Document pBEYLo0eMMJmQ9z4M0EnjJp0k

Im-: Scho o l o f Pu b lic He alth 55 Van Dyke S t . , Bo s t o n , M a s s .. Mar ch 1 0 , 1 9 2 5 . Dear Ca l: R e fe r r in g t o my l e t t e r o f y e s t e r d a y and t h e c u e s t i n o f a ir m otion w it h in th e c a b in e t , p le a s e remember t h a t th e c a b i n e t volu m e i s a b o u t 7 5 ,0 0 0 l i t e r s and t h a t we a r c n o t sam p l i n g c o n t in u o u s ly . Some c o n v e c t io n c u r r e n t s a r e i n e v it a b le fr om t e m p e r a t u r e d iffe r e n c e e ffe c t s and th e w it h d r a w a l o f 30 t o 150 l i t e r s a t v a r io u s t im e s . V'hen a i r i s w it h d r a w n , i t i s r e p la c e d t h r o u gh a m ask im p e n e t r a b le t o t h e fume p a r t i c l e s . Air flo w s t h r o u gh t h e Tyn d a llm e t e r a t ab ou t 20 l i t e r s p e r -'m in . a n d p is blown b a ck a ga in in t o -t h e c a b in e t . I t i s t r u e ?t h a t Tolman and, VT ia t fo u n d t h is p r om oted f l o c c u l a t i o n o f t h e fume p a r t i c l e s and we h ave foxxnd t h is t o b e t h e c a s e , b u t t h e ir ca b ir ie t w a s,' I t h in k , ve r y s m a ll. Vie h a ve t o r u n s e v e r a l fa n s to .g e t th e same r e s u l t . 1 I do n o t h e r a ld our cu r ve s a s a n y t h in g new or u n e xp e ct e d and hope yoxx d id .n o t g e t t h i s i d e a . They r e p r e s e n t s t i l l a i r ' ;c o n d it io n s or come a s n e a r t o i t as you c a n . We ca n n o t r u n " the p r e cip it a t o r in s id e the ca b in e t nor d isch a r ge the a ir e s c a p in g fr om i t in t o t h e c a b in e t , a s i t i s t o o h ig h ly io n is e d and of it s e lf e ffe c t s flo c c u la t io n . I f you want to read the . Tyn d a llm e t e r in s id e t h e c a b in e t yoxx a r e w elcom e t o t h e jo b p e r s o n a lly I d o n 't b e ca u s e you w ould have t o -w e a r a mask t h e e n t ir e t im e , - 24 h o u r s . Ob s e r ve r s ca n n o t ke e p g o in g in ,and o u t a s fume a lw a ys e s ca p e s w h ich s p o i ls t h e c o n t in u it y o f t h e exp er im en ts. As a m a t t e r o f f a c t I t h in k t h e s e cxxr ves s u p p o r t t h e Bu r e a u o f Min es r e p o r t r a t h e r t h a n c o n t r a d ic t i t . They show some r e a son fo r the h igh p e r ce n t a ge o f p a r t ic le s e xh a le d in ' t h e ir b r e a t in g e xp e r im e n t s . Wo go t co m p a r a b le r e s u lt s in ga s m asks - t h e P b 3 r 2 fume p a s s e d thr oxxgh f a i r l y e a s i l y and w ould n ot p lu g th e mask - flo c c ix la t in g s u b s t a n ce s lik e 5n0 p lu g masks r a p id ly and r a p id ly make them ve r y e f f i c i e n t f i l t e r s . I w r ote Mr . Ya n t a t th e Bu r e a u o f Min e s and s e n t him t h e c u r v e s . I am g o in g t o sen d him s l i d e s o f t h e fum es fo r m icr o s co p ic stxxdy - s o m e t h in g w h ich t h e y have a p p a r e n t ly i g n or ed xxp t o t h e p r e s e n t a lt h o u g h f u l l y aw ar e o f i t s s i g n i f i canee in the q u a n t it y in h a le d and r e t a in e d . H ie ld n e r and Sa ye r s have a lr e a d y seen some o f m in e . Sin c e r e ly yoxxrs, :-v yt^ cC. P h ilip Dr in ker (sign e d ) Hi 001731V N2 2 2 7 6