The indications of cure, which the class of astringent medicines are capable of fulfilling, may be deduced from the following sources. 1. From the altera tion they produce on the state of the moving solids : whence they may be em ployed, to obviate original delicacy ; to restore natural compactness to parts morbidly relaxed ; to restore diminished tonic power ; to diminish mobility when morbidly increased. 2. From the altera tion they produce on the state of the containing vessels : whence they may be employed, to diminish secretions mor bidly augmented ; to increase the power of retaining excrementitious matters when morbidly diminished ; to produce a constriction on the orifices of ruptured vessels.
These indications may be illustrated and confirmed from practical observations concerning the effects of astringents in cases of histeria, epilepsy, hemorrhage, and diarrhea.
The cautions to be observed in the employment of astringents, as derived from their nature, chiefly respect the stimulant and caustic powers possessed by many individuals belonging to the class : the effects of an alteration pro duced in the solids, if carried beyond the natural state ; and, in a particular man ner, their influence as diminishing secre tions ; and as increasing the power of the system for the retention of excrementi tious matters. The conditions of' the sys tem which chiefly require attention in their employment, are, old age, me lancholic habits, and particular mor bid affections of the stomach. The cir cumstances chiefly to he attended to in the regimen necessary, respect the avoiding a relaxing diet ; and the keep ing the patient in a cool temperature and dry air.
Astringents are chiefly contra-indi cated by the presence of the following morbid states; a high degree of rigidity in the system in general ; remarkable insensibility in the moving fibres ; and particular diminution of the excretions from the body.
12. Of Tonics.
The medicines thus denominated are those which increase the tone of the muscular fibre, are supposed to brace the system when constitutionally relaxed, and give it vigour when debilitated by immediate disease. They may be divid ed into stimulants, as various prepara tions of mercury, iron, zinc, and other metals ; and astringents, as chamomile flowers, myrrh, Peruvian, and other barks, and gentian. It is hence obvious, that this class of medicines has a near re lation to those noticed in the class that immediately precedes, and immediately follows it. On which account we shall dismiss it with a single additional obser vation or two. The changes induced in the system by the use of tonics are, in crease of muscular power, greater mode ration, and a firmer stroke of the pulse, increased desire for food, and an aug mented vivacity of the animal spirits. Hence their use is clearly indicated in all cases in which there is a deficiency of these natural powers or desires. They are therefore contra-indicated by the ex istence of a plethoric habit, constitutional predisposition to maniacal affections, or topical haemorrhage, and a sanguineous temperament.
13. Of Stimulants.
These, like the last, are medicines which have a power of exciting the ani mal energy ; but for the most part topi cally, rather than generally, or for a short er period of time. They occasion a par ticular sensation referred to the part more immediately acted upon ; frequently a sense of pain ; they increase the action of muscular fibres in that part, particularly in its vessels ; they increase the energy of the sensorium ; they increase the nervous energy in the moving fibres through the system in general. The changes induced in the system from the primary effects of stimulants, are, acceleration of the motion of the blood in the part to which they areparticularly applied ; an increase of the force of circulation in the system in general ; an increase of excitement in the powers of sensation ; and an augmenta tion of mobility and vigour in the muscu lar organs. They may be divided into the following heads : topical, of which we have examples in mustard-seed, cantha rides, mercurial preparations ; diffusible, of which we have instances in volatile al kali, electricity, heat ; cardiac, such as cinnamon, nutmegs, and other spices, and wine.
The indications of cure which stimu lants are capable of fulfilling, may be de rived from the three following sources : 1. From their affecting the state of circu lation : whence they may be employed, to facilitate the passage of blood through parts in which it is morbidly obstructed ; to augment the force and celerity of the circulation, where it is morbidly slow and weak. 2. From their acting on the pow ers of sensation : whence they may be employed, to quicken the senses where morbidly dull ; to rouse the mental facul ties when in a lethargic state ; to exhila rate a despondent condition. 3. From their acti ng on the moving fibres : whence they may be employed, to restore the power of motion where morbidly defi cient ; to increase the strength of motion where morbidly weak. These indications may be illustrated and confirmed from practical observations concerning the ef fects of this class of medicines, as em ployed in cases of syncope, apoplexy, and palsy. The cautions to be observed in employing stimulants, are, the pain they excite, the violence of circulation, or the flow of the animal spirits which they produce, the mobility of the system which arises from their employment, and the collapse, which is the consequence of high and sudden excitement. The con ditions of the system, which chiefly re quire attention in their employment, are delicate and irritable habits. The cir cumstances chiefly to be attended to in the regimen necessary, respect the diet and temperature best adapted to the sti mulant employed, and the nature of the particular disease in which it is used. The individuals belonging to this class are chiefly contraindicated by the presence of the following morbid states : a high degree of morbid irritability ; the circu lation uncommonly accelerated ; and a preternatural disposition to ha:morrhage.