Liquefaction of Gases, 299 



u But in his last experiments and lectures respecting the 

 liquefaction of considerable quantities of oxygen and air and 

 their employment as cooling agents, Professor Dewar has 

 thought fit not to make any mention of my labours in the 

 same field, which had been published several years before 

 Professor Dewar went over them again. In the number for 

 June 1890 of the Bulletin International de V Academie de 

 Cracovie, I have described an apparatus serving to liquefy a 

 greater quantity of oxygen or air in a steel cylinder, from 

 which it can be poured out into an open glass vessel, and used 

 as a frigorific agent. It is entitled ' K. Olszewski. Transvase- 

 ment de Poxygene liquide \ and a brief report on the subject 

 is contained in the Beibldtter of Wiedemann, vol xv. p. 29, 

 under the title ' K. Olszewski. Ueber das Giessen des 

 fliissigen SauerstofTs.' That my labours should have thus 

 been passed over in silence is all the more astonishing, 

 because as soon as the above-mentioned Bulletin was printed 

 I sent a proof of it to Professor Dewar ; 1 also forwarded 

 him proofs of my other researches, knowing that they interest 

 him.''. . . . 



" From this summary of researches, as well as of dates, it 

 follows that the first apparatus serving to produce large 

 quantities of the liquefied so-called permanent gases, with 

 the solitary exception of hydrogen, was constructed by me. 

 This apparatus can be enlarged at will by increasing its parts, 

 but without changing anything in its construction, so that it 

 might be used to obtain liquefied gases in factories should 

 they at any time prove of practical utility. By means of this 

 apparatus I obtained as large quantities of liquid gases as 

 I wanted ; and they were used for the first time on a large 

 scale as cooling agents (for instance, in my attempts to liquefy 

 hydrogen) , or as an object of scientific researches (the absorp- 

 tion spectrum of liquefied oxygen, its coefficient of refraction, 

 &c.). 



" The experiments of Professor Dewar are merely the 

 repetition and confirmation of these researches, most of which 

 were published several years before his corresponding investi- 

 gations. His work is really original only as to the magnetic 

 properties of liquid oxygen : that which is not borrowed from 

 my researches is a development of ideas struck out by another 

 — as, for instance, the experiments on electrical resistance at 

 low temperatures, which were begun by Clausius, continued 

 by Cailletet and Bouty, and brought ten years ago by my 

 former fellow-worker, the late Professor Wroblewski, to the 

 temperature of the freezing-point of nitrogen, then several 

 degrees below the temperature attained in the experiments of 



