity that ordinarily would be ingested by a human being, either in the form of a food product or a medicine, and taking into consideration the proportional bulk of the human subject with that of the rabbit, it is reasonable to believe that the reaction of the human to the ethylene glycol would be inappreciable. Ethylene glycol in 5 and 10-cc. doses, administered to animals in 50 per cent solution with water daily over a period of a month, produced no outward manifestation except a slight indisposition to eat after the administration of the PHYSIOLOGICAL
8 These tests mere conducted under the direction of 0. B. Hunter, George Washington University Medical School, Washington, D. C.
dose. No true pathological symptoms were observed. autopsies showed the thoracic and abdominal viscera t o be normal and no microscopic changes in the liver or spleen. The brain, spinal cord, and eyes were unaffected. Doses of 15 to 20 cc. of a 50 per cent solution of ethylene glycol with water produced no outward manifestations. The animals received these strong doses over a considerable period, the total amount of glycol administered varying from 75 cc. up to 450 cc. The abdominal viscera usually showed some passive congestion when the subjects were autopsied, and there was evidence of chronic gastritis.
' The
CONCLUSIORS From the experiments conducted, the author is led to the conclusion that ethylene glycol is suitable for use in the preparation of food and medicinal products, and he recommends to those specializing in physiological chemistry exhaustive research to determine whether or not the substance is innocuous. Should further research affirm his opinion, this material should prove a valuable substitute for some of the solvents now employed. From the food control angle the author believes that as a general proposition there is no objection to the use of a substance like ethylene glycol in food products, provided it is innocuous. When it is used as a solvent or as a preservative in a commodity of standard character, such as a flavoring extract, its presence as a substitute for the customary agent will have to be indicated. Precautions as to the proper branding of any food product employing glycol as a solvent or preservative will of necessity always have to be taken into consideration, just as with similar substances.
A Simple Turbidiscope' By W.I). Home and E, W. Rice 175 PARKAvE., YONKCERS, N. Y.
I
N EXAMINING solutions for turbidity it is necessary to detect very faint degrees of cloudiness, if erroneous conclusions are to be avoided. The method commonly used, of holding the bottle or tube of solution directly between a source of light and the eye of the observer, fails to show the presence of very minute solid particles held in suspension and capable of giving more or less trouble. By employing the ultramicroscopic method of illumination, however, these extremely minute particles are caused to reflect the light from the side and transmit it to the eye of the observer, who, looking through the solution against a black background, easily detects minute refleeting particles or a faint cloud where none was seen before. In order to examine filtrates from bag filters, filter presses, boneblack, and other sources, a very easily built apparatus has been constructed to take advantage of these conditions. The source of light is a good, nitrogen-filled, concentratedfilament, incandescent lamp bulb, hung in a tin cylinder fitting quite closely around it and extending a little above the top of the lamp and about 1 cm. below the filament. About 1 cm. below this cylinder a second tin cylinder is attached by three soldered wires, and both are painted black on the outside and inside to prevent dispersion and reflection. Around each cylinder is a metal annulus perforated with holes to accommodate test tubes. At the bottom is soldered a broader annulus of tin to serve as a support for the test tubes. It can also serve as a base for the ap1 Presented before the Division of Sugar Chemistry at the 67th Meeting of the American Chemical Society, Washington, n. C., April 21 to 26, 1924.
Vol. 16, KO. 6
paratus, but it is better to support it by the lamp socket, as illustrated, so that it can be easily turned and will be air-cooled. Wheq the solution to be examined is put into a tube and set in the rack, there becomes apparent Tyndall's phenomenon of the reflection of light by the minute suspended particles, all viewed against a black background. The determination of turbidity can be made quantitative through comparing an observed sample with a tube containing a known amount of fine material in suspeiision. Care should be taken, however, not to compare turbidities in solutions of different degrees of color, without taking account of the fact that faint turbidity in a nearly colorless solution may be easily visible, while an equal amount of suspended matter may be hidden in a solution containing any considerable amount of color.
