300 Professor Dewar on the Liquefaction of Gases. 



Messrs. Dewar and Fleming, who, it is true, extended their 

 examination to various metals, alloys, and non-metals. But 

 the execution of these labours meets with no difficulty ; for 

 the method of getting large quantities of liquefied gases is 

 now generally known/'' 



Let us see what Professor Olszewski said in that paper 

 entitled " Transvasement de 1'oxygene liquide," June 1890. 



" A flask of wrought iron, 5 litres in capacity (such as is 

 used to hold liquid carbon dioxide), containing oxygen under 

 a pressure of 80 atm., is joined by a narrow copper tube to 

 the upper end of a steel cylinder tested at a pressure of 

 200 atm. This cylinder, having a capacity of 30-100 cubic 

 centim., according to the quantity of oxygen which we wish 

 to liquefy at a time, is immersed in liquid ethylene, of which 

 the temperature may easily be lowered to — 140° C. by means 

 of an air-pump. The lower end of the cylinder is joined by 

 a narrow copper tube to a little stopcock, through which the 

 oxygen, liquefied in the cylinder, can be poured down into 

 an open glass vessel kept cool by the surrounding air." 



In other words, replace the glass tube in my apparatus of 

 1884 by a small steel cylinder and attach to its lower end a 

 narrow copper tube with a stopcock, and the Olszewski appa- 

 ratus of 1890 would result. As a matter of fact Pictet had used 

 the same principle in the year 1878, and to take credit for 

 originality in repeating his device seems a little absurd. Now 

 on the 11th of June, 1886, 1 delivered a lecture on " w Recent 

 Researches on Meteorites," and the report in the ( Proceedings 

 of the Royal Institution ' contains a sectional drawing of an 

 apparatus (reproduced on the other page) solely constructed 

 of copper, together with a valve for drawing off liquid oxygen, 

 entirely different in type from the plan Olszewski adopted in 

 1890. I may mention that the plan of the apparatus was repro- 

 duced immediately after the delivery of the lecture both in 

 England and America. The section is confined to the refrige- 

 rator, all the accessories of liquefied and compressed gas-bottles, 

 compression and exhaust gauges, &c. having been omitted. 

 From this plan of the refrigerator, any person so desiring 

 could increase its capacity so as to work on a larger scale. The 

 drawing shows the apparatus arranged for the special ex- 

 periment of ejecting liquid oxygen into a vacuum-chamber, 

 but it is clear the apparatus discharged more easily into an 

 ordinary open vessel. It is the form of apparatus that is 

 in dispute, not the result of any particular experiment. The 

 special object for which it was in use in this lecture was 

 to cool a piece of Meteorite before insertion into an Electric 



