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THE POPULAR SCIENCE MONTHLY. 



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 remark- 

 able 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 past- 

 ure, 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 success- 

 fully, 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 qui- 

 chobos, while they do not appear either in 

 the lower Cuando or the Zambesi. I ex- 

 plain this fact by the greater ferocity of the 

 crocodiles in the Zambesi and lower Cuan- 

 do. which would make short work of so de- 

 fenseless 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 sea- 

 water in a free state, and cites in support of 

 his view Torno, of the Norwegian Deep-Sea 

 Expedition, who has been quoted, errone- 

 ously it seems, on the opposite side. It ap- 

 pears from a careful examination of Tor- 

 no's essay that that author, in the course of 

 his experiments, found that sea-water had 

 an alkaline reaction, and then began to be- 



lieve that the carbonic-acid gas which had 

 been taken from the water in other experi- 

 ments had been produced by the decomposi- 

 tion of neutral carbonates during the boil- 

 ing. He then proved by experiment that 

 the saline mixture in sea-water, on the tem- 

 perature 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 milli- 

 grammes entered into the formation of neu- 

 tral carbonates, and that the remaining 

 forty-four milligrammes, instead of occur- 

 ring 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 photog- 

 raphy to photometric measurements. It 

 not only permits the registration of all the 

 visible rays, but also reaches the ultra-vio- 

 let rays, and is competent to give valuable 

 ideas relative to the temperature of bodies. 

 While ordinary photometric comparisons be- 

 tween two sources of light are essentially 

 fugitive, and require the simultaneous pres- 

 ence 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 rel- 

 ative photogenic intensities of two different 

 sources may be easily ascertained by caus- 

 ing 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 dimen- 

 sions ; 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 





