14 
a low temperature as well as pressure to reduce them. Acting 
on this principle, Cailletet, on Dec. 2nd, 1877, and Pictet a few 
days later, succeeded in liquefying oxygen by cooling it to a low 
temperature and applying some two hundred atmospheres of 
pressure. Olezewski and Wroblewski similarly liquefied oxygen, 
nitrogen, and finally hydrogen, in 1884. 
About 1895 the method was revolutionized by the invention of 
the regenerative process. By this method no preliminary cooling 
is necessary, except in the case of hydrogen. The gas is pumped 
to a high pressure in a receiver. It is then liberated, expanding 
as it issues from its receiver and becoming lowered in temperature 
by expansion. The gas so cooled is made to cool that not yet 
expanded, the latter becoming thus further cooled. By this 
“regenerative ’’ process a gas can be made to cool itself to a tem- 
perature approaching the absolute zero, and the most refractory 
gases have thereby been condensed to the liquid state at ordinary 
atmospheric pressure. They can be placed in open Dewar non- 
conducting vessels and used for investigation on the laboratory 
table. 
The lecturer then made a series of experiments with liquid air. 
This liquid, which resembles water, and which he poured from one 
Dewar vessel to another, has a temperature of —187 deg. C. (about 
300 deg. F. ‘‘ of frost’). Anobject placed in it caused it to boil, 
as a red-hot iron in water. The moisture of the air around the 
vessel was precipitated as hoar frost. Fresh flowers placed in the 
liquid were frozen, so that they broke into dust in the hand; a 
soft rubber ball so frozen broke in fragments on the floor ; mercury 
became solid, and could be bent like lead ; alcohol and ether were 
frozen to solid white substances. Dr. Spencer showed experi- 
mentally that the colour of many substances tends to disappear 
at this low temperature. The tube conveying ordinary coal gas 
to a lighted jet was surrounded by liquid air. All the constituents 
of the gas were thereby condensed except the hydrogen, which 
alone passed to feed the flame. The luminous jet was thus re- 
duced to a small blue jet of hydrogen. 
Friday, April 3rd, Mr. Henry Clarke, J.P., in the chair. 
Dr. E. F. Bashford, Director of the Imperial Cancer Research, 
gave a lecture on Cancer, its characteristics, its incidence, 
and the investigations that are being made by the Research. The ~ 
lecturer expressed his regret at the inability of the President of ~ 
the Society to be present that evening, as it was in 1847 that Sir 
