132 VETERINARY MATERIA MEDICA. 



base. Chloral was discovered by Baron Liebig in 

 1832, but was not employed in medicine till 1869. 

 It is prepared by passing chlorine gas through alcohol 

 until saturated, then purified by distillation with 

 H2SO4, and finally mixed with H^O to form the solid 

 chloral hydrate. Dose: H., si.-ij.; D., gr. v.-xx. 



Physiological Action. — Chloral is a powerful 

 depressant of the cerebro-spinal centres, a good hyp- 

 notic and calmative, an antispasmodic, antiseptic, 

 antiferment, and counter-irritant. Compared with 

 chloroform it is more hypnotic but less ansesthetic. 

 It cannot be used subcutaneously, as it is too irritant 

 and would cause extensive sloughing of the skin at 

 the point of injection. Large or concentrated doses 

 may cause severe gastritis, while in the smaller ani- 

 mals nausea and vomiting are frequently produced. 

 Chloral has a selective action on the brain, causing a 

 cerebral anaemia, which produces a very normal-like 

 sleep, and from which the animal may be readily 

 awakened, but shortly after falls into, until the hyp- 

 notic action of the chloral is exhausted. An impor- 

 tant point in chloral narcosis is that it but seldom 

 leaves any bad after-effects or serious depression, al- 

 though this is more noticeable in animals in which 

 instead of producing sleep it has caused delirium and 



f 



excitement. Full doses, when first given, briefly 

 stimulate the heart, but soon this vital organ becomes 

 depressed, arterial tension is lowered, oxidation is di- 

 minished, and bodily temperature lowered. Large 

 doses rapidly cause a profound narcotism, abolish- 

 ment of the reflexes and sensibility, complete muscu- 



