of Iodine and Codeine, 107 



favour, two equivalents of iodine remain, which must have 

 passed into some other state of combination. The quantity 

 of material at my disposal was too small to admit of detailed 

 experiments to determine this point ; and, after all, the close 

 approximation in two of the determinations of iodine may be 

 merely fortuitous. 



I shall not attempt to enter here upon the question of the 

 exact constitution of the teriodide of codeine, which cannot 

 be satisfactorily deduced from the examination of an isolated 

 substance. In order to do. so we should require a complete 

 investigation of the analogous compounds of the other bases, 

 of which at present we know almost nothing. Many of these 

 compounds are exceedingly beautiful substances, and have 

 been partly examined by Pelletier and others, although not 

 in a satisfactory manner, and all of them both require and 

 deserve reinvestigation. 



Barrande on the Silurian System of Bohemia. Communicated 

 by James Nicol, F.R.S.E., Professor of Geology, Queen's 

 College, Cork. 



A general account of the structure of Bohemia from the 

 pen of Sir R. Murchison, who had shortly before visited that 

 country, and examined its more interesting localities, formerly 

 appeared in this Journal.* That distinguished geologist has 

 kindly communicated to us some portions of a work now in 

 course of publication, by M. Joachim Barrande, already so 

 well-known from his " Preliminary Notice of the Silurian 

 System of Bohemia," and his descriptions of the Brachiopods 

 of that country. The present work, now publishing by sub- 

 scription, is intended to form three quarto volumes, and will 

 be illustrated by many plates of the organic remains. Some 

 of these, chiefly of the trilobites, which occur in such abun- 

 dance and fine state of preservation in Bohemia, are now 

 before us, and are very beautifully executed. Any general 

 account of the work must, however, be deferred, till it is more 

 nearly completed, and the following notices of some of the 



* See Jameson's Edinburgh New Philosophical Journal, for January 1848. 



