i&ogai Institution of ffireat 



WEEKLY EVENING MEETING, 

 Friday, January 20, 1893. 



Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary 

 Secretary and Vice-President, in the Chair. 



Professor Dewar, M.A. LL.D. F.R.S. M.B.L 



Liquid Atmospheric Air. 



The prosecution of research at temperatures approaching the zero of 

 absolute temperature is attended with difficulties and dangers of no 

 ordinary kind. Having no recorded experience to guide us in 

 conducting such investigations, the best instruments and methods of 

 working have to be discovered. The necessity of devising some 

 new kind of vessel for storing and manipulating exceedingly volatile 

 fluids like liquid oxygen and liquid air, became apparent when the 

 optical properties of the bodies came under examination. The 

 liquids, being in active ebullition, were in a condition which rendered 

 optical measurements impossible. All attempts at improvement on 

 the principle of using a succession of surrounding glass vessels, the 

 annular space between such vessels having the cool current of the 

 vapour coming from the boiling liquid led through them, proved a 

 failure. Apart altogether from the rapid ebullition interfering 

 with experimental work, the fact that it took place involved a great 

 additional cost in the conduct of experiments on the properties of 

 matter under such exceptional conditions of temperature. 



While suffering great anxiety on the question of expenditure, the 

 Goldsmiths' Company came forward with the handsome contribution 

 of 1000/. to continue the work with improved apparatus. Personally, 

 I desire to express my grateful thanks to the Goldsmiths' Company 

 for tendering such encouragement and support. 



On careful consideration it became apparent that the proper way 

 of attacking the problem was to conduct a series of experiments 

 on the relative amounts of heat conveyed to boiling liquid gases ; 

 firstly, by means of the convective transference of heat by the 

 gas particles, and, secondly, by radiation from surrounding bodies. 

 The early experiments of Dulong and Petit on the laws of radiation 

 had proved the very important part played by the gas particles sur- 

 rounding a body in dissipating heat otherwise than by pure radiation. 

 In the year 1873 I used a highly-exhausted vessel in calorimetric 

 experiments " On the Physical Constants of Hydrogenium " (Trans. 



Vol. XIV. (No. 87.) b 



