Gas lighting was introduced in Edinburgh in 1818. The production of
coal gas generated considerable residues of
coal tar and
ammoniacal liquor which were further processed at the Bonnington Chemical Works. The Bonnington facility was located on Newhaven Road in
Bonnington (between Edinburgh and
Leith) near the south bank of the
Water of Leith. George Dixon Longstaff recorded that the chemical works began in 1822 for the purpose of
distilling coal tar to separate
naphtha. This was supplied to
Charles Macintosh for him to make waterproof fabrics, as epitomised by the
Mackintosh. Longstaff was at that time assistant to Dr John Wilson Anderson, who taught practical chemistry at the
University of Edinburgh. When Anderson resigned from the university to concentrate on his growing chemical plant, Longstaff took his academic post. By 1830, the factory was making and selling naphtha, pitch oil (later called
creosote),
pitch, and lampblack (
carbon black) from the coal tar, while the ammoniacal liquor was processed into sal ammoniac (
ammonium chloride). Anderson also made the
sulphuric acid and
hydrochloric acid he needed in processing and sold the associated products
magnesium carbonate and
sodium sulphate. Anderson believed he was the first in Britain to commence making black ash and soda ash (
sodium carbonate) using the
Leblanc process when the salt tax was repealed in 1823. For some years he also made
soap. Macintosh remained a special customer until at least the late 1830s, and probably well beyond, receiving a significant discount on his large naphtha orders. In 1847, the works was taken over by
John Tennant and
John Tennent, who had both been close associates of Macintosh. Tennant was the eldest son of industrialist
Charles Tennant, and Tennent was of the Tennent family who ran
Wellpark Brewery. The firm became one of the Tennant group of companies. They added to the product line
sodium sulphite and
sodium thiosulphate (which they sold as
antichlor) and
copper sulphide marine
anti-fouling paint. The large scale of processing precipitated the construction of a
pipeline to pump the gasworks residues directly from Edinburgh to Bonnington over
Calton Hill. Tennent's brother-in-law Dr
Edmund Ronalds took over the management of the plant in 1856. He retained most of the existing products and conducted further distillations to make
benzene and also coke oil and
coke. Products were shipped as far as Russia and America. ==References==