_Gutta Percha Baths_ (Vol. vii., p. 314.).--In "N. & Q." for March 26, I
ventured to recommend to H. HENDERSON gutta percha, as a material for
nitrate of silver baths. I did this from a knowledge that hundreds of
them were in use, but chiefly because I have found them answer so well.
In the same Number the Editor gives MR. HENDERSON very opposite advice;
and, had I seen his opinion before my notes appeared, I should certainly
have kept them back. But it is, I think, a matter of some importance,
especially to beginners, to have it settled, whether gutta percha has
the effect of causing "unpleasant markings" in collodion pictures or
not. With all due deference to the Editor's opinion, I do not believe
that gutta percha baths are injurious to the finished picture. I have
never any markings in my glass positives now, but what may be traced
with certainty to some unevenness in the film or dirtiness on the glass.
And I hope that the number of beginners who are using gutta percha
baths, and who are troubled with these unpleasant markings (as all
beginners are, whether they use glass or gutta percha), will not,
without some very careful experiments, lay the fault upon the gutta
percha. In the Number for April 2, the Editor thanks me for what he is
pleased to call "the very beautiful specimen of _my skill_." This was a
small glass positive, which I sent him in accordance with an offer of
mine in a former note. Now, _that_ was rendered sensitive in a gutta
percha bath, which I have had in use for months; and I think I may
appeal to the Editor as to the absence of all unpleasant markings in it.
Probably it may be a good plan for those who make the baths for
themselves to adopt the following simple method of cleaning them at
first. Fill the bath with water, changing it every day for a week or so.
Then wash it with strong nitric acid, and wash once or twice afterwards.
Always keep the nitrate of silver solution in the bath, with a cover
over it. Never filter, unless there is a great deal of extraneous matter
at the bottom. If glass baths are used, cemented together with
sealing-wax, &c., I imagine they might be as objectionable as gutta
percha. The number of inquiries for a diagram of my head-rest, &c., from
all parts of the kingdom--Glasgow, Paisley, Manchester, Leicester,
Leeds, Newcastle, Durham, &c. &c.--proves the very large number of
photographic subscribers "N. & Q." possesses. I think, therefore, it
cannot but prove useful to discuss in its pages the question of the
advantage or disadvantage of gutta percha.