?44 



NA TURE 



[October 3, 1895 



— even better without, perhaps. The next alternative is 

 between isolated vascular bundles, and vascular bundles 

 m a cjlinder. connected with other characters, entailing 

 previous teaching and study, which should largely con- 

 sist of acquiring a knowledge of natural orders. Never- 

 theless this book may prove useful, especially to the 

 collector desirous of determining the natural orders of 

 his plants in the field or at home. So far as we have 

 tested it, it is carefully compiled and edited, and we can 

 conscientiously recommend it to those who know the 

 characters of manv natural orders in advance. 



\V. B. H. 



LETTERS TO THE EDITOR. 



[ The Editor does ttot hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, refected 

 manuscripts intended for this or any other part of Naturk. 

 No notice is taken of anonymous communications. ] 



Attempt to Liquefy Helium. 



I HAVE received a letter from Prof. Olszewski, of Krakau, in 

 which he informs me that having exposed a sample of helium 

 which I sent him to the same treatment as was successful in 

 liquefying hydrogen — namely, compressing with a jiressure of 

 140 atmospheres, cooling to the temperature of air boiling at 

 low pressure, and then expanding suddenly — he has been unable 

 to delect any sign of liquefaction. 



The density of helium being, roughly speaking, twice that of 

 hydrogen, it is verj- striking that its lique^ing point should lie 

 below that of hydrogen. It may be remembered that argon, 

 which has a higher density than oxygen, liquefies at a lower 

 temperature than oxygen ; and it was jjointed out by Prof. 

 Olszewski that this behaviour was not improbably connected with 

 its apparently simple molecular constitution. The similar fact 

 now recorded for helium may therefore l>e regarded as evidence 

 of its simple molecular constitution. I use the word " its "' in- 

 stead of " their," although further research may corroborate 

 Prof. Runge's contention that what is termed helium may in 

 reality be a mixture of two, if not more than two elements. If 

 this contention is true, both, or all, must have extraordinarily 

 low boiling-points. \Vii.i.i.\M Ramsay. 



September 23. 



Helium and the Spectrum of Nova Aurigae. 



In the paper on the constituents of the gas in cleveite that we 

 read before the British .\.ssociation, we said that in the first 

 spectrum of Nova Aurig.u the principal lines 50l6and 4922 of the 

 lighter constituent were far more intense than those of the other 

 constituent. But we were puzz.led at the line 6678 not having 

 been observed, as it is also a strong line in the spectrum of the 

 lighter constituent. On inquir)-. Dr. and Mrs. Hugglns were 

 kind enough to give us Iwller information. Dr. Muggins writes : 



" I think there is no doubt that we did see the red line at 

 6678 in Nova Aurigw. We were unable to measure in that part 

 of the spectrum, but on three nights we .saw a bright line a little 

 below C. This w.-is a pure estimation under difficult circum- 

 stances. In the map we put the line, as a mere guess, at a little 

 over t)70O. On the first night we put the line in a rough 

 diagram, made at the time, a little nearer C, .almost exactly at 

 6678. (Jn a subsequent night, we made the estimation a little 

 below 6700, but the line w.as not then s<i bright."' 



Ixmdun, Scpleml>cr 27. C. Rl'MiK ANf> !•". I'A>rui-.s. 



Latent Vitality in Seeds. 



TliKRF. Is no doubt, .-is M. Casimir de Oindolle has re- 

 cently shown in his paper on latent li e in seeds, that all the 

 functions of seeds can remain completely quiescent for a long 

 period ; probably in some cases this pcrifxl may be indefinitely 

 ]Ong. In 1878 1 published a paper ' on the resistance of seeds, 



' mi semi all' .-vjonc prulunK.ita di agcnli 



fiimica italiana, ix., 1879, p. 199;. and 



NO. 1353, VOL, 



, y, p. 199. 



especially of Medicago sativa, or lucerne, to the action of 

 gaseous and liquid chemical reagent.s. An abstract of my experi- 

 ments was published in N.\Tl'RE, vol. xxv., 1882, p. 32S. 



Recently I have examined portions of the seeds used in tlie 

 experiments of 1877 and 1S78, to see if after the lapse of so 

 many years, during which the seeds have rem.iined constantly 

 surrounded by special gases, or immersed in difterent solutions, 

 they had retained their vitality. The results have been remark- 

 able, for in some cases a large proportion of the seeds have 

 maintained their vitality after a lapse of 15, t6, and nearly 17 

 years of special external chemical conditions. 1 summarise 

 the results of some of my experiments. 



