Reading and writing fill in the blanks

To learn the speech of alchemy it helps to think back to a time when there was no science: no atomic number or weight, no periodic chart, no list of elements. To the scientistsalchemistspeoplepharmaceuticals alchemists the universe was not made of molecules, which are made of atoms, which are made of leptons, bosons, gluons, and quarks. Instead it was made of substances, and one waysubstancethingexample substance — say, walnut oil—could be just as purematureabsolutesame pure as another—say, silver—even though modern waysscientiststechnologieschemistry chemistry would say one is heterogeneous and the other homogeneous. Without knowledge of atomic structures—or access to an Encyclopaedia Britannica with a periodic table—how would it be easyreliabledifficultpossible possible to tell elements from compounds?