Aug. 4, 1870] 
NATURE 
277 
are everywhere and at all times present in the atmosphere. Mr. 
Tomlinson has shown experimentally that a crystal of the salt 
properly treated can be inactive in a solution of sodic sulphate.* 
The following experiments show that an atmosphere pre- 
sumably saturated with the salt may be inactive without any 
precautions whatever :— 
7. Three solutions of sodic sulphate were prepared ; a glass 
rod was dipped in melted tallow and left to cool for five minutes 
in a bottle of the salt, without touching the salt or the sides of 
the bottle. Then the three solutions were successively touched 
with the rod ; inactive in all. Rod replaced in the bottle for ten 
more minutes ; then all three again touched. The third crystal- 
lised aftera minute or two. Rod replaced for fifteen minutes ; 
active only in the second; replaced for fifteen minutes, active 
in the last. Thus this greasy rod was inactive in one of the 
solutions after an exposure of thirty minutes, and after being 
six times dipped in solutions of the salt. 
8. An open test tube, containing a strong solution of sodic 
sulphate, remained supersaturated for a week suspended in the 
same large bottle of the salt. The bottle was frequently moved 
without producing any effect. On removing the cork, the solu- 
tion crystallised instantly. 
On the whole I am afraid we must for the present fall back 
upon that refuge for the destitute, ‘* Catalytic action.” 
Birmingham J. G. GRENFELL 
Derivation of the Term “ Horse-Chestnut” 
THE explanation of the above name by Mr. E. A. Connell in 
your last issue, though ingenious, is not, I think, the true one. 
In a work entitled ‘‘ Etymons of English Words,” by John 
Thomson, Edinburgh, 1826, the term is explained thus:—‘‘ Horse- 
Chestnut. The arsh-chestnut ; but the F. and the Swedes have 
translated it as horse.” Following this he gives in support of 
horse, being the corruption of harsh, horse-faced, Aarsh-faced, 
hard-featured, horse-radish, /arsh-radish ;” and harsh, rough, 
sour, austere, grating, S. Aersk, T. harsch, D. harsk. So that, 
accepting this explanation, harsh-chestnut is the more scientific 
term. J. JEREMIAH 
Trehelig, Llangadock, Carmarthenshire, July 16 
Ozone and Thunderstorms 
In reference to the production of ozone it may interest your 
readers to know that the quantity developed here has been 
unusually great during the last few days. On Sunday evening, 
during the electrical agitation that occurred and ended in a 
slight discharge, accompanied by heavy rain, we had the highest 
reading. Mr. Burrows’ test paper registered 9, and was almost 
black. This observation was taken at 10 A.M. During the 
period of this development the air was very moist. Last evening 
and this morning have caused the ozonometer to register 7, and 
this is above the average. To-day, Tuesday, the hygrometer 
indicated the point of saturation. I may add that old Gilbert 
White’s remark as to activity of swifts during thundery weather 
has been greatly confirmed. They have kept up an almost 
incessant screaming during the last few days. 
Great Malvern, August 2 SAMUEL BARBER 
The Sun’s Corona 
A LETTER of mine, addressed to you a fortnight since, has, I 
fear, miscarried. It had special claim to admission as complain- 
ing of an editorial remark. 
I now renew my objection to the editorial note upon my 
letter referring to Professor Pritchard’s critique on my ‘‘ Other 
Worlds.” As an uncourteous comment upon a passage in which 
T had paid a high but not undeserved compliment to Mr. Lock- 
yer, I had just reason to be surprised at its appearance. 
First, because my account of Mr. Lockyer’s views respecting 
* It would seem from the experiments of Dr. L. C. de Coppet (which do 
not appear to be as well known as they deserve) that the treatment adopted 
by Mr. Tomlinson for rendering the sodic sulphate inactive really changes 
the salt. Dr. de Coppet finds that a supersaturated solution of sodic sul- 
 eeraP ia be prepared by dissolving the anhydrous salt in cold water ; and 
e writes—‘‘I have arrived at the conclusion that the anhydrous sodic sul- 
phate obtained by the efflorescence of the crystals with ten molecules of 
water, undergo a change of constitution when heated to temperatures 
superior to 33 or 34°; for the contact of a particle of the effloresced sulphate 
always causes the crystallisation of a supersaturated solution of this salt, 
whereas anhydrous sodic sulphate heated above 33° does not necessarily 
determine the crystallisation.”—Bull. Soc. Vaud. Sc. Nat. X., p. 15r. 
