Experiment XX
Take good Syrrup of Violets, Imprægnated with the Tincture of the flowers, drop a little of it upon a White Paper (for by that means the Change of Colour will be more conſpicuous, and the Experiment may be practis’d in ſmaller Quantities) and on this Liquor let fall two or three drops of Spirit either of Salt or Vinegar, or almoſt any other eminently Acid Liquor, and upon the Mixture of theſe you ſhall find the Syrrup immediatly turn’d Red, and the way of Effecting ſuch a Change has not been unknown to divers Perſons who have produc’d the like, by Spirit of Vitriol, or juice of Limmons, but have Groundleſsly aſcrib’d the Effect to ſome Peculiar Quality of thoſe two Liquors, whereas, (as we have already intimated) almoſt any Acid Salt will turn Syrrup of Violets Red. But to improve the Experiment, let me add what has not (that I know of) been hitherto obſerv’d, and has, when we firſt ſhew’d it them, appear’d ſomething ſtrange, even to thoſe that have been inquiſitive into the Nature of Colours; namely, that if inſtead of Spirit of Salt, or that of Vinegar, you drop upon the Syrrup of Violets a little Oyl of Tartar per Deliquium, or the like quantity of Solution of Potaſhes, and rubb them together with your finger, you ſhall find the Blew Colour of the Syrrup turn’d in a moment into a perfect Green, and the like may be perform’d by divers other Liquors, as we may have occaſion elſewhere to Inform you.
Annotation upon the twentieth Experiment.
The uſe of what we lately deliver’d concerning the way of turning Syrrup of Violets, Red or Green, may be this; That, though it be a far more common and procurable Liquor than the Infuſion of Lignum Nephriticum, it may yet be eaſily ſubſtituted in its Room, when we have a mind to examine, whether or no the Salt predominant in a Liquor or other Body, wherein ’tis Looſe and Abundant, belong to the Tribe of Acid Salts or not. For if ſuch a Body turn the Syrrup of a Red or Reddiſh Purple Colour, it does for the moſt part argue the Body (eſpecially if it be a diſtill’d Liquor) to abound with Acid Salt. But if the Syrrup be made Green, that argues the Predominant Salt to be of a Nature repugnant to that of the Tribe of Acids. For, as I find that either Spirit of Salt, or Oyl of Vitriol, or Aqua-fortis, or Spirit of Vinegar, or Juice of Lemmons, or any of the Acid Liquors I have yet had occaſion to try, will turn Syrrup of Violets, of a Red, (or at leaſt, of a Reddiſh Colour, ſo I have found, that not only the Volatile Salts of all Animal Subſtances I have us’d, as Spirit of Harts-horn, of Urine, of Sal-Armoniack, of Blood, &c. but alſo all the Alcalizate Salts I have imploy’d, as the Solution of Salt of Tartar, of Pot-aſhes, of common Wood-aſhes, Lime-water, &c. will immediately change the Blew Syrrup, into a perfect Green. And by the ſame way (to hint that upon the by) I elſewhere ſhow you, both the changes that Nature and Time produce, in the more Saline parts of ſome Bodies, may be diſcover’d, and alſo how ev’n ſuch Chymically prepar’d Bodies, as belong not either to the Animal Kingdome, or to the Tribe of Alcali’s, may have their new and ſuperinduc’d Nature ſucceſsfully Examin’d. In this place I ſhall only add, that not alone the Changing the Colour of the Syrrup, requires, that the Changing Body be more ſtrong, of the Acid, or other ſort of Salt that is Predominant in it, than is requiſite for the working upon the Tincture of Lignum Nephriticum; but that in this is alſo, the Operation of the formerly mention’d Salts upon our Syrrup, differs from their Operation upon our Tinctures, that in this Liquor, if the Cæruleous Colour be Deſtroy’d by an Acid Salt, it may be Restor’d by one that is either Volatile, or Lixiviate; whereas in Syrrup of Violets, though one of theſe contrary Salts will destroy the Action of the other, yet neither of them will reſtore the Syrrup to its native Blew; but each of them will Change it into the Colour which it ſelf doth (if I may ſo ſpeak) affect, as we ſhall have Occaſion to ſhow in the Notes on the twenty fifth Experiment.