Experiments on the Thames, New River, and Hampstead Waters, which in general are in use in the Cities of London and Westminster.
| Subjects employed. | Thames, at Somerset House. | Inferences from the experiments on Thames water. | New River. | Hampstead. |
| Quantity of insoluble matter in one pint, one grain and a half. | Quantity of insoluble matter in one pint, one grain and a half. | In 24 hours discharges air, lets some light sediment fall, and grows clearer. | ||
| Quantity of water used two ounces. | Quantity of water used two ounces. | Quantity of water used two ounces. | ||
| Infusion of campechy wood to a dark orange. | A pink color heighten to crimson. | A calcarious earth dissolved in a marine acid, perhaps something of a volatil alkaly, whence the water appears unfit for the scarlet dye. | A paler pink; but heightens as Thames. | A pink bloom; upon standing heightens; after fades, and comes to the color of old Canary Wine. |
| 1 grain of cochinelle, in powder. | A pink bloom heightens to crimson; fades to a pale muddy purple, letting fall obscure green clouds. | Confirms the preceding experiment. | The same as the Thames water. | A very beautiful crimson; heightens upon standing; in 12 hours suffers no diminution of color. |
| Alcaline lye, 5 drops. | Slight milky cloud; becomes milky all over; a light sediment of pale earth coats the glass, and is found at bottom. | Charged with terrine parts, dissolved by means of an acid; at high water more acid in the water than at low, and the alkaline principle in this river more at low water than at high. | Less milky, with less sediment. | Of alkaline lye used ten drops.--Worked no sensible change in this water. |
| Solution of Soap. | A pearl-colored milkiness, but no coagulation. | Confirms the former observation. | Less milky; no coagulation. | Mixes smoothly, and causes a slight lactescence. |
| A diluted acid of vitriol. | No perceptible change. | Shews an alkaly not predominant. | No sensible change. | Upon standing shews some air bubbles, and seems somewhat brighter. |
| Mercury sublimate dissolved in pure water, 10 drops. | No change; upon standing, a mother of pearl colored pellicle covered the surface; the liquor beneath slightly milky. | The quantity of alkaly inconsiderable. | The same appearance as Thames; rather slighter precipitation. | The same appearance, but rather slighter than any of the other two. |
| A solution of mercury in the acid of nitre. | Pale clouds at every drop; 1st white and milky, then yellowish four drops more got the same color all over; upon standing, a slight pale pellicle arose, and a muddy ochre-colored sediment subsided. | Shews some absorbent earth, by means of an acid, suspended in the water. | The same as Thames, but slighter. | Upon dropping, no change appears; upon standing grows milky, then to a pale yellow, with a slight pearl-colored pellicle; shews no air nor sediment; the glass slightly coated upon standing; precipitated fairly. |
| A solution of lead in distilled vinegar, at every drop as far as 4 drops. | A bright milky cloud, which, growing more opac and white, subsided; upon being stirred, had a milky opacity all over; upon standing, threw up a pale pellicle, and let fall white precipitate. | Confirms the preceding observation. | The same as Thames, but in a lower degree. | The same as New River. |
| A solution of silver in the acid of nitre, 4 drops. | Caused a pearled milkiness; upon standing subsided a violet purple colored precipitate. | Shews some portion of sea-salt, of which the Thames has more at high water than at low. | The same effects, but slighter; the precipitate of a pale violet color. | Pale bluish white clouds; the precipitate, a bluish slate color, thinly covered the sides and bottom of the glass. |
All these waters appear to be sufficiently pure for the common uses of life; the difference between them is very trivial, if any: those of Hampstead approach nearest to the simple state this element is to be wished for. Although it cannot be said to have an immediate relation to this work, yet it may not, perhaps, be disagreeable or useless here to add the quantities of water the cities of London and Westminster, and the adjacent buildings, are daily supplied with.
From the New River Company 57897 Tons per Day.
| London Bridge, | 8500 | |
| Chelsea, | 1740 | |
| Hampstead, | 1200 | |
| York Buildings, | 849 | |
| Hartshorn Lane, | 205 | |
| ——— | ||
| 70391 | Tons required every 24 hours. |