VOL. XXXI.] PHILOSOPHICAL TRANSACTIONS. 4^3 



method of discovering them, I would not he so far misunderstood, as if I were 

 averse from using other experiments in finding them out. On the contrary, I 

 could heartily recommend another method, hitherto much neglected, and which 

 I am convinced would be of great use, if accurately gone about ; and that is, 

 their infusion in different liquors, in order to find out the proper menstruum 

 for extracting their more useful parts. 



Every physician is sensible that there are several simples, and these specific 

 too, which adhibited in substance, are of great efficacy; whereas, if their con- 

 texture is dissolved, their parts can never be so reunited as to produce the same 

 effect. Thus, cortex peruvianus is never so effectual, as when given in powder. 

 That there are others which will communicate their useful particles, when in- 

 fused, to one liquor, and not to another; and that the same substance will im- 

 pregnate two liquors differently, according to the different menstruums. That 

 expert chemist, Mr. Lemery, advises to infuse opium in water and spirits of 

 wine, separately ; and afterwards to mix both infusions together, in order to 

 make the laudanum or extract ; wisely considering, that the water will be im- 

 pregnated by the more soluble saline particles, whereas the spirit will only im- 

 bibe the more resinous ; for water is the proper menstruum for a saline sub- 

 stance, which will not dissolve in spirits of wine ; this rather hardening and 

 preserving it from being dissolved, either by air or water. Thus the most con- 

 venient way to preserve the volatile salts of animals, is to keep them in brandy; 

 and every one knows, that water immediately dissolves sugar, which brandy 

 will not do. Therefore senna will impart its purgative quality to water or ale, 

 having its saline particles more disengaged ; but the purgative virtue of jalap, 

 consisting in its resin, requires wine or brandy for the menstruum or dis- 

 solvent. 



Therefore, in my humble opinion, a most proper way to find out the vir- 

 tues of plants, is to have recourse to the proper menstruums. A simple may be 

 infused in rain-water, snow-water, or pure fountain water; if its texture is loose, 

 and it abound with saline particles, those pure elements will be impregnated by 

 it; but if the texture be more compact, firm and solid, if its particjes are more 

 fixed, then mineral waters are best ; or by the addition of a proportional quan- 

 tity of the fixed salt of a plant, a proper menstruum may be prepared. And 

 next to the exhibiting of bitters in substance, such as wormwood, gentian, and 

 camomile flowers, this is the most convenient way of administering them : not 

 but their tincture extracted by brandy or wine may do very well : but since they 

 abound very much with a fixed salt, a great deal of their virtue may be com- 

 municated to a less spirituous liquor, when a more spirituous will not extract it. 

 The proper means to know which menstruum will best extract the more useful 



