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not felt; and that an unsuccessful attempt to renew the interrupted actions produced the return of the coldness and di. minished action where it was formerly increased, attended with a consequent fall of temperature.

3d. When the abstraction of caloric continues without any symptom of the interrupted action being restored, or the sti, mulated action successfully performed, the Sensation of cold is permanent.

Sometimes it happens that after going into the cold bath the temperature does not rise to the natural standard, but always keeps below: in these cases the cold Sensation continues. Sometimes librations of the tem perature are observed keeping pace with the decrease and increase of the coldness. It may be said that the rise of temperature is the cause of the diminution of the coldness, and not the latter the cause of the former. To this I answer, not if the Sensation decreases before any sensible rise of temperature can be perceivedas I have found by experiment it does.

When the bands are exposed to a cold moist wind, they in general soon become somewhat swelled, and acquire a red or purple colour--symptoms which denote that the actions of the vessels of the part whether habitual or stimulated are retarded, a natural consequence of the greater accumulation of the fluids propelled into it by the circulation, as that accumulation is a natural consequence of the decreased action which the abstraction of caloric produced. Hence the Sensation of cold becomes more and more painful as the fluids accumulate and increase the resistance to the action of vessels. But increased resistance to action is interruption in degrec. Therefore the general fact is proved as far as regards the abstraction or defect of caloric.

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SECOND INSTANCE. An occasional supply of food is as necessary to the unremitting continuation of the digestive actions of the stomach and lacteals, as a certain quantity of free caloric is to the vital actions in general. When the usual quantity of food has been taken into the stomach, it is certain this gives employment for a time at least to the whole powers of digestion. But in course of time this food is either absorbed by the lacteal vessels there, or carried forward into the small intestines, the stomach being again left empíy, and the actions of the digestive powers of course interrupted-as certainly interrupted as the action of the lieart and arteries would be if they were deprived of blood. Under this state of interrupted action of the organs of digestion, a Sensation of hunger is felt, evidently

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arising from that interruption, because it soon ceases after a new supply of food is taken into the stomach which permits them to return to unconstrained action free of sensation.

But sometimes the sensation of hunger goes off, if the supply of food has been withheld beyond the usual time. May not this depend on the same cause that produces a cessation of the coldness in the bath, although the abstraction of caloric continues the same, namely, an increase of action in other parts of the system ? May not the action of the absorbents be increased in this case, and the living solids themselves be sometimes absorbed ? Under privation of food with loss of appetite, is not there a more sudden loss of flesh and strength, than under similar privation when the appetite continues ? It is extremely difficult to determine these questions in a manner that does not admit of some doubt. The following facts, however, the correctness of which may be depended on, seem to answer the last of these questions in the affirmative.

A person, with whom I am well acquainted, resolved to abstain entirely from food as long as he could, without any material inconvenience. He was in good health at the commencement of his abstinence. He became hungry at the usual time, but the hunger soon went off and did not return; but he was seized with bead-ach, chilliness, great languor over his whole body and quick pulse. These symptoms were so much aggravated, and he became so feverish, that he thought it prudent, after persevering in his abstinence for four and twenty hours, to take a little food, although he had no appetite for it; and it is wortliy of remark, that very soon after taking food, the headach ceased, the other symptoms abated, and in a few hours he felt himself perfectly recruited.

The same person at another time limited himself to the fol. lowing diet. To breakfast be took about one ounce and an half of bread and one cup of tea. To dinner about the same quantity of bread, and one ounce of animal food ; and in the evening as much bread with a cup of cold water. He persevered in this diet for three days, at the end of wbich he returned to bis usual mode of eating. During these three days his appetite continued almost without intermission, the Sensation in his stomach becoming more painful every day. The food he took had very little effect in abating the hunger, which returned as keen as ever in less than a quarter of an hour after eating. The painful craving Sensation at his stomach was particularly troublesome after lying down in bed, and prevented sleep the greater part of the night. All this time he had neither headach, nor other uneasy sensation (that at his stomach excepted), his pulse seldom rose above

64 beats

64 beats in a minute, and, what is remarkable, he felt no perceptible diminution of his strength.

