John Stevens Henslow to Faraday   5 January 1851

Hitcham Hadleigh | Suffolk | 5 Jany 1851

My dear Sir,

I shall be most careful in unpacking the box¹. I know of old what a disagreeable inmate is Bromine. I had some in a glass stoppered bottle which gradually evaporated & attacked several minerals in the same drawer. I do not mention it that you should think of repeating the preparations of this & Chlorine - but the thought strikes me a globe, rather than a tube, would be the best way of securing mass enough to see the colour of the gases.

I have had some correspondence with the assayer, & have asked his advice about the mode of securing the metal disks.

My idea is to procure a number of square blocks of wood, all of the same size, & coat them with some (?) varnish, which may serve as a cement to the disks, the glass covers, & keep out the air. This would admit of ready re-arrangement in an additional covering of a glass case large enough to contain the whole series. Perhaps one of the simplest arrangements would be to take either the S.G’s, or the Atomic Weights, leaving such as are not known at the bottom of the series. According to intrinsic values I have suggested disks of 4 sizes suitable to 1.oz - 1/2oz - 1/4oz - 1/8oz. I never saw Silicium, & do not know whether it can be thus exhibited. As for carbon I suppose a very small diamond would be the best specimen - with a sample of charcoal? or plumbago? - or these latter are hardly pure enough. I see the Assayer has some of the Earths also - & it will be as well to have a selection of such as are common, as an introduction to the geological series.

Believe me | Very sincerely Yours | J.S. Henslow

Address: M. Faraday Esq | Royal Institution | Albemarle | London