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TRANSACTIONS OF THE SECTIONS. 53° 
winds almost constantly sweeping through the glen. In conclusion, he stated that 
he had as yet been unable to prove the existence of any natural deposits of iron ore 
in the vicinity of Loch Goil, but intended to examine the locality more fully on an 
-early occasion. 
On the Purification of Large Towns by means of Dry Cloace. 
By Dr. Luoyp. 
On the Atomie Weight of Aluminium. 
By Professor J. W. Maruer, University of Alabama, United States. 
_ Some experiments were described by the author which he had made upon metallic 
aluminium prepared in Paris and in Berlin, The composition of the commercial metal 
was found to be— 
Paris, Berlin. 
MOO eye eat es betes 6h, a tO eeGOO 96°2538 
Pratt. tre cue ha nae. BPG St ARB Oo 3°293 
HUGO fan Panta et ete la ceteke of ALA, 454 
‘COTE TNS 7S Ns leva OY coe ee trace trace 
PREATUD a Lenk vast cebd sf.) ceinn.s Pils trace? 
100 100 
Dissolying the metal in dilute muriatic acid, precipitating with ammonia, weighing 
the precipitate, and calculating from the results, and from the above composition of 
the crude metal, the weight of pure alumina yielded by a given weight of pure alumi- 
nium was found, and hence the equivalent of the element. The number deduced 
from one experiment, out of four made, differed so seriously from that given by the 
other three, that the investigation must be looked upon as still quite incomplete. The 
apparent cause of the discrepancy was pointed out; namely, the retention by alumina 
of a small amount of water at even a very high temperature. The importance of a 
speedy revision of the atomic weight of aluminium was insisted upon, the method by 
which the number now admitted was obtained being noticed as ill-suited to give an 
accurate result, 
On the Melting-points of Bodies. By Dr. Mtauu. 
Notices of Photography. By M. v’Asst Moreno. 
The Asst Moreno presented, in the name of M. Bertsch, ‘ Microscopic Photo- 
graphs;’ in the name of Mr. Bingham, ‘ Improved Photographic Copies of Oil Paint- 
ings;’ and in the name of M. Niépce de St. Victor, ‘ A perfectly New Method of exhi- 
biting, by means of Photography, the Phosphorescence and Fluorescence of Bodies.’ 
There are two methods of rendering evident this new action of light upon bodies 
submitted to its influence. The first consists in the exposure to light of an engraving ~ 
which has been kept in a dark place, and which after exposure is placed upon a sheet 
of photographic paper. After twenty-four hours’ contact the engraving leaves its 
image upon the latter, the black parts of the drawing making a white expression 
on a dark ground. In this experiment the engraving may be replaced by any 
other body: wood, paper, ivory, porcelain, &c., all act more or less in the same 
manner. If the interior of an opake metallic tube closed at one end and lined with 
_ paper or card-board, be exposed to the sun for about an hour, and then taken into a 
_ dark room, it leaves the impression of its circular orifice on photographic paper; and 
if after exposure its extremity be closed and sealed up, the interior will preserve its 
__. radiating power for a considerable length of time, and will act on photographic paper 
_ on being opened. 
_ A drawing made upon paper with fluorescent or phosphorescent substances, such 
as sulphate of quinine, &c., and exposed to the sun, prints itself on photographie 
paper in the dark, far better than those parts of the paper which the salt has not 
touched. A plate of either ordinary glass, or of glass coloured by oxide of uranium, 
when placed between the drawing which has been exposed to light and the photo- 
_ graphic paper, prevents the impression taking place. If the drawing in sulphate of. 
