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Question

Difficulty: HardExplicit Detail Retrieval

In her 1923 treatise on early photographic chemistry, conservator Eleanor Vance reassessed the adoption of the wet collodion process introduced by Frederick Scott Archer in 1851. Contrary to the prevailing assumption that nineteenth-century photographers abandoned the daguerreotype exclusively due to the collodion method's shorter exposure times, Vance demonstrated that iron-based chemical developers played a pivotal role in this transition. While early collodion practitioners relied on pyrogallic acid, which required extended solar exposure and yielded harsh tonal contrasts, the substitution of ferrous sulfate as a reducing agent reduced development time by half and rendered subtle middle-tone gradations previously unattainable on glass plates. However, Vance emphasized that this technical refinement introduced a distinct conservation vulnerability: unlike pyrogallic-developed negatives, which exhibited long-term chemical stability under ambient atmospheric conditions, ferrous sulfate-developed plates retained residual iron salt complexes that, when exposed to relative humidity exceeding 60 percent, catalyzed the localized oxidation of silver grains. Consequently, museum archives that failed to maintain sub-50 percent relative humidity experienced irreversible silver mirror degradation along the peripheral margins of mid-nineteenth-century collodion negatives.

According to the passage, Vance attributed the localized oxidation of silver grains in certain mid-nineteenth-century collodion negatives to which of the following factors?

  1. The retention of residual iron salt complexes in plates processed with ferrous sulfate when exposed to relative humidity levels above 60 percentAnswer
  2. B
    The extended solar exposure required when using pyrogallic acid as a chemical reducing agent during negative development
  3. C
    The failure of nineteenth-century photographers to completely replace glass plates with chemically stable organic substrates
  4. D
    The exposure of pyrogallic-developed glass plates to storage environments with relative humidity maintained below 50 percent
  5. E
    The inherent instability of silver grains when subjected to significantly shortened image capture exposure times

Answer

The localized oxidation of silver grains was caused by the presence of residual iron salt complexes in ferrous sulfate-developed plates when subjected to relative humidity exceeding 60 percent.
The passage explicitly notes that plates processed with ferrous sulfate retained residual iron salt complexes, which catalyzed localized silver grain oxidation when exposed to relative humidity greater than 60 percent. The option stating this fact accurately paraphrases these exact textual conditions.

Step-by-Step Solution

1
Locate the explicit mention of silver grain oxidation in the text.
The text states: '...ferrous sulfate-developed plates retained residual iron salt complexes that, when exposed to relative humidity exceeding 60 percent, catalyzed the localized oxidation of silver grains.'
Explicit detail retrieval questions require direct mapping of text assertions to option statements.
2
Match the explicit details of the cause to the paraphrased option choices.
The option citing residual iron salt complexes from ferrous sulfate processing under relative humidity exceeding 60 percent directly paraphrases the passage statement.
Correct GRE Reading Comprehension options paraphrase explicit facts without altering conditions or scope.

Key Concept

Explicit Detail Retrieval
Estimated Time:2m 0s
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Explicit Detail Retrieval

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