354 Proceeditigs of the British Association. 



found deficient in the phosphates, there is reason to believe the 

 subsoil might in many cases be made, by proper management, 

 to impart to it what was wanting. It is now some years since 

 the discovery, by Mr. Buckland, in the lias and other secondary 

 rocks, of the solid feces of certain extinct animals, consisting of 

 phosphate of lime, induced Dr. D. to test a variety of specimens 

 of limestone, with a view of ascertaining whether traces of the 

 same ingredient might be found in them. The result was that 

 phosphate of lime in minute quantities was much too commonly 

 distributed to be attributed to coprolitic matter, or to afford any 

 independent evidence of its presence. When indeed we recol- 

 lect that the shells of invertebral animals contain from three to six 

 per cent, of phosphate of lime, and that according to Mr. Connel, 

 the scales of extinct fish, taken from rocks as old as the coal for- 

 mation, possess no less than fifty per cent, of the same ingre- 

 dient, it would be wonderful, indeed, if all traces of this sub- 

 stance had disappeared from rocks, which appear often to be 

 made up in a great degree of the debris of shells and other ma- 

 rine exuviae. Dr. Daubeny was therefore not surprised at being 

 informed by M. Schweitzer, who is entrusted with the manage- 

 ment of the German Spa at Brighton, that he had detected in 

 the chalk of Brighton Downs, as much as a thousandth part of 

 phosphate of lime. From experiments since made by Dr. D. in 

 the same rock, taken from various localities, he was inclined to 

 believe that minute portions of this substance are present not 

 uncommonly in that formation. The frequent occurrence of 

 phosphate of lime in calcareous rocks, and the probability of its 

 being derived from the shells, or bony matter of the living beings 

 contained in the calcareous rock, led Dr. Daubeny to suspect that 

 traces also of the organic matter which contributed to make up 

 the animal structure, might likewise be found accompanying it. 

 To determine this, the Dr. had applied a test to about fifty different 

 specimens of limestone selected from his cabinet, and found, that 

 whilst the solutions of the pure marble, such as that of Carrara, 

 continue unaffected, the equally pure and white limestones taken 

 from the chalk and tertiary limestones in general become dis- 

 tinctly darkened by the addition of nitrate of silver. — Dr. D. 

 read a letter from M. Schweitzer, who had been precluded from 

 employing the secondary limestones in obtaining carbonic acid 

 wherewith to impregnate his mineral waters, owing to an empy- 





