Faraday to Robert Alsop¹   3 May 1828

Royal Institution, May 3, 1828.

Sir, - I have examined and analysed the mixed salt which you sent me, and find that 78.3 grains of it, after being dissolved in water, afford very nearly the following proportions:-

Carbonic acid (free) - - - - 2.56 grains

Carbonate of soda - - - - 0.5

Chloride of sodium - - - - 41.3

Sulphate of soda - - - - 22.7

Sulphate of magnesia - - - 6

(Sulphate of lime, absent from this specimen by design.)

Protoxide of iron - - - - 0.8

Water - - - - - - 4.44

I am also satisfied that when the salt is put into a sufficient quantity of water, the whole of the iron is dissolved, being retained in solution by carbonic acid; and I think that your method of bringing the protoxide into solution, and uniting its presence with that of free carbonic acid, is a very excellent one.

I am, sir, your obedient servant, | M. Faraday.

Mr. Alsop.