74 



[April 17 



as per patent of Henry Ellis, Great Britain, No. 2267. It was not shown, 

 however, that it was purchasable as ink in this country in 1868. 



The decision of the Chancellor in favor of the contestants was sustained 

 in 1894 by the Court of Errors and Appeals. 



While an alkaline aurine solution produces an ink very similar to 

 cosine in many properties and reactions, it differs widely in others and es- 

 pecially in not having greenish yellow fluorescence of eosine in diluted 

 solution and in not showing the same absorption spectrum and derivative 

 spectra. 



The accompanying maps show the spectra observed with thin layers of 

 various inks. A Donne lactoscope proved very useful in varying the 

 thickness of the layer until the most characteristic appearance was obtained. 

 The same absorption bands were afterwards recognized when pen marks 

 made with these inks were examined under a microscope to which a Zeiss 

 spectroscopic eye- piece was adjusted. 



The spectroscopic examination of the ink while on the document should 

 be followed whenever allowed by observations of the spectra produced 

 when the ink is subjected to the action of chemicals. 



Very marked changes occur, and since even colorless solutions may 

 show absorption bands this means of identification possesses the double 

 advantage of an accurate physical test without injury to the document 

 together with a combined chemical and physical test where the application 

 of reagents is permitted. 



Stated Meeting^ April 17^ 1S96. 



President, Mr, Fraley, in the Chair. 



Present, 20 members. 



Mr. Georges Bertin, a newly elected member, was presented 

 and took his seat. 



Minutes of meeting of April 10 were read and approved. 



Letters of acknowledgment were received from the Public 

 Library, Wellington, N. Z. (147); Universitatis Lundensis, 

 Lund, Sweden (147); Profs. Friedrich MUller, Edward Suess, 

 Vienna, Austria (148) ; Naturforschende Gesellschaft, Bam- 

 berg, Bavaria (147) ; K. Sachs. Meteorol. Institut, Chemnitz 

 (148) ; Yerein fiir Erdkunde, Dresden, Saxony (147, 148) ; Wet- 

 terauische Gesellschaft, Hanau, Germany (147); Verein fiir 



