Sept. 9, x88o] 



NA TURE 



435 



sures, the details of which will shortly be published, have led to 

 the following conclusions in reference to the conditions necessary 

 for the existence of any substance in the liquid state. These are 

 two in number, viz. : — 



1. In order to convert a gas into a liquid the temperature 

 must be I'chnv a certain point (termed by Andrews the critical 

 temperature of the substance), otherwise no amount of pressure 

 is capable of liquefying the gas. 



2. In order to convert a solid into a liquid the pressure must 

 be al'ove a certain point, which I propose to call the critical 

 presiure of the substance, otherwise no amount of heat will melt 

 the substance. 



If the second of the above conditions be true, it follows that 

 if the necessary temperature be attained, the liquefaction of the 

 substance depends solely on the superincumbent pressure ; so 

 that if by any means we can keep the pressure on the substance 

 below its critical pressure, no amount of heat will liquefy it, for 

 in this case the solid substance passes directly into the state of 

 gas, or in other words it sublimes without previous melting. 



Having come to this conclusion, it was easily foreseen that if 

 these ideas were correct it would be possible to have solid ice at 

 temperatures far above the ordinary melting-point. After several 

 unsuccessful attempts, I was so fortunate as to attain the most 

 perfect success, and have obtained solid ice at temperatures so 

 high that it was impossible to touch it without burning one's self. 

 This result has been obtained many times and with the greatest 

 ease, and not only so, but on one occasion a small qu.antity of 

 w ater has frozen in a glass vessel w hich was so hot that it coold 

 not be touched by the hand without burning it. I have had ice 

 a considerable length of time at temperatures far above the 

 ordinary boiling-point, and even then it only sublimed away 

 without any previous melting. These results were obtained by 

 maintaining the superincumbent pressure below 4 '6 mm. of 

 merciu-y ; i.e., the tension of aqueous vapour at the freezing- 

 point of w-ater. Other substances also exhibit these same phe- 

 nomena, the most notable of which is mercuric chloride, for 

 which latter the pressure need only be reduced to about 420 mm. 

 On letting in the pressure the substance at once liquefies. 



For the success of these experiments in the case of water one 

 or two details of manipulation are necessary, but these will be 

 subsequently described. Thos. Carnelley 



Firth College, Sheffield, September 6 



A Doubtful British Mollusk 

 I H.WE just observed that I am quoted in Dr. Gwyn Jeffreys' 

 " British Conchology " (vol. v. p. 161) as an authority for the 

 discovery of Clausilia pai-'ula (a Continental snail) in Stafford- 

 shire. Many years ago, when I was a schoolboy, I found six or 

 seven specimens at Kinver, near Stourbridge. I took them at 

 first for a smooth variety of C. rugosa, but noting other differences 

 sent them to Dr. Jeffreys, who identified them as above. I 

 never had another opportunity of visiting the spot, but brother 

 conchologists, who went on my recommendation, failed to find 

 any specimens. The sheep-walk on which I picked them up 

 W'as close to the grounds of Enville, where there are many foreign 

 shrubs, and I have now little doubt that they were introduced. 

 At the same time the large size of the specimens seemed to 

 indicate that they had been long acclimatised, as northern indi- 

 viduals are larger than southern. Grant Allen 

 Broad Street, Lyme Regis, Dorset 



A Halo 



May I mention a strange appearance which I saw in the 

 heavens on August 29, and ask for an explanation of it? It w'as 

 a rainbow without rain, and in the same quarter of the heavens 

 as the sun. 



At 5.45 p.m. I observed in a little nearly circular opening in 

 the clouds, at the same height above the horizon as the sun, and 

 about 23° to the north of it, all the colours of the rainbow. They 

 were very vivid, and lasted for several minutes. Two persons 

 who were with me also saw this strange sight, which I cannot 

 account for in any way. Was it seen by any of your readers ? 

 And what could be the cause of it ? L. Soames 



Brighton, September 2 



[This was probably a portion of the ordinary halo of 22°. I' 

 so, it indicates the presence of ice-crystals (not of drops of water) 

 in the upper atmosphere. Such things are common enough in 

 autumn, especially when there is a sudden lowering of tempera- 

 ture by an anticyclone. — Ed.] 



