Document 0gBEkYGakkbBkVbYe1233do9J

August 6, 1957 Dr. J* M. Zfesslofe B* X* DuPont do Nemours and Go# DuPont Building Wilmington, Delaware Dear Doctor Messlcks X am sending you herewith a report of out^naljsis of a large sample of urine obtained frorn^H||HH^ #1520# You will note that the results obtSffie^on this sample of urine are somewhat higher than those reported in connection with the spot sample* However, this finding is not dangerously high, and in my opinion it does not modify the conclusion expressed in my former letter to you For your Information, X wish to call your attention to the fact that the method of analysis which we are using now yields somewhat higher results than those which X published, and which X have discussed with you previously# Our chemical method yields an average loss of about 0*0? milligrams per sample, whereas the present method gives results which have a much smaller error but which may be either on the high side or on the low. That is to say, the results obtained by the method we are now using represent substantially absolute quantities with a very minute error# If we were to translate this result into comparative terms with those previously given you, wo would subtract at least the 0*07 from the 0*19 milligrams actually found in the sample# On this basis a recalculation of the milligrams per liter would give 0*07 instead of 0*12* You see, therefore, that the result obtained is not significantly hl$x, and is not compatible with the existence of more than the most minor symptomatology# Very truly yours. RAX* is N14022 Robert A# Kehoe, M#D