GHEMICAL GORPS BIOLOGICAL LABORATORIES

PS DIVISION

Biophysics Branch
Camp Detrick, Frederick, Maryland

8 January 1952

Dr. Joshua Lederburg
Department of Genetics
University of Wisconsin
Madison, Wisconsin

Dear Dr. Lederburg:

or. Braun told me recently that you had expressed an
interest in a method developed here for preparing uniformly
dispersed samles of particulate material.

The method is extremely simple and I believe of very
wide applicability. One merely mixes the particles with a dilute
protein solution. When a few microliters of this mixture are
applied with a micropipette to a water surface the protein spreads
to form a insoluble monolayer, and in so doins disperses the
particles over the surface. . The monolayer with its embedded
particles can then be transferred to a glass slide for nicro-
scopic examination, to wire mesh screens for examination in the
electron microscope, or to pieces of membrane filter for studies
of the effects of irradiation, zrowth rates, and so forth. The
transfer from the liquid to the solid surface is done by with-
drawing the immersed plate throuch the air-liquid interface
occupied by the film.

I do not know whether this provides the information
that you need. A detailed description of procedure would be
rather dull and it would be very much easier to demonstrate the
technique to you if you are in this part of the world. If not,
I shall certainly be happy to amplify this description.

With kind regards,

Yours sincerely,
TBR bere.

J.B. BATEMAN
Chief, Biophysics Branch
PS Division

JBB: gmt