“Have you any evidence to show that sewer-water does contain sulphuretted hydrogen in such large quantity as to be prejudicial and even fatal to animal life?” “With a view of determining this question, I made the following experiments:—A given quantity of Thames water, known to contain living infusoria, was added to an equal quantity of sewer-water; examined a few minutes afterwards, the animalculæ were found to be either dead or deprived of locomotive power and in a dying state. A small fish, placed in a wine glass of sewer-water, immediately gave signs of distress, and, after struggling violently, floated on its side, and would have perished in a few seconds, had it not been removed and placed in fresh water. A bird placed in a glass bell-jar, into which the gas evolved by the sewer-water was allowed to pass, after struggling a good deal, and showing other symptoms of the action of the gas, suddenly fell on its side, and, although immediately removed into fresh air, was found to be dead. These experiments were made, in the first instance, with the sewer water of the Friar-street sewer (near the Blackfriars-road); they were afterwards repeated with the water of six other sewers on the Middlesex side, and with the same result, as respects the animalculæ and fish, but not the bird; this, although evidently much affected by the noxious emanations of the sewer-water, yet survived the experiment.”
“Would you infer from these experiments that sewer-water, as contained in the Thames near to London, is prejudicial to health?” “I would, most decidedly; and regard the Thames in the neighbourhood of the metropolis as nothing less than diluted sewer-water.”
“You have just stated that you found sewer-water to contain much vegetable matter, and but few forms of animal life; the vegetable matter you recognised, I presume, by the character of the cells composing the several vegetable tissues?” “Yes, as also by the action of iodine on the starch of the vegetable matter.”
“In what way do you suppose these various vegetable cells, the husks of wheat, &c., reach the sewers?” “They doubtless proceed from the fæcal matter contained in sewage, and not in general from the ordinary refuse of the kitchen, which usually finds its way into the dust-bin.”
“Sewer-water, then, although containing but few forms of animal life, yet contains, in large quantities, the food upon which most animalculæ feed?” “Yes; and it is this circumstance which explains the vast abundance of infusorial life in the water of the Thames within a few miles of London.”
The same gentleman (a fellow of the Linnæan Society, and the author of “A History of the British Fresh-water Algæ,” or water-weeds considered popularly), in answer to the following inquiries in connection with this subject, also said:—
“What species of infusoria represent the highest degree of impurity in water?” “The several species of the genera Oxytricha and Paramecium.”
“What species is most abundant in the Thames from Kew Bridge to Woolwich?” “The Paramecium Chrysalis of Ehrenberg; this occurs in all seasons of the year, and in all conditions of the river, in vast and incalculable numbers; so much so, that a quart bottle of Thames water, obtained in any condition of the tide, is sure to be found, on examination with the microscope, to contain these creatures in great quantity.”
“Do you find that the infusorium of which you have spoken varies in number in the different parts of the river between Kew Bridge and Woolwich?” “I find that it is most abundant in the neighbourhood of the bridges.” [Where the outlet of the sewers is common.]
“Then the order of impurity of Thames water, in your view, would be the order in which it approaches the centre of London?” “Yes.”