One of Mushet's replies to the paper itself took the form of the announcement of his provisional patent for the use of his triple compound which, in the opinion of The Mining Journal appeared to be "but a very slight modification of several of Mr. Bessemer's inventions." Another half dozen patents appeared within two months, "so that it is apparent that Mr. Mushet's failure to make the public appreciate his theories has not injured his inventive faculties."[72 ] These patents include, besides variations on his "triple compound" theme, his important patent on the use of tungsten for cutting tools, later to be known as Mushet steel.[73 ]
Mushet's formal pronouncement on Bessemer's paper, dated June 28, 1859, is perhaps his most intelligible communication on the subject. He alone "from the first consistently advocated the merits and pointed out the defects of the Bessemer process," and within a few days of the British Association address he had shown Ebbw Vale "where the defect would be found and what would remedy" it. It was not, in fact, the presence of one-tenth of a percent of sulphur or phosphorous which affected the result if the Bessemer process were combined with his process by adding a triple compound of iron, carbon, and manganese to the pig. "There never was a bar of first-rate cast steel made by the Bessemer process alone"; (and that included Goransson's product) "and there never can be, but a cheap kind of steel applicable to several purposes may be thus produced." After emphasizing the uniqueness of his attempt to make Bessemer's process successful, he asserts:[74 ]
In short, I merely availed myself of a great metallurgical fact, which has been for years before the eyes of the metallurgical world, namely that the presence of metallic manganese in iron and steel conferred upon both an amount of toughness either when cold or when heated, which the presence at the same time of a notable amount of sulphur and phosphorous could not overcome.
The succeeding years were enlivened, one by one, by some controversy in which Mushet invoked the shadow of his late father as support for some pronouncement, or "edict," as some said, on the subject of making iron and steel. In 1860, on the question of suitable metal for artillery, later to be the subject of high controversy among the leading experts of the day, Mushet found a ready solution in his own gun metal. This he had developed fifteen years before. It was of a tensile strength better even than that of Krupp of Essen who was then specializing in the making of large blocks of cast steel for heavy forgings, and particularly for guns. Indeed, he was able publicly to challenge Krupp to produce a cast gun metal or cast steel to stand test against his.[75 ] A year later his attack on the distinguished French metallurgist Fremy, whom he describes as an "ass" for his interest in the so-called cyanogen process of steel making, did little to enhance his reputation, whatever the scientific justification for his attack. His attitude toward the use of New Zealand (Taranaki) metalliferous sand, which he had previously favored and then condemned in such a way as to "injure a project he can no longer control,"[76 ] was another example of a public behavior evidently resented.
By mid-1861, on the other hand, Bessemer was beginning to meet with increasing respect from the trade. The Society of Engineers received a dispassionate account of the achievement at the Sheffield Works from E. Riley, whose firm (Dowlais) was among the earlier and disappointed licensees of the process.[77 ] In August 1861, five years after the ill-fated address before the British Association, the Institution of Mechanical Engineers, meeting in Sheffield, the center of the British steel trade, heard papers from Bessemer and from John Brown, a famous ironmaster. The latter described the making of Bessemer rails, the product which above all was to absorb the Bessemer plants in America after 1865. After the meeting, the engineers visited Bessemer's works; and later it was reported,[78 ] "at Messrs. John Brown and Company's works, the Bessemer process was repeated on a still larger scale and a heavy armor plate rolled in the presence of some 250 visitors...."
These proceedings invited Robert Mushet's intervention. Still under the impression that his patent was still alive and, with Martien's, in the "able hands" of the Ebbw Vale Iron Company, he condemned Bessemer for his "lack of grace" to do him justice, and took the occasion to indict the patent system which denied him and Martien the fruits of their labors.[79 ]
The Engineer found Mushet's position untenable on the very grounds he was pleading—that patents should not be issued to different men at different times for the same thing; and showed that Bessemer in his patents of January 4, 1856, and later, had clearly anticipated Mushet. In a subsequent article, The Engineer disposed of Martien's and Mushet's claims with a certain finality. The Ebbw Vale Iron Works had spent £7,000 trying to carry out the Martien process and it was unlikely that they would have allowed Bessemer to infringe upon that patent if they had any grounds for a case. Bessemer was not imitating Mushet. The latter's "triple compound" required manganese pig-iron (with a content of 2 to 5 percent of manganese) at £13 per ton while Bessemer used an oxide of manganese (at a 50 percent concentration): at £7 per ton.
The alloy of manganese and other materials now used in the atmospheric process contains 50 percent of manganese a proportion which could never be obtained from the blast furnace, owing to the highly oxidisable nature of that metal. And it is absolutely necessary, in order to apply any useful alloy of iron, carbon and manganese, in the manufacture of malleable iron and very soft steel that the manganese should be largely in excess of the carbon present.[80 ]
Sufficient answer to Mushet was at any rate available in the fact that many hundreds of tons of excellent "Bessemer metal" made without any mixture of manganese or spiegeleisen in any form were in successful use. And, moreover, spiegeleisen was not a discovery of Robert Mushet or an exclusive product of Germany since it had been made for twenty years at least from Tow Law (Durham) ores. If Bessemer had refused Mushet a license (and this was an admitted fact), Bessemer's refusal must have been made in self-defense:
Mr. Mushet having set up a number of claims for "improvements" upon which claims, we have a right to suppose, he was preparing to take toll from Mr. Bessemer, but which claims, the latter gentleman discovered, in time, were worthless and accordingly declined any negotiations with the individual making them.[81 ]