916 



Transactions of the American Institute. 



Into this last I pour a little extract of the seeds of the stramonium, 

 which lights up, as you see, with a green color. 



Note.— To compare the fluorescent 

 power of different solutions, the apparatus 

 shown in Fig. 1, was employed. In this a 

 number of nitrogen spectrum tubes G, G, G, 

 etc., were jacketed by tubes I, I, I, etc., and 

 supported in a stand with a minute channel 

 of mercuiy at the bottom, so arranged that 

 the current from an induction coil would 

 be made to traverse any number of them. 



The solutions tb be tested are placed in 

 the jackets and directly compared. 



The stramonium extract and the sesculin, and also the quinine, 

 when painted on paper, show, likewise, a fluorescence which is very- 

 marked, as these specimens testify. 



The fluorescent painting of a flower, which I first showed you, had 

 its leaves painted with a new body, which I recently discovered in cer- 

 tain petroleum distillates, namely, in the last run of the still,. when 

 the residues left from the distillation of illuminating oils are redistilled 

 for lubricating oils and paraffine. , 



For this substance I would propose the name thallene, from the 

 Greek word BaXXos, meaning a fresh sprout or twig, which is appro- 

 priate not only to its brilliant green fluorescence, but also to the fact 

 that when its fluorescent light is observed with the spectroscope, two 

 brilliant green bands appear as the most prominent features. 



The flower is painted with a substance which I have obtained from 

 the foregoing, by exposing its solution to sunlight, and for it I would 

 propose the compound name petrollucene, in allusion to the fact that 

 it comes from petroleum, and shines as you see by fluorescence, with 

 a very vivid blue light. 



The solutions of both these substances are richly fluorescent with a 

 blue color, as I will show you presently in another way ; but as these 

 bodies are only soluble in such inflammable liquid as alcohol, benzine, 

 benzole, and the like, I did not think it prudent to handle, in this 

 place, such large quantities as would be needed to show you the pro- 

 perties of these bodies in the manner just employed with those soluble 

 in water. 



A solution of morin, which is a principle obtained from the yellow 

 dye-wood, called fustic or Brazil wood, gives a brilliant green fluores- 

 cence. A solution of bi-chloranthracene in alcohol, gives a rich pur- 

 plish blue, and so does a solution of comenamic acid in water with 



