Chloral-hydrate, which has been employed medicinally since 1869, is much less frequently a cause of mental disturbance than morphine or cocaine. Krafft-Ebing describes its use combined usually with other drugs as causing moroseness, depression and mental dulness. He speaks, too, of a delirium due to sudden withdrawal. This condition, he says, may also be caused by paraldehyde. The craving for chloral, on the part of those who have acquired the habit, is much less intense than that for morphine or cocaine. Other drugs are very readily substituted for that reason. A prolonged use leads to digestive disturbances, constipation alternating with diarrhea, jaundice, flushing of the face, congestion of the conjunctiva, fulness of the head, palpitations, weak pulse, dyspnea and general malnutrition with erythematous, urticareous or pustular skin eruptions, etc. Hyperesthesias, anesthesias, paresthesias, pains in the limbs, sensations of heat and cold, tremors, occasional loss of muscular power and sometimes ataxia appear. The reflexes are usually decreased. Epileptiform convulsions have been observed although they are infrequent. The mental disturbances of chloral have been studied by Wilson.[233] He describes the habitué as "dull, apathetic, somnolent, disposed to neglect his ordinary duties and affairs. He passes much of his time in a state of dreamy lethargy or in deep and prolonged sleep, from which he awakes unrefreshed and in pain." Headache is an almost constant symptom. It is associated with "confusion of thought, inability to converse intelligently or to articulate distinctly, and other evidences of cerebral congestion." Vertigo is also common. The mental state is characterized by dulness, apathy and confusion, alternating with periods of irritability and restlessness. The depression is not so marked as in morphinism. Inability to concentrate the mind, loss of memory, and intellectual enfeeblement are terminal conditions. Occasionally in the worst cases hallucinations, delusions, clouding and states of excitement are observed. Abstinence symptoms are headache, insomnia, neuralgia, pains in the limbs, nervousness, restlessness and formication. A delirium similar to that of alcoholism has been referred to by various writers.