Tales from End to End
The Manufacturer’s Tale
North Yorkshire’s First Heavy Industry:
Alum-Making in 1835
by Sir George Head on a visit to Sandsend
‘I walked along the edge of the cliffs to Lord Mulgrave’s alum-works, to the northward, close to the sea, about three miles distant, where the extent of the excavations, and the magnitude of the heaps of alum-rock (or shale as it is called), then in a state of smouldering combustion, produced a magnificent effect, such as I had not anticipated. The scale of operations may be partly imagined by those who have chanced to see the chalk and lime works on the Thames at Northfleet: the cuts, several feet in thickness, are commenced at the top of the cliff, here one hundred and eighty feet high, and then worked down perpendicularly to the bottom; and thus, by degrees, a vast portion of the material has been scooped out, leaving, as it were, an extensive irregular semicircular bowl, the area of which is the theatre of operations, and in appearance truly volcanic. The blue colour of the surrounding cliffs of alum-rock, the burning mountains below, and the whole scene, round and about, is such as, when seen from the summit, give the whole together the character of one enormous crater. At all parts work-men are seen driving their loads in wheelbarrows, sometimes across rude bridges and planks, perilously planted from one precipice to another; or along narrow ledges of rocks, and platforms supported by rough blocks of stone.
The process of preparing the alum is sufficiently simple. After having quarried the shale, which, from the softness of the substance, is performed without much difficulty, it is piled in the enormous heaps before mentioned: these; being ignited, burn for several months together, till the whole is reduced to a red calcined ash or cinder. At the commencement of the formation of each fiery mountain, a nucleus is, in the first instance, created by a layer of faggots or bushes placed on the ground, and set fire to. On these is thrown a layer of the alum-shale. As soon as the latter becomes red-hot, a second layer of shale is placed upon it, upon which the workmen stand, and supply from the rear with alum-shale a second layer of bushes placed in front. Thus the heap extends, by layer after layer of bushes in front being fed with stone brought from the rear; and, as the heap increases in height and dimensions, the material is wheeled across the top, from one end to the other, in wheelbarrows, and shot over from the summit upon the new-laid layer of bushes in front.
How it is possible for a living creature to exist and work in such an atmosphere, I do not comprehend, for the fumes of sulphur predominate in such a degree as almost to stop the breath. Such is the pestiferous effluvium which arises, that the edges of many deep fissures are abundantly fringed with flower of sulphur; and as the smoke and steam ooze upwards the air trembles in the sunshine, as may be observed in a field of burning bricks. Nay, besides the appearances above stated, red heat is not only visible through the cracks in many places underneath, but by merely scratching a few inches with a stick below the surface may be discovered glowing everywhere. Even with so shallow a covering, the part that comes in contact with the feet is cool.
The shale being reduced to a calcined mass, and allowed sufficient time to cool, in order to extract the alum, the ashes or cinders are immersed in water in shallow tanks cut in the ground, like salt-pans; from which the liquor passes away by a channel cut for the purpose underground, full half a mile in length, to the boiling-houses.
The liquor is here boiled in several large cauldrons one after another till the water, having sufficiently evaporated, it is poured into barrels, containing three hundred gallons each, and then allowed to cool. As it cools, the crystallization takes place; the crystals adhere to the sides of the barrel, the water settles in the middle, just as the milk lies within the cocoa-nut, and the nut cleaves to its shell. When cold, the barrels being purposely constructed to take to pieces, the hoops and staves are removed, and the crystals remain in a solid mass, the usual proportion being two-thirds of crystals to one-third of water. A hole is bored to let the water off, and the alum cut with a saw in blocks for the market. On an aperture being made in one of these masses when entire, the crystals within assume, as may be readily imagined, a splendid appearance’.
Between 1600 and 1850 some 20+ alum works, the largest employing 150 men, provided all the mordant for the dyeing of textiles in England as well as exporting it. The works extended in an arc northwards up the coast from Ravenscar to Saltburn and inland round the scarp face of the Cleveland Hills, past Guisborough, to Osmotherley with outliers in the valley of the River Esk.
From ‘A Tour Through the Manufacturing Districts of England in 1835’ by Sir George Head.