TAILIEUCHUNG - Cracking the toefl ibt part 25

Tiếng anh là tiếng nói chung của các dân tộc trên thế giới. Mọi người sử dụng tiếng anh để trao đồi vì thế nó như một ngôn ngữ thứ hai của chúng ta. Toefl là một tài liệu hay và giúp chúng ta dễ dàng sử dụng tiếng anh thật tốt. | 22. Which of the following is mentioned in paragraph 6 as a detail recorded realistically in a daguerreotype Only a small number of professional photographers ever had any practical experience-os dagueneotypists. those technicians who made photographs through the daguerreotype process. By strictest definition Daguerreotypes the daguerreotype process was common for 20 years in the mid-1800s. Other ways oi making photographic images on metal plates. Such as tintypes and terrotypes were developed rapidly alter the advent ill the daguerreotype They quickly eclipsed it In popularity. Today the surviving photographs produced by these methods are often referred Io æ daguerreotypes but hat designation is incorrect II is not surprising thar photography enthusiasts began looking for alternatives to ttiE daguerreotype almost immediately. The materials It required were bolt expensive the plates contained silver and one of the developing solutions contained gold and extremely risky Strict adherence to pntpsr WraMy MMM was necessary in order to word Paragraph 6 is marked with an arrow w poisoning by noxious gas . The steps involved in preparing and exposing a daguerreotype were as laborious ano frustrating as they were hazardous. Images were recorded on copper plates to which several thin coats of silver had been applied. After being fastened to wooden blocks the plates were scoured with alcohol and squares of soft flannel Since even one speck of dust could easily create a deep enough groove to render the tinal image worthless they had to be perfectly buffed. The plates were then bathed in solutions of bromlneand Iodine. The thin layer of bromo-iodine that formed on them i. made them sensibve Io light af which point they were ready tor exposure. After exposure the plates were dipped alternately in heated mercury and treeáng-coId water. The mercury vapors helped fix the images to the plates and developed them. The chilled water kept the plates from breaking I up during The .