303 
pointed out that the “tincture afforded by the wood must proceed 
from subtiler parts of it drawn forth by the water” and also 
How greatly he, and with him others, was impressed by the strange 
phenomenon, may be seen from the fo owing quotation :—* These 
and other Phoenomena, which I have observ’d in this delightful 
Experiment, divers of my friends have look’d upon not without 
some wonder, and I remember an excellent Oculist finding by 
accident in a friends Chamber a fine Vial full of this Liquor, which 
I had given that friend, and having never heard anything of the 
Experiment, nor having any Body near him that could tell him 
what this strange Liquor might be, was a great while apprehensive, 
as he presently after told me, that some strange new distemper was 
Invading his Eyes. And I confess that the unusualness of the 
Phenomena made me very solicitous to find out the cause.of this 
Experiment, and though I am far from pretending to have found it, 
yet my enquiries have, I suppose, enabled me to give such hints, as 
may lead your greater sagacity to the discovery of the cause of 
this wonder.” For that, however, the times were not ripe, and it 
was long before a satisfactory explanation of the phenomenon was 
given, not deduced, it is true from the Lignum nephriticum 
infusion—for this wood was by that time completely lost—but 
holding good for it. Boyle, in the course of his researches, became 
acquainted with Kircher’s account, and was inclined to criticise it, 
ut on the whole it is fairly correct as far as it goes. To judge 
from his description of the wood as white, he probably worked with 
os Shes or young wood, and his infusions were accordingly light 
coloured, or they were greatly diluted, notwithstanding whic they 
might in very strong light still have shown distinct blue fluorescence, 
and as to the variety of colours, Boyle himself came very near 
when using a round phial. With a fairly strong infusion in a glass 
globe, and sunlight falling in through several windows in front, and 
with a dark background, all the beautiful colour effects deseribed 
by Bauhin and Kircher may be obtained. In 1689 and 1690 
Rud. Jac. Camerarius, who then occupied the chair of physics in 
the University of Tiibingen, was engaged in similar researches, an 
published a “Schematismi Colorum infuso ligno — nephritico 
propriorum,” followed by a “ Continuatio T entaminum cirea lignum 
hephriticum,” but I have seen neither. Newton” also experimented 
*Opticks, ed. iv., p. 166. 
