When great thirst has been excited either by bodily labour or by external heat, it will generally be more effectually as well as safely quenched by drinking moderately of tepid than of cold fluids. A tepid draught—a cup of tea for example—produces no disturbing action in the stomach, and, being immediately absorbed, supplies the deficiency of liquid without changing the balance of the circulating fluids, thus relieving thirst very much in the same way as Dupuytren did by injecting tepid water into the veins; whereas cold drink, by the suddenness of its impression, disturbs the balance of the circulation, and excites a degree of reaction which increases the original discomfort. If the system is at the same time weakened by fatigue, cold drinks are always injurious.
Of late years a change in the treatment of horses in this respect has taken place. Formerly it used to be considered dangerous to give water to a horse in a state of perspiration. Now, however, it is a common practice to allow post and stage-coach horses a little water before their run is completed, however warm they may be: but, in the first place, the quantity allowed is small, and is always given before the strength is exhausted; and, in the second place, the excitement of the subsequent exercise prevents any considerable disturbance in the balance of circulation, and thus ensures the safety of the animal. If even the same moderate quantity were given at the end of the stage, and the horse were then allowed to rest, inflammation would almost inevitably result.
The same principle applies to the human frame, and affords an easy explanation of the occasional instances we see of persons heated by exertion drinking cold water without injury. If the exertion have been merely sufficient to produce excitement without fatigue, and heat without debilitating perspiration, and especially if it be resumed after the draught, little or no harm will ensue. But if exhaustion or fatigue have been induced, and the individual be allowed to drink freely of the cold water and then rest, the probability of mischief resulting from it will be greatly increased. Many accidents result from losing sight of this distinction, and from acting alike in circumstances so essentially different.
On the subject of the kind of drink which ought to be taken a great deal might be said, were it necessary to discuss here the qualities of all the liquors that are in use. But as my purpose is very different, a few general remarks will be enough.
Water is a safe drink for all constitutions, provided it be resorted to in obedience to the dictates of natural thirst only, and not of habit, and with the precautions already pointed out; but unless the desire for it is felt, there is no occasion for its use during a meal, for the mere purpose of obeying a general rule. Toast and water, whey, beer, barley-water, aërated and soda water, and other liquids of a similar kind, which are little stronger than pure water, may be used, according to the same general principle, by those who prefer them and find them agreeable to the stomach. But with regard to such fermented liquors as porter, ale, spirits, and wine, much greater restriction is necessary, because much good or evil may be done by them when properly or improperly administered.
The primary effect of all distilled and fermented liquors is to stimulate the nervous system and quicken the circulation. In all conditions, therefore, in which the action of these requires to be increased or supported, they are calculated to be useful; and, on the contrary, where it requires to be soothed and abated, they are sure to be prejudicial. To shew the utility of this principle as a standard, we shall notice a few of its applications.
Among the higher classes, it is common to give children an allowance of wine every day from a very early age. To determine the propriety of doing so, let us examine what is then their constitutional state.
In infancy and childhood the circulation is rapid and easily excited, and the nervous system is strongly acted upon even by the slightest external impressions. Hence slight causes of irritation readily excite febrile and convulsive disorders. The object of the parent, therefore, is not to stimulate, but rather to abate nervous and vascular action. Wine, accordingly, is not only unnecessary, but positively detrimental to children, and it is wrong to accustom them to it. There are individual children, no doubt, who are so imperfectly and sluggishly constituted as to require some stimulus to rouse the system to healthy action, and to whom wine is beneficial as a medicine. But these are the exceptions to the general rule, and to them it should be given only under medical sanction.
In youth the natural tendency of the constitution is still to excitement; and consequently, as a general rule, the stimulus of fermented liquors is injurious. During rapid growth, however, the animal functions are sometimes so enfeebled by the great demands made upon them, that not only a full supply of nourishing food, but also an allowance of wine and malt liquor, is required for a time to sustain their energy. In this case the beneficial influence of the fermented drinks is apparent, by their giving tone to the system without raising the pulse or increasing nervous sensibility; but whenever any of these effects is produced, their employment ought to be discontinued.
In mature age, when digestion is good and the system in full vigour, if the mode of life be not too exhausting, the nervous functions and general circulation are in their best condition, and require no stimulus for their support. The bodily energy is then easily sustained by nutritious food and a regular regimen, and consequently artificial excitement only increases the wasting of the natural strength. Where, however, the system has been long accustomed to the use of wine, it will, in general, be better to leave it off gradually than to make a sudden change. In old age, when the powers of life begin to fail, moderate stimulus may be used with evident advantage.