SCIENTIFIC SUMMARY. 
101 
Lamps for Thotograpliy . — Two forms of lamp have been recently devised 
which deserve notice. One is the ingenious Electric Lamp of Mr. Browning, 
and the other the Magnesium Lamp of Mr. Solomon. Mr. Browning’s lamp 
is so contrived that the charcoal points are always kept together by means 
of an electro-magnet and armature. The upper bar containing the upper 
charcoal point, is the one which is clamped by the magnet when the current 
travels through it. This lamp is especially suitable for lanterns, giving a 
good 9 feet disc with a Grove’s battery of about 8 cells. Mr. Solomon’s 
Magnesium Lamp has, as usual, clockwork for uncoiling the ribbon off the 
bobbin. The ribbon is about 50 yards long, and will give a steady light for 
about two hours. 
Landscape Photography in Cloudy Weather. — Mr. M. Whiting, Jun., sends 
the following note to our interesting contemporary. The British Journal of 
Photography, No. 449: When taking distant views and a variety of scenery 
on a dry plate (especially in Scotland), on a cloudy day, where a part of 
the view may contain dark woods or other foliage, which, with an ordinaiy 
exposure would hardly come out sufficiently distinct, great assistance can be 
secured by the following plan : Suppose the whole exposure will require 
four minutes : first give two or three minutes with the average light, and, 
for the remainder, only uncap the lens when that part of the view you wish 
more fully to expose is lit up by the sun and the other part is in shadow. 
This is far more easy to do than it appears to be.” 
A new Mount for Photographs has been brought out by Mr. Fox, and is 
favourably spoken of. The new mount, instead of having a tint for imme- 
diate contact with the picture, surroimded by a broad white margin, is 
printed with a broad tint, which constitutes the margin, with a space of 
plain white in the centre, leaving a margin of white to come into contact 
with the picture itself. This effect with many pictures is very pleasing. 
For instance, in landscapes where the sky has printed through to a delicate 
tint, the print, if mounted on an India tint, would appear to have a white 
sky \ mounted, however, in contact with the white portion of a board having 
a tint beyond, the atmospheric tint of the sky receives its full value, and the 
picture becomes effective. The same is true of vignetted portraits in which 
the background softens into a grey tint instead of into white, and in a 
number of other cases the new style will produce a more pleasing result 
than any yet devised. 
Cheap Magnesium. — A writer in the Builder says : “ There is now a fair 
prospect of a reduction in the price of magnesium through some recent im- 
provements in its manufacture, and it is probable that in the course of next 
year we shall see the metal retailed at or under one shilling per ounce.” 
Photographic Paper. — A contemporary states that a prize of 2,000 fr. has 
been oftered in France for the production of the best photographic paper. 
The prize will be awarded in 1869. — Photo. Neics, Dec. 15. 
Treating Negative Baths. — Mr. M. Carey Lea gives the following results 
obtained by Dr. Jacobsen when treating disordered negative baths with per- 
manganate of potash : The first bath tried was an ordinary negative bath 
which had ceased to work clean. A solution of permanganate was dropped 
carefully in, so long as its deep red colour was destroyed by stirring up the 
bath. As soon as a drop of permanganate left a coloration which did not 
