between which a fall of 700 feet took place. These specimens were likewise found to be nearly identical in composition, with neither the carbon nor the nitrogen diminished by the aëration consequent upon the fall. The introduction of mineral matters often produced very much greater effects than it was possible to show to be connected with aeration, and which varied in a considerable degree according to the nature of the matters added. From his experiments on this point, Professor Hartley derives the conclusion that the peaty coloring-matter in water "acts like an organic acid, and that it is probably a body of the type of alizarine or litmus, and is only slightly soluble, or is even insoluble in pure water, but is readily dissolved in water containing traces of alkali, or of soluble carbonate, such as ammonia or potash. With metallic oxides, iron and alumina, it forms insoluble compounds of the nature of lakes. Lime-water also precipitates it. Mineral acids, sulphuric, hydrochloric, and nitric, precipitate it. Peaty water may be perfectly bright and free from turbidity. These facts, and a further observation that subsidence will not clear a peaty water of its coloring-matter, lead to the conclusion that the coloring-matter is held in solution, and is precipitated as a lake, by various mineral bases." These conclusions are applicable to organic matter of a peaty character only.
Traits of Ancient American Civilization.—Max Steffer, in a recently published book on the "Agricultural Economy of the Civilized Ancient American Peoples," declares that it is really shameful to our boasted Caucasian superiority that European agency, instead of advancing the civilization of those nations, utterly destroyed it. The relics we have of them represent the vestiges of a civilization which in its way not only yielded nothing to that of the avaricious Spaniards, but in many respects surpassed it. They furnish evidences of a thorough systematic regulation of affairs, and of the cultivation of the soil by steady industry, with careful foresight and skilled practice. The Mexican people had secured an irrigation of the soil by means of canals without machines, to which the only counterparts in Spain were the works, not more ingenious, which the Moors had left; and the Spaniards betrayed their incapacity to appreciate the value of such constructions by allowing them to go to ruin, and sometimes destroying them in the expectation of finding golden water-pipes within them. The cultivation and irrigation of the soil were matters of public interest, and agriculture was placed under similar regulations to those which prevail in China and Japan. The division of the land and all changes in possession were made under the direction of the magistrates. Many conditions in the details of management were similar to those prevailing in Japan. Both people were without yoke-animals, and their estates were so small, and their manner of living such, that the employment of such animals was not necessary. The cultivation was rather that of the garden than of the field, and, as animals were not kept, the additional land they demand was not required. In the absence of domestic animals, minute and painstaking devices to get manure, like those prevailing in China, were adopted. The Peruvians enjoyed an advantage in having guano. Like the Eastern Asiatics, the ancient Americans also had no milk, although they possessed in the llama an animal that might have furnished them that aliment, with all its products.
Hints on Furnace-heating; and Ventilation.—Mr. E. S. Philbrick, C. E., of Boston, has given some useful hints in "The Sanitary Engineer" on the management of heating apparatus and furnace-ventilation. If the air-box of the furnace is not opened after a wind subsides, if it is not open enough at any time, or, if, during windy weather, the air-box is not large enough to supply all the demand, the air is often taken by natural laws from one room down to the furnace and through it, to supply another room. The former room then becomes cooled off. In the last case the rooms on the windward side of the house are always the ones cooled, for it is hard to force the air into them from the hot-air pipes, unless an open fire is supplied to draw off the surplus pressure. Open fireplaces are efficient, generally, in promoting the comfort of the family, even if no fires are lighted in them. Air can not be induced to enter a tight room unless some