and §, No 3., Jan. 19. °56.] 
tion of a name only renders an investigation some- 
what difficult. He refers me, for instance, to 
“ Constable's reply to Courayer on this particular 
point.” In what work of Constable is this reply 
to be found? Iam acquainted with one work 
only of Constable, viz. his Remarks upon F. Le, 
Courayer's Book in Defence of the English Or- 
dinations, by Clerophilus Alethes (attributed to 
Constable) ; but this cannot be the work referred 
to by T. L., as it is a reply to Courayer’s Dis- 
sertation, whereas the reference to Coke’s charge 
by Courayer is in the second vol. of his Defence 
of the Dissertation, which I am not aware that 
Constable ever answered. And, after all, who 
was Constable ? A writer who implicitly believed, 
and unhesitatingly adopted the monstrous fable of 
the Nag’s Head Consecration! —a story utterly re- 
jected by Lingard himself as a palpable forgery! 
— History of England, vol. vi. p. 668., edit. 1849. 
E, C. Harineton. 
The Close, Exeter. 
PHOTOGRAPHIC CORRESPONDENCE. 
Abbé Desprats on Dry Collodion. — The Abbé Desprats 
has addressed a communication to Za Lumiere on the sub- 
ject of photography on glass with dry collodion. He 
considers that all the dy photographic processes (that is, 
albumen on glass, waxed paper, &c.) are founded on the 
‘same principles ; and that we have only minutely to inves- 
tigate those principles, and carefully to follow them out, 
to obtain the same results with dry collodion as with 
alvumen or any other substance. The following process 
is the result of his experiments on that subject, and he 
considers that it can scarcely fail of success : — 
“The collodionized glass plate is sensitized for sixty 
or eighty minutes, as usual, in a sutliciently weak bath 
of nitrate of silver; four per cent. is quite strong enough. 
After taking it out of the sensitizing bath, the glass plate 
is carefully washed with distilled water. To do this, it is 
placed at the bottom of a shallow flat dish, the collodion 
side upwards; then gently covered with a centimetre, or 
more, of distilled water, and the saucer moved about 
gently for a minute or less. The plate is then taken out, 
and a stream of fresh distilled water poured on both 
sides, and then placed upright to drain on blotting-paper, 
and left to dry in complete darkness, When it is once 
dry, it can be acted upon by the light. 
“ The duration of the exposure varies according to the 
sensibility of the collodion. We have not remarked, in 
working the next day with the dry plate, that the sensi- 
bility had been perceptibly diminished, and less so than 
the wet plate would be. 
“ The image having been impressed on the glass plate, 
_ if is necessary to make it appear. . This part of the pro- 
cess, which until now has been the cause of many failures, 
is by a very simple precaution the easiest thing in the 
world. 
__ Take the dish which’was used for the first bath of 
distilled water, and, having emptied and washed it with 
care, pour into it two centimetres of fresh distilled water. 
Set the glass upright, near one of the edges, and lower it 
gently by means of a hook, the collodion upwards; move 
the plate up and down in draining it, and raising it by 
turns so as quite to assure the contact of the collodion 
and the liquid. Do this fora minute or more, until the 
NOTES AND QUERIES. 
61 
surfuce of collodion has become completely transparent. If 
by means of the feeble light passing through yellow 
glass, any bubbles of air are seen adhering to the surface 
of the collodion, the glass should be raised and the bub- 
bles got rid of by blowing the surface. The glass plate, 
having well imbibed the water, it should,be let to drain 
gently by a corner, and submitted a second time to the 
first sensitizing bath. It should be left there longer than 
the first time, and the plate often moved up and down in 
the bath by means of a hook of silver or platinum, which 
should support it, and should be kept there all the time; 
but in such a manner, as that the hooked part shall not 
touch the collodion; scratches, however, are less to be 
apprehended than in the wet process. After sixty or 
eighty seconds of immersion, the plate is taken out and 
let to drain slightly; it is put on a levelling stand, and 
covered immediately with pyrogallic acid, acidulated 
with crystallizable acetic acid in the ordinary proportions. 
The image will not be long in appearing; at the end of 
five minutes perhaps the details will be nearly complete. 
At this moment pour the solution of pyrogallic acid into 
a small bottle, where you have dropped several drops of 
a weak neutral solution of nitrate of silver of three per 
cent., and cover the plate again with this liquid; the 
blacks become directly very strong, and the action of the 
bath must be stopped when the desired effect has been 
arrived at. The only thing now to be done, is to wash 
the plate with common water, and fix it by means of a 
saturated solution of hyposulphite of soda; and then 
wash it and diy it as usual.’’ 
These photographs, the Abbé Desprats says, are re- 
markable for their beauty and regularity; and there is 
much less danger of stains, &c., than with the wet pro- 
cess. He much prefers collodion to albumen; and says, 
in fact, that the dry collodion process possesses all the 
advantages of other photographic processes, without any 
of their inconveniences. 
He considers this process to be very applicable to 
printing on glass for the stereoscope. On the collodion 
the lights are very clear, and the darks decided; but great 
delicacy is necessary, owing to the degree of sensibility of 
the collodion, which ordinarily is too great. The sensitive- 
ness of the dry collodion is quite sufficient; for, in print- 
ing, sometimes eyen the fraction of a second is too much 
to expose it in full daylight; and he has found it possible 
to print a positive from a negative on albumenized glass, 
by passing it for three minutes before the red flame of a 
candle. In printing, he considers it to be an advantage 
to have a collodion not very sensitive. 
With collodion two years old, and that had turned red, 
he has obtained very good positives on glass by an ex- 
posure of scarcely a second to a moderately bright dif- 
fused light. 
Photographic Society’s Exhibition. — We had purposed 
giving a detailed account of the beautiful series of Pho- 
tographic Pictures now exhibiting by this society; but 
really the progress recently made by the art is so great — 
the general excellence of the pictures exhibited so un- 
questionable —that we must content ourselves with 
urging all who love truth and beauty to go and judge 
for themselves, reminding® them (which it may be con- 
venient for many to know) that the Exhibition is open in 
the evening from seven till ten. One remark we must. 
make, namely, that great as is its progress as an art ge- 
nerally, photography has made special progress in that 
division for which, as we have so long insisted on in this 
journal, it is particularly adapted—namely, that of giving 
faithful representations of objects of antiquarian interest. 
Let the visitor examine Mr, Fenton’s Cuneiform Inscrip- 
tions (of the size of the originals), and his other anti- 