[These experiments render it probable that the so-called supersaturated 
solutions really contain the anhydrous salt in a state of unstable equilibrium, 
only requiring a disturbance to cause it to assimilate water, and thus produce 
a less soluble compound.— Eb. ] 
the corona agrees in all essential points with that given in the 
note, whereas the contrary is implied. 
Secondly, because I have not mis-stated Dr. Gould’s evidence, 
though forced to interpret it otherwise than he does. 
Thirdly, because my whole reasoning on the corona has been 
founded on evidence, and is therefore unjustly described in 
the note as ‘evolved from the depths of my moral conscious- 
ness”? (an old witticism, which, however, would have borne 
repeating had it been to the point.) * 
To the personalities in the note, as to the reference to my age, 
and so on, Imake no objection whatever, caring only to notice 
what seems worthy of notice. 
Let me add, however, my protest against a mode of speaking 
which implies that observers only are to be considered as astro- 
nomical workers. Not on my own account, but on behalf of.a 
long list of honoured names, I oppose the assumption that the 
careful study of observations (whether those observations have 
been made by others or not) is not to be regarded as work. If 
observers claim with pride such names as Herelius, Galileo, Ty- 
cho Brahe, Bradley, and many_more, the advocates of thought- 
ful theorising may point no less confidently to Copernicus, to 
Kepler, and to Newton, and in our own times to Adams and 
Leverrier. Those who, like the Herschels, have been able to 
work successfully in both ways, are few indeed in number. 
Observations will never be so little useful as when the at- 
tempt to utilise them is discouraged. 
RICHARD A. PROCTOR 
P.S.—Mr. Lockyer seems not to be aware that what he claims 
to have proved respecting the corona is accepted by me as proved, 
and forms an essential part of my theory. I am as well satis- 
fied as he can be (and on the same grounds) that the corona 
is not a solar atmosphere, 
VON GRAEFE 
PEAKING of the loss of Von Graefe, whose death, at 
the age of forty-one, we reported last week, the Revue 
des Cours Scientifigues remarks that Germany has sus- 
tained a loss equal at least to the loss of a battle. Von 
Graefe’s death was the sequel of a long consumption, 
during which he neither diminished his work nor took 
ordinary precautions. His grand discovery of the cure 
for Glaucoma was made when he was only twenty-six 
years old. The British Medical Fournal thus sums up 
his professional worth :— 
In him the world loses its foremost opthalmologist, one whose 
brilliant originality was equalled only by his steady industry. 
Not only was Graefe great in the practice of his profession, but 
as a teacher his influence was almost unbounded. Although 
comparatively young himself, he had taught almost all the 
present school ot ophthalmic surgeons. His introduction of 
iridectomy was, without doubt, the greatest step in the operative 
surgery of the eye since the introduction of operations for the 
cure of cataract. Probably, there are now living some thousands 
in the possession of sight, who but for him would have been in 
darkness. It is one of those gains which is complete in itself, 
permanent, and beyond the reach of scepticism. It is priceless. 
Graefe was an untiring observer, and never allowed his pressing 
engagements to interfere with the record of his vast experience 
for the good of others. Although he had done a vast amount of 
other work, still, however, his discovery of iridectomy shines 
with such pre-eminent lustre that the inscription, 
“ HE CURED GLAUCOMA,” 
would be by no means inappropriate. As aman, Graefe was 
everything that fis admirable, and secured the love of all who 
knew him. He was open, generous, unostentatious, eager both 
to give and receive knowledge. His personal appearance was as 
remarkable as the qualities of his mind. The Wiener Medizen 
Wochenschrift, in announcing Graefe’s death, says: ‘‘ German 
science loses in him one of her greatest celebrities, and suffering 
humanity one of its greatest benefactors. With Gracfe, a com- 
bination of geniality, erudition, self-devotion, energy, and amia- 
bility, such as is rarely found in one man, has descended into 
the grave. His name will ever remain most prominently con- 
nected with the history of ophthalmic surgery.” 
* Still holding to our comments we gladly state that they were not written 
in the spirit in which Mr. Proctor has read them. He is known to all as an 
astronomical worker, and our objection to his mathematical result was that 
it was based upon data among which the principal point <t issue was ac- 
cepted as proved.—Ep. 
