English Language · English

The first sentence (S1) and the final sentence (S6) are fixed. Rearrange the middle sentences A, B, C, and D to construct a meaningful paragraph: S1. The 18th and 19th century brought a deeper understanding of how the willow leaves work to alleviate pain and swollenness. A. In 1793, the Reverend Edward Stone carried out one of the first clinical trials, using willow bark powder in patients with malaria. B. Later, Johann Buchner and Henri Leroux purified willow bark to obtain salicin, a yellow, needle-like crystal. C. But it was the Italian Raffaele Piria who discovered and described, in 1838, the chemical structure of salicin. D. He then split the salicin molecule into salicylic acid, thus turning the yellow crystals into colourless ones. S6. By 1859, industries started to make salicylic acid at a large scale, widening its use as a medicine.