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IX. The Absorption Spectra of the Alkaloids. 
By W. N. Hartley, F.R.S., Professor of Chemistry, Royal College of Science, Dublin. 
Received November 19, 1884, and March 5, 1885.*—Read December 11, 1884, and March 12, 1885. 
[Plates 53-56.] 
Contents. 
Introduction.-. 
Experimental details . 
Method of determining the wave-lengths of absorption spectra 
Index to the solutions examined. 
The measurements and descriptions of spectra . .. .. 
Summary . 
Conclusions ... 
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Introduction. 
Many of the poisonous alkaloids give no distinctive chemical reactions by which they 
can be identified, and in certain cases the means of recognising them are restricted to 
observations on their crystalline form and physiological action. Some of the alkaloids 
have never been crystallised, and even such as are usually obtained in crystals are not 
always recognisable, because their shape is not invariably a well-marked or characteristic 
feature; moreover the form and grouping of crystals is occasionally modified by such 
reactions or treatment as may be necessary in the extraction of an organic base. 
Small admixtures of foreign substances also modify crystalline character, and not 
infrequently cause a crystalline substance to become amorphous. No absolute reliance 
* This communication was presented to the Society in two parts. The information concerning 
aconitine, pseudaconitine, japaconitine, morphine, narcotine, codeine, theba'ine, papaverine, oxynarcotine, 
apomorphine hydrochloride, cotarnine hydrobromide, tet.racetyl morphine, diacetyl codeine, quinine, 
quinine sulphate, cinchonine sulphate, quinidine sulphate, cinchonidine sulphate, veratrine, piperine, 
brucine, strychnine, narceine, aconitine (foreign), cevadine, atropine, solanine, hyoscyamine, digitaline, 
picrotoxine, nicotine, and caffeine formed Part I. (Received November 19, 1884. Abstract published in 
Proc. Roy. Soc., vol. xxviii., p. 1.) That concerning pyridine, piperidine, quinoline, tetrahydroquinoline, 
quinoline hydrochloride, and the specimens of aconitine received from Dr. Stevenson formed Part II. 
(Received March 5, 1885. Abstract published in Proc. Roy. Soc., vol. xxviii., p. 191.) 
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