82 Proceedings of the Royal Irish Academy. 



platinum shot (probably from attrition) ^i^as found to be only 0-0001 

 per cent, during the solution of four grammes of alloy. I may mention 

 that the platinum shot referred to can be procured at any of the 

 metallurgists Avho produce the fused platinum in this form. 



4. — Oil Fluorescence as a Means of detecting Adulteration, 



The following note will be interesting as illustrating how the fluor- 

 escence of any substance may be used for its detection in the presence 

 of a non-fluorescent substance : — 



About seven years ago, I made use of this phenomenon for the 

 detection of turmeric when present in mustard in a report upon the 

 commercial aspect of that substance.*-' 



Lately it has been referred to by one of the public analysts in 

 England, as a method by which turmeric may be detected, and as it is 

 so extremely delicate in its results, and yet so easy of application, I 

 have thought it desirable to draw attention to the general principles 

 upon which this phenomenon of fluorescence may be used for such 

 purposes, and also with the view of laying claim to the idea. 



If the adulterant is fluorescent, and the substance into which it is 

 introduced is non-fluorescent, we have at once a ready means of 

 examining any number of samples with much more delicacy than the 

 usual chemical reactions will give. Thus, let us take the one to which 

 we have already referred, the mustard of commerce. 



The seeds of the black or white mustard jueld a yellow, colouring 

 matter soluble in spirit of wine which is devoid of fluorescence. 

 Turmeric is always present in the inferior qualities of this condiment 

 because the actual adulterant is wheaten flour or rice, the turmeric 

 being necessary to bring the white adulterant up to the same shade 

 as the ground mustard seeds, therefore the samples vary from O'o 

 per cent, to 0*05 per cent, of turmeric. ISTow, with such minute 

 quantities of turmeric the alkaline test is very unsatisfactory — in fact, 

 all chemical reactions are unsatisfactory when dealing with such a 

 minimum of adulteration. 



But the great elegance of this fluorescent test consists in the fact 

 that within reasonable limits, the more dilute the solution the more 

 strongly does the fluorescence test come out. The non-fluorescence of 

 the colouring matter of all substances that are adulterated with a 

 fluorescent substance should, in the first instance, be exactly and 

 scientifically determined. This is easily done by any one who has the 

 necessary arrangements. In the case of the mustard yellow, Mr. H. 

 Draper kindly examined it for me, by the light of the spark formed 

 between two steel wires (such a spark being the best for the 

 purpose). 



* Medical Press and Circular, — Report on the Adulteration of Mustard. Vol. 8. 



New Series. 



