May 17, 1895.] 



SCIENCE. 



543 



on striking the ground. Later researches 

 of Olszewski and Krzyzanowski have shown 

 that this liquid could not have been hydro- 

 gen, and that the gas obtained, as Pictefs 

 was, I'rom potassium formate and caustic 

 potash is by no means pure hydrogen. To 

 Cailletet and Pictet belongs the credit of 

 being the pioneers in this field, and to them 

 in 1878 was awarded the Davy medal of the 

 Koyal Society. 



A few j-ears later (1883) the work was 

 taken up by Wroblewski and Olszewski at 

 the University of Cracow, and after the 

 death of the former in 1886 was carried on 

 by Olszewski alone, and more recently by 

 Olszewski and Witkowski. The apparatus 

 used was derived from that of Cailletet, the 

 production of cold being by the boiling of 

 liquid ethylene in a vacuum. 



The aim of Olszewski's researches has 

 been the exact investigation of the proper- 

 ties and conditions of matter at low tem- 

 peratures. Many physical constants of the 

 so-called peiinanent gases have been deter- 

 mined, and especially the optical properties 

 of liquid oxygen have been thoroughly 

 studied. More recently Olszewski was en- 

 trusted l)y Lord Rayleigh and Professor 

 Ramsay with the liquefaction of Argon, and 

 the results of this investigation have been 

 widely published. His lati'St work is the 

 determination of the critical temperature 

 (— 2:?:r) and the boiling point (—243°) of 

 hydrogen, the last gas which still resists 

 condensation to a static liquid. 



Professor Dewar, in his position at the 

 Royal Institution of Great Britain, has been 

 looked upon, perhaps, rather as a public 

 lecturer and brilliant experimenter than as 

 an exact investigator. In 1884 he delivered 

 an address at the Royal Institution on the 

 work of 'Wroblewski and Olszewski, during 

 which oxygen and air were liquefied for the 

 first time in public. He later so improved 

 the .apparatus, which was founded on the 

 principles used by Cailletet and by Olszew- 



•ski, that he could obtain with safety and 

 without great difticulty very considerable 

 quantities (' several pints') of liquid oxy- 

 gen or air, and his public experiments with 

 this li(juid are famous. By tlie use of 

 liquid air he has studied the electrical re- 

 sistance of metals and alloys at low temper- 

 atures, extending greatly the work of Clau- 

 sius, Cailletet and Bouty, and Wroblewski 

 in this direction, and has undertaken work 

 on the tension of metals at low tempera- 

 tures. As far as these latter experiments 

 have been carried, they seem to show that 

 the breaking stress of metals increases de- 

 cidedly at low temperatures ( — 182°) and 

 hence that there is no decrease of mo- 

 lecular attraction as absolute zero is ap- 

 proached, although the most powerful chem- 

 ical affinities are in abeyance, as Professor 

 Dewar has shown. He was also the dis- 

 coverer of the magnetic properties of liquid 

 oxygen. 



In his earlier work Professor Dewar cer- 

 tainly did not fail to give Professor Olszewski 

 due and full credit. Of late years he has 

 failed to often refer to him, and the charge 

 that he has sometimes apparently claimed 

 as his own that which he should have at- 

 tributed to the Polish professor is, perhaps, 

 not wholly unfounded ; yet the claim of 

 the latter for priority was so well under- 

 stood by scientific men that his attack on 

 Professor Dewar was at least unnecessarj'. 

 That the Englishman, possibly somewhat 

 rankled that his countrymen should have 

 called on a foreigner to .assist in their study 

 of Argon, was led to make a spirited 

 rejoinder, to pose as more of an inde- 

 pendent investigator than the facts warrant, 

 and to depreciate the work of his op- 

 ponent, is perhaps not to -be wondered 

 at, but certainly not to be excused. Alto- 

 gether the discussion is profitless and un- 

 fortunate. 



Jas. Lewis Howe. 



■Washisoton and Lek University. 



