Faraday to Peter Henry Berthon   16 February 1858

Royal Institution | 16 Feby. 1858

Sir

I beg to report to you the results of the Analyses of the ground White leads received on the 10th instant1. I have had to delay these & partly in consequence of my desire to be quite sure in respect of the adulterated sample.

No.I. (Pilcher & Sons 8 Feb 1858).

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The Sul baryta was very white - it appears to enable the mixture to take up more oil without settling out at the top

No.II. H. Grace2 Bethnal green (Feb 1858)

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No.III. Tudor3 (Feb 1858)

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Clear oil. settled out at the top of this specimen

No.IV. Pontifex Wood

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There was no other impurity in any of the samples except the mere traces which are inevitable in all manufactured articles. I do not like to see Sulphate of baryta even in so small a quantity as 0.8 per cent because it seems to show that the adulteration is sometimes present in the mills. I suppose however that some instances require an adulterated article occasionally. The quantity of oil held by the sample No.I. is retained by the presence of the baryta. The next large quantity in the pure preparation No.III separated partly in small clear portions at the surface4[.]

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

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

2
Henry Grace. White lead supplier of Hollybush Gardens, Bethnal Green Road. POD.
3
Samuel and William Tudor. White lead suppliers of 166 and 167 Upper Thames Street. POD.
4
This letter was read to Trinity House Wardens Committee, 23 February 1858, GL MS 30025/25, p.299. It was agreed to place the order with Pontifex.

Please cite as “Faraday3395,” in Ɛpsilon: The Michael Faraday Collection accessed on 28 April 2024, https://epsilon.ac.uk/view/faraday/letters/Faraday3395