2 INTRODUCTORY [CH. 



Boyle (107), we find the following directions: 'Take good Syrrup of 

 Violets, Impregnated with the Tincture of the flowers, drop a little 

 of it upon a White Paper... and on this Liquor let fall two or three drops 

 of Spirit either of Salt or Vinegar, or almost any other eminently Acid 

 Liquor, & upon the Mixture of these you shall find the Syrrup imme- 

 diately turn'd Red,... But to improve the Experiment, let me add 

 what has not... been hitherto observ'd,... 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, & 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 again in The Anatomy of Plants of 1682, Nehemiah Grew (1) 

 tells us that " ...Spirit of Harts Horn droped upon a Tincture of the 

 Flower of Lark-heel & Borage turn them to a verdegreese Green. 7 ' 



" S'pirit of Sulphur on a Tincture of Violets turns it from Bleiv to 

 a true Lacke, or midle Crimson." 



"Spirit of Sulphur upon a Tincture of Clove- July -Flowers makes 

 a bright blood Red. Into the like Colour, it hightens a Tincture of 

 Red Roses." 



It is not clear from the writings of Boyle and Nehemiah Grew 

 whether these authors considered the great variety of shades to be the 

 expression of one or of many substances, though it is clear that Nehemiah 

 Grew differentiated between red, blue and green pigments as regards 

 their solubilities. For he says, "...The Liquors I made use of for this 

 purpose, were three, sc. Oyl of Olives, Water, & Spirit of Wine. The 

 Water I used was from the Thames, because I could not procure any 

 clear Rain Water, & had not leasure at present to distill any. But 

 next to this, that yields as little Salt, as any." The oil he found dis- 

 solved the green colour, " ...But there is no Vegetable yet known which 

 gives a true Red to Oyl, except Alkanet Root." This root "which 

 immediately tinctures Oyl with a deeper Red, will not colour Water 

 in the least. Next it is observable, That Water will take all the Colours 

 of Plants in Infusion except a Green. So that as no Plant will by 

 Infusion give a perfect Blew to Oyl; so their is none, that I know of, 

 which, by Infusion will give a perfect Green to Water 1 ." Boyle, on the 

 other hand, was evidently impressed by the uniformity of the acid 



1 This is entirely in accordance with our present-day knowledge of the pigments. 

 Chlorophyll, like all plastid pigments, is insoluble in water, but soluble iu oil. The red, 

 blue and purple anthocyanin pigments are soluble in water, but insoluble in oil. The 

 red pigment of Alkanet root is not an anthocyanin and has quite different solubilities. 



