458 GREEN-SAND. 



the moistened point of a pen-knife; and if it be "green-sand," the 

 granule will inash like fine soapy clay, and make a vivid green 

 smear. 



For greater accuracy, let the earth (or marl) be well washed by 

 agitation in water, and pour off the pure clay and other lighter mat- 

 ters which will remain longer suspended in the fluid. The grains 

 of green-sand will then be left with no-thing else but the quartz or 

 silicious sand, and moreover the former will be made more percepti- 

 ble, in consequence of being cleared by the washing of any previous 

 covering of fine clay. 



My first published account of this earth was made in or about 

 the year 1828, in the old series of the ." American Farmer."- A 

 much more extended article u On the Gypseous Earth of James 

 River," I afterwards published, July, 1833, in the first volume of 

 the Farmers' Register, beginning at page 207. Though up to that 

 time I had never so much as heard of the term " green-sand," and 

 though I adopted and used the new and unauthorized designation 

 of "gypseous earth," the earth inquestion was described so minutely 

 and accurately that it was impossible for any intelligent and atten- 

 tive reader of the article, and subsequent observer of the kind of 

 earth in question, to mistake the subject of description. In this 

 piece I also asserted the identity of this gypseous earth with the 

 " green marl" of New Jersey. I trust that I may be pardoned for 

 thus specifying my claim to the first discovery of this earth in Vir- 

 ginia, inasmuch as that merit (if it be one) would be ascribed by 

 every otherwise uninformed reader of the first report of the geolo- 

 gical survey of Virginia, and some other of the publications from 

 the same source, to the author of these pieces.* Upon this occasion, 

 it would be improper to say more on this question than thus con- 

 cisely and explicitly to assert my just rights. 



Before proceeding to offer the more precise and more valuable 

 information concerning this earth obtained by very recent investi- 

 gations, it will be proper to state something of the progress and 

 changes of opinion on this subject, which operated at different 

 times either to encourage or to obstruct the use of this earth as 

 manure. 



From 1818 to 1835 inclusive, I made numerous trials, and in 

 some cases extensive applications of the Coggins Point gypseous 

 earth as manure. The results of my general practice, and also of 

 many particular experiments, noted at the times when made, were 

 reported in a communication to the Farmers' Register, commencing 

 at page 118, vol. ix. The effects stated were very different and 

 apparently contradictory sometimes beneficial and profitable in a 

 remarkable degree, but more generally of little value, or of no 



* Professor W. B. Rogers, formerly Geological Surveyor of Virginia. 



