July 19, 1900] 



NA TURE 



287 



hydrogen is about one-quarter that of liquid air, just as that of 

 liquid air is about one-quarter of that of the average mean 

 temperature. In subjecting bacteria, therefore, to the tempera- 

 ture of liquid hydrogen, we place them under conditions which, 

 in severity of temperature, are as far removed from those of 

 liquid air as are those of liquid air from that of the average 

 summer temperature. By the kindness of Prof. Dewar, the 

 specimens of bacteria were cooled in liquid hydrogen at the 

 Royal Institution. The following organisms were employed : 

 Bac. acidi lactici, B. typhosus, B. diphtheriae, Proteus vulgaris, 

 B. anthracis, B. colt communis. Staphylococcus pyogenes aureus, 

 Spirillum cholerae, B. phosphorescens, B. pyocyaneus, a Sarcina 

 and a yeast. 



The above organisms in broth culture were sealed in thin 

 glass tubes and introduced directly into liquid hydrogen con- 

 tained in a vacuum jacketed vessel immersed in liquid air. 

 Under these conditions they were exposed to a temperature of 

 about -252 C. (21° absolute) for ten hours. At the end of the 

 experiment the tubes were opened, and the contents examined 

 microscopically and by culture. The results were entirely 

 negative as regards any alteration in appearance or in vigour of 

 growth of the micro-organisms. It would appear, therefore, 

 that an exposure of ten hours to a temperature of about - 252° C. 

 has no appreciable effect on the vitality of micro-organisms. 



We hope to extend these observations on the influence of the 

 temperature of liquid hydrogen on vital phenomena, and to 

 make them the subject of a future communication, and to discuss 

 their bearing upon problems of vitality. 



June 21. — ' ' On the Viscosity of Gases as affected by Tempera- 

 ture." By Lord Rayleigh, F.R.S. 



A former paper ^ describes the apparatus by which I examined 

 the influence of temperature upon the viscosity of argon and 

 other gases. I have recently had the opportunity of testing, in 

 the same way, an interesting sample of gas prepared by Prof. 

 Dewar, being the residue, uncondensed by liquid hydrogen, from 

 a large quantity collected at the Bath springs. As was to be 

 expected,^ it consists mainly of helium, as is evidenced by its 

 spectrum when rendered luminous in a vacuum tube. A line, 

 not visible from another helium tube, approximately in the 

 position of D, (Neon) is also apparent.^ 



The result of the comparison of viscosities at about 100° C. 

 and at the temperature of the room was to show that the tem- 

 perature effect was the same as for hydroqen. 



In the former paper the results were reduced so as to show to 

 what power («) of the absolute temperature the viscosity was 

 proportional. 



«. c. 



Air 0754 ... III-3 



Oxygen 0782 ... 128-2 



Hydrogen V /-o 



Helium / °68i ... 72-2 



Argon 0815 ... 150-2 



Since practically only two points on the temperature curve 

 were examined, the numbers obtained were of course of no 

 avail to determine whether or no any power of the temperature 

 was adequate to represent the complete curve. The question 

 of the dependence of viscosity upon temperature has been 

 studied by Sutherland,* on the basis of a theoretical argument 

 which, if not absolutely rigorous, is still entitled to considerable 

 weight. He deduces from a special form of the kinetic theory 

 as the function of temperature to which the viscosity is pro- 



Ivrtional 

 7^716 (^)' 

 J Roy. Soc. Proc, vol. Ixvi. (1900), p. 68. 

 J Roy. Soc. Proc, vol. lix. (1896), p 207 ; vol. Ix. (1896), p. 56. 

 'I speak doubtfully, because to my eye the interval from Di to D3 

 (hehum) appeared about equal to that between D3 and the line in question, 

 whereas, according to the measurements of Ramsay and Travers (,Koy. Soc. 

 ^^^ Proc., vol. Ixiii., 1898, p. 438), the wave-lengths are : 



\^^ ^2 5889-0 



f^^ D3 5875-9 



D5 5849-6 



o that the above-mentioned intervals would be as 19-1 : 26-3 [June 23.— 

 Mibscquentobservations with the aid of a scale showed that the intervals 

 ilKJve spoken of were as 20 : 21. According to this the wave-length of the 

 line seen, and supposed to correspond to Dg, would be about 5855 on 

 Rowland's scale, where Di = 5806-2, 02=5890-2, 03 = 5876-0.] I may 

 record that the refractivity of the gas now under discussion is 0-132 

 relatively to air. 

 * Pkil. Mag., vol. xxxvi. (1893), p. 507. 



