32 
ON THE EXISTENCE IN ANIMALS 
tower having been fired, and the immense mass of burning embers which the beams left, 
the conflagration, if such it may be called, continued steadily to diminish as the barrels 
burst, and the powder literally smothered out the fire. Before nightfall the light in the 
tower had quite dimmed down, and it was generally believed that in a few hours more 
it would go out of itself, leaving half the barrels untouched and their contents in powder, 
when separated from the mixture, as little injured as if they had never left the magazine. 
— Times, June 22. 
ON THE EXISTENCE IN THE TEXTUEES OF ANIMALS OF A FLUO- 
KESCENT SUBSTANCE CLOSELY KESEMBLING QUININE. 
BY HEXRY BENCE JONES, A.M., M.D., F.R.S., HON. SEC. R.I. 
(^Delivered at the Royal Institution, Friday, March 23, 18GG.) 
When I last year brought to your notice the fact that “a single dose of lithium in a 
few minutes passes, through the circulation, into all the ducts, and into every particle 
of the body, and even into the parts most distant from the blood circulation, and when 
I showed you that it remains there for a much longer time than it took to get into the 
textures (probably for three or four days, varying with the quantity taken), and that 
then it diminishes, and finally, in six, seven, or eight days, the whole quantity is thrown 
out of the body,” I little expected that by prosecuting an investigation into this chemi¬ 
cal circulation in the body I should come upon that discovery which forms the title for 
this evening’s discourse. 
No imagination could have anticipated that this line of research into the rate of 
passage of substances into and out of the textures would lead to the supposition that 
man and all animals possess, in every part of the body, the most characteristic pecu¬ 
liarity of the bark of the cinchona-trees of Peru. 
After determining the rate of passage of lithia, and other mineral matters, into and 
out of the body. Dr. Dupre and I proceeded to endeavour to trace the rate of passage of 
quinine into and out of the textures of animals. 
Wo chose quinine because of that splendid test which led Professor Stokes to the dis¬ 
covery of the change of refrangibility of light. 
Here, for example, are different solutions of quinine ot different strengths, and by 
means of the production of fluorescence in the electric light, you see how we can deter¬ 
mine which of these solutions contains the greatest quantity of quinine; and by form¬ 
ing standard solutions it would be easy to measure how much quinine existed in each of 
these solutions. Moreover, Professor Stokes discovered that when a solution of common 
salt was added to this quinine solution, the fluorescence entirely disappeared. Though 
this may be so for sun-light, it does not disappear in this electric light; and, moreover, 
on adding a solution of sulphate of soda to a solution of chloride of quinine, the fluo¬ 
rescence in great measure returns. 
Still further. Professor Stokes showed that one solution of quinine entirely stopped 
these rays from passing into a second solution of the same substance, so that you might 
almost tell whether you had a solution of quinine by seeing whether it cut off the fluo¬ 
rescence from a second solution of quinine. 
Our first object was to determine the delicacy of this reaction for quinine. We 
arrived at the following results, when the spark from a Euhmkorff coil was the source 
of light:— 
Sulphate of quinine gave slight fluorescence when 
„ feeble ,, 
„ distinct ,, 
sooVoo of ^ grain was present. 
_ 1 _ 
330000 V 
_ _1 _ 
2'S'OOOO 
One grain of sulphate of quinine in one million eight hundred parts of water showed 
the blue fluorescence distinctly in 20 grains of the solution. In another experiment, 
the same amount of quinine in one million four hundred and forty-four parts of water 
showed fluorescence very distinctly. 
Having thus got our test, we proceed to apply it to determine the passage of quinine 
into and out of the textures of guinea-pigs. 
