away so long as the pores remained open. Removing the cotton filter, the charcoal was allowed to drain, the water displaced by alcohol, and the alcohol by sulphuric ether, without removing the coal. Some oil was found in the alcoholic fluid, while the aqueous ether was colored by it some tint of yellow, to a light olive color. By evaporation at 90° to 100°, the ether left some globules of fluid oil, but by far the larger bulk of residue was a soft solid in granules, without crystalline form. By warming this solid with a little acid, a base was dissolved, generally lime, or lime and ammonia, while the oil floated on the fluid and was left by evaporation of the water. As thus obtained, this oil was of a light yellow color, presenting both oleic and stearic acids. Its specific gravity was the same as that of lard-oil. Alcohol dissolved it without residue. A solution of carbonate of soda saponified it when warmed; proving the acid condition of the oil. With sulphuric acid it blackened, and chlorine changed its color to dark brown. The oil, as separated from the ethereal solution in different experiments, assumed a solid state at 80° or 90° F. Acids eliminated oily fluids constantly, with the emission of a peculiar odor. Treated with carbonate of soda when the soap was decomposed, an odor resembling that from adipocere was perceptible, generally. When the charcoal, while wet from the water, was distilled, the vapor which was first condensed had a strong fish-like odor. It would putrefy and run through the changes, resulting in the production of confervæ.

"The mass of the water supply was constantly changing from its state of approach to putrefactive fermentation in which free crenic acid and crenates appeared, with a large volume of carbonic acid to its more nearly normal state. At one time, twenty-eight volumes of water evolved, by boiling, one volume of gases. Twenty-five volumes of the gases were diminished only one volume by phosphorus warmed and left twenty-four hours; or about four per cent. of oxygen, seventy of carbonic acid, and twenty-six of nitrogen. Such a gaseous atmosphere dissolved in the water could not support animal life, in the higher forms of organization. As the oxygen gas increased in volume, the apocrenates and humates appeared, and the water, which had no action on iron, assumed its ordinary action on this metal. The crustacea increased in quantity and size, the cyclops and daphnia became predominant, and the cotton filters were soon closed by their bodies. Attention was now given to the mass collected on the filter, as had already been done with the sponges and some vegetable organisms, including confervæ.

"The fishlike odor was mostly retained by the filter, which had not been the case in the earlier experiments, and it became easy to separate from the gelatinous mass on the cotton the oil with the odor, or apart from it. As separated from this mass, the oil possessed a fugitive green color at times, but the dried filter, extracted by ether, afforded a yellow oil. The variations in color were found to be due to the state of the matter on the filter, which, evidently of animal origin, decayed rapidly, and the oil and odor became merged in a body, much like adipocere. The water which had been purified by means of animal charcoal was free from taste and odor; its vapor did not possess odor, and the larger part of the organic matter had disappeared.

"As the chief contaminating substance in this water was arrested from a current, by even a coarse filter, and the experiments had been repeated so frequently as to leave little else for chemical trials, I placed in the hands of Dr. John Bacon, for microscopical examination, the substance like that from which the odorous oil had been taken.

"Dr. Bacon at once detected the source of the oil, the bodies of the cyclops and daphnia being in large part filled with it. Ten or fifteen globules, of different sizes, could be seen in a single subject; but the most remarkable fact in this connection is the varied colors of the oil. Under the microscope, while many subjects presented a yellowishbrown oil, some were filled with colorless oil, and not a few had oil apparently of a blackish blue, shading to indigo blue. This fact explains the production of green and olive-green ethereal solutions, and it was found that the decomposing remains were often red and yellowish brown, and then afforded light yellow solutions. No substance but those named, and animalcula, was found among numerous collections, which could afford oil; the connection between the chemical proofs and microscopical observations was most skilfully made by Dr. Bacon, in the way of extracting the oil, while the subject was in the field of the instrument.

"At this point in the research, a series of experiments was undertaken which demonstrated that the fluid oil, first obtained by means of animal charcoal, was really due to broken up and dead crustacea, which were then abundant in the water. Certain modifications of the oil, which had been observed, could be traced to the state of the mass of the crustacea before the ether was used. As collected at the present time from a portion of water by means of filters of different 23

VOL. III.

degrees of fineness, from coarse to very fine, we have the water on one hand free from taste, while the filters retain the matter which rendered the water impure. A portion of this matter placed in pure water gives to it the taste of Cochituate water, while another portion under the microscope presents only living and dead crustacea. Dr. Bacon has kindly recorded his observations, and allowed me to append his account of them to this paper.

"The experimental evidence, having proved the origin of the socalled taste of the water to arise from the presence of an odorous oil contained in the bodies of carnivorous crustacea, there are two practical points to which attention should be called.

"Compared with the water of a pond or lake, where a natural balance exists between the fish, crustacea, infusoria, and subaqueous plants, this water is contaminated by an oily food, which affords subsistence to an unnatural number of crustacea. To restock the lake with several varieties of fish, and by legislative action to protect their growth and increase, seems the proper course to be pursued in correcting the evil. If efficiently carried out, such steps may so improve the quality of the water, that this source of supply will have all the purity of the best known sources, without the variations observed.

