April io, 1891.] 



SCIENCE. 



201 



■were also completely eliininaterl, the oxygen having been left in 

 contact under pressure with solid caustic potash for a week. In 

 view of this fact, that oxygen in the liquid state transmits a pre- 

 ponderating quantity of blue light, M. Olszewski's latest experi- 

 ments upon its absorption spectrum are specially interesting. In 

 a former paper to the Monatshefte. an account of which was given 

 in Nature, the absorption spectrum of a layer 7 millimetres thick 

 was shown to exhibit two strong dark bands, — one in the orange, 

 extending from wave-length 634 to wave-length 6.^2, distinguished 

 for its breadth; and one in the yellow, wave-length 581-573, dis- 

 tinguished for its intensity. When the thickness of the layer was 

 increased to 12 millimetres, two further bands appeared, — a very 

 faint one in the green, about wave-length 535, and a somewhat 

 stronger one in the blue, extending between wave-lengths 481 and 

 478. M. Olszewski now tinds that his layer 80 millimeti-es thick, 

 which possesses the blue color, exhibits a fifth band in the red, 

 corresponding with Fraunhofer's A. Tliis band is rendered still 

 more apparent when a plate of red glass is held between the 

 source of light and the slit of the spectroscope. It is stronger in 

 intensity than the band of wave-length 535, but fainter than the 

 other three bands. This observation of the coincidence of an 

 oxygen band with the telluric band A of the solar spectrum is of 

 considerable interest: for Angstrom, in 1864 expressed the ojiinion 

 that this band A was not due to the aqueous vapor of the atmos- 

 phere; and Egoroff and Janssen, who examined the spectrum of 

 long layers of compressed gaseous oxygen, were of opinion that it 

 was due to oxygen. In conclusion, M. Olszewski remarks that 

 the color exhibited by his 30-millimetre layer is exactly what one 

 would expect from the nature of its absorption spectrum. He 

 also suggests that the blue color of the sky may be simply due to 

 the atmospheric oxygen, which in gaseous layers of such extent 

 may exhibit the same color as when compressed into a few centi- 

 metres of liquid. Apart from the discussion of this debatable 

 subject, the fact is certainly of interest to chemists, that ordinary 

 oxygen and its condensation allotrope ozone, when compressed 

 into the liquid state, are thus related as regards color, the former 

 possessing a bright blue and the latter a deep blue tint. 



— Professor Elihu Thomson, according to Engineering of 

 March 27, has recently completed some very remarkable experi- 

 ments on the physiological effects of alternate currents. He Bnds 

 that the danger of the current diminishes as the number of alterna- 

 tions per second is increased. Thus it took twenty times as strong 

 a current to kill a dog when the alternations were 4,500 per sec- 

 ond as when they were 120 per second. When the alternations 

 were 300 per second, the current was only half as dangerous to 

 lite as when the alternations were 120. 



— Traffic in the Suez Canal continues to expand, and now the 

 gross tonnage of vessels using it is about ten millions, and it is 

 interesting to note that Britain continues to own a preponderating 

 proportion of that tonnage. Last year, according to Engineering, 

 3,389 vessels traversed the canal, and, curiously enough, the num- 

 bers were practically equally divided between outward and home- 

 ward vessels. At the Port Said entrance 1,694 vessels passed in, 

 while 1,695 entered the canal at Suez. This total has thrice been 

 exceeded. In 1885 the maximum was reached at 3,624 vessels, 

 and has not been equalled; while in 1888 the number was 3,440, 

 and in 1889, 3,425 vessels. The tonnage, however, shows a steady 

 expansion. It is well known that the average size of English 

 sea-going steamers is increasing, and this is satisfactory for the 

 canal authorities. It does not affect the dues paid for transit, and 

 admits of a larger tonnage passing within a given time. It is 

 found, for instance, that while the number of vessels passing in 

 1885 was 240 more than in the past year, the tonnage now is 

 nearly half a million greater : in other words, the average size of 

 vessels in 1885 was about 1,750 tons, and it is now over 2,000 tons. 

 The transit receipts show clearly the growing popularity of the 

 canal route to the East. In 1869, the first year of the canal, the 

 receipts totalled only £2,076; in the year following they were 

 £200,000; in 1873 they reached £656,300, and five years later this 

 sum was more than doubled. Between 1880 and 1882 there was 

 a great forward movement, the total being increased to £3,421,832. 

