FOOTNOTES

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Sir William de Wiveleslie Abney
  1. Footnote [1]

    Such things as test-tubes should be found in every photographer's work room; they cost little, and are always useful for working solutions. The sizes recommended are 3/8-inch, 1/2-inch, and 1-inch diameter. A dozen of each will not be out of the way.

  2. Footnote [2]
    Sodium Chloride and Silver Nitrate form Silver Chloride and Sodium Nitrate.
    NaCl + AgNO3 = AgCl + NaNO3
  3. Footnote [3]
    Chlorine and Potassium Nitrite and Water give Hydrochloric Acid and Potassium Nitrate
    2Cl + KNO2 + H2O = 2HCl + KNO3

    and

    Chlorine, Silver Nitrate, and Water give Silver Chloride, Hydrochlorous Acid and Nitric Acid.
    2Cl AgNO3 + H2O = AgCl HClO + HNO3
  4. Footnote [4]

    With the former we have this action—

    Silver Chloride gives Silver Sub-chloride and Liberated Chloride.
    Ag2Cl2 = Ag2Cl + Cl

    With the latter the silver in combination with the organic matter, which is in a state of oxide, is probably reduced to the state of sub-oxide.

  5. Footnote [5]

    Sulphuretted hydrogen may be prepared by pouring dilute sulphuric acid on ferric sulphide. The chloride or the silver compound, when damped, may be held over it, taking care that no liquid is spirted up on to it.

  6. Footnote [6]

    Those who prepare collodio-albumen plates will find the upward filtration arrangement of immense value, as bubbles are unknown by it.

  7. Footnote [7]

    If bubbles are seen, they must be broken, and the sheet floated again for another minute.

  8. Footnote [8]

    The drainings are added to the next batch of albumen which is prepared.

  9. Footnote [9]

    "Instruction in Photography," 4th edition, page 121.

  10. Footnote [10]
    Chlorine and Water give Hydrochloric acid and Oxygen.
    Cl + H2O = HCl + O
  11. Footnote [11]
    Nitric Acid and Silver Carbonate give Silver Nitrate and Carbonic Acid and Water.
    2HNO3 + Ag2CO3 = 2AgNO3 + CO2 + H2O
  12. Footnote [12]
    Silver Nitrate and Aluminium Sulphate (Alum) give Silver Sulphate and Aluminium Nitrate.
    6AgNO3 + Al2(SO4)3 = 3(Ag2SO4) + 2Al(NO2)3
  13. Footnote [13]
    Silver Nitrate and Hydrochloric Acid give Silver Chloride and Nitric Acid.
    AgNO3 + HCl = AgCl + HNO3
  14. Footnote [14]

    Suppose it is salted with ammonium chloride, we have—

    Ammonium Chloride and Silver Nitrate give Ammonium Nitrate and Silver Chloride.
    NH4Cl + AgNO3 = NH4NO3 + AgCl
  15. Footnote [15]

    Several other methods are given in "Instruction in Photography," in the Appendix.

  16. Footnote [16]

    One part of nitric acid to 4 parts of water.

  17. Footnote [17]

    The shutter may be made of American leather, covered over with one quarter-inch strips of oak or well-seasoned pine. The shutter should fit into a groove formed along the sides and bottom of the front of the cupboard.

  18. Footnote [18]

    In fig. 18 the fastening for only one of the pressure-bars is given, to avoid complication.

  19. Footnote [19]

    See "Instruction in Photography" (page 67), fourth edition.

  20. Footnote [20]

    For this reason, amongst others, it is desirable that photographers should use glass for their negatives which is at least tolerably flat.

  21. Footnote [21]

    See "Pictorial Effect in Photography" (Piper and Carter).

  22. Footnote [22]

    Hydrofluoric acid is always supplied by chemists in gutta-percha bottles, as it attacks glass. A spare gutta-percha bottle can easily be procured.

  23. Footnote [23]

    This calculation is near enough for our purpose. There are certain niceties which might be introduced, such as the "critical angle of the glass."

  24. Footnote [24]

    The boxes in which children's puzzles are often packed will give an idea of what is meant.

  25. Footnote [25]
    Silver subchloride and gold trichloride give silver chloride and gold.
    3Ag2Cl + AuCl3 = 6AgCl + Au
  26. Footnote [26]

    "Instruction in Photography," 4th edition.

  27. Footnote [27]

    "Instruction in Photography," 4th edition.

  28. Footnote [28]

    Or ten minims of ammonium lactate.

  29. Footnote [29]

    See Mr. W. Brooks' article in Photographic Almanac, 1881.

  30. Footnote [30]

    The crucible should be of Stourbridge clay.

Transcriber's Note:

Hyphenation, variations in spelling and inconsistent numbering of, and references to, figures have been retained as in the original publication.

Apart from spaces within compounds (which have been removed), formulae have been retained as originally published, excepted where noted below.

Changes have been made as follows:

Page 3
Nitric Acid changed to
Potassium Nitrate

Page 6
If the operator carefully collect the white changed to
If the operator carefully collects the white

Page 14
theoretical limit to amount changed to
theoretical limit to the amount

Page 19
2AGNO3 changed to
2AgNO3
Nitratem changed to
Nitrate.

Page 22
AgNo3 changed to
AgNO3

Page 23
Ammonium Nitrate Silver Chloride changed to
Ammonium Nitrate and Silver Chloride
NH4,NO3 changed to
NH4NO3
AgNo3 changed to
AgNO3

Page 40
8 inches. changed to
18 inches.

Page 41
printer could not hope to do it successfully. changed to
printer could not hope to do it successfully."

Page 46
the ordinary consistency, than changed to
the ordinary consistency, then

Page 49
enable the operator to guage changed to
enable the operator to gauge

Page 53
centreing his imagination in changed to
centring his imagination in

Page 64
light on B would be only four twenty-fifths changed to
light on B would be only four-twenty-fifths

Page 65
and cut out an aperature corresponding changed to
and cut out an aperture corresponding

Page 66
at a proper heigth from changed to
at a proper height from

Page 69
Having discribed in the last changed to
Having described in the last

Page 70
as it sometimes called changed to
as it is sometimes called

Page 71
and the effect be improved.. changed to
and the effect be improved.

Page 83
If he find that he is not changed to
If he finds that he is not

Page 87
so dilute the reduction takes places very slowly changed to
so dilute the reduction takes place very slowly

Page 88
common desinfecting powder changed to
common disinfecting powder
it as as well to have two changed to
it is as well to have two

Page 90
a littler acetic acid or common salt changed to
a little acetic acid or common salt

Page 91
must be rememberd we are changed to
must be remembered we are

Page 92
when the sodium hypsulphite is changed to
when the sodium hyposulphite is

Page 95
and, with a squegee changed to
and, with a squeegee

Page 101
floated on— changed to
floated on:—

Last page of advertisements
BEST IN THE WORD! changed to
BEST IN THE WORLD!





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