Februarv 14, 1895 J 



NATURE 



365 



Every one must admire, and praise the skill which 

 fashioned, the vacuum receiver; for storing and experimenting 

 with comparatively large quantities of liq lid oxygen and air, 

 which Prof. Dewar used in public for the first tim? on 

 January 20, 1893, so far as can be gathered from the Proued- 

 iiii^i of the Royal Instituiion (see Proi. P. I. xiv. i.) The 

 f)llowing sentences occur in the published abstract of Prof. 

 Dewar'-i lecture on that date: "The prosecution of research 

 a temperatures approaching the zero of absolute temperature 

 is attended with difficulties and dangers of no ordinary kind. 

 Hai'iiig no recorded experience to guide us in conducting such 

 investigations, the best instruments and methods of working 

 have to be discovered." (The italics are mine.) {Prflc. R. f. 

 xiv. I.) Now, in June 1890, that is two and a half years before 

 Prof Dewar made the statement I have quoted, Prof. Olszewski 

 was able to say: "My new apparatus excludes the incon- 

 veniences of the former one, and renders it possible to preserve 

 the liquid oxygen a longer time under the ordinary atmospheric 

 pressure." And ag^in : "Thus was solved the problem of 

 liquefying considerable quantities of oxygen wi'hout the slightest 

 danger." (See Olszewski, Phi/. Alug. Fehruaiy 1895, 193-3.) 

 l.very reader of Prof Olszewski's papsr will agree that these 

 statements are justified. Moreover, in October 1S91, that is, 

 fifteen months before Prof. D;war diiclared there was " no re- 

 corded experience to guide us in condujlinij such investigations," 

 Prof Olszewski (in conjunction with M. Wiikowskij described a 

 method for not only sioring. but also experimenting with, 

 considerable cjuantities of liquid oxygen {Cracovic Bulletin, 

 October 1S91). So far back .is 1887 he published, in 

 ll'icde/nann's Annalen (xxxi. 58), a full ac».ount of methods for 

 'ietermiiiin^ ihe densities of liquid oxygen, nitrogen, and marsh 

 1,'as. In 1887, al-c, he determined the boiling p jint of liquid 

 ozone, and he began his measurements of the abs')r(ition 

 spectra of liquid oxygen and air (IViedcmaiin's Annalen, 

 xxxiii. 570) ; and in 1891 he published further measurements of 

 the absorption spec'rum, an I the refiactive index, of lM|iid 

 oxygen (iliid. xlii. 663 ; see also Phil. Mag. February 1895, 

 197-9, and 206-8.) 



It is ju-t these jiropcrties. namely, the optical properties, of 

 liquid oxygen which had been elaburaiuiy studic 1 by P.of. 

 Olszewski f 0111 188710 1891 that are largely dwelt on by Prof. 

 Dewar in his discourse of January 1893 ; and it is the ilkntrai ion 

 of these piopcrties that is prefaced by the remark, there is 

 "no recorded expeiicnce to guide us in conducting such inves- 

 tigaiions." 



On January 20, 1893 (Proc. R. I. xiv. 10) Prof. Dewar said 

 that liqiiiil oxygen is " the most convenient substance to use (or 

 the production of tcmpeiatures about -20o''C. Liquid nitrogen, 

 carbonic oxide, or air can conveniently be made at the ordinary 

 atmospheric pressure, provided ihey are brought into a vessel 

 cooled by liquid oxygen boiling under the preisure of about 

 half an inch of mercury." It is interesting to compare with 

 this Prof. Olszewski's words published in June 1890 (C;ac. Bull.: 

 I quote from the translation in Phil. Mug February 1895, 192) : 

 " I proved long ago [Com//, rend. c. 350 (iS85<J that liquid 

 • 'xygen is the best cooling agent ; for it easily gives thetempera- 

 ;ure of - 21 1^'5 C. if the pressure is lowered 9 mm. of mercury, 

 and it does not fieeze even at the pressure of 4 mm." It may 

 he said lint the simila'ity between these statements is merely a 

 coincidence. Perhaps it is, Neveith-less, Prof. Dewar's 

 statement conveys the impression that he was the first experi- 

 menter to employ liquid oxygen for obtaining, and maintaining, 

 very low temperatures. Another of Prof. Dewar's statmients 

 which imply more than they express, occurs in his lecture of 

 June 10, 1S92 [Proc. R. /., xiii. 695) : " He hoped that even- 

 ing to go several steps further, ana to show liquid air, and to 

 render visible some of its more extraordinary properties." 

 Remembering that air had been liquefied by Piof Olszewski at 

 least eight years befoie the lecture whertin this statement occurs 

 was delivered, one must regret that Prof, Dewar did not choose 

 words which should hive made it impossible for the English 

 public to suppose "that the liquefaction of oxygen and oiher 

 so-called permanent gasi-s was ach eved for the first time by 

 [him] " (See Prof. Olszewski's letter in Naturi: of January 

 10). 



