New Species of Animal Concretions. 43 



" The chemical characters of the constituent of these calculi 

 agree so exactly with those of ellagic acid procured from the 

 infusion of gall-nuts, as to leave no doubt of their being com- 

 posed principally of that substance. When heated they do 

 not fuse, but emit a slight balsamic odour and partially sub- 

 lime ; if more highly heated they catch fire, burn with a low 

 flame, give off the smell of burning wood, and leave behind a 

 carbonaceous ash. If the powder of the calculus be heated 

 in a glass tube a yellow sublimate is produced, which con- 

 denses in the form of long spear-shaped crystals of a yellow 

 colour, with a shade of green. These crystals do not differ 

 in their chemical habitudes from the powder of the calculus, 

 and they are identical in shape and appearance with those 

 procured from the ellagic acid of the gall-nut when similarly 

 treated. When the calculus is reduced to powder and dif- 

 fused through water, several days elapse before the whole of 

 the powder is deposited, and the water remains opalescent 

 even for weeks. It is also difficult to separate the powder by 

 filtration, as the liquid passes turbid for some time. 



" Ellagic acid calculi easily dissolve, with the exception of a 

 few flocks, in a cold solution of caustic potass or soda. The 

 solution is of a deep brownish red colour, with a shade of 

 green ; when the ellagic acid is, however, freed from some ex- 

 tractive or colouring matter with which it is generally mixed 

 in the calculus, the solution is of so deep a yellow as to ap- 

 pear red when viewed in bulk. Muriatic acid throws down 

 from the potass solution a greenish, buff-coloured powder, 

 while the supernatant liquor is of a light red colour. If the 

 precipitate be examined by the microscope, it is seen to con- 

 sist of small thread-like particles, generally blunt, but some- 

 times tapering at their extremities, and which are occasionally 

 twisted or curved, especially if the solution from which they 

 were thrown down was hot: they are not transparent, and can 

 scarcely be termed crystals. 



" When the potass solution is exposed to the air, oxygen and 

 carbonic acid are absorbed, the solution becomes much darker 

 coloured, and a silky greenish yellow precipitate is deposited, 

 consisting of ellagate of potass. This precipitate appears under 

 the microscope as thin rectangular plates, frequently arranged 

 in stellate groups. If a current of carbonic acid is passed 

 through the solution, a buff-coloured precipitate of ellagate of 

 potass is thrown down, while the supernatant liquid remains 

 of a dark reddish colour. 



" Ellagic acid calculi are very sparingly soluble in solution of 

 ammonia; the liquid acquires a yellow colour, which on ex- 



