166 POISONS : THEIR EFFECTS AND DETECTION. [§ I99. 
the molecule up, and the resulting chloride may be titrated, as in water 
analyses, by silver nitrate and potassic chromate. 
§ 199. Effects of Chloral Hydrate on Animals. —Experiments on 
animals have taught us all that is known of the physiological action of 
chloral. It has been shown that the drug influences very considerably 
the circulation, at first exciting the heart’s action, and then paralysing 
the automatic centre. The heart, as in animals poisoned by atropine, 
stops in diastole, and the 
blood-pressure sinks in pro¬ 
portion to the progressive 
paralysis of the cardiac 
centre At the same time, 
the respiration is slowed and 
finally ceases, while the 
heart continues to beat, 
k The body temperature of 
the warm-blooded animals is 
very remarkably depressed, 
according to Falck, even to 
7-6°. Vomiting has been 
rather frequently observed 
with dogs and cats, even 
when the drug has been 
taken into the system by 
subcutaneous injection. 
The secretion of milk, 
according to Rohrig, is also 
diminished. Reflex actions 
through small doses are in¬ 
tensified ; through large, 
much diminished. -025--05 
grm. (*4--7 grain), injected 
subcutaneously into frogs, 
causes a slowing of the respiration, a diminution of reflex excita¬ 
bility, and, lastly, its complete cessation ; this condition lasts several 
hours ; at length the animal returns to its normal state. If the dose is 
raised to -1 grm. (1*5 grain) after the cessation of reflex movements, the 
heart is paralysed—a paralysis not due to any central action of the 
vagus, but to a direct action on the cardiac ganglia. Rabbits of the 
ordinary weight of 2 kilos, are fully narcotised by the subcutaneous 
injection of 1 grm. ; the sleep is very profound, and lasts several hours ; 
the animal wakes up spontaneously, and is apparently none the worse. 
If 2 grms. are administered, the narcotic effects, rapidly developed, are 
much prolonged. There is a remarkable diminution of temperature, and 
