The village and lands of Melfort, in Campbell ownership since the 14th century, were purchased by an English gunpowder company, Harrison Ainslie & Co in 1838 as an ideal location for the manufacture of gunpowder. Not only was it secluded, but it had plentiful supplies of scrub oak and a deep water pier for deliveries of raw materials and export of gunpowder.
To understand the advantage of these features, one needs to have a quick look at the actual manufacture of black powder as it was practised at Melfort. The first stage was preparing the raw materials by refining the salt-petre and sulphur, manufacturing the charcoal from the oak scrub, pulverising the ingredients separately and mixing them in required proportions. The gunpowder was then incorporated by mechanically grinding and crushing the ingredients into an intimate mixture. At this stage the gunpowder was in the form of a damp paste known as millcake. This was pressed in hard slate-like sheets of press cake corned or formed into grains of various sizes, dusted, glazed and finally dried. Charcoal was the variable factor in the composition and its preparation involved selection of the wood to be used and control of the burning process. The traditional method of charring wood in stacks made excellent charcoal for the fuel but the product was too impure and uneven as an ingredient of gunpowder.
A new method of distilling wood in sealed retorts was therefore developed in the late 18th century. Coppices were planted around powder mills to supply the necessary wood. Salt-petre in the form of fine crystals could be used straight from the refinery but the charcoal and sulphur had to be pulverised. This was done traditionally in crushing mills with stone-edged runners rolling upon a circular bedstone and in the 19th century machines similar to giant coffee grinders were introduced for pulverising charcoal. The powdered ingredients were each sieved to ensure uniformity to remove any gritty particles which might cause an explosion during manufacture. The saltpetre, charcoal and sulphur were then weighed out normally in the proportions of 75/15/10 and mixed in a revolving drum to produce the green charge for the incorporating mills.
Incorporating mills with stone-edged runners were introduced in Britain in the early 18th century. The charge was moistened and kept damp throughout theincorporating process which lasted for about 2 hours for common blasting powder, and 8 hours or more for the finest sporting grades. Production was continuous with the workforce operating a shift system.
In the 19th century steam engines and later water turbines were introduced to drive incorporating mills and other equipment, the remnants of which are still evident at Melfort. Improvements were made in the design and this enabled a larger charge to be processed. Pressing the millcake to increase its specific gravity was introduced in the 18th century. Granulating machines with toothed rollers cut the press cake into pieces. After it was corned, the remaining dust was removed by tumbling the powder in gauze-covered revolving cylinders. The powder was dried normally by heating of steam pipes and traditionally packed in oak barrels and kegs of various sizes. Most powder mills had their own cooperage and this employed a large proportion of the workforce.
For transport within factories, punts were used on mill streams wherever possible and tramways were laid to connect the different buildings, with the trams pulled by horses or pushed by workmen. Gunpowder was stored in factory magazines while awaiting despatch. There was a considerable coastal traffic in gunpowder for which the Government and several private firms like Harrison and Ainsley maintained their own fleets of sailing barges.
Minor accidents were commonplace and most mills would experience a fatal explosion occasionally. At Melfort in 1867 for example, an explosion took place resulting in the total destruction of the powder works as recorded in the”Oban Times” of 9 March. This article tells of a bale of cloth being thrown from the last building to a distance of about a mile. Many of the windows in the houses were smashed by the concussion of air.