iSyg.] Molecular Physics in High Vacua. 41 1 
stance of its own structure, and giving up the healthful, 
life-giving oxygen to the atmosphere again. This process is 
so regulated as exadbly to keep pace with the liberation of 
carbonic acid through the agencies mentioned above. Other 
deleterious gases are thus taken in and rendered innocuous. 
The blue gum (Eucalyptus globulus), of Australia, has become 
famous for absorbing the deadly gases in miasmatic distri< 5 ts, 
and thus rendering them healthy. Thus the leaf labours 
preparing food for all living animals, and raiment and fuel 
for the lords of creation, as well as all wood and bone and 
ivory used in the arts. It also purifies the air, making 
animal life possible, and clothing the earth with beauty 
that the life thus preserved may be replete with the highest 
enjoyment . — Kansas City Review of Science and Industry . 
IV. MOLECULAR PHYSICS IN HIGH VACUA.* 
By William Crookes, F.R.S. 
k'\3^7"HEN I was asked, a month or two ago, to illustrate 
in this theatre some of my recent researches on 
Molecular Physics in High Vacua, I exclaimed 
“ How is it possible to bring such a subjedl worthily before 
a Royal Institution audience when none of the experiments 
can be seen more than three feet off?” If to-night I am 
fortunate enough to show all the experiments to those who 
are not far distant, and if I succeed in making most of 
them visible at the far end of the theatre, such a success 
will be entirely due to the great kindness of your late 
Secretary, Mr. Spottiswoode, who has placed at my disposal 
his magnificent indudbion-coil, — not only for this ledture, 
but for some weeks past in my own Laboratory, — thus 
enabling me to prepare apparatus and vacuum tubes on a 
scale so large as to relieve me of all anxiety so far as the 
experimental illustrations are concerned. 
Before describing the special researches in molecular 
physics which I propose to illustrate this evening, it is 
necessary to give a brief outline of one small depart- 
ment of the modern theory of the constitution of gases. 
* A short-hand report of a Le&ure delivered at the Royal Institution, on 
Friday, April 4, 1879. 
VOL. IX. (N.S.) 2 E 
