The changes induced in the system, from the primary effects of errhines, are, violent agitation of the body ; commotion of the nervous system ; sudden changes in the circulation ; a diminution of the quantity of circulating fluids ; more free circulation through the mucous glands, on which the errhine acts ; a change in the balance of circulation subsisting be tween these and the neighbouring parts The use of errhines may hence be as certained by the following results : 1, From their producing agitation of the system in general ; whence they may be employed to discharge morbid accumula• tions of mucus in the cavities surrounding the nose ; to remove a state of torpor in the nervous system ; to obviate nervous affections of the convulsive or spasmodic kind. 2. From their producing determi. nation to the nose. Whence they may, be employed to promote the secretion o mucus in the nose when morbidly dimin ished ; and to occasion derivation frost parts morbidly affected in the neighbour hood of the nose. These indications ma3 be illustrated and confirmed from practi cal observations concerning the effects o this class of medicines when employed it cases of apoplexy, palsy, head-ach, ant opthalmics.
The cautions to be observed in the em ployment of errhines, as derived fron their nature, respect chiefly, the agita Lion they produce in the system in gene ral, and the change they occasion in de termination, whether as producing : greater flow to the nose, or derivation from other parts. The conditions of the system chiefly requiring attention in the employment, are, infancy, old age, irrita ble and hwinorrhagic habit, those which are morbidly torpid, and those formerly accustomed to the frequent use of the same stimulus. The circumstances to be attended to in the regimen necessary, respect the means of obviating inflamma tion when excited, and the avoiding sud den exposure to cold air.
The different individuals belonging to the class of errhines, are chiefly contra indicated by the presence of the follow ing morbid states : a high degree of ple thora; morbid debility of the viscera ; uncommon sensibility of the nose ; pre ternatural determination to the nose ; and ulceration of the nose or of neighbouring parts.
8. Of Sialasogues.
Sialagogues are medicines which excite an uncommon flow of saliva. They stimulate the salivary glands, or their cx cretories. They increase the action of the vessels secreting saliva. They ac celerate the circulation through the sali vary lands, and through the blood-ves sels in the neighbourhood of these. They produce a preternatural discharge Of saliva, both in point of quantity and consistence. The changes induced in the system, from the primary effects of siala gogues, are, a change in the distribution of the fluids circulating through these ves sels to which the action of the sialagogue extends, and through the vessels in the neighbourhood of these ; a diminution of the quantity of circulating fluids in gene ral ; and a change in the state of the re maining mass, independently of the dimi nution of quantity. They may be distri
buted into topical, as squills, tobacco, pepper's and other aromatics ; and gene ral, as mercurial preparations.
The use of sialagogues may be deter mined as follows : 1. From their effects as changing the balance of circulation, whence they may be employed to dimi nish the impetus of the blood against parts morbidly affected in the neigh bourhood of the salivary glands; nish the action of the vessels when mor bidly increased in these neighbouring parts ; to promote free circulation of the blood through the salivary glands, when morbidly obstructed there. 2. From their effects, as producing evacuation, whence they may be employed to evacuate mor bid accumulations of serum; to produce a thorough change in the fluids of the body, when morbidly vitiated.
These uses may be illustrated from practical observations hi cases of tooth ach, angina, dropsy, and siphilis.
The cautions to be observed in the em ployment of sialagogues, as derived from their nature, respect chiefly the stimulus they occasion to the salivary glands and neighbouring parts ; the time required by the order of interim for the produc tion of evacuation ; the difficulty, per haps, in some cases, the impossibility, of exciting salivation by means of the inter ns; and the debility induced in the sys tem from excessive evacuation. The conditions of the system chiefly requir ing attention in their employment, are, old age, constitutions habituated to siala gogues ; peculiarities in constitution, de termining the mercury to act on other parts than the salivary glands ; menstrua tion ; and pregnancy. Sialagogues are contra-indicated, where there is an un common determination to the salivary glands; preternatural sensibility in them; deficient serosity ; and general debility of the system.
9. Of Emollients.
By emollients are meant medicines which have a power of relaxing the living animal fibre, independently of me chanical action ; they render the part to Which they are immediately applied more soft and flexible than it was be fore. They excite a peculiar sensation indistinctly referred to the part to which they are applied ; they produce through the rest of the system an effect, in some degred analogous to that taking place in the part on which they more immediately act. The changes induced in the system from the primary effects of emollients are, a dimunition of the power of cohe sion in various parts of the animal body; a diminution of the tonic power in the system ; an increase of the capacity of containing vessels in the part on which they more particularly act, and in some degree in the system in general; and an increase of irritability and sensibility through the entire frame.