ACTIONS AND TOXIC EFFECTS 381 



in water, on which they float as oily drops, while, instead of 

 hypnosis, they produce nervous excitement. 



ACTIONS AND USES. Like other members of the alcohol 

 group, chloral hydrate is antiseptic and a topical irritant. 

 When absorbed it has a sedative hypnotic action on the 

 central nervous system. Toxic doses, after slight and 

 temporary stimulation, notably depress and paralyse the 

 cerebro-spinal centres. Medicinal doses are hypnotic, 

 analgesic, and feebly anaesthetic. It is used topically as a 

 stimulant, anodyne, and antiseptic. 



GENERAL ACTIONS. It destroys micro-organisms ; one 

 part in a thousand hinders development of anthrax bacilli ; 

 it has about the same antiseptic strength as carbolic acid. 

 Personne exhibited at the Academy of Sciences, Paris, the 

 body of a dog perfectly preserved in chloral hydrate for 

 fifty-five days. Solutions exceeding 20 per cent, are 

 topical irritants, and hence when swallowed cause a burn- 

 ing sensation in the throat, and sometimes vomiting and 

 purging. Diluted solutions are readily absorbed. The 

 drug acts on the central nervous system apparently without 

 undergoing decomposition into chloroform, which is not 

 discovered in the blood tissues, or expired air of animals 

 receiving chloral, and only appears in the urine when that 

 fluid contains sufficient free alkali to decompose the chloral. 

 Small doses produce drowsiness and lower blood pressure. 

 Fuller or repeated doses slow circulation and respiration, 

 and produce sleep, usually natural and deep, from which the 

 animal awakes without discomfort. Anodyne and anti- 

 spasmodie actions are likewise produced. Anaesthesia 

 cannot safely be induced by giving the drug by the mouth, 

 but is produced by intravenous, intraperitoneal, or rectal 

 injection. Larger doses lessen reflex irritability and sensi- 

 bility, cause shallow respiration, a marked fall in blood 

 pressure, weakening of the heart muscle, and lower tem- 

 perature, sometimes to the extent of 6 or 8 Fahr. This 

 fall of temperature is due to the great loss of heat from the 

 dilated cutaneous vessels. By moderate doses, and during 

 safe anaesthesia, the pupil is contracted ; but it is dilated 

 when the doses are dangerously large, or the anaesthesia 

 deep or long continued. Death results from cardiac and 



