No. 11. 



x.in Efi.tai/ on .i^gricalliire. 



831 



Since we liave arrivod at a knowledge of tlie 

 circiil.ition of the blood, we have bf>on able fn 

 discover that oxyijen is necessary to animal 

 life ; that upon beinuf inlialod it unites with 

 the dirk venous blood, and chanjres it into 

 the briifht arterial, in which process carbon 

 is eliMfiinaied, and all the nifroircn is res- 

 pired except a very small portion, which, as 

 stated by D.ivy, is absorbed by the blcwd, and 

 lijrrns one of the constituent parts of animal 

 matter. 



That dnn:if should be hi<jhly useful as a ma- 

 nure, may be readily understood, when it is 

 remembered that the urine, feces, and other 

 feculent substances which make up the mass 

 of the deposit of our barn-yards and compost 

 heaps, are quickly liable to fermentation, and 

 to the liberation of such matters as are ac- 

 knowledijed to be the nutriment of plants, and 

 that their threat solubility renders them of 

 ready and very beneficial application. But 

 the modus operandi of plaster of paris is not 

 60 well understood. The discovery of the 

 usefulness of this article has been attributed 

 by some to a Mr. Mayer, a (Jerman Clergy- 

 man. Judge Peters, however, who was de- 

 cidedly the most active in introducinsr its use 

 into tliis country, had his attention called to 

 it by a German of the name of Burge, tlien 

 residinf^ upon the commons near Philadel- 

 phia, who stated that the discovery of its 

 fertilizino- properties was accidentally made 

 by a laborer in Germany, employed in makinir 

 stucco mortar, who saw that the path made by 

 him in goin? from his work to his cottac^e, 

 threw up a luxuriant crop of clover, in the 

 succeedinof se'ison, when all other parts of the 

 field exhibited sterility. This he attributed 

 to the dust falling from his clothes. Some 

 have thought the advantages to be derived 

 from plaster must be attributed to its calca- 

 reous base; but surely all the lime that enters 

 into this sulphate, spread upon the ground in 

 the sparse manner in which gyp-'um is gene- 

 rally strewn, could have but very inconsidera- 

 ble effect. By many it is supposed to acl 

 merely as a stimulus, but by what process of 

 reasoning they come to such a conclusion, I 

 know tiot. Others, with more plausibility, 

 have supposed that its chief operation de- 

 pends upon its attracting moisture from the 

 atmosphere, and yielding it to the plants 

 around which it is thrown. This was the sup- 

 position of Judge Peters, but it was objected 

 to at the time by Dr. Priestly, and other chem- 

 ists, on the ground, that gypsum was insolu- 

 ble when exposed in the usual way. To ex- 

 plain, then, the operation of that great agent 

 is still a desideratum in science: the rays of 

 light that have been thrown upon it must be 

 admitted to be faint indeed ; and as it is at once 

 important and abstruse. I would approach the 

 inquiry with more diffidence if the views 



which I am about to offer were not concurred 

 in, and mostly originated by my fiither; who, 

 as the members of the Cabinet are aware, 

 has devoted many years to chemical research. 

 If the positions which may be assumed should 

 not prove to be entirely correct, they may at 

 least elicit some light, and aid the labors of 

 others. The first proposition then is, does 

 plaster promote the growth and perfection of 

 vegetables 1 



Scroiidli/. Are its effects in the promotion 

 of vegetation as sensible and important in 

 seasons of a sufficiency of rain as in dry sea- 

 sons 1 



Thirdhj. Are vegetables that have been 

 plastered, more apt to be found wet with dew 

 in the morning, tlian the same variety grow- 

 ing upon ground where no sulphate of lime has 

 been used ? 



With respect to the first query, the mass 

 of evidence is so great and so well known, 

 that plaster does promote the growth and per- 

 fection of vegetables, that to di.scuss it would 

 be only a waste of time. 



That its cfiects are scarcely sensible, and 

 consequently of but little importance in rainy 

 seasons, is proven by the concurrent testimony 

 of many experienced farmers. Sufficient 

 evidence can also be given of the facf, that 

 grasses which have been plastered, are more 

 apt to be wet with dew than the same varieties 

 growing upon adjacent grounds which have 

 not been simihrly treated. Assuming then 

 the position, that plaster does promote the 

 growth and perfection of vegetables under 

 certain circumstances; that it is useless in 

 j seasons of a sufficiency of rain, and that dew 

 j is more apt to be found upon grasses that have 

 I been plastered than others, we will proceed 

 1 to the examination of the causes that may 

 j prob.ibly produce these effects. Water, as be- 

 j fore observed, seems to be necessary to carry 

 I on the process of vegetation; it aids in the 

 I preparation of the proper food for plants, and 

 I in the promotion of the decomposition of ani- 

 mal and vegetable matter acting as a solvent 

 by which the substances necessary may be 

 taken up by the vegetable ab.sorbents : it is no 

 doubt decomposed by veiretables, and the oxv- 

 cren and hydrogen of which it is formed, are 

 appropriated to the production of different 

 parts of the plants. As the chief importance 

 of the use of plaster may probably be that of 

 furnishing water, I shall now endeavor to show 

 i how that e.Tect is produced. In the first pJace^ 

 j it does not appear probable that sulphare of 

 lime can, of itself, attract much moistui-o from 

 [the atmosphere: but, secondly, it is welt 

 known that sulphuric acid attracts it power- 

 fully; hence, if we can produce a decomposi- 

 tion of this substance, and liberate the sul-» 

 iphuric acid from its combination with the 

 lime, we shall then have a medium fortheal' 



