Faraday to John Barrow   5 June 1837

Royal Institution | 5 June 1837

Sir

I received in due time some sheets of iron from Commander Crawford¹ [sic] coated in the same manner as the former pieces and proceeded to experiment upon them²[.]

I first tried them in dilute acid and in that case did not find that the prepared plates were any way superior to good tinned iron plates[.]

I then tried them in a solution of salt of about twice the strength of sea water; the comparison being here between the prepared plate, common tinned plate, and sheet copper. These trials have as yet continued for a fortnight only; but for that time the prepared plate exhibits considerable superiority[.] It is a little acted on but its iron has not suffered. The tin plate has had its iron very much acted on at the edges; and the copper plate has suffered all over its surface[.]

These trials are not as yet of sufficient extent as regards time: and the results with the dilute acids may not properly be taken as shewing what continued time & sea water would effect[.] The impression on my mind at present is, that the prepared plate will resist the action of sea water much better than tinned plate and perhaps better than unprotected copper. But there is also the probability that if on a ship's bottom plants & animals would adhere abundantly to it.

The iron plates are prepared by being first coated with zinc & then covered with tin[.]

I have the honor to be | Sir | Your Obedient Humble Servant | M. Faraday

Sir John Barrow | &c &c &c &c

Endorsement: 9 June Ack recd and thank him JB June 9th

Acquaint Capt Craufurd 2 Charles St Berkeley Sq 12th June