In the early London Gas industry a system seems to have evolved that meant that individuals or companies working as sub-contractors made ammonia salts. There were a number keen to try - in 1824 Imperial, for instance, had received an offer from an otherwise unknown, Mr. Maples 'to manufacture ammoniacal liquor into saleable products'. This offer was not taken up.
In June 1828 Imperial sold some sulphate of ammonia to a Mr. Sergeant and the next January received a report from him on the future manufacture of ammonia salts'. In the meantime Sergeant had approached Chartered with the results of his tests on sulphate and they allowed him to set up ammonia work on site in their Brick Lane and Westminster works. He was allowed to do this as long as the apparatus, which was kept in the yard, was 'in tune with present arrangements' and he was also allowed to make use of the 'waste heat'.
Soon Chartered was 'very dissatisfied' with Mr. Sergeant's sulphate of ammonia and they decided to employ a Mr. Greenhalgh. He was asked to make sal ammoniac for the company so that they could 'keep the vessels in use'. Next, they decided to manufacture their own ammonia products at Brick Lane without the help of either Greenhalgh or Sergeant.
Sergeant meanwhile had returned to Imperial with a sample of his sulphate. At the same time he went to the South London based Phoenix Company with the same samples and offered to make ammonia salts for them. Phoenix instructed their engineer Munro to make them himself.
This series of interactions shows that ammonia salts were made from the 1830s in London by Chartered, Phoenix and Imperial Gas Companies. They also probably continued to allow salts to be made on their behalf by contractors - in 1837 Frank Hills made sal ammoniac for the Chartered. There is no reason why both activities should not have taken place concurrently.
It is very unlikely that the other East London Companies, except for the City, made salts. Smaller gas companies, like Ratcliffe and the Independent never seem to have started on chemical manufacture but disposed of liquor by selling it raw. The experimental work undertaken by the early companies themselves seems to have come, very largely, to nothing.
Chemical manufacturers from outside the gas industry, like Frank Hills, seemed more able to manufacture the salts and make money from it than the gas companies themselves. Perhaps they were more able to cultivate their market than the gas companies, whose business was, after all, to sell gas.