163 



as determined by Dumas ; and the most probable rational 

 formula he stated to be 



IK 4- 3 (i + da). 



Calculating from this formula, its composition would be 



Iodide of potassium . 12.26 



Iodine 28.08 



Oil of cinnamon . . 59.66 



100. 



This compound he considered interesting under many 

 points of view ; in consequence of its complexity, the peculi- 

 arities of its properties, and its presenting a case of in- 

 compatibiHty which had not been previously suspected. 

 Also, as suggesting means which wovild probably lead to 

 the production of an entire new series of substances hav- 

 ing an analogous composition. 



Dr, Apjohn stated, that this compound had been brought 

 under his notice by Mr. Moore of Anne-street, and that he 

 and Mr. Moore had investigated conjointly its properties, 

 and the best process for obtaining it. Of the specimen exhi- 

 bited to the Academy, sixty-one grains were obtained from a 

 single gallon of cinnamon water. 



Professor Lloyd read a paper " on a Declination Instru- 

 ment, made for the Magnetical Observatory of Dubhn." 

 The instrument, which was made by Mr. Jones of London, 

 was laid upon the table of the Academy. 



The principle employed in this apparatus is the well 

 known optical principle of the collimator of Kater. The 

 needle is a rectangular bar, twelve inches in length ; it is 

 provided with three sliding pieces, one of which is at the 

 middle of the bar, the other two near the ends. To the for- 

 mer is attached the suspension thread ; one of the latter cair- 

 ries an achromatic lens, whose focal length is somewhat less 

 than the length of the bar ; the other, which is to be adjtisted 



