A crystalline solid, CCl3CH (OH)2, the hydrate of trichlor-acetaldehyd (chloral), CCl3.CHO.

Properties : Hydrated chloral occurs as colorless and transparent crystals, having an aromatic penetrating odor, and a bitterish, caustic taste. It is very soluble in water, alcohol or ether.

Incompatibilities : Hydrated Chloral is incompatible with alkalies and alkali carbonates, which cause the formation of chloroform. In mixtures containing hydrated chloral, an alkali, bromid and alcohol, a compound of chloral believed to be chloral alcoholate sometimes separates.

Action and Uses: Hydrated chloral acts on the central nervous system, producing a feeling of weariness followed by quiet sleep in which the pulse and respiration are slowed in the same manner as in normal sleep and the reflexes are not abolished. From this sleep the person can readily be awakened. Larger doses produce more rapid and deeper unconsciousness and abolition of reflexes. There is slowing of the respiration and fall of blood-pressure. The cutaneous vessels are dilated and a marked fall of temperature occurs. With fatal doses death occurs ordinarily by paralysis of the respiratory center but sometimes by paralysis of a weakened heart. Hydrated chloral is therefore to be used with special caution in cases of a weakened heart or blood-vessels.

Hydrated chloral is a very reliable hypnotic in insomnia due to nervous excitation. It is not so valuable when the sleeplessness is primarily due to a painful affection. In such cases morphin or codein is preferable. At times it may be combined with opium or morphin. It should not be used when there is a degeneration of the heart-muscle. In other cases of heart disease and in arteriosclerosis it may be given cautiously.

Hydrated chloral may be given in moderate doses as a nervous sedative, especially in conjunction with the bromids

Hydrated chloral is also a valuable remedy to relax spasm. For this purpose it is often used in the first stage of labor to overcome rigidity of the os uteri. It is valuable in tetanus, in which it must be given boldly to overcome the convulsions. In delirium in fever it may be administered in small doses. It should not be given, however, if the delirium can be controlled by other means. It is useful as an antispasmodic in obstinate cases of hiccup. Hydrated chloral is a good antidote to strychnin.

Dosage: From 0.30 to 1.30 gm. or from 5 to 20 grains dissolved in water and given on cracked ice. The dose may be repeated in three hours, if needed, but the condition of the pulse and respiration should be carefully watched when large doses are given.

While hydrated chloral has the reputation of being espe-cially dangerous, this refers to large doses. Smaller doses. 0.3 gm. or 5 grains, are about as effective as the ordinary doses of other hypnotics and relatively safe. Habit formation is quite common, perhaps more so than with some other hypnotics.