Tone of Violins 



I SAW a little time back, but omitted to note it at the time, a 

 brief notice of some German experiments showing that the strings 

 of good old instruments of fine tone tended far more than in the 

 case of inferior violins to vibrale in closed curves or simple 

 curves. I have searched Nature in vain for some weeks, but 

 cannot find it, though I thought it was in these columns. I am 

 particularly anxious to recover it for jurposes of my own con- 

 nected N\ ith another branch of physics, and shall be obliged if 

 any reader can refer me to the notice, or to the paper, or any 

 translation of it. Lewis Wright 



August 30 



ADOLPH EDOUARD GRUBE 



T) Y the sudden death of Prof. Grube of Breslau on 

 -'-' June 23, zoological science has been depri\-ed of one 

 of its enthusiastic and veteran cultivators. Born in 

 Konigsberg on May 12, 1812, he entered the university 

 of that city in 1831, and graduated in medicine in 

 1837. Thereafter he became a private lecturer on zoology 

 in Konigsberg. In 18-J.4 he was appointed to the Pro- 

 fessorship of Zoology in the University of Dorpat, and 

 lastly was transferred, in 1857, to a similar post in the 

 University of Breslau, where he laboured till his death. 



He chose for the subject of his inaugural dissertation 

 (in 1837) the structure oi Plcionc ctiruiiculaia, Pallas, and 

 it is interesting that at this early age he selected one of 

 the group in which his chief work in after-life was accom- 

 plished ; for though he published various valuable re- 

 searches in other departments [e.g., those on the Branchio- 

 pod Crustaceans), still the Annelida most benefited by his 

 labours during the subsequent forty-three years. Moreover, 

 he observed so carefully, as wellas laboured so industri- 

 ously, that he was facile priiiceps in the department at his 

 death. The bare enumeration indeed of his zoological 

 works and papers is formidable ; and their perusal bears 

 imperishable witness to the well-directed energy- and great 

 ability of their author. He himself, with great modesty, 

 used to state that his work fell far short of that of the late 

 M. Claparede, who, with a delicate physique, nevertheless 

 accomplished a marvellous amount of valuable work, both 

 with pen and pencil. But though perhaps less of an 

 artist than the talented Swiss, the greater tenacity of con- 

 stitution in the stalwart German, combined with his in- 

 domit.able energy and perseverance throughouta longer life, 

 enabled him to overtake a much greater amount of work, 

 especially in descriptive zoology. 



The conscientious manner in which he carried on his 

 scientific labours is well shown in his " Familien der 

 Anneliden " (1851), a work which even now is of great 

 value, and indispensable to workers in the department. 

 The same may be said of his " Entwicklung der Anne- 

 liden" (1S44) and his " Annulata CErstediana '' (1857). 

 In his original papers in the Aixliiv fiir Natiirgeschichte 

 and in the recent admirable series in the Sitzitng der 

 ScJtksisdien Gescllschaft, on the families of the .Anne- 

 lida, he deinonstrated the encyclopa;dian and critical 

 knowledge which he had of the whole group in a remark- 

 able manner, just as his " Bemerkungen iiber Anneliden 

 der Pariser Museums" showed his great experience in 

 discriminating the species described by others. His last 

 large publication (a work of 300 pp., 4to, and fifteen fine 

 plates by his tried assistant Assman) is devoted to the 

 numerous Philippine annelids collected by Prof. Semper, 

 and is a lasting memorial of his accuracy and patient 

 industry. 



Nor was he a zoologist who confined his researches to 

 a single group. He was an accomplished carcinologist, 

 and his faunistic treatises, tf.^., his "Actinien, Echino- 

 dermen u. Wiirmer des Adriatischen u. Mittelmeers," 

 his " Ausflug nach Triest u. dem Ouarnero," as well as 

 his special papers on the Echinodermata, on Ptn'pa/us 

 and ot';er Arthropods, testify abundantly to the breadth 



