hotographers who have attributed an occasional want of success to this
cause. I have, however, never myself seen good iodized paper deteriorated
by age. Many friends tell me they have used it when several years old; and
I can confirm this by a remarkable instance. On Tuesday (Dec. 6) I was
successful in obtaining a perfectly good negative in the usual time from
some paper kindly presented to me by Mr. Mackinly, and which has been in
his possession since the year 1844. I should add, the paper bears the mark
of "J. Whatman, 1842," and has all the characters of Turner's best
photographic paper. It appears to be a make of Whatman's paper which I have
not hitherto seen, and, from its date, was evidently not made for
photographic purposes.]

[Footnote 6: The paper may be iodized by pouring over it 30 minims of the
iodizing solution, and then smoothing it over with the glass rod. Care must
however be taken not to wet the back of the paper, as an unevenness of
depth in the negative would probably be the result.]

[Footnote 7: Much more attention should be paid to the purity of the
distilled water than is generally supposed. In the many processes in which
distilled water is used, there is none in which attention to this is so
much required as the calotype process. I mention this from having lately
had some otherwise fine negatives spoiled by being covered with spots,
emanating entirely from impurities in distilled water purchased by me
during a late excursion into the country.]

[Footnote 8: It is very requisite that the glasses of the frames should be
thoroughly cleansed before the excited papers are put into them. Although
not perceptible to the eye, there is often left on the glass (if this
precaution is not used) a decomposing influence which afterwards shows
itself by stains upon the negative.]

[Footnote 9: If boiling water is carefully poured in the negative in a
porcelain dish, it will frequently remove a great deal of colouring matter,
thereby rendering the negative still more translucent. It is astonishing
how much colouring matter a negative so treated will give out, even when to
the eye it appears so clean as not to require it.]

[Footnote 10: MR. SHADBOLT suggested a remedy for the disasters referred to
by DR. DIAMOND with regard to the gutta-percha vessels. Gutta-percha is
perfectly soluble in chloroform. MR. SHADBOLT therefore showed that if the
operator carries a small bottle of chloroform with him, he would b