 Since then the progress has been neither so steady nor so great 



But during the past three years the upward movement has con- 

 tinued, the total last year being £3,680,436. Of the total tonnage, 

 Britain owns nearly 78 per cent. There has been a great develop- 

 ment in the number of vessels using the canal at night, and navi- 

 gating by the electric light. Of the total number passing through 

 the canal last year, 2,836 went at night, or 48 per cent. The 

 number per month varied from 376 in December last, to 309 in 

 August. In 1887 the night passages were 395, or 13.6 per cent of 

 the total; in 1888, 1.611, or 47 per cent; in 1889, 2,445, or 71.5 per 

 cent. According to Consul Burrell, from whose report to the 

 foreign office these figures have been taken, the average time of 

 transit has been reduced to 24 hours 6 minutes, against 25 hours 

 60 minutes in 1889, 31 hours 15 minutes in 1888, and 36 hours in 

 1886. By night with electricity the passage takes a shorter time 

 than by day, the average last year being 22 hours 9 minutes; in 

 1889, 23 hours 30 minutes; in 1890, 23 hours 34 minutes. The 

 shortest passage last year was 14 hours 15 minutes by electric fight, 

 and the fastest on record. For the transit with electric light the 

 great majority of the vessels obtain the apparatus from different 

 shipping agents at a uniform rate of £10 for the transit. 



— We learn from Engineering that in a lecture delivered before 

 the students of Sibley College. Mr. O. Chanute, president of the 

 American Society of Civil Engineers, dealt with the question of 

 aerial navigation. Reasoning from the results obtained by Capt. 

 Renard with "La France," he concludes that with a balloon 330 

 feet long, with a maximum diameter of 55 feet, a speed of from 

 tweirty-five to thirty miles an hour might be attained. Mr. 

 Chanute thinks, however, that the problem of flight is more 

 likely to be solved by means of the aeroplane than with the bal- 

 loon. To obtain a speed of twenty-five miles an hour with aero- 

 planes, he estimates that 5.87 horse-power would be required per 

 ton of weight. The inclination of the supporting surface should 

 be between one degree and two degrees to the horizon. The great 

 difficulty. Mr. Chanute states, is that of obtaining a light enough 

 motor. The weight should not exceed fifty pounds per horse- 

 power ; and the lightest steam-engine he is acquainted with, es- 

 pecially built for aerial navigation, weighed thirteen pounds per 

 horse-power. Mr. Brotherhood has obtained a Iiorse-power with but 

 little over one pound of weight in his three-cylindered engine used 

 in Whitehead torpedoes. These engines work with compressed air. 



— We learn from the Journal of the Society of Arts, London, 

 that sawdust and shavings, practically waste substances, are 

 turned to account by M. Calmant of Paris for the production of a 

 finely divided vegetable charcoal, which is intended to be applied 

 for the removal of unpleasant flavor in ordinary French wine, 

 otherwise unsalable as wine, although suitable for distillation. 

 The charcoal is also available as a filtering medium, especially in 

 distilleries, where it is said to be capable of filtering forty times 

 its volume of alcohol; whereas the vegetable charcoal of com- 

 merce, gradually becoming scarcer and dearer, and which requires 

 grinding and often recarbonization, wiU only filter about three 

 times its volume. If not already separate, the sawdust of hard 

 and soft woods must be separated, because the former requires a 

 heat of 700° C, whereas 500° C. suffice for carbonizing the latter. 

 Carbonization, which lasts about an hour, is effected in fire-clay, 

 plumbago, or cast-iron retorts, of about 600 cubic inches capacity ; 

 but previous to this process, the sawdust must be sifted, first 

 tlirough a coarse screen to remove splinters and extraneous mat- 

 ter, and then thi'ough a fine sieve, which only permits passage of 

 the actual wood-dust with the adherent calcareous matter. The 

 product of carbonization must again be sifted to get rid of this 

 calcareous matter which has become detached during the process, 

 when it will, if the operation has been carefully performed, resist 

 the action of hydrochloric acid. Shavings of either hard or soft 

 woods, also kept separate, must be subjected to preliminary treat- 

 ment (which consists in a beating, to detach the adherent dust, 

 and then a high degree of compression in a hydraulic or other 

 press), when they are carbonized in the same manner as the saw- 

 dust, and then ground in a mill to reduce them to the same degree 

 of fineness. Great care must be exercised to prevent the charcoal 

 absorbing moisture from the atmosphere, and with this object it 

 must be enclosed in air-tight recipients until required for use. 



