856 HI. Morton on the color of Fluorescent solutions. 
any other liquid is substituted for the air, its greater refracting 
power (approaching that of glass) will diminish the above 
named action, so that much more of the light will reach the 
eye. The truth of this explanation was supported by the ob- 
servation that the nearer the index of refraction in the liquid 
came to that of glass, the brighter was the light seen through 
it, while a liquid of higher refraction, like carbon bisulphide, 
seemed a little to weaken the effect by diffusion. 
his fact renders of no account the observations before made 
on filtered and diluted solutions of turmeric, but a fresh obser- 
vation with the spectroscope on tubes free from fluorescence 
has fully confirmed my former conclusions as to the true color 
of fluorescence in this liquid. 
creasing, however, the quantity of cosmoline oil until its color 
begins to take effect, the tint of the fluorescence gradually 
changes to a ric 
By a little care a blue solution may be superposed on a green 
One in the same tube. 
_ Another semi-solid preparation of cosmoline, which has a very 
light color, gives a solution with benzine fluorescing of a mag 
nificent blue. 
I have this substance now under investigation, and hope 
soon to be able to make some further observations upon it. h 
Returning to the solutions of turmeric, I have found that yet 
fluorescent body in that substance is not its essential oil nor ™% 
brown coloring matter, but either the yellow coloring es 
itself, or something so closely allied to it in solubility that 
have thus far been unable to effect an separation. — ts 
In connection with this, let me say that Iam much indebted en 
Mr. Robt. F. Fairthorne, of Philadelphia, who has aided a 
greatly in the preparation of the various constituents of turmeM’ 
In a state of purit ee 
‘1 my former paper I mentioned that uranium nitrate in 8” 
lution gave a very faint fluorescence. re 
___*Mr. Houghton tells me that “cosmoline ” is prepared from crude petroleum 
chennie nin vacuo and filtration through animal charcoal only | 
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