are no fluids known except such as contain water, which are capable of
being made the medium of connexion between the metal or metals of the
voltaic apparatus."--Elements of Chemical Philosophy, p. 169.

399. Other substances, which could not be melted on glass, were fused by
the lamp and blowpipe on platina connected with one pole of the battery,
and then a wire, connected with the other, dipped into them. In this way
chloride of sodium, sulphate of soda, protoxide of lead, mixed carbonates
of potash and soda, &c. &c., exhibited exactly the same phenomena as those
already described: whilst liquid, they conducted and were decomposed;
whilst solid, though very hot, they insulated the battery current even when
four troughs were used.

400. Occasionally the substances were contained in small bent tubes of
green glass, and when fused, the platina poles introduced, one on each
side. In such cases the same general results as those already described
were procured; but a further advantage was obtained, namely, that whilst
the substance was conducting and suffering decomposition, the final
arrangement of the elements could be observed. Thus, iodides of potassium
and lead gave iodine at the positive pole, and potassium or lead at the
negative pole. Chlorides of lead and silver gave chlorine at the positive,
and metals at the negative pole. Nitre and chlorate; of potassa gave
oxygen, &c., at the positive, and alkali, or even potassium, at the
negative pole.

[Illustration]

401. A fourth arrangement was used for substances requiring very high
temperatures for their fusion. A platina wire was connected with one pole
of the battery; its extremity bent into a small ring, in the manner