H. H. H. (Ashburton). All the best authorities concur in the uncertain properties of the salts of gold. We have seen some Daguerreotypes which have been executed about three years, and were treated with the salts of gold, and which are now mere shades.
C. M. M. (Abbey Road). Your question as to the spots has been carefully answered in a late Number. The film which you notice on the surface of your nit. silver bath depends upon the remaining portion of ether in the collodion being liberated, which, not being very soluble in water, causes the greasy appearance. It soon evaporates, and is of no consequence.
T. Cook is thanked for his offer of a cheap and easy method of obtaining pictures for the stereoscope. We shall be glad to receive it.
Dr. Diamond's Photographic Notes.—We share in the desire expressed by W. C., J. M. S., and many other Correspondents, for the speedy publication of this volume. But we believe the delay is not to be regretted. It is a very easy matter to write a book upon Photography; but it requires no small labour, and great consideration, to produce such a volume as Dr. Diamond proposes, in which it is his desire to explain everything so clearly, that a person living in a remote part of the country, or in the colonies, may, from his directions, make a good photograph.
Errata.—P. 25., last line, read "campus" for "campres;" p. 26., fourth line, read "iaro" for "iars;" p. 36., 2nd col. line 18., read "regularity" for "irregularity."
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GILBERT J. FRENCH,
BOLTON, LANCASHIRE,