3.--MEDAL CASTS.--I have some medals which I should like to copy. Having tried several times, and failed, I thought that I would ask advice through your query columns. I do not know of what the medals are manufactured. They are, I suppose, made to imitate bronze. I have tried casting them in plaster of Paris molds, but have had very poor success, as the surface of the medals was covered with small holes. The metal used was lead and antimony, seven to one. I should like to know, if there be any metal that I can cast them of, and bring out the bronze color afterwards, or if there be any metal that I can cast them of, and afterwards color by some solution. Also, of what should I make my molds?--J. E. M. 4.--REMOVING THE TASTE OF TAR FROM RAIN WATER.--Will some of your correspondents tell me if rain water, which runs off a gravel roof, and tastes very strongly of tar, is unhealthy, and if there be anything that will prevent its tasting, as it is very disagreeable for cooking purposes?--C. E. H. 5.--SORGHUM MOLASSES.--How can I separate the molasses from the sugar, in sorghum sugar mush, to make a dry merchantable sugar? 6.--FLUX FOR ALUMINUM.--Will some of your readers tell me, through your columns, the best flux to use in melting and mixing aluminum and copper? * * * * * INVENTIONS PATENTED IN ENGLAND BY AMERICANS. [Compiled from the Commissioners of Patents' Journal.] APPLICATIONS FOR LETTERS PATENT. 350.--BREECH-LOADING FIRE-ARMS.--Eli Whitney, New Haven, Conn. February 10, 1871. 352.--GOVERNOR.--Stilliman B. Allen, ----, Mass. February 10, 1871. 357.--WINDMILL.--A. P. Brown, New York city. February 11, 1871. 332.--FURNITURE CASTERS.--F. A. Gardner and H. S. Turrell, Danbury Conn. February 8, 1871. 339.--WIRE FABRICS FOR MATTRESSES.--Samuel Rogers, New York city. February 9, 1871. 340.--SCREW PROPELLER CANAL BOATS.--Thomas Main, Pierpoint, N. Y. February 9, 1871. 362.--FLYER FOR SPINNING MACHINERY.--Thomas Mayor and Geo. Chatterton, Providence, R. I. February 14, 1871. 373.--TELEGRAPHIC APPARATUS AND DETECTORS.--W. B. Watkins, Jersey City, N. J. February 14, 1871. 381.--STEAM AND OTHER SAFETY VALVES.--Walter Dawson Scranton, Pa. February 15, 1871. 388.--IRON RAILS AND BARS, AND MODES OF MANUFACTURING THE SAME.--Eldridge Wheeler, Philadelphia, Pa. February 15, 1871. * * * * * OFFICIAL LIST OF PATENTS. ISSUED BY THE U. S. PATENT OFFICE. FOR THE WEEK ENDING MARCH 7, 1871. _Reported Officially for the Scientific American._ SCHEDULE OF PATENT FEES