NO. 1603, VOL. 62] 



■ 



c being some constant proper to the particular gas. The simple 

 law e*, appropriate to " hard spheres," here appears as the 

 limiting form when 9 is very great. In thife case, the collisions 

 are sensibly uninfluenced by the molecular forces which may act 

 at distances exceeding that of impact. When, on the other 

 hand, the temperature and the molecular velocities are lower, 

 the mutual attraction of molecules which pass near one another 

 increase the number of collisions, much as if the diameter of the 

 spheres was increased. Sutherland finds a very good agreement 

 between his formula (i) and the observations of Holman and 

 others upon various gases. 



If the law be assumed, my observations suffice to determine 

 the values of c. They are shown in the table, and they agree 

 well with the numbers for air and oxygen calculated by Suther- 

 land from observations of Obermayer. 



" Underground Temperature at Oxford in the Year 1899, as 

 determined by Five Platinum Resistance Thermometers." By 

 Arthur A. Rambaut. M. A, D.Sc, Radcliffe Observer. Com- 

 municated by E. H. Griffiths, F.R.S. 



Royal Microscopical Society, June 20. — Mr. Carruthers, 

 F.R.S., President, in the chair.— Mr. G. H. J. Rogers exhi- 

 bited a modification of the Rousselet compressor, in which two 

 thin indiarubber bands, sunk into grooves, were employed to 

 keep the cover-glass in position, instead of having it cemented, 

 the advantage claimed for this modification being the facility 

 with which a broken cover-glass can be replaced. — Mr. Chas. 

 Baker exhibited an achromatic substage condenser which was a 

 modification of Zeiss's model of the Abbe condenser, the N.A. 

 being I -Q, aplanatic cone 90°, lenses 1'5-inch diameter, working 

 distance y^^y-inch. With the front lens removed the condenser is 

 suitable for use with low-power objectives. — A short paper by Mr. 

 E. B. Stringer, on a new projection eye-piece and an improved 

 polarising eye-piece, was taken as read, — A paper by Miss Loraine 

 Smith, on some new microscopic fungi, was also taken as read, 

 the President giving a short rhtim^ of it and expressing his 

 opinion that the paper would be an important addition to our 

 knowledge of microscopic fungi. Mr. Bennett said there was 

 one special point with regards to parasitic fungi which might 

 prove to be of considerable practical importance — he referred to 

 the cultivation of fungus parasites on certain insects It had 

 been proposed to do this on the Continent and in Australia and 

 America, with a view of getting rid of insect pests — locusts and 

 others ; and if efforts in this direction were successful they might 

 be the means of producing very beneficial and economic results. 

 — The President then read a paper, and gave a lantern demon- 

 stration, on the structure of some palaeozoic plants. He said the 

 intelligent study of palaeozoic plants was not yet a century old, for 

 although their presence had long been noticed, they appear to 

 have been regarded simply as freaks of nature. The importance 

 of fossils was first recognised by Wm. Smith, who observed that 

 strata could be identified by the organised fossils found in them. 

 He published this important fact in 18 16, and thus laid the 

 basis of stratigraphical geology. The majority of fossil plants are 

 found in the shales, and although the tissues had been converted 

 into carbon, the form and venation of the leaves and occasionally 

 the aspect of the fruits had been preserved. The most important 

 information, however, had been obtained from specimens in 

 which the tissues had been replaced by minerals dissolved in the 

 strata enclosing them. He had arranged for the lantern sections 

 of plants from the carboniferous system, but before exhibiting 

 them he wished to point out to what group of plants they be- 

 longed. The cellular plants, with few exceptions, had been 

 lost. Sir Wm. Dawson found specimens of a remarkable stem 

 in the lower Devonian rocks of Canada, to which he gave the 

 name of Protaxites. From a microscopic study of specimens he, 

 the President, was led to publish a paper in the Society's y^wr/ia/ 

 in 1872, in which he demonstrated that the stem was that of a 

 cellular plant belonging to the Algae, a view which was ulti- 

 mately accepted by Sir Wm. Dawson. Fungal remains had been 

 detected by Alder, and also by himself. The plants which had 

 been certainly determined were vascular plants belonging to the 

 Equisetaceae, Filices, and Selaginellaceae, among Cryptogams, 

 and to the Coniferae, groups which existed in the present flora 

 of the globe, and were represented in the indigenous flora of 

 Britain. The President proceeded to describe the principal 

 characteristics of the fossil and existing forms of the four orders 

 of plants referred to. In illustration of his remarks a number of 

 preparations were shown on the screen. — Mr. Bennett wished to 

 say a few words to elicit an opinion on a matter of great interest. 



