JOSEPH ASPDIN AND PORTLAND CEMENT.
To the Editor of The Yorkshire Post.
Sir, — The following facts may be of interest in reference to recent correspondence your paper on the subject of a proposed Aspdin Memorial (Note 1).
In the year 1756, the important action of clays in natural or artificial conjunction with carbonate of lime in the production of hydraulic or water resisting cement was first demonstrated by Smeaton, and utilised by him in the construction of the original Eddystone Lighthouse. (Note 2)
The principle was afterwards applied experimentally by Mr. Vicat, in France, in 1818, and further developed by Pasley and Frost in this country about the year 1826.
Sir C. W. Pasley is said have been the first to use Medway clay in the manufacture of hydraulic cement at Chatham, and very shortly afterwards Frost started the manufacture on a commercial scale at Greenhithe, Kent, on the actual site of the present well-known works associated with Messrs. White.
The patent specification of Joseph Aspdin, the bricklayer, of Leeds, is dated December 15th, 1824, but was clearly anticipated in 1810 by patents granted to Edgar Dobbs, of Southwark, and also in 1818 by a patent granted to Maurice St. Leger, of Camberwell. In all these patents the claim relates to the manufacture of cement by a suitable mixture of lime or carbonate of lime with clay or other substances containing alumina and silica; the mixture being afterwards burnt in kilns and ground to powder.
It is, however, certain that neither Joseph Aspdin nor his predecessors attempted to burn the mixed materials to the point of vitrefaction (sic) - an essential feature in the manufacture of what is now known as Portland cement. This appears to have been first adopted by a son of Joseph Aspdin (Note 3), who about 1828-39 (Note 4) was engaged at the works known Robins's, at Northfleet, in Kent, now the property of the Associated Portland Cement Manufacturers (Limited); at these works the kilns erected by the younger Aspdin are still in existence (Note 5). The materials used were the local chalk and alluvial clay still employed in the neighbourhood by the largest makers Portland cement.
At an early stage the manufacture as carried on at Northfleet was developed and improved upon (Note 6) by Messrs. White, the successors of Frost at Greenhithe, and by Messrs. Francis, at Cliffe, and Hilton and Anderson, on the Medway.
So far as Joseph Aspdin is concerned, apart from the name "Portland cement," which he adopted in his specification from a fancied resemblance of the cement to Portland stone, he can only be said to have worked somewhat crudely on the lines of his predecessor and contemporaries, and the material which he produced artificially manufactured hydraulic lime.
We may, however, be content in recognising that Portland cement is essentially an English invention, which has been developed to the degree of excellence now attained by the best makers in the country and locality of its origin.
The memorial of its founders may be seen in the great constructive works of the last half-century throughout all parts of the world, and that its pioneers are still abreast of the times is evidenced by the fact that the most extensive modern plant in Europe is now in operation at White's works at Greenhithe, where Frost made his experiments, and in close proximity to the old kilns of Robins's works, where Portland cement was first produced on a commercial scale.
W. ILLINGWORTH. (Note 7)
Popplewell's Chambers, 9. Market Street, Bradford.