Sir William Crookes had already suggested in 1892 in the Fortnightly Review (February 1892) that such an application might be 1 Nuovo cimento, series iii.
The earliest communications were carried on by means of "raps," or, as Sir William Crookes calls them, "percussive sounds."
Crookes in 1860, may also be noted.
The extraordinary patience requisite to a successful termination of such an analysis can only be adequately realized by actual research; an idea may be obtained from Crookes's Select Methods in Analysis.
Formerly the sparkand absorption-spectra were the sole methods available; a third method was introduced by Crookes, who submitted the oxides, or preferably the basic sulphates, to the action of a negative electric discharge in vacuo, and investigated the phosphorescence induced spectroscopically.
