1885.] 



The Absorption Spectra of the Alkaloids. 



191 



periodic law in regard to the atomic weight of an element, and shows 

 that snch deductions will in future form one of the most important 

 factors in fixing a doubtful atomic weight. The author did not 

 appreciate the full value of the periodic law when he wrote his 

 former paper, otherwise he would probably have stated his conclu- 

 sions less positively. 



March 12, 1885. 



THE TREASURER in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "The Absorption Spectra of the Alkaloids. Part II." 

 By W. N. Hartley, F.R.S., Professor of Chemistry, Royal 

 College of Science, Dublin. Received March 5, 1885. 



(Abstract.) 



Having lately completed an examination of a series of aconitines 

 from different sources, kindly sent to me by Dr. Stevenson, Lecturer 

 on Chemistry and Medical Jurisprudence at Guy's Hospital, London, 

 I beg leave to offer the results to the Royal Society. 



The list of specimens, which was accompanied by remarks upon 

 them, is the following : — 



No. 1. " Exotic aconitine, probably German, rather inert." 



No. 2. " A fine specimen of crystallised aconitine, special, prepared 

 by T. Morson and Son, 124, Southampton Row, London." 



No. 3. " Aconitine, from Burgoyne, Burbidges, and Co., 16, Coleman 

 Street, London." 



No. 4. " Nitrate of aconitine." (This specimen was accidentally 

 destroyed.) 



No. 5. " Aconitine of uncertain source." 



Of these specimens only two, namely, No. 2 and No. 3, were found 

 to exhibit absorption-bands, and the corresponding curves were drawn 

 from photographs of their spectra. 



Morson's fine specimen, the crystals of which were one and even two 

 millimetres in length, was found to absorb the rays at two points, the 

 two absorptions being equally strong. It is noticeable that the most 



