350 TRANSACTIONS OF THE 



tion to ascertain the expense at which we might artificially combine the 

 ingredients ; but taking lime at ten cents per bushel, unslacked, salt at 

 $4.50 per ton, and plaster at $6 per ton, we get all the ingredients, except 

 potash and phosphoric arid, for $2,29, weighing 1,218 lbs. This leaves 

 but twenty-one cents to equal the expense of marl. It would cost much 

 more to collect these materials. Hence we have this excess, together with 

 all the potash and phosphoric arid, as clear gain in using marl. It was, 

 therefore, useless to continue the calculation. 



These amounts are not conclusive even with the assumption that the 

 compounds are of equal value. In the marl we have a natural compost 

 easily worked ; and at a given short distance from the pits it will cost less 

 to haul the loam mixed with the inorganics, than to mix loam artificially 

 with pulverized barilla ; but in my case, where the freight on loam costs 

 three cents per bushel, it requires a calculation of the expense of manipu- 

 lation to prepare the barilla for the land, together with the expense of 

 procuring the barilla, before a fair comparison of expense can be made. 



We must not, however, carry theory (or established truth) beyond its 

 proper bounds, and assert the value of these ingredients to be the same in 

 the form of marl, as in some other form where their worth has been esta- 

 blished. Glass bottles, trap rock, and granite, contain valuable fertilizing 

 substances ; but in these forms they are nearly or totally inert, because 

 insoluble. So may it be in part with marl. From the remarks quoted at 

 the end of this article, we may infer that the " seasoning" may be a pro- 

 cess similar to the form at io7i of granite ; or that the silex having remained 

 in a soluble form, as long as wet, becomes fixed on being dried, and cannot 

 be re-dissolved either by water or arids, as in the ease of chemical analy- 

 sis, where the silica is separated in this manner. Thus the alkalis, although 

 present in marl, as shown by the chemist, with the aid of extra alkalis, 

 strong heat and strong acids may still be there, as in the case of glass, 

 granite and trap rock, in the form of insoluble silicates, especially since 

 marl contains a large excess of silex. How far it is chemically combined 

 is not stated ; this requires testing. If the potash can be easily extracted, 

 this marl would supply the world with alkali for soap, gvmpowder, &c. 



The comparison of these analysis of the green sand marl, with those of the 

 ashes of sea weed, appears to me to show conclusively that the marl is of 

 vegetable origin. It is not only composed exclusively of the same materi- 

 als as the inorganic constituents of plants, but it contains them all. Even 

 the proportions bear a striking resemblance to the ashes of the sea weed, 

 differing materially from upland vegetation. The presence of shells in all 

 these marls adds to the presumption that they are of marine, and not like 

 coal, of fresh water origin, since some of the shells resemble those at pres- 

 ent in the ocean. Lime, in some specimens, is less than in barilla; in some 

 more ; the mean is a little more. The same is the case with the magnesia, 

 the alkalies forming 44 per cent, are identical. Phosphoric acid in marl is 

 in excess 3 to 1, (from the bones of fish I) Sulphuric acid deficient 1 to 5, 

 (washed out !) 



