INDUSTRIAL AND ENGINEERING CHEMISTRY
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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.
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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.
