Page:Popular Science Monthly Volume 20.djvu/442

428 and set at a slight angle to each other, "twisted around the axis without losing their rectilinear shape," and terminating in a broad spiral. The feet are furnished with long hoofs similar to those of the sheep, and are curved at their points; and this arrangement, together with the sedentary habits of the animal, renders this remarkable ruminant unfitted for running. "Its life is therefore, in a great measure, passed in the water, it never straying far from the river-banks, on to which it crawls for pasture, and then chiefly in the night-time. It sleeps and reposes in the water. Its diving powers are equal, if not superior, to those of the hippopotamus. During sleep it comes near to the surface of the water, so as to show half its horns above it. It is very timid by nature, and plunges to the bottom of the river at the slightest symptom of danger. It can easily be captured and killed, so that the natives hunt it successfully, turning to account its magnificent skin and feeding off its carcass, which is, however, but poor meat. Upon leaving the water for pasture, its little skill in running allows the natives to take it alive; and it is not dangerous even at bay, like most of the antelope tribe. The female, as well as the male, is furnished with horns. There are many points of contrast between the life of this strange ruminant and that of the hippopotamus, its near neighbor. The rivers Cubangui, Cuchibi, and the upper Cuando offer a refuge to thousands of quichobos, while they do not appear either in the lower Cuando or the Zambesi. I explain this fact by the greater ferocity of the crocodiles in the Zambesi and lower Cuando. which would make short work of so defenseless an animal if it ventured to show itself in their waters."

Does Sea-Water contain Free Carbonic Acid Gas?—M. P. Martin Duncan maintains that carbonic-acid gas is not present in seawater in a free state, and cites in support of his view Tornö, of the Norwegian Deep-Sea Expedition, who has been quoted, erroneously it seems, on the opposite side. It appears from a careful examination of Tornö's essay that that author, in the course of his experiments, found that sea-water had an alkaline reaction, and then began to believe that the carbonic-acid gas which had been taken from the water in other experiments had been produced by the decomposition of neutral carbonates during the boiling. He then proved by experiment that the saline mixture in sea-water, on the temperature being raised to the boiling-point, decomposed neutral carbonates, and that all previous experiments for measuring the carbonic-acid gas in sea-water had been faulty. Of ninety-seven milligrammes of gas per litre of water found in one specimen, he estimated that about fifty-three milligrammes entered into the formation of neutral carbonates, and that the remaining forty-four milligrammes, instead of occurring free as gas, united with the carbonates to form bicarbonates. In one passage of his essay he speaks of sea-water as "an alkaline fluid which does not contain the smallest trace of free carbonic acid."

Photometry.—M. J. Janssen attaches importance to the application of photography to photometric measurements. It not only permits the registration of all the visible rays, but also reaches the ultra-violet rays, and is competent to give valuable ideas relative to the temperature of bodies. While ordinary photometric comparisons between two sources of light are essentially fugitive, and require the simultaneous presence of both bodies, photography furnishes permanent terms of comparison which we may bring to bear whenever we will, and may even bequeath to the future. The relative photogenic intensities of two different sources may be easily ascertained by causing them to act in succession on two similar plates. Comparisons of the photographic power of the sun and a star may be made directly, but it is necessary to obtain an image of the star of perceptible dimensions; this may be done by putting the plate on which the image is to be received out of focus, so that the rays from the star, instead of falling upon a point, shall form a small circle of light.

Disinfection of Alcohol.—M. Naudlne recently described to the Chemical Society of Paris a method which he had discovered for relieving alcohol of the bad taste it often acquires from the substances from which it