257 



tioned the existence, in the eastern coast of England, of exten- 

 sive beds of nodules of phosphate of lime, which are used as a 

 manure with a similar good effect. Some of these nodules are 

 casts of Ammonites and other fossils. Similar fossils he thought 

 would be found in all the green sand deposits of the Continent. 

 They had been found in Hanover and in France. During his 

 stay in Boston his assistant had analyzed, at his suggestion, two 

 specimens of the New Jersey green sand, and found in one IJ 

 per cent, and in the other 1 per cent, of phosphate of lime, a 

 smaller quantity than had been looked for, but constituting, he 

 thought, the fertilizing element in this deposit. 



Dr. Jackson asked if Prof Johnston had noticed any fertilizing 

 property in phosphate of iron, as this mineral occurs in the green 

 sand of New Jersey in considerable quantities, sometimes filling 

 fossil shells with its crystals. Prof. Johnston replied, that he 

 had never seen it in such quantities, but if it were mixed with 

 marl it would make phosphate of lime. 



Dr. Pickering confirmed Dr. Jackson's statement as to the 

 presence of phosphate of iron in the New Jersey green sand, 

 and mentioned another ingredient of fertilizing power, namely, 

 potash. 



Mr. Desor inquired if Prof. Johnston's statements had refer- 

 ence to the upper or lower layer of green sand ; he replied, that 

 he spoke of both. 



Dr. Jackson said he thought if phosphate of iron could be 

 made useful for agricultural purposes, that bog iron ore combined 

 with lime would be of similar use. 



Prof. Rogers said, that he had long held the opinion that the 

 alkali is the fertilizing ingredient in the green sand of New Jer- 

 sey, although he had been aware of the presence of phosphates, 

 which he had considered as belonging to the clay included in 

 the sand. In preparing the sand for chemical analysis the clay 

 was washed out, removing with it the phosphate of lime. This 

 would account for his failure to detect this element in the pure 

 green sand. He was still of opinion that the potash was a fertil- 

 izing ingredient, as he had seen from 100 to 200 bushels of 

 Indian corn to the acre, raised upon loose sand which had been 

 manured with it. 



Mr. Desor exhibited to the Society a shark's tooth from the 



PROCEEDINGS B. S. N. H. 17 MAY, 1650 



