Document nmRakVXpdgyNO7qEeBMOLRRv2

The Saranac Laboratory for the Study of Tuberculosis OF THE EDWARD L. TRUDEAU FOUNDATION POST OFFICE BOX 551 7 CHURCH STREET Saranac Lake, N.Y. August 3, 1937 Dr. B. L. Vosburgh General Electric Company Schenectady, N. Y. Dear Dr. Yosburgh: This morning's mail brought two requests for comment on the protective action of aluminum and there have been more. It is my impression that aluminum falls in the same category with iron and gypsum, with which we have experimented. I believe that each is an example of a general principle. Whether all non-slliceous substances behave in the same way, or whether there are quantitative differences in their inhibitory effect, I have no means of knowing at the present time. You will recall from the discussion at the symposium tha t we found quite definite evidence to suggest that the presence of these materials in the atmosphere with silica prevent the inhalation of both dusts, probably by the formation of clumps which settled out of the air and which did not pass the protective barriers of the upper respiratory tract. In the case of Iron there also seemed to be a modifying action,after the substance was in the body, which prevented Interaction between the cells and the silica. No one has gone far enough to evaluate these facts at the present time but they are something to be reckoned with in future calculations. With best regards. WV-19935