Document oMpBZN9ypkrQKmq3XpJNwyomw

I November 22, 1932 Dr. El^on L. Belknap 23I W. Wisconsin Avenue Milwaukee, Wisconsin Dear Docbor Belknap: Replying to your request of November 15th for our methods of analysing lead In excreta, I am sending you several reprints which not only describe methods but give certain data which may be of interest to you. X do not know the Lederer method for de termining lead in urine, or at least I do not know 11 by that name. If you wish to send me a description of it, I shall be pleased to give you my opinion. Other wise -i- might have t o rspend a considerable amount of time finding this method in the literature. My guess is that It Is not sufficiently accurate since so far as I know there are only some four or five methods described in the literature which are sufficiently accurate for the purpose. None of these have been in use for more than seven years, and for this reason most of the Information on lead in biological material prior to this time is inaccurate. The chief difficulty with most of the methods is that they are not sufficiently uniform to give com parable results. In lead analysis I do not believe that anything short of high accuracy is useful since it is Impracticable to have a method which is sensitive, let us say to .25 or of a milligram of lead. So far as our experience goes, any method which is this low In sensitivity gives such high variations In the results as to make any conclusions impossible* Cordially yours. RAN:IS I