208 ANNUAL OF SCIENTIFIC DISCOVERY. 



able fertilizing properties. He instanced the hop-lands in the south- 

 ern counties of England, worth $2,500 an acre, whose crops had 

 been wonderfully increased hy the application of the green-sand, act- 

 ing by the phosphate of lime it contains : in some of these lands the 

 marl, sometimes six feet deep, contains 14 to 20 per cent, of this salt. 

 Green-sand probably contains the same fossils, the same phosphate of 

 lime in various quantity, in all the tertiary formations of the globe, 

 and everywhere will doubtless be of great value to the agriculturist. 

 He had examined some poor specimens in the United States, which 

 contained only 1 or 1 per cent, of the salt. To show that it may 

 prove of considerable value even here, he mentioned that a single com- 

 pany in England got out from 60 to 100 tons a week, which, having 

 been powdered, and prepared by solution in sulphuric acid, sold for 

 $ 50 a tori. Dr. C. T. Jackson remarked that phosphate of iron in 

 fossil shells, and in conjunction with carbonate of lime, was common ; 

 and he thought the application of these substances, by double decom- 

 position into phosphate of lime and carbonate of iron, would be advan- 

 tageous in certain soils. He also mentioned the bog-iron ore, which 

 contains much phosphoric acid ; by adding lime to this, a valuable 

 agricultural benefit might perhaps be obtained after the real amount 

 of acid was known. Dr. Pickering observed that the green-sand of 

 New Jersey contained phosphate of iron, and potash in considerable 

 quantity ; it there never becomes consolidated, and does not come to 

 the surface, being covered by several feet of quartzose sand ; it is 

 in some places brought to light by streams which have cut through 

 it, and has been dug out profitably. Prof. Rogers remarked, that for 

 a long time the fertilizing property of the green-sand was supposed to 

 depend on potash, or some other alkali contained in it ; the presence 

 of phosphate of lime has been omitted in all our analyses, even to the 

 present time. He thought this might be easily accounted for from the 

 fact, that this salt does not enter into the composition of the siliceous 

 green-sand, but is an accidental ingredient introduced from the clay in 

 which it is embedded ; the washings of the clay have not been ana- 

 lyzed, but only the sand ; hence only a series of silicates has been 

 found ; the true way is to analyze the marl and clay as well as the 

 green granules. The green-sand is very efficacious in small quanti- 

 ties ; 25 bushels to an acre of good land will double the crops ; even 

 blown sand, with 100 bushels of this to the acre, has been made to 

 produce a very respectable crop of corn, its efficacy here being due 

 principally to the contained potash. 



AVAILABILITY OF THE GREEN-SAND AS A SOURCE OF POTASH 



AND ITS COMPOUNDS. 



AT the meeting of the American Association at New Haven, Mr. 

 Wurtz, of New York, presented a communication on the availability of 

 the green-sands of the cretaceous formation of New Jersey as a source 

 of potash. The vast importance of potash and its compounds in the 

 arts long ago impressed upon chemists the necessity of finding some 

 source for this substance other than the ashes of forests. Experiments, 



