Faraday to Peter Henry Berthon   28 February 1862

Royal Institution | 28 Feby 1862

Sir

I received from you four samples of White lead¹ labled [sic] as follows

No. I Grace & Co²

II. Pilcher & Son

III. Pontifex & Wood

IV. S & W. Tudor

The oil in these was not very different No. IV contained the least being 6.8 per cent. No. II the most 9.4 per cent[.]

Nos. III & IV contained the least impurity & what little there was was no doubt accidental - No. II contained 0.4 per cent which was not white lead - nor Sulphate of baryta - No. I however contained 1.8 per cent of Sulphate of baryta or heavy earth - it may have been accidental but if so I think must have crept in from mills used to grind this substance³[.]

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

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