SCIENTIFIC SUM MANY. 
385 
other extinct modifications, such as the Alabastine, the Elephantinon, the 
Melainotype, &c., in the well-filled lumber-room of oblivion. At a recent 
meeting of the Philadelphia Photographic Society, the eminent photographer 
and able experimentalist, Mr. Wenderoth, gave the results of his practical 
experience with such of these processes as still linger amongst us, and his 
conclusions are those which our best English photographers have also arrived 
at. He denounces the whole class as equally mischievous, but says of the 
collodio-chloride modification, “ It is of this style particularly that the cry of 
fading has been raised by those who have been practising it. When first 
published, I gave it a fair trial, and obtained some fair pictures, but soon 
found that its results could not be depended on.” This experience accords 
with that we have met with in many other quarters, and was questioned, 
we believe, by none of the authorities who were present at the reading of Mr. 
Wenderoth’s interesting paper. With wet collodion, with dry collodion, 
with the collodio-chloride, with gelatino- chloride, with albumen, and with 
salted collodion, the pretty and attractive opaltypes seem equally fugitive, 
their career being measured, not, as in the case of silver prints, by years, but 
by months. 
Magic Photographs. — A playful application of photography for the pro- 
duction of a new kind of “ parlour magic ” has sprung into existence since 
our last summary was written. This has been termed “Magic Photography.” 
A piece of apparently plain albumenized paper is supplied the purchaser, 
together with a piece of blotting-paper ; by placing the latter over the 
former, and wetting it, an image is developed. As light has nothing to do 
with this process, it is regarded by the uninitiated as very wonderful, but 
the explanation is amusingly simple. When immersed in a saturated solu- 
tion of bichloride of mercury, a fixed untoned print, which has been well 
washed, will gradually disappear. A piece of blotting-paper, which has been 
soaked in a weak solution of hyposulphite of soda and dried, will, however, 
when wetted and laid over the paper, restore the image very quickly, and 
when the image so restored is well washed, it is permanent. 
The Nitrate of Silver Bath. — A contributor to Loj Science pour Tous points 
out the danger photographers run of being deceived as to the actual strength 
of the silver baths by the inconsiderate use of the ordinary argentometer. 
An old bath contains a considerable quantity of iodide of silver in the place 
of nitrate, although its density may remain but slightly changed from that it 
had when new ; and the author accordingly recommends the dissolved iodide 
of silver to be precipitated by adding to the bath its own bulk of distilled 
water, filtering off the clear solution when it has settled, and then strengthen- 
ing with fresh nitrate of silver. This suggestion is not new, but, as it has 
been neglected, it is worth repeating. 
Perspective and “ Composition Photography .” — The term “ Composition Pho- 
tography ” has been applied to one of the most unscientific and inartistic of all 
the many applications of photography as an art ; and one which directly violates 
every rule of good taste and pictorial truth. It represents a species of patch- 
work process, by which pictures taken at different times and from different points 
of view are “ composed,” or rather incongruously combined, in the printing, 
for the sake of producing a photograph larger in size and more ambitious in 
its supposed pretensions than others. As this process, strange to say, has 