Not only docs Prof Olszewski claim to hive devised the 

 methods, and constructe 1 the apparatus, for liquefying con- 

 siderable quantities of the m ^re permanent gises, but he also 

 asserts that most of the exieriments on the properties of these 

 liquefied gases which have been performed by Prof. Dewar are 



NO. 1320. VOL. 51] 



only repetitions, on a larger scale, of work done by others. 

 What, then, are these experiments? 



Measurements of the refractive index of liquid oxygen, 

 for the sodium light, and also of the absorption spectrum 

 of liquid oxygen, were published by Profs. Liveing and 

 Dewar in August 1S92 (Phil. Mag. (5) xxxiv. 205 ; see 

 also Dewar in Proc. R. I., June 10, 1892 ; and Liveing 

 and Dewar in Phil. Mag. for August 1894). The re- 

 fractive index of liquid oxygen had been measured, and deter- 

 minations of the absorpti m spectrum had been made, by 

 Olszewski and Wiikowski in October 1891, and these measure- 

 ments were the complement of work begun, and published, by 

 Prof. Olszewski in 18S7 {U'iedcfnann's Annalen, xxxiii. 570. 

 See Olszewski in Phil. Mag., February 1895, 197-9). It is true 

 that preliminary experiments on the absorption spectrum of 

 liquid oxygen had been made by Profs. Liveing and Dewar in 

 1889. In their paper in Proc. R. S., June 6, 1889, they say : — 

 " We have observed repeatedly the absorption of liquid oxygen 

 in thicknesses of 8 and 12 mm. Our observations confirm 

 those of Olszewski." 



On December 10, 1891, Prof. Dewar announced, in a note 

 to the President of the Royal Society, that liquid oxygen is 

 attracted by the poles of a magnet. This note was followed by 

 another, on December 17, 1891, saying that liquid ozone was 

 also attracted by the poles of a magnet. These detached, but 

 inieres'.ing, experiments, which followed up work done by 

 Faraday many years ago, must be placed to the credit of the 

 Fullerian Professor at the Royal Institution. 



A paper published in Phil. Afag. (5) xxxiv. 326 (1892) by 

 Dewar and Fleming, on the electrical resistances of metals and 

 other bodies at very low temperatures, contains the only piece 

 of exact investigation to which Prof Dewar's name is attached 

 wherein liquid oxygen or air is used as an instrument of re- 

 search, with the exception of the measurements of the optical 

 properties of liquid oxygen, which have been shown to be 

 mainly repetitions of the work of Olszewski and Witkowski, 

 This research carries on and supplements earlier work done 

 by Cailletet and Bouty, and by Wroblewski {Comptes rendus, 

 ci. 161 (1885), 



A lew observations have been made by Prof Dewar on the 

 phosphorescence ol various substances at the temperature of 

 boiling oxygen, and on the cessation of chemical action, and 

 the continuance of photographic action, at the same temperature 

 (see Proc. R.I. June 26, l8gi and June 10, 1892, also January 

 20, 1893; also Prcc. Royal Soc. .A-pril 19, 1894, and Proc. 

 Chcm. Soc. June 28, 1894). The subject of chemical action at 

 very low temperatures was investigated by Pictet in May and 

 November 1S92 (Comptes lendus, cxiv. 1245 ; cxv. 814) in a 

 much more exhaustive way than has been done by Dewar, who 

 has only touched the Iringe of the matter (compare also 

 Olszewski, Phil. Mug. Februaiy 1895, 208-9). The observa- 

 tions on the sensitiveness of the Eastman film at very low 

 temperatures are ii.tercsting ; but, so far as it has been pub- 

 lished, the work is too slight to present material for detailed 

 criticisms ; and the same may justly be said of the lecture 

 illustrations of phosphorescence at low temperatures. It may 

 be remarked that Prof Dewar's paper on photographic action 

 at low tempera' uies has appeared only in ihe Proceedings, not 

 in the Transactions, of the Chemical .Society. 



Prof Olszewski's work on the properties of liquefied gases 

 was begun, and accounts of his accurate expenmtnls were 

 published in recognised scientific journals, long before Prof. 

 Dewar's expeiiments were heard of The work of the Polish 

 I'lofessor is being continued in the same exact, modest, and 

 scientific manner (see his paper on the optical dispersion of 

 liquid oxygen in Ciacovie Bulletin, July 1894, noticed in /'/;//. 

 ■ Uag., February 1895, 208 ; and his determinations of the boil- 

 ing and freezing points, and other constants, of argon communi- 

 cated to the Royal Society, January 31. 1895). 



It seems to me that I'rol. Olszewski has established a case 

 which demands the instant and serious consideration of those 

 who are truly interested in the advance of science, and are 

 jealous of the good name of the scientific men of this country. 



Cambridge, February 7. M. M. Pattisox Muir. 



ThI'; object of the communications on the liquefaction of 

 g.ases, which have recently appeared in Naiure and the 

 Phitosofhical Magazine, is to depreciate the work of Cailletet 

 and Pictet, to smother away the first-class work of the deceased 



