152 MEDICINAL PLANTS 



been supposed. Rectified spirit of wine extracts a bitterness, but 

 no astringency, from a residuum of twenty affusions of cold water; 

 and water extracts astringency, but no bitterness, from the resi- 

 duum of as many affusions of rectified spirit. The residua of both 

 are insipid. 



From many ingenious experiments made on the Peruvian bark 

 by Dr. Irving, published in a Dissertation which gained the prize- 

 medal given by the Harveian Society of Edinburgh in 1783, the 

 power of different menstrua upon Peruvian bark, is ascertained 

 with greater accuracy than had before been done : and it appears* 

 that with respect to comparative power, the following fluids act in 

 the order in which they are placed: Dulcified spirit of vitriol: 

 Caustic ley : French brandy : Rhenish wine : Soft water : Vinegar 

 and water: Dulcified spirit of nitre: Mild volatile alkali : Rectified 

 spirit of wine : Mild vegetable alkali : Lime-water. The* antisep. 

 tic powers of vinegar and bark united are double their sum taken 

 separately. The astringent power of the bark is increased by acid 

 of vitriol ; the bitter taste is destroyed by it. 



Though the bark on its first introduction, and even some time 

 afterwards, was reprobated by some eminent physicians as a dan- 

 gerous remedy ; yet these prejudices are entirely done away, and its 

 character is now universally established : so that the disputes which 

 at present subsist are confined to its mode of operation, or the 

 manner in which it is most efficaciously administered. To detail 

 these, however, or even to give a circumstantial relation of the 

 various states of disease in which the bark might be advantageously 

 employed, would far exceed our limits : we are therefore confined 

 to state briefly those diseases to which this medicine is more especi- 

 ally adapted. 



The bark first acquired its reputation for the cure of intermittent 

 fevers, and in these, when properly exhibited, it rarely fails of suc- 

 cess. For this purpose, some practitioners prefer giving it just 

 before the fit, some during the fit, and others immediately after. 

 Dr. Cullen, who is of the first opinion, says, " I am satisfied that 

 giving a large dose of the bark immediately before the time of 

 accession, is the most proper practice : but as that dose must not 

 be under two drams of pale bark, so there are some stomachs which 

 will not bear even that quantity, or a larger that might be neces- 

 sary. It is commonly, therefore, convenient to give small doses, 



