26 On the Chemical Constitution and 



variable proportions of iron, sulphur, and carbonaceous matter. 

 The relative proportions of the principal ingredients, appear 

 to differ somewhat in different specimens, and even in different 

 parts of the same specimen ; hence no formal analysis has been 

 attempted : but the phosphate of lime may, perhaps, be esti- 

 mated to constitute from about one-half to three-fourths of the 

 whole mass. 



Dr Prout conceives this composition to prove that the basis 

 of these coprolites is bone ; and that Professor Buckland"'s opi- 

 nion, that they are of fajcal oi'igin^ or of the nature of Album 

 grjEcum, offers a very satisfactory explanation of their occur- 

 rence, and accounts at once for their chemical composition, their 

 external form, and their mechanical structure. Dr Prout has 

 also examined all the most important specimens of coprolite 

 that are mentioned in Dr Buckland's papers, and concurs with 

 him in believing them to be all derived from digested bones. 



The Guano, or dung of sea-birds, on the coast of Peru, and 

 islands adjacent, affords an analogous example of the preserva- 

 tion of recent faeces, in beds and masses, which are stated to bo 

 sometimes fifty or sixty feet in thickness. This Guano, how- 

 ever, differs chemically from any fossil coprolites that have been 

 examined by Dr Prout, and contains much urinary matter. 



Dr Buckland proposes to add this Guano to his series of co- 

 prolites by the name of Ornitho-coprus. 



On the Chemical Constitution and Temperature (tf' Springs^ in 

 reference to the Rock Formations in their Vicinity. By 

 Dr and Prof. Gustavus Bischoff *. 



J. HE facts stated in our work quoted below, shew an evident 

 connexion between the volcanic ridge of the Westerwald, Tau- 

 nus, &c., and the numerous springs found there. Our mineral 

 waters at Geilnan, Fachingen, and Sellers, as well as several 

 others in these mountains, experimented on by different che- 

 mists, are remarkably distinguished by their containing dif- 

 ferent salts of soda, such as the carbonate, sulphate, and nm- 



" Dr Guslavus Bisclioft", iiber die Vulkanischen Mineral (juellen Dentsch-. 

 hinds luid Frankreklis, I vol. Svo. Bonn. 1826. 



