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JOURNAL O F CHEMICAL EDUCATION PHYSICAL CHEMISTRY Mathematics Requirements for Phys. Chem.. . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Problem Method of Teaching Phys. Chem.. . . . . . . . . . . . . . . . . Aims and Viewpoints in Teaching P h y s Chcm.. . . . . . . . . . . . Phys. Chem. a t Pennsylvania State College.. . . . . . . . . . . . . . . . Physical Chemistry for Medical Students.. . . . . . . . . . . . . . . . . . Methods of Measuring Osmotic Pressure. . . . . . . . . . . . . . . . . . . Vapor Density of Steam.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p H Concentration from Thermodynamic View.. . . . . . . . . . . . .
MARCH,1931
Page 254 258 260 263 272 280 98 107 1658
Date 2/29 2/29 2/29 2/29 2/29 2/29 1/29 1/29 10129
Brilliant Green Hailed as Most Potent Germ-Killer. Wounds in surgical operations may soon be sewed with bright green catgut affording to patients the greatest possible protection against infection, according to reports to the American Medical Association from Odessa, where Dr. S. Baccal has been experimenting with powerful antiseptics. Dr. Baccal covered the lips of a wound with brilliant green, an anilinc dyestuff. and the wound remained sterile during a period of seven days after the operation and it was impossible to obtain germ colonies from samples taken from the wound. Brilliant green kills all bacteria promptly, in smaller amounts and in more dilute solutions than any of the antiseptics known previously. I t is not irritating; it can be applied to mucous membranes, i t can be even placed in the eye. In the surgical clinic of Odessa i t is now exclusively used for washing the surgeon's hands before operations, becausc it never leads to infections. Dr. Baccal also found that the saturation of silkworm catgut with alcohol and brilliant green did not make this suture-material less soft, elastic, or pliable, and a t the same time increased its safety causing no suo~uration whatever. .. This brilliant stuff has only one defect, i t stains the hands of the surgeon a bright green which cannot he washed away for several days. Dr. Baccal is therefore anxious to find a formula far a bleach which will remove the color.-Science Service Engineer Shows Which Foods Are Hardest to Freeze. Some foods freeze more readily than others, housewives with mechanical refrigerators have learned when they put the eggs or the apples too near the icing unit and returned a few hours later to find them as hard as rocks. Engineers who design refrigerators and who quick-freeze foods to the solid statc to be shipped and sold in small packages have also learned just how much easier it is to freeze one food than another. They have found the amount of heat t h a t must be taken from a food in order t o freeze it. A list of common foods and this value of heat, called the latent heat of fusion, is contained in a report made by A. H. Cooper to the American Society of Refrigerating Engineers. Water is hardest t o freeze, i t being necessary t o take 143.4 British Thermal Units of heat from a pound of water a t 32 degrees Fahrenheit to change it to ice a t the samc temperature. Ranging down from 135 to 107 B. T. U.'s are lettuce, strawberries, onions. milk, apples, green beans. Irish potatoes, grapes, eggs, beef, and sweet potatoes. For all practical purposes, Mr. Cooper states, the latent heat of the food can be found by multiplying the percentage of water in the food by 143.4, the latent heat of fusion of the water in the food. Thus less heat h a s t o be taken from foods that contain little water, and it is easier to freeze them than to freeze foods containing much water. In this group are pork, cheese, bacon, and butter.-Science Service ~
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