William Losh (1770 in Carlisle – 4 August 1861, in Ellison Place, Newcastle) was a chemist and industrialist who is credited with introducing the Leblanc process for the manufacture of alkali to the United Kingdom.
The firm manufactured akali and saltsake by processes patented by Archibald Cochrane.
Subsequently, when Stephenson was building the Stockton and Darlington Railway, he decided to use wrought-iron rails obtained from the Bedlington Ironworks.
This caused a permanent rift with William Losh, who had believed that he had an agreement with Stephenson to use his own rails.
In addition to being an alkali manufacturer he worked as a colliery agent and as consul for Prussia, the Scandinavian countries and, later, for Turkey.