“It appears from the table that the granite furnishes little or no magnesia to the water, whilst the quantity from the macadam is considerable.
“On the other hand, the quantity of potash is far greatest in the water derived from the granite.
“The traffic, as was before seen, has a very great influence on the quantity of the soluble salts. It seems also to influence their composition, for we find no carbonates either in the water from the granite, or that from the macadam, where the traffic is little; whereas, when it is great, carbonates of lime and potash are found in the water in large quantity, a circumstance which is no doubt attributable to the action of decaying organic matter on the mineral substances of the pavement.
“ANALYSIS OF THE SOLUBLE MATTER IN DIFFERENT SPECIMENS OF STREET DRAINAGE WATER.
| Grains in an Imperial Gallon. | ||||
|---|---|---|---|---|
| Great Traffic. | Little Traffic. | |||
| Granite. No. 10. | Macadam. No. 6. | Granite. No.12. | Macadam. No. 7. | |
| Water of combination and some soluble organic matter | 77·56 | 29·07 | 22·72 | 13·73 |
| Silica | ·51 | 2·81 | ... | ... |
| Carbonic Acid | 15·84 | 12·23 | None | None |
| Sulphuric Acid | 36·49 | 38·23 | 46·48 | 34·08 |
| Lime | 6·65 | 13·38 | 25·90 | 16·10 |
| Magnesia | None | 23·51 | Trace | 3·50 |
| Oxide of Iron and Alumina, with a little Phosphate of Lime | 2·58 | 1·25 | ... | ... |
| Chloride of Potassium | None | 10·99 | None | 2·79 |
| „ Sodium | 53·84 | 44·88 | 18·44 | 19·70 |
| Potash | 82·76 | 18·27 | 8·75 | 5·23 |
| Soda | ... | ... | 1·58 | ... |
| 276·23 | 194·62 | 123·87 | 95·13 | |
“The insoluble matter in the waters consists of the comminuted material of the road itself, with small fragments of straw and broken dung.
“The quantity of soluble salts (especially of salts of potash) in many of these samples of water is quite as great, and in some cases greater, than that found in the samples of sewer-water that have been examined; and it is open to question and further inquiry, whether the water obtained from the street-drainage of a crowded city might not often be of nearly equal value as liquid manure with the sewer-water with which it is at present allowed to mix.”
With regard to the “ballasted pavement” mentioned by Professor Way, I may observe that it cannot be considered a street-pavement, unless exceptionally. It is formed principally of Thames ballast mixed with gravel, and is used in the construction of what are usually private or pleasure walks, such as the “gravel walks” in the inclosures of some of the parks, and upon Primrose-hill, &c.
Of the Master Scavengers in former Times.
Degraded as the occupation of the scavenger may be in public estimation; though “I’d rather sweep the streets” may be a common remark expressive of the lowest deep of humiliation among those who never handled a besom in their lives; yet the very existence of a large body who are public cleansers betokens civilization. Their occupation, indeed, was defined, or rather was established or confirmed, in the early periods of our history, when municipal regulations were a sort of charter of civic protection, of civic liberties, and of general progress.