The sum which Elkington paid him for his 'thermo-electrical battery' for depositing solutions of gold, silver, and copper was £1600, less £110 for the cost of the patent. Although quite successful at the time, other and cheaper processes speedily supplanted it; but the young German had gained a footing and the money he needed for future experiments. When he came back to Germany he was looked upon as quite a hero by his admiring family circle. It was indeed a creditable exploit for a youth of twenty. When he returned to England again in February 1844, he received so much encouragement from leading engineers and scientific men for his 'chronometric governor,' that he decided to settle permanently there, and he became a naturalised British subject in 1859. He joined with a civil engineer, named Joseph Woods, for the promotion and sale of his patents. 'Anastatic printing' was one of his early inventions, which, however, never became profitable. Then came schemes in paper-making, new methods of propelling ships, winged rockets, and locomotives on new principles, all of which were a continual drain on his own and his friends' resources without a corresponding return, so that in 1845 he took a situation and earned some money by railway work, which enabled him to pay another visit to Germany. In 1846, undaunted by previous failures, he threw himself heartily into the study of the action of heat as a power-giving agent, and invented an arrangement known as the 'regenerator' for saving certain portions of this waste. As afterwards applied to furnaces for iron, steel, zinc, glass, and other works, it was pronounced by Sir Henry Bessemer a beautiful invention, at once the most philosophic in principle, the most powerful in action, and the most economic of all the contrivances for producing heat by the combustion of coal. He now secured an appointment in 1849 with Fox & Henderson, Birmingham, at a fixed salary of £400 a year, and his interest in his patent. Here he profited largely by the experience gained, but the engagement terminated in 1851, when he afterwards settled as a civil engineer in 7 John Street, Adelphi, in March 1852.
His next great achievement was the production of steel direct from the raw ores by means of his regenerative furnace, which the President of the Board of Trade in 1883 mentioned in the House of Commons as one of the most valuable inventions ever produced under the protection of the English patent law, and he said further that it was then being used in almost every industry in the kingdom. Siemens had spent fourteen years in perfecting this regenerative furnace, and it took him other fourteen to utilise it, and perfect it in making steel direct from the raw ores. Martin of Sireil, who made one or two additions to the Siemens steel furnace, has been termed its inventor, but this claim has no foundation. What is known, however, as the 'Siemens-Martin process' is now competing very effectively with the Bessemer process. It consists essentially in first obtaining a bath of melted pig-iron of high quality, and then adding to this pieces of wrought-iron scrap or Bessemer scrap, such as crop ends of rails, shearings of plates, &c. These, though practically non-infusible in large quantities by themselves, become dissolved or fused in such a bath if added gradually. To the bath of molten metal thus obtained spiegeleisen or ferro-manganese is added to supply the required carbon and to otherwise act as in the Bessemer converter. The result is tested by small ladle samples, and when it is of the desired quality a portion is run off, leaving sufficient bath for the continuation of the process.