(a) Experiments in Gases. 



In all these experiments the gases were aVj', for in these con- 

 ditions moisture is rapidly f;\tal to the seeds. The seeds were 

 introduced into small bulbed tubes, into which the dr)- gas w.as 

 made to p.-iss for some time, after whicn the tubes were rapidly 

 sealed at a spirit-lamp flame. The tubes were then kept in the 

 dark. 



In the following summary I give the dates of the sealing and 

 opening of the tubes : — 



Hydrogen. — Lucerne seeds, from September IJ, 1S77, to 

 August 5, 1894, a period of 16 years, 10 months, and 20 days. 

 Out of 51 seeds sown, none germinated. Seeds of wheat, vetch, 

 Cynara cardunculus and coriander, kept in hydrogen, gave the 

 same negative results. There is some suspicion that the hydrogen 

 had not been originally well dried. 



Oxygen. — Lucerne, from May 19, 1878, to .August 4, 1S94, 

 16 years, 2 months, and 15 days. Out of 293 .seeds sown, 2 

 germinated, or 068 per cent. The seeds were not thoroughly 

 dr)'. 



Nttrogcn.^lMC&rae, from April 12, 1878, to August 21, 

 1894, 16 years, 3 months, and 22 days. Out of 320 seeds, l8i 

 germinated, or 56-56 per cent. 



Chlorine and Hydrochloric Acid Gas. — Lucerne, from .\pril 

 28, 187S, to August 3, 1894, 16 years, 3 months, and 5 days. 

 Out of 342 seeds, 23 germinated, or 6-72 per cent. Originally 

 these seeds had been put into pure chlorine ; but the gas had 

 acted on the seeds, carbonising a portion of them, so that at 

 the end of the experiment the seeds were in an atmosphere 

 composed chiefly of hydrochloric acid gas, mixed with carbon 

 dioxide. 



In a second experiment with lucerne seed, kept in chlorine, 

 and then hyilrochloric acid, during the same jieriod, out of 167 

 sown, 10 germinated, or 5 98 per cent. In this experiment the 

 tube was carefully opened in •■acuo, to protect the seeds from 

 the moisture condensed by the hydrochloric acid gas at the 

 moment when it is brought into contact with common air. 



Sulphuretted Hydrogen. — From October 14, 1877, to August 

 5, 1894, 16 years, 9 months, .and 22 days. After the opening 

 of the tube, filled with the strongly .smelling gas, the seeds were 

 left in contact with the air for 24 hours, before sowing them in 

 the moist .sand of the germinator. Out of loi lucerne seeds, one 

 germinated, or 099 per cent. Out of 50 seeds of wheat, none 

 germinated. 



Arseniurclted Hydrogen. — From April 4, 1878, to August 4, > 

 1894, 1 6 years .and 4 months. On opening the tube the garlic * 

 smell of AsII., w.os .strongly evident. Out of 255 lucerne seeds 

 sown, i8l germinated, or 70*98 per cent. In a second experi- 

 ment with seeds kept in arsenmrctted hydrogen, out of 247 

 lucerne seeds 170 germinated, or 68-82 per cent. 



Carhon Monoxide. — From April 3, 1878, to August 4, 1S94, 

 or 16 years and 4 months. Out of 266 lucerne seeds, 224 ' 

 germinated, or 84-2 per cent. 



Carbon Dioxide. — From September 8, 1877, to August 5, 

 1894, or 16 years, 11 months, and 27 days. The same tube 

 contained seeds of lucerne, wheat, vetch, 6j'/;iia-<i, and coriander. 

 None germinated. Perhaps the large number of seeds ci>nlained 

 in a rel.atively .sm.ali tube rendered the carbon dioxide damp, and 

 therefore noxious. 



Nitric Oxide. — From May 2, 1878, to August 4, 1894, or 

 16 years, 3 months, and 2 days. On opening the tube, abun- 

 dant red fumes were produced by contact with air. Before sow- 

 ing, the scc<ls were left dry for 24 hours. Some of the seeds were 

 brownish, the rest retained their natural colour. Out of 309 

 lucerne seeds, 3 germinated, or 0-97 per cent. In a second 

 ex|x.-rimenl, the tube containing the lucerne seeds was opened 

 /// ''ai 110 : out of 320 seeds, 2 gerniin:ilud, or 0*62 per cent. 



