OF ARTS AND SCIENCES. 177 



" The fishlike odor was mostly retained by the filter, which had not 

 been the case in the earlier experiments, and it became easy to sep- 

 arate 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 fugi- 

 tive green color at times, but the dried filter, extracted by ether, afford- 

 ed 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 dis- 

 appeared. 



" 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 yellowish- 

 brown oil, some were filled with colorless oil, and not a few had oil 

 apparently of a blackish blue, shading to indigo blue. This fact ex- 

 plains 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 sub- 

 stance but those named, and animalcula, was found among numerous 

 collections, which could afford oil ; the connection between the chem- 

 ical 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 under- 

 taken 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 difTerent 



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