Henry Thomas De La Beche to Faraday   5 November 1838

Swansea, South Wales, 5 Nov. 1838

My dear Faraday

Barry¹, the architect, two others and self, lately made a tour by direction of government in order to enquire into the building-stone capabilities of our land, the more immediate object being to ascertain what material might be most proper to employ in the construction of the new parliament houses². During the trip we obtained numerous specimens, certain chemical and physical experi‑ments on which would appear very desirable for a right understanding of the subject. I have indirectly heard that you have expressed a willingness to help us in this matter, the management of which, as Director of the Museum of Economic Geology has been handed over to me³. Is or is not this news too good to be true? I trust that it is true and that you really will help us; at all events see what is wanted.

1. We have found that the atmosphere acts very differently on buildings and therefore it becomes most desirable to find out, if possible, what difference there may be in the stones employed as regards their chemical composition in the first place. There is no difficulty in distinguishing ordinary mineralogical differences, but more delicate work is required for some materials[.] As for in‑stance, in the case of the magnesian limestones, while some varieties are extremely desirable others decompose very readily. Thus, though both York Minster and Southwell Church⁴ are built of this stone, the former is in a wretched state while the latter is nearly in as good condition as when erected by the Normans.

In the case again of many sandstones in which the grains are composed of quartz, while some are very durable others decompose readily, arising apparently from differences in the chemical composition of the matter cement‑ing the grains of quartz.

2. Even supposing the chemical composition nearly the same it would often appear as if the relative porosity of rocks, that is the relative facility with which they imbibe rain, or permit the atmosphere to enter among their particles, causes much difference in the durability of the stone. Some experiments to ascertain this relative porosity become important.

3. As stone which seems to stand well enough in the country does not last when employed in London, as is the case with the best Portland stone, and any newly employed material in London may do the same, it becomes very impor‑tant to see if there is any thing in the London atmosphere particularly affecting some rocks, such as limestones, which might not affect others in which there is no calcareous matter. Hence if any thing in the London atmosphere may be considered pernicious the specimens might be submitted to an highly dosed with it [sic] and the relative effects observed.

I should observe that Lichens would appear greatly to protect buildings in the country from atmospheric influences while in London buildings would be without that protection - it being supposed that even on the highest parts of S. Pauls, lichens are not found.

4. As some stones resist the action of frost so much better than others, 1st. in consequence of not imbibing moisture so readily as them, and 2dly. by pos‑sessing greater cohesion of parts, experiments to ascertain the relative powers of the specimens to absorb water (both in given short times and when fully saturated) and to see how they respectively resist artificial cold, such as might be considered equal to that of our winters, become valuable and desirable.

5. Experiments to show the relative power of the specimens to resist pressure.

Some fortnight or so since, I wrote to Wheatstone about No. 4 and 5 especially in consequence of a conversation we had at the Athenaeum about 6 [MS torn], but have not yet heard fr<<om>> him. As I asked if he could tell me the part [MS torn] perhaps he is waiting to ascertain it.

Now, my dear Faraday, will you help us, - pray do, - and assist in dissipating some of the confounded jobbery and humbug which has very generally been hitherto practised as to the stone employed in our public buildings - Pray drop me a line about this and send it to me under cover to T.W. Philipps⁵ Esq. &c &c. Office of Woods, &c Whitehall Place, putting your name in the corner of your direction to me.

Ever sincerely yours | H.T. De La Beche

Address: Dr. Faraday | Royal Institution | Albemarle Street | London