TO JOHN HENRY VIVIAN, ESQ.
London, Jan. 9, 1822.
MY DEAR SIR,
As you expressed a wish that I should commit to writing those opinions which I mentioned in conversation, when I had the pleasure of visiting you at Marino, after inspecting your furnaces and witnessing your experiments on the smoke arising from them, I lose no time in complying with your desire.
It is evident that the copper ore cannot be properly calcined without a copious admission of air into the furnaces, which must cause the sulphurous acid gas formed in the calcination to be mixed with very large quantities of other elastic fluids, which presents great mechanical, as well as chemical difficulties to its condensation or decomposition.
To persons acquainted with chemistry, a number of modes of effecting these objects are known. Of condensation, for instance, by water, by the formation of sulphuric acid, by alkaline lixivia, by alkaline earths, &c. Of decomposition, by hydrogen, by charcoal, by hydro-carbonous substances, and by metals; but to most of these methods there are serious and insurmountable objections, depending upon the diluted state of the acid gas, and the expenses required.
To form sulphuric acid, or to decompose by charcoal or hydrogen, or to condense by alkaline lixivia, or by alkaline earths, from the nature of the works, and of the operations for which they were intended, I conceive impracticable except at an expense that could not be borne; and the only processes which remain to be discussed are those by hydro-carbonous substances, and by the action of water.
There can be no doubt that the gas may be decomposed by the action of heated hydro-carbonous gases from the distillation of coal; but for this purpose there must be a new construction of the furnaces, and more than double, probably triple, the quantity of fuel would be required, supposing even the Swansea coal to contain the common average of bitumen; and this method must be infinitely more expensive, and liable to many more objections, than the one you have so ingeniously employed—absorption by water.
As water costs nothing, and as a supply is entirely in your power, the application of it offers comparatively few difficulties; and it has the great advantage of freeing the smoke from fluoric and arsenious compounds, which would not be perfectly effected by any other method.
The experiments of MM. Phillips and Faraday prove, that your shower baths have already entirely destroyed all the fluoric and arsenious fumes of the smoke, and by a certain quantity of water, the smoke may undoubtedly be entirely freed from sulphurous acid gas.