Page:Proceedings of the Royal Society of London Vol 60.djvu/45

Rh The latter line is seen only in the absence of m anganese, as it very nearly coincides w ith one of the group of strong m anganese lin e s ; it is, therefore, obscured in the spectra of th e Bessem er flame and of the crude iron.

The oxide of gallium was separated as far as possible from all other substances and heated in the oxy-hydrogen flame and the ch aracteristic spectrum was then photographed from this oxide.

The roasted Cleveland ore was heated alone for thirty-five m inutes in the oxy-hydrogen flame, it gave only a very fain t indication of one line in the spectrum of gallium. The solution extracted from the ore by digesting it w ith w arm dilute hydrochloric acid of double normal strength, when boiled w ith am m onium acetate gave a pi'ecipitate, the spectrum of which contained the line 4171*6 fa irly strong.

The silicious residue insoluble in strong hydrochloric acid, when decomposed by fusion w ith caustic potash and subsequent boiling w ith water, after concentration of the solution so as to retain the gallium, gave a spectrum containing both lines, 4171*6 and 4032*7. AH other elements had been removed.

The wave-lengths given are on Row land’s scale. The lines were measured on many plates and also repeatedly on the same plate, the results being the same in each case.

The experiments were made upon six specimens of Malapterurus electricus, 12 to 15 cm. in length, brought from the River Senegal by Mr. A. Ridyard (ss. “ N ig e r”), and generously placed at the disposal of the authors by the Liverpool Corporation Museum Committee, to whom and to Ur. Forbes, the Director of the Museum, the authors desire to express their thanks.

Three of the specimens were killed, in order to carry out experiments upon the isolated organ. The instrumental methods employed by the authors for determining for the first time the characters and time relations of the activity of the organ response were chiefly the following :—

(a.) The record of the frog nerve muscle galvanoscope.

(b.) The galvanometer connected with a suitable rheotome.