September 1849 he wrote to Losh and Wilson informing them that the partnership with Pattinson "would necessitate my relinquishing the office I at present hold in your firm". Establishing a partnership with Robert Stirling Newall in 1850, Bell set up the first factory in the world with machines able to manufacture steel rope and submarine cable. Two years later his brothers Thomas Bell and John Bell joined him to build a major iron works at Port Clarence, Middlesbrough on the north bank of the River Tees. By 1853 there were three blast furnaces, each with a capacity of just over 6000 cubic feet, making them the largest in Britain at the time. The works produced iron for bridges and steel rails for railways across the British Empire including the North Eastern Railway company, of which Bell was a director from 1864 onwards, and deputy chairman from 1895 until his death. The Bell brothers' company operated its own ironstone mines at Normanby and Cleveland, and its own limestone quarries in Weardale, employing about 6000 men in mining and manufacturing. By 1878 the firm was producing 200,000 tons of iron per annum. Bell was a professional metallurgist and industrial chemist, constantly pioneering processes such as the recycling of heat from escaping flue gases, and trialling many process improvements. In 1859 Bell opened Britain's first factory able to manufacture aluminium, a metal which had been as costly as gold because of the difficulty of chemically reducing the metal from an oxide. On the day it opened at Washington, Bell toured Newcastle in his carriage, saluting the crowds with an aluminium top hat. The plant used the new Deville sodium process. he described how critical it was to make aluminium pure in The Technologist: In 1863, Bell exhibited "several pounds" of the recently discovered element thallium when the British Association met in Newcastle that autumn. The metal was obtained from the flue deposits (mainly lead sulphate) from the manufacture of sulphuric acid from pyrites, one of the products of the Washington works. All the credit was given to researcher Henri Brivet, who was "chief" of the laboratories at Washington, having experienced "languor and headache" then known to be caused by breathing thallium fumes. The Cleveland ironstone had been considered inferior for steelmaking, as it contained a relatively high percentage of phosphorus at 1.8 to 2.0%, weakening the resulting iron. Bell directed large-scale experiments at