A writer is editing a draft of an essay about photographic history.
[1] In 1842, astronomer and chemist Sir John Herschel invented the cyanotype, a photographic printing process that produces a Prussian blue monochrome image. [2] Herschel was primarily looking for a reliable way to copy his extensive mathematical and astronomical notes without having to rewrite them by hand. [3] The process involves coating paper with a solution of ammonium iron(III) citrate and potassium ferricyanide, which is then dried in the dark. [4] When exposed to ultraviolet light, the chemicals react to form an insoluble blue dye, while the unexposed areas remain white after being washed with water. [5] Herschel's invention eventually became highly popular among architects and engineers in the twentieth century for reproducing technical drawings, which is how the term 'blueprint' originated.
The writer is considering deleting Sentence 2 from the passage. Should the writer make this deletion?
- AYes, because the sentence introduces details about Herschel's personal notes that are irrelevant to the chemical explanation of the cyanotype process.
- BYes, because the sentence shifts the focus of the paragraph from the history of cyanotypes to Herschel's other achievements in astronomy.
- No, because the sentence explains the original purpose that motivated Herschel to develop the cyanotype process.Answer
- DNo, because the sentence provides essential historical evidence showing that copying notes by hand was a common practice in the nineteenth century.