Engraving by E D Clarke of men making tar from pine trees in a Swedish forest, with barrels and tools in the foreground. Primarily used to preserve the wood used to make boats, the tar is extracted from pine trees through a proces of burning the tree's roots with peat and turf. The resulting product is high in turpentine and is transported in barrels labelled 'Stockholm'. Tar became one of Sweden's most profitable exports with even the worst quality tar from Sweden being considered better than that deriving from Rusia and Finland. From a collection of prints and books documenting the early history of the gas industry amased by Sir Arthur Elton.
© Science Museum / Science & Society Picture Library