SA 
TRANSACTIONS OF THE SECTIONS. 49 
(Statice Armeria), which had grown close to the sea-shore and contained iodine, and 
found fluorine in the plant, 
When all those facts are considered, it is not too much, the author thinks, to urge 
that fluorine should now take its place among the acknowledged constituents of sea 
water. He has entered at length into the consideration of the natural distribution 
of this element, and into other details connected with it, in a paper in the Transac- 
tions of the Royal Society of Edinburgh, vol. xvi. part 7, and in a communication 
made to the Association at its Southampton meeting. The author further notices, 
incidentally, that the only ascertained plant, so far as he knows, in which fluorine had 
previously been detected, is barley, in which Will found it. In 1846 the author 
detected this element in American potashes, and it now appears to be one of the 
constituents of the kelp sea-weeds, although the observations which were made on 
commercial kelp are liable to the objection, that the fluorine detected might be de- 
rived from sea water which had dried upon the kelp weed before it was burned. 
The Statice Armeria may certainly be added to the list of plants containing fluorine, 
and so may the Cochlearia Anglica, in specimens of which obtained from the Bass 
Rock, and analysed in Dr. Wilson’s laboratory, Dr. Veelcker has also detected this 
element. 
Specimens of etched glass were shown to the Section in illustration of this com- 
munication. 
P.S. The specimens of etched glass sent, are seen to most advantage if placed on 
a sheet of paper and held in direct sun-light, or any other bright flame, so that the 
shadows of the grooves which form the letters may fall upon the paper. 
Analytical Investigations of Cast Iron. By F. C. Wricutson. 
This series of analyses showed the influences of the hot blast in producing the so- 
called ‘cold short iron,” by occasioning an increased reduction of phosphoric acid, 
and the consequent increase of phosphorus in the “hot-blast” iron. The respective 
per-centages were :— ; 
F I. II. TI. IV. Ve VI. ‘VII. 
Cold blast ...... wee 047 0°41 0:31 020 021 0:03 0:36 
Hot blast ...,....+6. . O51 055 050 O71 054 0:07 0-40 
The irons differed also considerably as to the state in which the carbon was con- 
| tained, the hard white iron resembling impure steel, containing nearly all its carbon 
in a state of chemical combination, whilst the carbon contained in the gray and 
| mottled varieties of iron was principally contained only as a mechanical mixture. 
The presence of sodium and potassium in all the specimens examined was also no- 
_ ticed for the first time, and it was thought probable that these might materially affect 
| the qualities of the metal. 

GEOLOGY AND PHYSICAL GEOGRAPHY. 
Notes on the Geology of the Channel Islands. 
By Rosert A. C. Austen, F.R.S. 
_ Tur object of the present short communication is not to give a detailed account of 
the mineralogical character of the various crystalline rocks which form so large a por- 
tion of this group, nor to lay down their topographical extent. The publication of facts 
of this class does not form any part of the objects of the British Association, and all 
that I would now attempt is a few general results, for the purpose of discussion, on 
One or two points in geological investigation, which these islands help to elucidate. 
The mineralogical constitution of Guernsey in particular, as is well known, was 
investigated by Macculloch, himself a native of that island. 
From the position of this group with reference to the coast of France, it is obvious 
_ that comparisons must be instituted rather with the formations of the Cotentin, than 
_ with anything on the English side of the channel. One great difficulty which every 
1849. 4 
