In 1839, Josiah Marshall Heath patented the important application of carburet of manganese to steel in the crucible, which application imparted to the resulting product the properties of varying temper and increased forgeability. He subsequently found out that a separate operation was not necessary to form the carburet--which is produced by heating peroxide of manganese and carbon to a high temperature--but that the same result could be attained by simply in the first instance adding the carbon and oxide of manganese direct to the metal in the crucible. He unsuspectingly communicated this after-discovery to his agent--by name Unwin--who took advantage of the fact that it was not incorporated in the wording of the patent, and so was unprotected, to make use of it for his own advantage. The result was one of the most remarkable patent trials on record, extending over twelve years, and terminating in 1855 against the patentee--a remarkable instance of the triumph of legal technicalities over the moral sense of right. A very important development of the manufacture of steel followed the introduction of the 'Bessemer process,' by means of which a low carbon or mild cast-steel can be produced at about one-tenth of the cost of crucible steel. It is used for rails, for the tires of the wheels of railway carriages, for ship-plates, boiler-plates, for shafting, and a multitude of constructional and other purposes to which only wrought iron was formerly applied, besides many for which no metal at all was used.