ATOMS AND SIR WILLIAMS CROOKE
William Crookes first young blood too kill the atomic theory
sir william crookes
Most notable among Crookes's chemical studies is that one which led to his 1861 discovery of thallium. Using spectrographic methods, he had observed a green line in the spectrum of selenium, and he was thus led to announce the existence of a new element, thallium. While determining the atomic weight of thallium, using a delicate vacuum balance, he noticed several irregularities in weighing, which he attributed to the method. His investigation of this phenomenon led to the construction in 1875 of an instrument that he named the radiometer.
In 1869 J. W. Hittorf first studied the phenomena associated with electrical discharges in vacuum tubes. Not knowing of this, Crookes, 10 years later, made a parallel but more extensive investigation. In his 1878 report he pointed out the significant properties of electrons in a vacuum, including the fact that a magnetic field causes a deflection of the emission. He suggested that the tube was filled with matter in what he called the "fourth state;" that is, the mean free path of the molecules is so large that collisions between them can be ignored. Tubes such as this are still called "Crookes tubes," and his work was honored by naming the space near the cathode in low pressure "Crookes dark space."
Crookes also made useful contributions to the study of radioactivity in 1903 by developing the spinthariscope, a device for studying alpha particles. He foresaw the urgent need for nitrogenous fertilizers, which would be used to cultivate crops to meet the demands of a rapidly expanding population. Crookes did much to popularize phenol (carbolic acid) as an antiseptic; in fact, he became an expert on sanitation. Mention should also be made of the serious and active interest he took in psychic phenomena, to which he devoted most of 4 years.