The water marked Barford contained 6·30 grs. of solid matter in the imperial gallon; when evaporated, scales of silicic acid separated from it in the same manner as from the water taken at Haslemere. Neither of these waters contained any trace of carbonic acid. Their relative hardness (distilled being unity) was--Barford 2·4, Boorley 1·5. * * * * * D. The fourth sample of water was drawn from the pump near the church in Bishopsgate-street. This water was selected as exemplifying the general composition of the shallow well-water of the City of London, when the well is situated near to a burial-ground, as is frequently the case with the parochial wells. The water from this well is perfectly bright, clear, and even brilliant; it has an agreeable soft taste, and is much esteemed by the inhabitants of the parish, although, as will be seen by the subjoined analysis, it is an exceedingly hard water, and the large quantity of earthy salts it contains renders it unfit for all culinary and for most domestic purposes. When heated to the boiling point, this water becomes turbid, and by continued boiling of an imperial gallon of the water for two hours, 23·03 grs. of solid matter were deposited, consisting of 22·15 grs. carbonate of lime, and 0·88 carbonate of magnesia, with a trace of phosphate of lime. An imperial gallon of this water, when evaporated to dryness and the residue dried at a temperature of about 300° Fahr., left a residue which amounted to 88·07 grs. From another sample of the same water taken a month afterwards, 84·53 grs. of solid residue were obtained. By an analysis, an imperial gallon of the water gave-- Carbonate of lime 28·97 Carbonate of magnesia 2·61 Sulphate of lime 17·85 Chloride of sodium 16·95 Nitrate of potass 12·40 Nitrate of soda 1·50 Nitrate of magnesia 4·92 Nitrate of ammonia 4·01 Silica 0·80 Phosphate of lime traces Organic matter ------ 90·01 The residue left by evaporation was of a light brown colour; when calcined at a low red heat it became slightly charred; but I could not, with any degree of certainty, determine the precise quantity of organic matter it contained: it was certainly very small. The excess of solid matter, as shown by the analysis, over the quantity obtained by evaporating the water to dryness, is owing to the decomposition of the nitrate of ammonia.