Document 2xoZOJM4ONX6RMvNK2gL2B3b

March 25, 1935 Dr* R* B. H. Qradwohl Gradwohl Laboratories 3514 Lucas Avenue St* Louis, Missouri Dear Dtr* Gradwohlt X beg to apologise for not having replied to your letter of March ljth before this tine* Un fortunately X have been buried under an avalanche of work and X simply have not had time to examine your abbreviated abstract of our method, or to make reply to your questions* I shall make somewhat fuller reply later, but X hasten now to give you the speolfio in formation which you requested in order that you may not be further delayed* As to the analytical steps about which you ask, you will note in the reprint from the Journal of / Industrial Hygiene* on page 261)., column 1, line 28 a sentenoe which reads, "The regular analysis Is carried on from this point"| on page 261)., column 2, line 12, "the usual analysis Is carried out". Both sentences refer back to page 261, column 2, line 1), or t;o page 263, column 2, line 6, where the solution Is "diluted to approximately 300 cc. etc". The analysis Is carried on from this point as described. The only question Is that of determining on the basis of the slse of the sample whether one or two sulphide separations are required. When the sample Is large and a considerable quantity of phosphates are present, two separations are advisable* Otherwise the two procedures are identical* I have no way of knowing Just what experience you have had with lead methods, ftflo 1 do not want to be presumptuous In discussing the matter* May I say, however In all sincerity and modesty that If you have not done analyses by substantially these methods, it would be highly desirable for you to run some blanks and some known amounts of lead in order that you may mee for yourself how satisfactory the method is working in your hands* The directions for the analyses as we have described them are rather speciflo* On the other hand, good results with the method are obtainable only after a considerable experience. 2 Dr. Gradwohl I should be very happy indeed to hear from you as bo how you have gotten along with thin method, and if I can be of any further service to you, do not hesitate to write. JUsfc as soon as I oan, I shall discuss In some detail the question of stippling which you raised In your first letter. This Is an Important but by no means a simple problem, and we have done a great deal of work over a period of years on several methods, the results of which 1 shall be glad to describe in some detail. Cordially yours. RAKjIS koberfe A. Kehoe, M.ti. ) VJt? 00376