474 
forget the impression I received when I first saw him 
burn diamond under liquid air—the gradual accretion 
of the carbon dioxide snow-shower and the blueing of 
the fluid by ozone, also demonstrated by the iodine 
test. Then the rapid uprush of the mercury in a 
barometer-tube full of air when the tube was cooled 
with liquid hydrogen: it all but knocked the top off. 
Or again, the production of ozone at the surface of 
solid oxygen by the impact of ultra-violet radiations. 
At such moments—and there were many such—the 
heart beat with joy at the significance of his feats of 
inspiration. 
To the outside world Dewar is known as the man who 
liquefied oxygen and other gases and as the inventor 
of the vacuum flask—his name will probably go down 
the years on this last account. It is due to his memory 
that this should be spoken of henceforward as the Dewar 
flask: it was his free gift to the public; had he pro- 
tected and developed the invention he might have 
amassed a fortune and fully endowed his chair. 
The real value of his work on gases, apart from the 
impetus it gave to the industrial use of liquefied air in 
particular, is to be found in the many new directions 
in which he developed the art of inquiry at low tempera- 
tures. Perhaps the most illuminating is the inquiry 
into the heat capacities of the elements at the tempera- 
ture of boiling liquid hydrogen: the discovery of a 
periodic variation, corresponding with that in atomic 
volume at ordinary temperatures, is not only surprising 
but may well prove to be of profound significance in 
the future interpretation of atomic properties in terms 
of electronic structure. 
Like his great predecessor, Dewar leaves a mass of 
material to be interpreted by his successors. Un- 
fortunately, he was all too careless in placing his work 
on record. Like Turner, he painted for his own 
pleasure, to give expression to his genius—but too often 
did not put the picture aside for a Ruskin to glory over. 
In two essays printed in the Proceedings of the Royal 
Institution—one on the “ Charcoal Vacuum Septennate”’ 
(1909), the other on the “ High Vacuum Septennate ” 
(1917)—I have briefly summarised his later and chief 
work at low temperatures ; in the latter I also briefly 
review his work generally as Fullerian professor up to 
1917. These essays may serve to guide students. With 
him, however, we lose a vast unrecorded experience. 
Of late years he had returned to a first love—the soap 
film ; it saved his life and was his solace, keeping him 
from utter despair during the War. He only left it to go 
to his last bed of sickness. It is to be feared the record 
of the work is a very imperfect one. Those who were 
at his last lecture on “ Soap Films as Detectors,” on the 
opening of the Friday evenings this year, will not forget 
the occasion. He was obviously in physical distress 
and feeble but mentally as alert as ever; the artist 
was never more to the fore. His appeal was that made 
in Cory’s beautiful Incantation. 

My sun is stooping westward. Entrancéd Dreamer 
haste, 
There’s fruitage in my garden that I would have thee 
taste. 
But he was the “ entrancéd Dreamer ”—the fruitage 
he gave us to taste was lovely ; nothing so exquisite 
had before been brought in such perfect form under the 
public eye. He recalled Young to us; then, playing 
NO. 2788, VoL, 111] 
NATURE 

[APRIL 7, 1923 
with a delicate pencil of air upon his liquid lute, he 
made visible, in hues of the rainbow, the multitude of 
its melodies, during over a third of his hour. He had 
never before lingered so long over a single demonstra- 
tion. He knew that we were,gazing upon no mere 
play of colour but upon a dance of the molecules such 
as is at the root of life—and death ! 
How many of us were serious listeners to the message 
he felt was to be his last, that he was most bent on 
making, to his urgent appeal on behalf of the Institution 
which he had served so long, so well, so nobly—was to 
serve even up to the moment of his death? He will have 
worked to no purpose if his appeal be unregarded. The 
fate and future of science in our country is at stake : 
nothing less. The Egyptians, thousands of years ago, 
could make worthy provision for the soul of a boy king 
of eighteen who had done nothing. Surely our civilisa- 
tion cannot be so backward, so thoughtless, so un- 
mindful of its present peril, that it will not properly 
maintain an altar and a virile priesthood to keep alive 
the. memory of men like Davy, Faraday and Dewar 
in the one way they would all wish—by extending their 
works in the service of mankind, to its salvation. 
H. E. A. 
Pror. A. S. BUTLER. 
ARTHUR STANLEY BUTLER, emeritus professor of 
natural philosophy in the University of St. Andrews, 
died at his residence at Upper Redpits, Marlow, Bucks, 
on March 3. He was a worthy scion of a family 
distinguished in the church, in education, in letters, 
and in athletics. His grandfather, the Rev. Dr. 
George Butler, senior wrangler, was the distinguished 
headmaster of Harrow; one uncle was Dr. Henry 
Montague Butler, master of Trinity College, Cam- 
bridge, whose charm of manner he possessed ; another 
uncle was the well-known Arthur G. Butler, Dean of 
Oriel, a not undistinguished athlete. His father, the 
Rev. George Butler, D.D., at one time vice-principal 
of Cheltenham College, was latterly Canon of Win- 
chester ; his mother, Mrs. Josephine Butler, an author, 
philanthropist, and active pioneer in higher education 
of women. 
Prof. Butler was born on May 17, 1854; educated 
at Cheltenham and at Exeter College, Oxford (of 
which his father—a Hertford scholar in his day—had 
been fellow), where he obtained first class in Modera- 
tions (mathematics) and first-class honours in the Final 
School. After further study at Oxford, at Cambridge 
in the mechanical workshop under Prof. James Stuart, 
and at Liverpool, he was appointed to the chair at 
St. Andrews in 1880. 
Prof. Butler’s experience, especially at Cambridge, 
made him realise how desirable it is that students 
of natural philosophy should carry out some experi- 
mental work in addition to attending lectures and class 
demonstrations. 
he had the difficulties of want of accommodation and 
suitable apparatus. In the first year at St. Andrews 
a special grant provided him with some necessary ap- 
paratus, and in a few years he succeeded in obtaining a 
good practical laboratory well furnished: and then all 
his students were required to do some practical work. 
As a lecturer Prof. Butler was highly successful. 
His lectures to the ordinary class were characterised 
But like his predecessor, Prof. Swan, — 
ET 
el Ps 
