| Show Heres Here's How Hov ow to Find in Out i if Dentifrice e Hurts I Your our Teeth Uncle Sam Tests 25 Brands in Placing Order Atlantic City With With a nickel nick nick- el and a piece of glass you youcan youcan youcan can make a simple test that will tell you whether your favorite favorite favorite fa fa- fa- fa toothpaste will scratch the toe enamel of your teeth The test Is one that the United States government requires for all toothpaste purchased and it was described described described de de- scribed at the meeting of the American Amer Amer- ican can Dental association here by Drs Whiner WIlmer Souder physicist and Irl C. C chemist of the national national na na- na bureau of standards Uncle Sam buys large quantities of toothpaste When an order for some d dozen zen tubes was contemplated contemplated con con- contemplated a a- a committee was appointed appointed ap ap- ap pointed to write specifications for a asale safe sale and effective cleanser for the teeth These specifications now adopted for tor use were reported here Must Not Contain Poison Safety for the tissues of the mouth and the thel teeth was the first consideration consideration consid consid- of these men when they meto metto metto met to o decide what must be contained In Uncle Sams Sam's toothpaste Next came the he question of efficiency in removing removing removing ing foreign materials from the matter of flavor or perfume A toothpaste must not be excessIvely excessively excessively either alkaline or acid it was decided It must not be caustic It must not contain arsenic or other poisons It must have a preservative preservative preservative tive that will insure that it keeps in good condition until used Twenty five popular brands of toothpaste were tested against the specifications as adopted for use in government t purchasing More than thanh h half lt failed to meet the requirements requirements requirements require require- ments Drs Souder and said Hardening separation of ingredients ingredients ingredients in in- and fermentation or spoilIng spoiling spoiling spoil- spoil Ing were the most common faults Some showed signs of chemical attack attack attack at at- tack upon the tube container and that was considered undesirable How Bow to Make lake Test Ten toothpastes among those tested tested test test- ed failed on the test for scratching This test as developed at the national national national na na- na- na bureau of f standards can cm be used by anyone who wants to be sure his dentifrice Is not scratching scratching scratching scratch scratch- ing the enamel of his teeth A piece of at glass and anda a piece of alloy metal of the size and hardness of a five- five cent piece are all that are needed for the experiment First test the glass for hardness by rubbing the edge of the m metal tal piece over it to tobe tobe be sure that the metal alone does not scratch the glass Human enamel and glass both vary in hard hard- ness Place some of the he toothpaste to tobe tobe tobe be tested on the glass and rub again with the coin If scratches result then you may expect scratches on your teeth This test is sensitive enough to detect one part of emery in one thousand parts of paste |
