Faraday to Jacob Herbert   26 February 1848

Royal Institution | 26 Feby 1848

My dear Sir

The specimen of Bardsey water which I received from you about ten days ago¹ is free from the peculiar organic matter which I mentioned in my letter of the 13th of January 1847². The extraordinary deposit of Carbonate of Magnesia in the bottle described in my letter of the 14th April 1847³ is also absent in the present case. The water now is brown from the presence of a little organic peaty matter in it and it is hard from the presence of common salt, muriate of magnesia & lime sulphate of lime & a little iron. It contains so much saline matter as to be bad for washing and is for domestic purposes a water not to be desired but I cannot say absolutely that it is unwholesome. The water however appears liable to great changes in its character at different seasons & under different circumstances and being a surface water this is natural enough. The common & magnesium salts in the present instance are derived from the spray of the sea & may continually change in their amount. If the Magnesia which occurred in the case of the last specimen (letter 14th April) was really derived from the water as then existing such a liability would make me decide that the supply was unwholesome but I think the deposit must have been in the bottle before the water was introduced[.]

I am My dear Sir | Very Truly Yours | M. Faraday

Jacob Herbert Esq | &c &c &c