Document 7R1ZpogxZO5rG6r1ZN9Oro33e

5tl ILIINU Ul* I'AKIKLtb Tlu1 United Stales Public it ml til Serviee* found (lull- tin* Sedg wick* Rafter cells ahniild k(mid rioiu JO III *20 minutes before ennui* tug to ullow Hie diiat particles to nettle. However* Tor dust collected iu plants making aaboHlua product*, our finding* indicate Hull n longer tiino is licccxMiry. Thin uiwt was allowed to xettlu iu the celt Tor :tl) minute* before any counting wuh done. We found that this add]* tional 10 iniuutes is required to permit a complete settling out of the particles. Experiments were conducted to determine the time factor for settling of this particular kind of dust in the cell. Figure 6 Is a series of curves showing the settling time of the dust particles. It will be noted that it was necessary to allow the ceil to stand 30 minutes before counting. SUMMARY Samples of dust, takeu in plants for fabricating uslteato* product*, were eollceted by a modified form of the standard method, using a 95.0 per cent l\S.P, ethyl alcohol as a medium. In this medium the particles were well distributed and readily counted. When diatiUcd water was utilised aa the collecting medium, agglomeration occurred immediately and made counting impossible. Dispersion of Hie dust in alcohol is good. A settling time of at least 30 minutea was re* quired before counting. The particle count iu any given field re mained constant after this period. A modified holster is described. It is constructed of leather straps, In such a way that the fluid in the impinger flask is visible at all times. BIBLIOGRAPHY 1. "Occupation nml Health/' International Labour Office, Geneva, 1930. 2. T. Hutch. II. WHrrcu, and P. Drinker: "Modified Form of the Greetiburg*8niith Iiupinger for Field Use, with ii Study of Its Operating Characteristics." Journ. Iud. Hygiene, vol. XIV, No. 8, Oct. 1932. 3. Leonard llreeuburg aud J. J. Bloomfield: "The finpiugcr Dust Sampling Apparatus ua Uaed by the United States Public Health Service." U. S. Public Health Reports, vol. 47, No. 12, March 18, 1932. 4. W. E. Cooke: `1 Asbestos Dust and the Curioua Bodies Found in Pulmonary Aabcatosia," British Medical Journ. S'28. 1929, vol. 2P. 578-80. 5. W. M. Myers: "Solubility of Finely Divided Rock Dusts in Water, Kerosene and Aleohol." Bur. of Mines, Reports of Investigations, Serial No. 2548, Nov. 1923.: 9