Frank Hills and a group of other industrial chemists became immersed in the problems of gas purification. Raw coal gas straight from the retort was not fit to use for lighting purposes and needed to be cleaned. Early lime-based purification methods left a noxious residue and the industry was faced with how to clean gas without incurring legal action for pollution resulting from waste disposal. Industrial chemists began to search for a means of cleaning the gas which would also leave a residue that could profitably exploited.
Throughout the 1840s and early 1850s these manufacturing chemists approached the gas companies with offers of various purifying schemes. An account of Angus Croll's offers to the Imperial Gas Company, together with Bevington, has already been described. The chemists offered deals with the gas companies and then took legal action against each other. For instance in an example taken at random, Angus Croll, asked the Patent Office to decide that Frank Hills was infringing his patent. He was then quick to explain to the Phoenix Gas Company directors that the Imperial Gas Company was no longer using Hills' process because of complaints about infringement. He offered to indemnify Phoenix against any legal action which Hills, or anyone else, might take against them. A few days later Frank Hills told Phoenix the same story - but in reverse and offered to indemnify the Board against legal action by Croll.
The visits, the threats and the offers went on for more than twenty years. Although a number of chemists were involved, Hills and Croll were most active and followed closely by Richard Laming. The progress of invention and discovery is almost impossible to follow since all of them were capable of telling the gas companies about new processes -sometimes giving details of completely different discoveries to different companies on concurrent days. A complete analysis of what each told each gas company might make an interesting, if extremely voluminous, story but one that bore little relation to what was really going on. The most impressive thing is that they seem to have kept track of these convoluted dealings.
One particular process, using metallic oxides, seems to have been developed in France by Richard Laming. He was an English doctor who went to France for unspecified reasons. It involved the 'revivification' of the purifying mixture with air, and this part of the process was to become crucial during successive legal challenges. Once 'exhausted' the mixture contained valuable substances that could be reclaimed. An aggressive campaign to sell this process to the gas industry was pursued by Laming, Croll and Hills. The legal battle over patent rights to the process lasted almost twenty years. Any attempt to interpret reports of successive cases is to enter a bewildering morass of claims and injunctions, of complicated chemical arguments involving almost unheard of substances, and finely argued points of patent law and legal procedures. Frank Hills held the key patent, if a decision went against him, he appealed.