on of 245
grains of iodide of potassium, a clear solution will be obtained; should it
not, a few more grains of the iodide of potassium will effect it. It may be
well to add that I believe neither of the solutions is injured by keeping,
especially if preserved in the dark.

I would here offer a caution against too great reliance being placed upon
the use of gutta-percha vessels when travelling, as during the past summer
I had a bottle containing distilled water which came into pieces; and I
have now a new gutta-percha tray which has separated from its sides. This
may appear trivial, but when away from home the greatest inconvenience
results from these things, which may be easily avoided.[10]

Dishes of zinc painted or japanned on the interior surface answer better
than gutta-percha, and one inverted within another forms, when travelling,
an admirable lid-box for the protection of glass bottles, rods, &c. On the
Continent wooden dishes coated with shellac varnish are almost entirely
used.

[Footnote 2: In a communication I formerly addressed to my friend the
Editor of "N. & Q.," one of the arguments I used in favour of the collodion
process was, that the operator was enabled at once to know the results of
his attempts; and was not left in suspense concerning the probable success,
as with a paper picture requiring an after development.

I made that observation not only from the partial success which had then
attended my own manipulations, but from the degree of success which was
attained by the majority of my photographic friends. But that objection is
now almost entirely removed by the comparative certainty to which the paper
process is reduced.]

[Footnote 3: The effect was illustrated in two negatives of the same
subject, taken at the same time, exhibited to the meeting, and which may
now be seen at Mr. Bell's by those who take an interest in the subject.]

[Footnote 4: For this purpose, strips of wood from 1 inch to 1-1/2 square
will be found much more convenient to pin the paper to than the tape or
string usually recommended. The pressure of a corner of the paper to the
wood will render it almost sufficiently adherent without the pin, and do
away with the vexation of corners tearing off.]

[Footnote 5: Some difference of opinion seemed to exist at the reading of
the paper, as to the propriety of preparing iodized paper long before it
was required for use, and I have since received some letters from very able
p