"While the impurities exist, it is prudent for families to use for drinking, and, if possible, for cooking, only such water as has been passed through a filter. Even coarse, temporary resorts of this kind will remove much that is offensive, while the better filters will completely purify the water."

Dr. J. Bacon exhibited under the microscope specimens of Cyclops and Daphnia in Cochituate water, containing visible globules of oil, to the great abundance of which was referable the present impurity in Cochituate water, as suggested by Dr. Hayes; and read the following paper, entitled "Observations on the Oil contained in the Crustaceans found in the Cochituate Water."

"The occurrence of numerous transparent globules in the bodies of the minute crustaceans found in the Cochituate water first attracted my notice in the spring of 1854, and I then ascertained by chemical tests that they consisted of oil. Supposing that they were ova in some stage of development, and were probably well known to naturalists, no further observations were made until the bad condition

of the Cochituate water attracted public notice; when I called the attention of one of the chemists employed to analyze the water to the presence of this oil, and suggested that it might be the cause of the evil. But it did not appear probable to either of us that a small amount of oil could occasion so serious an effect; and thus the matter rested until the commencement of the present year, when Dr. Hayes placed in my hands for microscopic examination the gelatinous substance collected by him on cloth filters. The microscope revealed an abundance of oily globules in the bodies of the Cyclops and other minute crustaceans, of which the mass on the filter chiefly consisted; and the source of the oil obtained in his experiments was at once evident. At this time (early in January) very few confervæ or other vegetable organisms were found. The empty siliceous shells of various Diatomacea were abundant, as usual, but scarcely any specimens were living, or contained organic matter. Yet the peculiar flavor of the water was as strongly marked as in the autumn, when Confervæ and other vegetable organisms abounded.

"The crustaceans in which the oil occurs are several species or varieties of Cyclops and Daphnia, and probably other allied genera of the division Entomostraca. In the living animals, the oil is clearly seen, by the aid of the microscope, through the carapace, which is mostly transparent; and is distinguished by its high refractive power, and other optical characters, from the other contents of the shell. It can also be extracted by ether, and still more satisfactorily by strong alcohol, from the body of the animal, while in the field of the microscope. The quantity present is exceedingly variable, not only at different times, but in different individuals collected at the same time. In a few specimens no globules are visible. In others, they are so abundant that the oil forms at least one quarter part of the bulk of the animal. These large quantities occur only in the Cyclops, which is by far the most abundant form present; the other crustaceans contain much less.

"Its distribution in the body of the animal is remarkable, being diffused irregularly in globules of various sizes (usually spherical and occasionally ovoid or pear-shaped), and in masses formed by the coalescence of globules; and it appears to tion with the internal organs of the animal. are seen, even in the last joints of the tail. ible around them, as they occur in the animal, or when liberated by

have no definite connec Sometimes small globules No sac or envelope is vis

tearing the body into fragments. Yet globules lying in contact in the body do not unite by moderate pressure, but regain their form when the pressure is relieved. A strong pressure causes them to run together. These facts are compatible with the absence of a proper enveloping membrane. No structure of any kind is visible in the globules. Their color, when isolated, is generally orange red or yellow; they range, however, from brownish red to an entirely colorless condition, in different specimens. As the carapace has frequently a tinge of red or green, the color of the oil is of course affected when seen through it.

Finding that the comparatively large size of the crustaceans allowed of their almost perfect separation from the other bodies suspended in the water, by means of a suitable filter, a quantity was collected from a Cochituate service-pipe, and thoroughly washed with distilled water. They were then introduced, mostly in a living state, into distilled water, in an open vessel. In about half an hour the water began to acquire an odor, and after some hours both the odor and taste resembled closely the peculiar flavor of the Cochituate. In a day or two a decided fishy flavor was developed. The water was now somewhat milky, and on microscopic examination an abundance of colorless oil globules were seen diffused through it, with some gelatinous matter, derived from the bodies of the dead crustaceans, with the fragments of which, together with exuviæ, the bottom of the vessel was covered. A large proportion were still living and active. In about a week, the water began to regain its clearness, and the odor and taste nearly disappeared. Many of the crustaceans were still alive, and it was noticed that a progressive diminution in the general amount of oil contained in their bodies was evident in the successive examinations.

"In the Cyclops, these globules are found equally in both sexes, and cannot therefore be derived from the ova; in many of the females, the granular ova-masses in the internal ovaries are seen in company with the globules, but they are not in connection, nor is there any indication of a transition from one form to the other. In the Daphnia, the small pellucid globules which constitute the earliest stage of the ova, and also the hibernating eggs, are visible in many specimens, and do not resemble the globules under consideration. The male Daphnia is rarely seen, and I do not know whether the oil is found in both sexes, as in the Cyclops.