Faraday to William Francis Cowper   12 March 1860

Royal Institution, 12 March 1860.

Sir,

In relation to the preservation of the stonework of the New Palace of Westminster, I hope you will do me the favour to refer to a letter on the subject of Mr. Szerelmey’s process, which I wrote to the late Chief Commissioner¹ on 1st July 1859²; it will make it unnecessary at this time to refer to anything more than the two bays, to which the attention of Sir Roderick Murchison and myself have been directed³. Mr. Ransome prepared the south bay, which I will call No. I.; Mr. Szerelmey prepared the north bay, No. II.; both were cleared of the loose surface by hard brushing, &c., and then dealt with. The time which has elapsed is about six months; and if the processes are of any value, is hardly sufficient to show a difference due to weather.

Compared together, I. has more of the natural colour and appearance of the stone than II.; it is softer, wets immediately, and by degrees the water is absorbed. No. II. is darker, an effect due to the varnish-like character of the last coat applied; is harder, and does not absorb water; the fluid runs from off it. The repellent coat appears to have much permanency, for alcohol and turpentine do not disturb it.

Though the time of trial is short, there is a place where, I think, evidence of difference appears. At a part of the wall having this form rain droppings have fallen on the part below 5, whilst that above has escaped; consequently the stone 3 has suffered more than 4; and this is very evident in many of the untouched bays. In the prepared bays (where the loose surface had been removed before preparation) I looked for a six months difference at these parts. In the bay II. I could find no sensible difference between the parts 3 and 4, both were equally hard and good in character; in the bay I., 3 was softer than 4.

I do not find in other parts of the building, where Mr. Szerelmey’s application is more than two years old, any signs of exfoliation, or separation of the prepared face of the stone; or any ground for fears in that respect. On the whole, therefore, and though the time of comparison is short, my belief is that his process will prove to be the best.

Though ever ready to aid the Government when it lies within my power, I am not professional. May I therefore be permitted to ask as a favour, that my opinion should not be communicated to either of the parties concerned to serve trade purposes.

I have, &c. | (signed) M. Faraday

The Right Hon. W. Cowper, M.P.