SCIENTIFIC SUMMARY. 
579 
But he had not succeeded, even on boiling nineteen out of twenty parts of 
the water away, in expelling the whole of the nitrogen. Water that has 
been so boiled rapidly absorbs air again. His general conclusions were, 
that water has a very powerful affinity for the gases of the atmosphere, and 
especially for nitrogen ; that by several processes the oxygen may be 
removed from water, but the nitrogen resists all efforts at separation, and 
therefore it is doubtful if absolutely pure water had ever been prepared ; 
and that ebullition in water consisted in the production and disengagement 
of bubbles of steam formed upon a nucleus of a permanent gas. 
Several letters to and fro, between Dr. Tyndall on the one hand and 
Professors Thomson and Tait on the other, respecting the manner in 
which Dr. Tyndall has treated the claims of Dr. Joule of this country in 
the subjects of heat, &c., versus those of Dr. Mayer on the Continent, have 
been published in recent numbers of the “ Philosophical Magazine,” and 
reach their climax in the number for June, in which Dr. Thomson 
declines to take part personally in any controversy with Dr. Tyndall. 
Dr. Matthieson and Dr. Vogt have examined the influence of tempera- 
ture on the electric conducting power of thallium, and find that thallium 
decreases in conducting power about 311? per cent, between the freezing 
and boiling points of water. 
The Rev. N. Callan describes in the June number of the “ Philosophical 
Magazine” “an induction coil of great power.” With this coil he has 
obtained electric sparks “ fifteen inches ” in length. This, if we recollect 
rightly, is less than that obtained by Mr. Siemens with his large induction 
coil exhibited at one of the soirees of the Royal Society, and described in 
a previous number of this Review. The length of wire in the secondary 
circuit of Dr. Callan’s coil was “ 150,000 feet.” 
Mr. W. Ellis has published in the “Philosophical Magazine” for May 
an account of some experiments he has been making “ on the change of 
rate produced in a clock by a particular case of magnetic action.” He 
describes the different conditions under which the clock was retarded or 
accelerated by the influence of approximated magnets. 
A paper by Dr. Angus Smith has been read before the Royal Society, 
“ On the Absorption of Gases by Charcoal.” He has found that charcoal 
absorbs oxygen so as to separate it from common air, or from its mixture 
with hydrogen or nitrogen at common temperatures, and that it absorbs it 
for at least a month, rapidly at first and slowly afterwards. It does not 
absorb hydrogen, nitrogen, or carbonic acid for the same period. Water 
expels mercury from the pores of charcoal by an instantaneous action. 
Mr. Hunter, of Queen’s College, Belfast, has also been experimenting 
in the same subject. He finds that logwood charcoal absorbs the most 
ammonia, fustic charcoal most carbonic acid, and ebony charcoal most 
cyanogen. 
ZOOLOGY. 
Species of Rhinoceros.— Mr. Blyth has been at great pains to examine 
into the statement of Heifer, that the three known species of Asiatic 
YOL. II. NO. VIII. 2 R 
