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American Hand Book of the Daguerrotype by S. D. (Samuel Dwight) Humphrey
page 59 of 162 (36%)
the resulting reddish powder is to be washed with water,
and the solution obtained filtered, and evaporated to dryness.
It is found that 100 parts of iodine yield 135 parts of very white,
but slightly alkaline, iodide of potassium.

* I shall present the preparation of only a few iodides,
and such as are more intimately connected with the Daguerreotype.

Experiment.--On projecting dry pulverized iodide of potassium
into fused anhydrous phosphoric acid, a violent disengagement
of iodine takes place, attended by a transient ignition;
fused hydrate of phosphoric acid liberates iodine abundantly
from iodide of potassium; this reaction is accompanied
by the phenomenon of flame and formation of a considerable
quantity of hydriodic acid.

Iodide of Mercury.--For the preparation of iodide of mercury,
Dublanc recommends to cover 100 grms. of mercury with 1 kilogrm.
of alcohol, to add 124 grms. of iodine gradually in portions of ten
grms., and agitating between each fresh addition, until the alcohol
becomes colorless again. After the addition of the last 4 grms.
the alcohol remains colored, the whole of the mercury having become
converted into iodide. The resulting preparation is washed with alcohol;
it is crystalline and of a hyacinth color.

Iodide of Silver.--This compound is formed upon every plate
upon which a Daguerreotype is produced. The vapor of iodine
coming in contact with the silver surface, forms an iodide
which is peculiarly sensitive to light.

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