Having, by your desire, submitted the following samples of water to chemical analysis, I now beg leave to lay before you the result; and also, at the same time, to reply to certain questions which you likewise proposed. The samples of water taken for examination were derived from the following sources:-- A. Water supplied by the New River Company. B. Water supplied by the East London Company. C. Water from a spring in the neighbourhood of Haslemere, Surrey. D. Water from a well in Bishopsgate-street. A. This water was taken from an upright pipe in a court-yard of the Guildhall. It was slightly opalescent, inodorous, and tasteless; numerous small particles floated in it, which took a considerable time to subside. The matter deposited was of a rust colour, and consisted of peroxide of iron, with a little sulphate and carbonate of lime, and organic matter. It is to be observed that, as the water from this pipe is seldom used, these impurities collect in the pipe, and are therefore in some measure accidental, although, prior to collecting the water, a considerable quantity had been allowed to run away. The water was allowed to free itself from these impurities by subsidence, before being submitted to analysis. By evaporation to dryness, an imperial gallon left a solid residue, weighing 17·33 grs., which consisted of-- Carbonate of lime, with a little oxide of iron 11·12 Carbonate of magnesia 0·60 Sulphate of lime 1·56 Chloride of sodium 2·40 Silicic acid 0·37 Organic matter 1·19 ----- 17·24 When heated, this water became turbid; and, by continued boiling for two hours in an apparatus so arranged that the whole of the steam was condensed and returned to the water, 10·95 grs. of the earthy carbonates, coloured by oxide of iron, were deposited. The relative hardness of this water, as determined by the soap test, distilled water being taken as unity, was 13·3. * * * * * B. The second sample of water was taken from a small tap in the house of Mr. Hall, Bishopsgate-street. The tap was attached to the main. This water was without smell or taste, and free from floating matter. After standing some time, it deposited a very small quantity of oxide of iron. Although clear and transparent, it was not bright. It contained 19·10 grs. of solid matter in the imperial gallon. The solid matter consisted of--