38 Faraday's Researches

general law already demonstrated, and which in these instances
came gradually, instead of suddenly, into operation.

141. The following are bodies which acquired no conducting
power upon assuming the liquid state:—

Sulphur, phosphorus; iodide of sulphur, per-iodide of tin;
orpiment, realgar; glacial acetic acid; mixed rnargaric and oleic
acids, artificial camphor; caffeine, sugar, adipocire, stearine of
cocoa-nut oil, spermaceti, camphor, naphthaline, resin, gum
sandarach, shell lac.

142. Perchloride of tin, chloride of arsenic, and the hydrated
chloride of arsenic, being liquids, had no sensible conducting
power indicated by the galvanometer, nor were they decom-
posed.

143. Some of the above substances are sufficiently remarkable
as exceptions to the general law governing the former cases.
These are orpiment, realgar, acetic acid, artificial camphor, per-
iodide of tin, and the chlorides of tin and arsenic. I shall
have occasion to refer to these cases in the paper on Electro-
chemical Decomposition.

144. Boracic acid was raised to the highest possible tempera-
ture by an oxy-hydrogen flame (137), yet it gained no conducting
powers sufficient to affect the galvanometer, and underwent
no apparent voltaic decomposition. It seemed to be quite as
bad a conductor as air. Green bottle-glass, heated in the same
manner, did not gain conducting power sensible to the galvano-
meter. Flint glass, when highly heated, did conduct a little
and decompose; and as the proportion of potash or oxide of
lead was increased in the glass, the effects were more powerful.
Those glasses, consisting of boracic acid on the one hand, and
•oxide of lead or potassa on the other, show the assumption of
•conducting power upon fusion and the accompanying decom-
position very well.

145. I was very anxious to try the general experiment with
sulphuric acid, of about specific gravity 1.783, containing that
proportion of water which gives it the power of crystallising at
40° Fahr.; but I found it impossible to obtain it so that I could
be sure the whole would congeal even at o° Fahr. A ten-
thousandth part of water, more or less than necessary, would,
upon cooling the whole, cause a portion of uncongealable liquid
to separate, and that remaining in the interstices of the solid
mass, and moistening the planes of division, would prevent the
•correct observation of the phenomena due to entire solidifica-
tion and subsequent liquefaction.quid matter, that con-