520 



THE SOUTHE 



RN PLANTER. 



[September 



with the finger nail. When pure, it is gen- 

 erally of a whitish colour, but according as 

 it is found mixed with foreign matter its 

 colour varies. It assumes a variety of 

 forms, compact, granular, fibrous, pulveru- 

 lent, crystaline, &c. Its crystals are some- 

 times perfectly limpid. Gypsum is plen- 

 tifully and widely dissiminated throughout 

 the crust of the globe, and is confined to 

 no age or particular formation. In some 

 cases it would appear to owe its existence 

 to the decomposition of the sulphuret of 

 iron in contact with limestone or, again, to 

 the action of sulphurous vapours upon that 

 rock. It is not often fossilif erous ; but that 

 which is found at Montmartre, in the envi- 

 rons of Paris, is an exception. At that 

 locality the remains of mammiferous ani- 

 mals, of birds, and reptiles, are very com- 

 mon. In certain formations the sulphate 

 of lime is usually found accompanying 

 common salt. It is also a constituent of 

 the marls, which occur along our sea-coast, 

 but only to a limited amount, comparatively. 

 In the State of New York it is found in 

 large quantities, and also in Nova Scotia, 

 whence it is imported into the United States, 

 forming by far the greater portion of that 

 which is used by, the farmers of the At- 

 lantic shore. 



Notwithstanding all the experiments that 

 have been made, and all that has been writ- 

 ten upon the subject, our knowledge of the 

 action of gypsum is limited and very unsat- 

 isfactory. 



Sir Humphrey Davy analyzed the ashes 

 of clover, and concluded, from the presence 

 of sulphate of lime, that the application of 

 gypsum acted as direct food. But subse- 

 quent investigations show that the amount 

 of sulphate of lime in the ash of clover, 

 grown Yipon gypsumed land, was not greater 

 than the quantity of the same salt, found in 

 the ash of clover, grown on ungypsumed 

 land. 



Professor Liebig explains the action of 

 gypsum, as a means through which ammo- 

 nia is presented to the plant. It is known 

 that ammonia and nitric acid are found in 

 the atmosphere, and that salt and carbonate 

 of ammonia are brought down by rains. 

 That fact may be easily verified by evapo- 

 rating snow, or rain water, to which a few 

 drops of muriatic acid have been added ; 

 crystals of muriate of ammonia will be found. 

 Indeed, without consulting the agency of 

 electricity for the formation of ammonia, it 



is a natural consequence of the decomposi- 

 tion of animal matters, which is ever pro- 

 gressing upon the surface of the globe, and 

 many plants emit pungent odors, apparently 

 containing more or less of that alkali. Ac- 

 cording to the eminent professor, the notion 

 of gypsum would be confined to the absolu- 

 tion of that gas, to be held in readiness, ac- 

 cording to the wants of the plant. But his 

 ingenious theory is no less satisfactory, for 

 it is stated that gypsum has no action what- 

 ever on the natural gases, which are stimu- 

 lated by organic manures. Nor does it ap- 

 pear, from careful experiments made by 

 M. Boussingault, that gypsum has the least 

 action upon wheat, oats or rye, upon which 

 it is known that nitrogenous manures act 

 most favorably. Rigaud de Lisle, in a pa- 

 per read before the Paris Society of Agri- 

 culture, in 1843, maintained that gypsum 

 only operates upon vegetation grown upon 

 soils without a sufficient amount of carbon- 

 ate of lime, and his declaration is borne out 

 by the practice in Flanders of applying 

 slaked lime, instead of gypsum, with equally 

 good results. We have heard the same 

 opinion expressed by practical farmers, who 

 knew nothing of the discussion. Having 

 limed their lands to the full requirement, 

 they would look upon the application of 

 plaster as a useless expense. 



SULPHATE OF BARYTES. 



Another assertion, which has its advan- 

 tages, gives the entire credit of the action 

 of gypsum to the sulphuric acid which it 

 contains; and this appears to be supported 

 by the fact that the addition of the sulphate 

 ot barytes is followed by as strongly marked 

 results as those that are derived from the 

 application of the sulphate of lime. Ex- 

 periments were made some years since in 

 Rockbridge county, Virginia, by Dr. Bar- 

 ton, upon whose farm a deposit of the sul- 

 phate of barytes was found. It was ground 

 and applied. We are informed by an intel- 

 ligent observer that the effect was manifest 

 five years after. A paper was written at the 

 time, and published in one of the agricultu- 

 ral periodicals of Virginia. We have not 

 had access to the article, but Dr. Barton re- 

 ceived the award of a gold medal for his in- 

 vestigations. Should the usefulness of sul- 

 phate of barytes be confirmed, it will be a 

 notable and important addition to the list of 

 fertilizers. It is sometimes called heavy 

 spar ; owing to its specific gravity, which is 



