Document MJ4eQQLabJ2Mdma0xQ6d1Y66k

March 25, 1935 Dr* R* B* H* Oradwohl Gradwohl La b o r a t o r ie s 55^4 Lucas Avenue St * Lo u is , Missou r i Dear Dr* Gradwohlt I beg to ap ologise fo r n ot having r e p lie d to your le t t e r o f March 15t h b e for e t h is time* Un fo r t u n a t e ly I have been b u r ied under an avalan che o f norie and I sim p ly have not had time to examine your a b b r e via t e d a b s t r a ct of our method, or to make r e p ly to your q u e s t io n s* X s h a ll make somewhat fu lle r r e p ly la t e r , bu t X h asten now to give you the s p e o lfio in for m ation which you r equested in or der t h a t you may not be fu r t h e r delayed* . As to the a n a ly t ic a l st e p s about which you a s k , you w ill note in the r e p r in t from the Jo u r n a l o f ( In d u s t r ia l Hygiene* on page 26I4., column 1 , lin e 2 a sentenoe which r e a d s , "The r e gu la r a n a lys is is ca r r ie d on from t h is p o in t "$ on page 26J+, column 2, lin e 12, "th e u su al a n a lys is is ca r r ie d o u t ". Both sentences r e fe r back to page 261, column 2 , lin e 4 , or t;o page 265, column 2, lin e 6 , where the s o lu t io n is "d ilu t e d to ap p r oxim ately 500 c c . e t c " . The a n a lys is is ca r r ie d on from t h is p oin t as d e s cr ib e d . The only qu estion is t h a t o f d eter m in in g on the b a s is o f the s is e o f the sample whether one or two su lp h id e se p ar a t ion s ar e r e q u ir e d . When the sample is la r ge and a con sid e r a b le q u a n t it y o f phosphates ar e p r e s e n t , two se p ar a t ion s ar e a d vis a b le * Otherwise the two procedures a r e id e n t ic a l* > I have no way of knowing Ju s t what e xp er ien ce you have had with le a d methods, MM I do not want to be presumptuous In d is cu s s in g the m atter * May X s a y , however, In a ll s in c e r it y and modesty t h a t i f you have not done an a lyse s by s u b s t a n t ia lly these m ethods, i t would be h igh ly d e s ir a b le fo r you to run some blan ks and some known amounts o f le a d in or der t h a t you may wee fo r y o u r s e lf how s a t is fa c t o r y the method is working in your hands* The d ir e ct io n s fo r the an alyses as we have d e scr ib ed them ar e r a t h e r s p c ifi On the oth er h a n d , good r e s u lt s w ith the method are ob tain ab le only a ft e r a con sid e r a b le e xp e r ie n o e . N24618 2- Dr . Oradwohl I sh ou ld ha ver y happy lndaad to hear from you as to how you have go t t e n alon g w ith th in method, and i f I can be o f any fu r t h e r s e r vice to you , do not h e s it a t e to w r it e . JUs t as soon as I ca n , I s h a ll d is cu s s In some d e t a il the q u e st ion o f s t ip p lin g which you r a is e d In you r f i r s t l e t t e r . This Is an Im por tant bu t by no means a sim ple pr oblem , and we have done a gr e a t d e a l o f work over a p e r iod o f ye a r s on s e ve r a l m ethods, the r e s u lt s o f which I s h a ll be gla d to d e scr ib e in soma d e t a i l. Co rd ially yo urs . RAKjXS ITo b e r b ^ A/ Ke ^ 'e ; '1g.'B. i HJZ3 00376