Your letter of Jan. 19. came to hand on the 15th inst. only. the experience of two wars has proved that the making of salt within ourselves is as important as the manufacture of gunpowder and arms; and I sincerely wish well to your undertaking. but I have so long withdrawn from all attention to things of that kind, and have particularly been so little acquainted with the construction of salt works, as to be unable to give you any opinion on the probable success of your invention. I know only that in Northern Europe they consider it essential to strengthen their water as much as possible by previous evaporation, and your machinery seems in theory to promise that. but it is experience alone which can determine that. I return you your drawing with my best wishes for the success of your enterprise and the assurances of my respect