Urgent Letter Written by Albert Einstein to Assist with

Urgent letter of response from Einstein with a sketch in his hand, in which he advises a scientist from the National Defense Research Committee regarding a possible way to separate fuels and oils from water, a critical problem during the course of WWII.
There was often much pollution produced in port areas due to the bombings. In the letter, Einstein advises them to deal with the problem by stirring the water, which will cause weakening of the surface tension of the water, such that it will be easy to collect the oil from the surface of the vortex.
The letter was sent on July 13th, 1943, to Dr. George Antonoff, who was a chemist at Fordham University in New York, and part of the Office of Scientific Research and Development. Dr. Antonoff was part of a group led by Dr. James Conant - head of the National Defense Research Committee who worked on finding a solution to a common problem in the Allies' ports, water pollution at and near the ports with oil and other fuels, as a result of bombings, submarine attacks or accidents involving oil tankers and other vessels. On July 8th, 1943, Dr. Antonoff wrote a letter (included) to Professor Einstein, in which he requests Einstein's assistance. Antonoff indicates that he needs Einstein's counsel and its explanation urgently, and a quick response is essential for the war effort.
Einstein's response helped Dr. Antonov, and he cites him in an article that he published on the topic in April, 1944.
[1] leaf paper with embossed stamp. 22x28 cm. Signature in his hand, and diagram, in blue pen. Very fine condition. Fold marks.