Employment for the microscope. : In two parts. I, An examination of salts and saline substances, their amazing configurations and crystals ... also occasional consideration on gems, poisons, the vegetation of metals, the resuscitation of plants, the formation of amber, corals, and many other subjects. II, An account of various animalcules never before described, and of many other microscopical discoveries ... Likewise a description of the microscope used in these experiments, and of a new micrometer serving to shew the size of magnified objects. Together with instructions for printing off any medal or coin. Illustrated with seventeen copper plates