poden THIRD INSTANCE. The circumstances attending the Sensation of thirst, seem to show that it arises from the interruption of the action of those yessels and glands which pour out and exhale the bland mucus which moistens the cavity of the mouth, fauces, stomach, &c. because thirst is felt when there is a total inter. ruption to these actions known by dryness of the mouth, throat, &c, or when the mucus secreted is too viscid, which cannot but interrupt these actions in a greater or less degree. In either case the want of that Auidity which is necessary to these actions being duly performed, is the exciting cause of the Sensation, and the proximate cause (if I may be allowed the term) is interrupted action from that defect. The following circumstances are farther proofs, that thirst arises from the action of these vessels and glands being interrupted by defect, of due fluidity. 1st. It often happens in cases of great thirst, that swallowing liquids has little or no effect in removing the sensation ; the cause of which is easily understood, when it is considered that the fluids which are necessary to exhalent action must be derived from the circulation; of course a draught of water, unless it is immediately absorbed, and produces a determination of the fluids to these vessels, can have no immediate effect in removing the thirst. 2d. Dr. Currie particularly remarked that the cold affusion in fever was generally followed by a complete extinction of thirst; which agrees with what would be expected to result from it, if interrupted action of the exhalents were the true cause ; for it is obvious that as the pabulum to these actions must be derived from the circulation, so nothing is better calculated or more likely to restore that, than determining the fluids copiously from the external to the internal parts. 3d. This is still further confirmed by what I have frequently observed in cases of fever attended with urgent thirst, which yielded to no kind of drink. Namely, that when a cathartie given operated with the effect of bringing off liquid evacua. tions, the thirst abated. But that the removal of the thirst was owing to the cathartic producing a greater determination of the Huids to the internal part, with a 'consequent renewal of the actions of the exhalent vessels, is obvious from this circumstance, that the sensation almost always went off before the medicine had produced any sensible evacuation. 4th. An emetic when it operateś obviously produces an increased determination of the fluids to the internal parts, particularly the

stomach stomach and mouth. But an emetic diminishes thirst, as appears from the great aversion which patients under the action of an emetic have to all kinds of drink. 5th. To a person that is thirsty nothing in general is more grateful than acid drinks, a small quantity of which often quenches thirst more effectually than a large quantity of water singly. But acids are well known to produce a greater flow of saliva, &c. and I suspect it is only in so far as they determine the fluids to the salival and mucous glands, and permit the interrupted actions to be renewed that they remove the sensation of thirst. 6th. Whatever greatly diminishes the quantity of the fluids in general, or much increases their viscidity, commonly causes a sensation of thirst ; such as too copious evacuations of any kind, or an extreme evolution of caloric. ..

From these facts we may surely safely conclude that thirst arises from the actions of the exhalent vessels and glands of the mouth, fauces, stomach, &c. being interrupted by defect of the fluidity these actions require.

FOURTH INSTANCE. The habitual use of spirituous liquors, opium, tobacco, and other narcotic substances of the like kind, undoubtedly establishes certain actions, wbich require these substances to support them, in the same manner, I suppose, as food is required for the support of the digestive actions. A person who has accustomed himself to the use of snuff experiences an uneasy sensation when it is not applied as usual; and this Sensation goes instantly off when the snuff is applied, and again returns when the effect of this application is worn off. The same is true of all other acquired habitual actions.

REMARKS. Each of the Sensations belonging to this general phenomenon is peculiar to the exciting cause. Thus the abstraction of caloric is always attended with a Sensation of cold : the privation of food with hunger, the defect of fluidity with thirst, &c. but all of them have this in common, that they are accompanied with a desire of the peculiar substance, which is necessary to the renewal of the interrupted action; and they further agree in this, that the Sensation instantly ceases wben the action is renewed by the necessary application : From which, and from the arguments before adduced, it is plain that uninterrupted action of the sensoreal power is not adequate to the production of sensation; and that the hy. pothesis which is built upon that supposition, instead of en.

abling

abling us better to understand Sensation, only serves to bewilder our minds and render this subject, naturally intricate, still more perplexing and unintelligible. That action and sensation are truly opposite conditions of vitality appears from the instances above adduced ; and this view of the subject seems to render Sensation more intelligible, as it is not difficult to conceive, that an active intelligent power should feel when its motions are interrupted. In my next paper I shall resume the investigation of this principle, and hope I shall be able to prove, by reference to the other general phenomena, that Sensation in these also proceeds from interruption to action habitual or stimulated.

I shall conclude at this time, Gentlemen, by observing, that as I cannot belp considering the idea here opened to be highly important, and I hope, useful in its consequences ; so I earnestly wish that any errors or oversights I have been or may be inadvertently guilty of in the prosecution of it, may not deter your intelligent readers from entering upon the examination of this interesting, though difficult subject, but rather stimulate them to assume the investigation, and supply the deficiencies of our knowledge by more able and diligent researches. . I am, respectfully, Gentlemen, Your most obedicnt Servant,

T. SMITH. · Bristol, April 10th, 1811.

To the Editors of the Medical and Physical Journal.

GENTLEMEN, YOUR Journal being a Miscellany for every principal as well as every collateral branch of medical science, likewise for every novelty in natural and philosophical history ; every case in medicine or surgery, which conveys information or novelty in practice, from whatever part of the world it may arise, does, and ought to find a place for the good of man. kind, in your useful publication of so extended a range.

I should not have troubled you with the following case, but for a communication, in Journal 143, of Dr. Harrison from his son in America, on the fatal effects of eating cherries; and the observations of Sepex on the treatment, which whether right or wrong 1 shall not comment upon ; nor have I any doubt as to the truth of Dr. Harrison's relation of the case, or the practicability of opening the arteries at the wrists or ankles. (No. 148.)

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