Th e Gr a s s e l l i Ch e mic a l Co .

; WORKMEN'S COMPENSATION T h e 3 In d u s t r ia l C o m m is s io n o f O h io 0.3 . 12&6 SPECIALIST'S REPORT Add-es .11 2&_g 93rd S tr e e t - C levela n d .

May 10, 1933 Dr Lawrence T* Fairhall School of Public Health Harvard University 55 Van Dyke Street Boston, Massachusetts Dear Dr* Falrhalli Allow me to thank you for your letter of May 5th* X do not doubt that your interest Is in the establish ment of the facta in the matter of normal lead* In this same spirit, I an replying, and for the present declining your invitation to come to your laboratory* It is impossible for mo to absent myself from my work before the second week of Tune, because of a teaching schedule which cannot be altered Just now* However, I should be lad to offer th same facilities to you which you have tendered to me* I and my associates will be glad to have you at your convenience, and we will be pleased to work out our differences as soon as you choose, and in any manner which aeras mutually desirable* I trust that what I have to say in the next paragraph of my letter will not Influence your willingness to accept this invitation as an expression of my personal cordiality* In the matter of our analytical methods, I should like to point out the critical differences, the Importance of which you can establish for yourself with a minimal amount of time* Without ooamenting upon slight differences In the pre paration of samples, or the necessity of the sulphate step, or the advisability of separating bismuth, - all of which are important - I wish to call your attention to your -us of 2 Q.c*. of glacial acetic acid in excess, at the chromate precipitation* If you will modify your procedure at this point to the use of dilute acetic acid \2 o*o* of 5%) you will find that amounts of lead below 0*5 milligrams will be precipitated as chromate, whereas with your method all auch amounts will be largely or entirely lost* By this slight change, the large proportion of all our discrepancies will b Ironed out* Let me cite a recent experience,in our*.laboratory, as^an example of the,importance of this variation* In a recent study of a normal subject, as a preliminary control on observations which were to be made, the results had been of th characteristic type for several weeks when a series of thirty successive faecal samples were found to yield "0 110 "* A prompt Investigation established that one of ay ) 2- assistants had used 2 o*c* of glacial acetic acid at the chromate step (The reagent bottles were similar, and by 3heer accident the glacial acetic acid bottle had been placed where the 5$ acetic acid should have been* Concentrated acid was added to very sample in that batch, and every result was lost.) '71th this error corrected, the subsequent samples were found to contain the customary amounts of lead* I wish to stress further, the fact that we do not use allquota of samples, tut complete and large samples, so as to reduce the experimental error* Therefore, we are not dealing with questionable amounts of lead, except in rare Instances, but rather amounts which are well outside the realm of spectrogrophlc traces.

i n t e r -o f f i c e co r r e spo n d e n ce : Et h y l Ga s o l i n e Co r p o r a t i o n Gh r y s l e r B u i l d i n g 4 0 5 Le x i n g t o n A v e n u e Ne w Yo r k June 3, 1937 Dr* Robert A* Kehoe My dear Bob: A reply to your letter of May 24th has been somewhat delayed because of my absence from the City, Our laboratory undoubtedly has -a lot of data on total lead in motor lubricating oil and I believe negative tests for tetraethyl lead* I have asked them for a report on the subject.

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THE ASSOCIATED ETHYL COMPANYLIMITED THE ADEEPHI, LONDON, W.C.2 Calles: ETHYLPORT, LONDON Jlegnmts: ETHYLPORT, RAND,LONDON Jelejh-On&: TEMPLE BAR 9831 ' [Directors: J.W.BOYt-jE G.H.M1CHLER (u.S.a) H.B.HEATH EVES R.W.

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