A Curious Discovery.

Scientific American 38, 9.6.1849

Mr. William Longmaid, of London, has recently taken out a patent in England for a new way of treating the oxides of iron and obtaining products from them for making paints &c. which is certainly novel.

The mode of operation is as follows:

The oxide of iron is to be reduced to a finely pulverized state, preparatory to the process, and in that state is to have intimately miced with it some resin or tar, or other carbonaceous material, the patentee preferring the use of resin or tar for the purpose; and the proportions he ´recommends to be from about 10 to 15 per cent of the carbonaceous material, according to its nature; the patentee prefers to use a quantity of the carbonaceous material a little in excess of that necessary for the operation. The carbonaceous material employed is to be reduced to a pulverized state when used in a dry state; but when they are fluid or semi-fluid, they are mixed with the oxide in that state, and afterwards dried and reduced to powder; the materials thus mixed are then put in retorts or other proper close vessels, etiher of cast iron or other material; these vessels being about five feet long, one end being open, and to be afterwards closed by a cover; this retort is to be afterwards charged with the mixed materials - the quantity of each charge being about 1½ cwt, and when the cover is secured upon the end of it, the retort is placed within a suitable furnace in a vertical position; the open end, upon which is the cover, being placed downwards, that the gaseous matters evolved during the process may pass into the furnace and be consumed; the retort is then to be gradually raised to a dull red heat, and when the contents of the retort have ceased to evolve the gaseous products, then the whole is suffered to remain for about two hours at this temperature, when the retort is to be removed from the furnace, and suffered to gradually cood down here the contents are withdrawn - as by allowing them to come in contact with the atmosphere while in a heated state, the quality of the producs would be injured; the product thus obtained is a dark.colored matter, which may be used as a pigment, or ground with oil, will form a paint. Instead allowing the gaseous products evolved to pass into the furnace, they may be collected by closely luting the cover of the retort, and applying a pipe to carry them off to a condenser and gasometer; these products being a volatile oil, and an inflammable gas fit for an illumination.