EDITORIAL OBSERVATIONS. 
169 
Salt has been considered as the natural stimulant to the 
stomach of most quadrupeds. To the ox-tribe it is some¬ 
times given in doses of a pound or more as a purgative. To 
the dog it is frequently administered as a vermifuge. The 
stomach of this animal will reject it at first, but by repetition 
it is passed onwards, and acts upon the bowels; in ac¬ 
cordance with the Liebigian theory— Cf If the amount of 
saline substance in solution, introduced into the intestinal 
tube, be larger than that contained in the blood, it will 
exercise a purgative action. On the other hand, if it be less, 
it will become absorbed, enter the circulation, and pass off by 
the kidneys.” The pig, however, seems to be highly 
susceptible of the influence of salt, nor does that animal 
manifest the same desire for it that others are known 
to do. 
“ Food and physic,” said Linnaeus, ee merge into each other 
by indefinable gradations.” The same may be said of physic 
and poisons; hence the difficulty of defining what a poison 
is. Salt, in small quantities, is necessary to the function of 
digestion ; in large quantities it often acts as an irritant 
poison, as is proved by the highly congested state of the 
mucous surfaces with which it comes in contact. 
In our detection of it we have to bear in mind certain well- 
known properties that it possesses, otherwise the nitrate of 
silver test, the usual reagent for the chlorides, will cause it 
to be confounded with hydrochloric acid, one of the acids 
met with in the stomach. 1. Common salt crystallizes in a 
cubicular form. 2. It yields hydrochloric acid by the action 
of sulphuric acid on it, when aided by heat. 3. Chlorine is 
evolved on the addition of peroxide of manganese and sulphuric 
acid to it. “ This,” says Dr. Taylor, “ is so delicate that 
one twentieth of a grain may be detected, if so be the ex¬ 
periment is performed in a proportionately small tube.” 4. 
It is entirely soluble in water. 5. Rectified spirit takes up a 
portion in solution, and when this is set on fire it burns with 
a yellow flame. 6. Its reaction is neutral. 
Doubtless much that is taken in is passed out with the 
egesta, yet generally a sufficient quantity will be found 
23 
XXXII. 
