;io 



NATURE 



[January 26, 1899 



will boil al a lower temperature the lower the pressure under 

 which il is volatilised. The question arises, how much lowering 

 of temperature can we practically anticipate? 



Calculations lead to the conclusion that, as the absolute boiling 

 point under atmospheric pressure is 35^ ebullition under 25 mm. 

 pressure ought to reduce the boiling point some 10" C. For some 

 timeexperiments have been in progress with the object of,determin- 

 ingthe temperature of hydrogen boiling umler about 25 mm. pres- 

 sure, but the difficulties encountered have been so great, and re- 

 peated failures sn exasperating, that a record of the results so 

 far reached becomes advisable. The troubles arise from the 

 conduction of heat by the leads ; the small latent heat of 

 hydrogen volume for volume as compared with liquid air ; the 

 inefficiency of heat isolation, and the strain on the thermometer 

 brought about by solid air freezing on it and distorting the coil 

 of wire. In many experiments the result has been that all the 

 liquid hydrogen has evaporated before the pressure was reduced 

 to 25 mm., or the thermometer was left imperfectly covered. 

 The apparatus employed will be understood from the figure. 

 The liquid hydrogen collected in the vacuum vessel a was sus- 

 pended in a larger vessel of the same kind B, which is so con- 

 structed that a .spiral tube joins the inner and outer test tubes of 



which 11 is made, thereby making an opening into the interior at 

 c. The resistance thermometer 11 and leads E pass through a 

 rubber cork i, and the exhaustion takes place through 1. In 

 this way the cold vapours are drawn over the outside of the 

 hydrogen vacuum vessel, and this helps to isolate the liquid 

 from the connective currents of gas. To effect proper isolation 

 the whole apparatus ought to have been immersed in liquid air 

 under exhaustion. .Arrangements of this kind add to the com- 

 plication, so in the first instance the liquid was used as described. 

 The liquid hydrogen evaporated quietly and steadily under a 

 pressure of about 25 mm. of mercury without the least appear- 

 ance of solidification or loss of mobility; still remaining clear 

 and colourless l<i the eye. Naturally the liquid does not last 

 long, so the resistance has to be taken quickly. Just before the 

 reduction of pressure began, the resistance of the thermnmeter 

 was o 131 ohm. This result compares favouralily with the 

 former observation on the boiling |)oint, which gave a resistance 

 of 0129 ohm. On reducing the pressure, the resistance 

 diminished to O'l 14 ohm, and kept steady for some lime. The 

 lowest reading of resistance was 0112 ohm. This value corre- 

 sponds to - 239' I ° C, or only <me degree lower than the l>oil- 



\Q. 1526, VOL. 59] 



ing pomt at atmospheric pressure, whereas the temperature 

 ought to have been reduced some 10" C, or in any case 5° under 

 the assumed exhaustion. 



No blunder having been detected in the observations, for the 

 present we nmsl assume that the platinum resistance thermo- 

 meter No. 7 acts in the manner described. It would be pre- 

 mature to discu.ss the inferences to be drawn from these results 

 until they are confirmed on another variety of platinum wire 

 made into a resistance thermometer. Kut as this will involve 

 the use of con.siderable quantities of liquid hydrogen, it will 

 take some time to complete the investigation. 



The same kind of anomaly appears in the case of the use of a 

 thermo-junctionat these low temperatures ; but this is a separate 

 matter, and must be dealt with in a fuither comnmnication. 



Linnean Society, December 15, 1898. — Dr. A. (lunther, 

 1'. R. S. , President, in the chair. — On behalf of Captain John 

 Marriott, two crustaceans were exhibited which had been pro- 

 cured by him on a recent journey to the Sinai I'eninsula, and 

 had been identified as G>apsiis macii/attii and Panu/irus 

 penicillatus. A brief account of the distribution and habits was 

 given by Mr. Ilarting. The Rev. T. R. .Stebbing referred to a 

 well-known case of P. pciiiciltalus in the Paris Museum, 

 exhibiting the singular monstrosity of an eye-stalk developing a 

 flagellum or lash-like termination, an observation which he 

 thought had not been confirmed. Prof. Howes remarked that 

 the ophthalmite if removed had been proved to regenerate as an 

 anlenniform appendage, by Ilerbst in Palaemon (" Archiv. f. 

