LIGNUM NEPHEITICUM SAFFORD. 275 



BOYLE'S EXPERIMENTS. 



The color phenomena displayed by the extract of Lignum nephriti- 

 eum were first investigated in a truly scientific manner by the Hon. 

 Eobert Boyle in 1663. The results of his studies were embodied in 

 his Experiments and Considerations Touching Colors, page 203, 1664, 

 a Latin translation of which (1667), and also a summary of the re- 

 sults of Boyle's studies in Eichard Boulton's edition of Boyle's 

 AA'orks (1700), are in the library of the Surgeon General of the Army 

 at Washington. Boyle's account, as published by Boulton, is as 

 follows : 



I am told that Ligmim, Nephriticiim is xis'd in the Country wliere it grows as 

 an excellent Medicine against the Stone ; which Virtues Monardes likewise as- 

 cribes to it given in Infusion. An Infusion of this Wood, if it be not too strong 

 will appear, betwixt the Eye and the Light, to be of a golden Colour, except that 

 upon the Top it will be covered with a sky colour 'd Circle ; but if your Eye be 

 plac'd betwixt the Window and the Vial, the Liquor will appear to be of a 

 lovely Blew. And this Experiment hath succeeded by Candle Light: If the 

 Liquor be held partly before the Eye and a Light, and partly betwixt the Eye 

 and an Opacous Body, it will half of it seem of a golden Colour, and half a 

 Blew ; but if turning your back on the Window you observe the Liquor as it is 

 poured out, it will at the first seem Blew; but when it hath fallen lower, and 

 the Rays of Light penetrate it more, it will seem Parti-coloured. If a little of 

 this Tincture be pour'd into a Basin of Water, partly in the Sun Beams and 

 partly shaded, it will afford several pleasing Pliwnomcnu. If some of it be 

 pour'd upon white Paper, the drops about it will appear of different Colours, 

 as the Position of the Eye in reference to them varies ; and when it is pour'd 

 off, the Paper will be dyed Yellow ; and if this be plac'd in a Window in the 

 Sun-shine, and a Pen held betwixt the Sun and part of the Paper, the Verge of 

 the Shadow next the Body that Causes it will be Golden, and the other Blew. 

 Which Phcenomena proceeded from the most subtile Parts of the Wood Swim- 

 ming in the Water, and in Several Positions variously reflecting the Rays of 

 Light. Some of this Liquor being carefully Distill'd, it yielded a colourless 

 Limpid Water, a deep ceruleous Liquor remaining behind. Spirit of Wine and 

 Salt of Harts-horn, being mixed together I observ'd, that it required a certain 

 proportion betwixt the Liquor and the Salt, which enabl'd it to vary it's Colour. 

 So that tho I was induc'd to believe that our Tincture receiv'd its Colour from 

 a Salt dispers'd through it, yet I suspected, that this Salt would be either 

 alter'd or incorporated by Acid Salts ; and accordingly, dropping Spirit of 

 Vinegar into some of the Tincture, it lost its Blew, but not the Golden Colour ; 

 but upon an Affusion of Oyl of Tartar per (JeUquium, that correcting the Acid 

 Salts, it presently regain'd its Blew Colour again, the ponderous Tartarous 

 Liquor first altering the Bottom of the Liquor and gradually rising again. 



And since KercJierus, Art. Mag. lucis <£• umbrae Lib. I, Part 3, writes some- 

 thing of this Exotick Plant, which agrees not with our account of it, since he 

 says it will, according to the difference of the Medium, in respect of Light and 

 its several Positions, vary its Colour; yet from the Account he gives of it, it 

 appears, that the Wood he made use of, was different from Ours since he calls 

 it a white Mexican Wood, whereas ours, as Monardes witnesses, is brought 

 from Nova Hispania, and is not of a White, but a darker Colour, except on the 

 outside, which part is much weaker than the other. Besides, he tells us that 

 his Tincture was like Spring Water when held betwixt the Light, whereas ours 



