Part 21

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.

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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--

Carbonate of lime, with a little oxide of iron 14·58 Carbonate of magnesia 0·44 Sulphate of lime 1·54 Chloride of sodium 1·71 Silicic acid 0·32 Organic matter 0·72 ----- 19·31

Like the preceding water it became turbid when heated to the boiling point, and by continued ebullition for two hours, 12·90 grs. of carbonate of lime, coloured by oxide of iron, were precipitated.

Hardness in reference to distilled water as unity = 19.

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C. This water was taken by ourselves from a spring-head near Haslemere, Surrey. The spring issued from the foot of a low sand-hill covered with bushes, and was received into a natural basin about four or five feet in diameter, the bottom of which was lined with pebbles and small gravel. From this basin the water flowed into a large shallow pond.

The temperature of the spring at its source was 49° Fahr., that of the air being 56° Fahr.

This water was perfectly clear and brilliant, but not sparkling. It had no appreciable taste, but was peculiarly soft and agreeable. It did not contain carbonic acid in a free state, for when mixed with a solution of chloride of calcium and of ammonia not the slightest turbidity was produced. When boiled it did not lose its transparency, nor produce any deposit, until concentrated to about one-sixth of its volume, when glittering scales of hydrated silicic acid separated.

An imperial gallon, when evaporated to dryness, left a solid residue, which weighed 5·24 grs.

This residue was perfectly white when dried at 300° Fahr.; when heated to low redness, it charred slightly at the edges. The quantity of organic matter was therefore exceedingly small.

Hardness in reference to distilled water as unity = 2·4.

On analysis, an imperial gallon was found to contain--

Carbonate of lime 2·00 Chloride of sodium 1·46 Sulphate of soda 0·407 Silicic acid 1·143 Organic matter 0·23 ----- 5·24

Traces of an alkaline nitrate were also detected.

During the short visit I made with you to Farnham, we examined several other springs near to their sources. In their general characters these waters closely resembled the preceding sample, all of them being remarkably soft, clear, transparent, inodorous, and free from any excess of organic matter, or of oxide of iron.

By your desire two samples were subsequently sent to me; one marked ‘Barford,’ the other ‘Boorley.’

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.

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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.