 Entwickelungsmechanik d. Org.," Bd. ii. p. 544), and by Hofer 

 in Aslacus Jluz'ia/ilis (" Verh. Deutsch. Zool. Cescllsch.," 1894, 

 p. 82). — Mr. Thomas Scott communicated a description of some 

 marine and freshwater Crustacea from Kranz-Josef Land, col- 

 lected by Mr. W. S. Bruce, of the Jackson- Harmsworth 

 Expedition. The Rev. T. R. Stebbing, who gave the substance 

 of the paper in the absence of the author, considered the 

 collection an important one. The number of species amounted 

 to 173, comprising Macrura 5 species, Schizopoda 2, Cumacea 

 5, Isopoda 5, .\mphipoda 46, Ostracoda 34, (Topepoda 66, and 

 Cirripedia 2. Of these 173 species 12 were new. — Mr. H. J. 

 Elwes, F.R.S., gave an account of the zoological and botanical 

 results of a recent journey to the Altai Mountains. The journey 

 commenced practically at Moscow in the middle of May, and 

 extended from the Ural Mountains through Omsk to the River 

 Obi, across a vast and unvarying steppe to Bilsk, where his 

 natural-history collecting began. .Vfter descril)ing the general 

 appearance of the country and the vegetation, Mr. Elwes stated 

 that he had brought home about 180 species of butterflies out of a 

 possible 200 (of w hich 141 had been collected by himselO, and 80 

 species of moths. As regards plants, finding the flora pretty well 

 known through the labours of Ledebour, Bunge,and Tchihatcheflt, 

 he thought it preferable to collect the plants of a small typical 

 valley rather than attempt a general collection made at random. 

 Unfortunately, owing to an accident when crossing a river, the 

 greater part of that collection was lost, lie was much struck 

 with the extraordinary beauty and abundance of the alpine 

 plants in certain marshy valleys from 6000 to 7500 feet in 

 altitude. There was a remarkable absence of peat-plants, and 

 hardly any ferns were seen in the Tchuja valley between the 

 Katuna River and the upper Tchuja steppe, a plateau about 

 6000 feet above the sea, south of which the greater |>art of the 

 observations were made. From this plateau he journeyed to 

 the high mountains of the south in quest of the famous wild 

 sheep. Oris amnion of Pallas, of which he secured three 

 specimens, which were now exhibited, one having a measure- 

 ment of 62 inches round the curve of the horn, which is about 

 the largest on record for this species. lie mentioned the scarcity 

 of game-birds in the Altai, though Tetraog:atlus altai;us was 

 often seen at an elevation of 8000-9000 feet, accompanying the 

 ibex (Cafra si/iin'ia) as in the Himalaya and Caucasus. He 

 mentioned the breeding on the mountain lakes of Oidemia 

 SUjiugeii, a North I'.acific species allied to our velvet scoter. 

 The great stag of the Altai, of which several heads were shown, 

 was evidently an .Asiatic form of the wapiti, the antlers having a 

 remarkably long fourth tine, and the peculiar back tine at the 

 top, characteristic of the American anmial, and not observable 

 in the European red deer. These were com|xared with four 

 adult pairs of horns of the Mantchurian Cen'iis LiihJorfi, which 

 had been kindly sent to him by the Duke of Bedford. Though 

 much smaller than either the .\nierican or .\ltai stag, these 

 horns showed the same typical wapiti character, and it appeared 

 iis though the races inhabiting the N.W. coast of .\merica and 



