limes unaltered; but, though stable per se, is readily decomposed in 

 presence of fixed bases : for this reason only the ammonia salt 

 could be obtained, and that in a peculiar way ; sufficient evidence 

 was given, however, of its being a true salt of the constitution 



NH, 0, C, H,0, Ci, H, O,. 



The author then gives a description of a curious change which 

 ensues when an alkaline ammoniacal solution of comenic acid is 

 boiled, and which results in the production of comenamic acid, which 

 he shews to be constituted like osamic acid, it being an acid amide. 

 It is derived from the bicomenate of ammonia by the elimination 

 of two atoms of water; consequently, its formula, as proved by 



analysis, is 



HO, C„ H, NO,. 



It crystallizes with four equivalents of water in beautiful micaceous 

 scales : its most distinctive property is the magnificent purple colour 

 it forms with persalts of iron. 



It forms crystallizable salts with a certain proportion of potass, 

 soda, or ammonia, which have an acid reaction. 



The formula of the ammonia salt is 



NH^ O, Ci2 H^ NO7. 



The corresponding salt of silver is transparent and jelly-like ; that 

 of baryta crystallizes readily ; its composition appears to be 

 BaO, 0^2 H4 NO7 + 2 HO. 

 A solution of the ammonia salt made alkaline gives with nitrate of 

 silver a yellow precipitate, which speedily becomes black, — and with 

 chlorine of barium, an insoluble white precipitate, which may be con- 

 sidered as having the composition expressed in the formula 



BaO, C^gH^NO^ + BaOHO. 



The author concludes, by saying he believes he has observed in 

 the behaviour of comenamic acid, under certain circumstances, phe- 

 nomena which will repay further investigation. 



3. On the Crystallization of Bicarbonate of Ammonia in 

 Spherical Masses. By Dr G. Wilson. 



The author exhibited these spherical concretions, which had formed 



