WE have received from Messrs. Oxo, Ltd. (Thames House, Queen St. Place, E.C.4), samples of metal caps for test-tubes. These caps have been used for some time in their laboratories, and Messrs.

A student set up six test tubes to investigate the rusting of iron. This is the method used for each test tube. Measure the mass of the nail using a balance. Leave the nail in the test tube for 6 ...