Faraday to Peter Henry Berthon   13 April 1864

R Institution | 13 April 1864.

Dear Sir

Having examined the specimen of White lead which you sent¹ one marked 1864 A. I find it free from heavy earth or sulphate of baryta or any other of the substances usually added to make weight discoverable by chemical means. The small quantity of extraneous matter present cannot be counted as an adulteration[.]

I am Sir | Your Very faithful Servant | M. Faraday

P.H. Berthon Esqr | &c &c &c