Document RJaBepY2eE4xNpwbj7zRkX5za

December 2 , 1935* Mr. C h arles Wesley Dunn, SOd Fifth Avenue, Hew York C ity * Dear Mr* Dunn: Dr. Horwitt and I w ish to make the fo llo w in g re p o rt o f an aly ses made o f eht e l e , government sample N.Y. 20113. T h is i s the sample we receiv ed from government o f f i c i a l s pursuant to your re q u e st f o r th e seam* Two 50 gram samples were ashed by a technique recom mended by the government ch em ist, Mr. lau g h rey. The s o lu tio n was d ilu ted to 200 cua* F i f t y on* were analysed by our di th izo n c method and th e remaining 150 c . c . by the ?~oveminent' s e le c t r o l y t i c method* The r e s u l t s a re a s fo llo w s: Dlthizone method E lectrolytie method 1 . (a) 5*90 parts per (b) 5*5 parts per m illion m illion 2* (a) 5*05 * n n (b) 5 .8 " " " As p re d ie te d , the e l e c t r o l y t i c method i s c o n s is te n tly lower because o f the q u a n tita tiv e d i f f i c u l t i e s asso ciated with the handling o f the lead sulphide p r e c ip ita te . B le c tr o ly tic sample lb was tr e a te d with sodium polysulphide to remove any t i n that m ight be p resen t* E l e c t r o l y t i c sample 2b was not tre a te d fo r removal o f t i n * On the b a s is o f the above r e s u lt s i t i s probable th a t the step c a llin g fo r removal o f t in , a procedure which I s time-consuming and o f q u estio n a b le m erit, may be om itted when a n a ly sin g c h i c l e f o r lea d by th e e l e c t r o l y t i c method* I t should be emphasized th a t th e above r e s u lt s a re fo r the p art o f the samples which we an aly sed , and, because o f th e nature o f the m a te ria l, m i^t reasonably bo q u ite d iffe r e n t from the r e s u lt s obtain ed w ith another p a r t o f th e same general sam ple. We a re continuing to make an aly ses o f other samples now a v a ila b le * In order to a s s i s t in your development o f c o n tro l work you should perhaps know th a t Merida, 8 th shipment, on a n a ly s is i s g iv in g h ig h er r e s u l t s , some samples o f t h i s p a r tic u la r shipment showing more than 10 p a rts par m illio n * As f a s t as we are a b le , we s h a ll re p o rt on th e se a d d itio n a l an a ly ses* Very tru ly yours, George R. Cow gill. Kf? 0006374 N 7569