Faraday to Jacob Herbert   30 January 1843

Royal Institution | 30th January 1843.

Dear Sir,

The Water which you sent me from the Well at the Wharf, came to me in a turbid state, but on standing awhile became quite clear, having deposited a portion of peroxide of Iron, as if the water were naturally a chalybeate. I will refer to this Iron hereafter, and now speak of the clear water.

This Water is excellent in taste and smell, and contains only a small proportion of Saline matter, for one pint yields but four grains of dry Salts; there is very little of Sulphates or Muriates present. Such character as the Water has from it's saline contents is given by carbonates and carbonic acid; for there is present carbonate of Lime and also carbonate of Magnesia in small quantities, held in solution by carbonic acid, so that when the water is boil'd, these earthy carbonates are separated, and fall down in a white flocculent form, and only a little carbonate Sulphate, and muriate of alkali is left:- the consequence is, that though the Water cannot be consider'd as ranking amongst hard waters, still it becomes more soft by boiling. The magnesian Salt, though not usual in such waters, does not do harm to the water here, because of it's small proportion, and probably may conduce to give it a more healthy character, as a water for drinking.

As to the Iron; it is possible that the Water may be a weak chalybeate at the place where it leaves the earth to enter the pump and Well Tubes; but I have a strong belief that the Iron which it has, it takes from the Works at the Well. I have been to the Well, and examined the Water by tests there. On opening the Well, I found that kind of smell in the enclosed air which consisted with an action of the Water upon the Iron. On bucketting some Water up out of the Well, it was found to contain Iron in solution. On taking some water out of the Wharfpipes, it also contain'd Iron in solution, but less than the former. On examining the Water from the top portion in the Tank, there was scarcely a trace of iron in Solution; and on examining some which had been standing in a Jug for two or three days, there was none in solution, all the Iron having been deposited as red oxide:- such was the case also with that I received.

The sum of the facts therefore as regards the Iron is as follows,- The Water comes from the Well in the first instance a true chalybeate, whether it have the Iron originally, or obtain it from the cylinders which it passes through; but this Iron is very soon completely separated by exposure to the air, and deposited entirely as a rusty sediment, and then the Water is an excellent Water for all domestic purposes¹.

I am | My dear Sir, | Your very obedient Servant | (sign'd) M. Faraday