Faraday to Thomas Leverton Donaldson   25 May 1837

Royal Institution | 25 May 1837

My dear Sir

I send you back such parts of the specimens of lead from Earl de Grey¹ as I have not used and now give you my impression in the form of an opinion only for I cannot go further: that opinion is that the lead has not suffered from being laid down upon prepared wood more than it would have suffered if laid down upon common wood other circumstances being the same²[.]

In the first place the adhering crust is as relates to the lead in it in the state of carbonate of lead. There is no mercury in it; nor in the surface of lead next to it; nor is there any chlorine in the crust. From Lord de Grey's note I understand that after the lead was laid down men were walking over it & work going on about it; now on removing as much of the crust as weak acid will take up so as to expose the form of the roughened surface of the metal that form appears to me to be more like that which would be given by pressure over particles of dirt &c than one honeycombed by corrosion of the metal[.] In fact in many of the little depressions the insoluble dirt remains after the acid has removed what it can dissolve, and shows that it has given shape to the cavity in which it is placed[.]

I cannot tell what degree of corrosion lead under common circumstances, i.e circumstances under all respects the same except the preparation of the wood, would have suffered; but I have often seen lead as much affected as that you sent to me. On the whole I do not attribute any of the action to the preparation of the wood; and though it is difficult to prove a negative, and I in this case do not pretend to prove one, still I should have no fear of using prepared wood under such circumstances[.]

It is not quite out of place to remind you that the congruent action of air & water is vastly greater on lead when the water is pure than when a little saline matter is present in it[.] This we can prove over & over again[.] Suppose lead were lying upon a wet board containing quite pure water; it would be more corroded than if the board had been prepared by being dipped into a weak saline solution[.]

Ever Dear Sir | Very Truly Yours | M. Faraday

T.L. Donaldson Esq | &c &c &c