In 1844 Croll read a paper to the Institution of Civil Engineers about a new method of making sulphate of ammonia. He suggested passing coal gas, which had been through the ordinary lime purifiers, and then through sulphuric acid. The resulting sulphate of ammonia was described, by Croll, as 'of remarkable purity'. It would provide the double benefit of clean gas and a high quality ammonia salt. It seems a pity that members of the Institution who listened to Croll's paper asked no questions about it, and preferred to discuss the porosity of pipes afterwards. Perhaps they didn’t understand it.
Croll's paper also described tests made on his sulphate of ammonia and its use for agricultural purposes. A subject which on which, he said, 'men of science, education and capital have for several years bestowed much attention'.
Croll was right, the use of ammonia in agriculture had been given considerable attention for many years. It is very likely that much of the sulphate of ammonia that the gas industry made went for agricultural use. Ammonia was probably first used like this around 1800 - which would have put the gas industry in a good position to become suppliers. A Mr. Cox had submitted a paper on this to the 1809 Parliamentary Enquiry into the Gas Light & Coke Co.20 The Board of Agriculture was also interested and in 1814 Sir Humphrey Davy had carried out some relevant experiments. Again, there are no details. Sir John Russell, commenting on this said that the sulphate of ammonia which Chartered Co. made in 1815 was intended for agricultural use but that it was 'unsatisfactory until further research' had taken place. In the early 1840s numerous experiments with potential fertilisers were made. These included the pioneering work of Baron Von Leibeig as well as that of John Bennet Lawes. Croll's paper was part of this movement - in fact he embellished it with quotations from Leibeig, the leading current authority.
The experiments on sulphate of ammonia for fertiliser, which Croll described, had been undertaken at Manor Farm, Havering Atte Bower - at the back end of Romford. This was remarkably near to a future address of Croll's - he later lived at Haroldswood Lodge only a mile or so from Manor Farm. There is just a suspicion that it might have been his farm - another possible indicator of Croll's wealth. The report omits to say who supervised the experiments - perhaps it was Croll himself. He said that the sulphate was applied as a 'top dressing' rather than by watering as with Davy's experiments. Croll however mentioned no other research or findings on the subject - despite the work done by Davy and others.
Croll had a commitment to research and education and was a founder supporter of the Royal College of Chemistry. He must also have known John Bennett Lawes, the best known agricultural chemist of his generation. Lawes' first fertiliser works was on Deptford Creek and he later moved to Atlas Works, Millwall. Thirty years later, the Lawes Manure Company, by then at Barking and without Lawes himself, bought 'patent ammonia’ from Croll's Alum and Ammonia Company.
Several manufacturing chemists tried to persuade the gas industry to take on their purification schemes. Richard Laming and Frank Hills were two leaders in this and along with Croll became enmeshed in rival processes and interminable litigation. An attempt to outline some of this saga will be made in another chapter. The whole process of patents, claims, counter-claims and legal cases went on for many years. Many volumes would be necessary to analyse and document exactly what was going on. If there were any winners then Frank Hills came out best while Richard Laming went out of his mind. Croll kept on for a while but eventually withdrew to pursue his many other interests.