The last is detrimental to its use with bromine, and is one cause of the complaint that "it will not take bromine." The hydrate of lime should, not be dried over a heat, as has been supposed by many, for in that case the hydrogen is expelled and it returns to a carbonate.

It is advisable to cool it in a damp place like a ground cellar.

Much of the lime in our market will not, except it be quite damp, combine with the bromine.

This is owing to impurities.

Nothing is equal to oyster-shell lime, which I use altogether.
Bromide of Lime .-- In preparing large quantities of this, we adopt the following method: Fill a four-quart bottle about two-thirds full of hydrate of lime; pour into this about one or two ounces of bromine; then shake well, add more of the bromine, shake well and let it stand for a few hours, adding sufficient bromine to give it a fine red color.
It is better when kept in the large bottles, as it forms a more perfect combination: in other words it improves by age.
Use .-- Coat over the iodine to a rose red and then over this mixture to a purple or slate; recoat over the first about one fourth as long as first coating.
Gurneys American Compound .-- Of this compound there are two combinations, one for use, when the temperature of the atmosphere is above 65 or 70 deg., and the other at a lower temperature.