Document 4JaD1RwgGbRE4aVK26OxwKyo1

War 19 s 1953 Mr. Lawrence ?* Fairhall ilo.wQ.rd University bobool of Public health Van Dyke Street Boston, Maas* Dar Mr. Fairhall: Allow to thank you again for your invitation to come to your laboratory at a later data* I am ai'raid, however, that it will be impossible for some to come, and I wish to repeat ray invitation for you to come here* 1 believe that the whole matter would be greatly facilitated by y*our doing this since we are carrying on a considerable volume of work of this type at present, and since you will therefore be able to See what you will on the minutest details of our work. My plans at present are such that I do not see how I can absent myself from the laboratory. I shall be teaching until well into the middle of June., after v/hich time*. I have some three or four engagements out of town which I can not avoid* I have made plans to begin my vacation on or about July 1st, and since these involve the plans of a number of other people as well as my own , I can not conveniently modify them. It would be qxiite convenient for us to have you here any time during the next six weeks, and I shall be veryglad to have you come* With regard to your U3 of acetic acid, I must confess that my conclusion that you employed 2 c.c. basic acetic acid In excess was arrived at somewhat indirectly* Your description of your method has not Included a state ment as to the precise amount of acid employed, while your data regarded in checking the me'hod has referred repeatedly to the use of such amounts* I naturally inferred that this representated your customary procedure* I should like also to remark that it is only when the amounts of lead in the samples are less than half a milligram that substantially quantitative precipitation falls to occur. Amounts above this are usually percipitated quantitatively even in the presence of an acidity represented by 2 c.c. of glacial acetld acid in excess. When the amounts are as low as one tenth of a milligram, there is usually not the slightest evidence of turbidity or of any percitptatlon at this acid N19593