252 [Senate 



against him might have been refuted. It appears, howeTcr, that be 

 never pursued the inquiry with much interest. 



Judge Peters of Pennsylvaniaj had done more than any other per- 

 son to extend the knowledge of this manure, and to favor its intro- 

 duction. He had been very diligent and minute in his inquiries, and 

 though not a professed chemist, became satisfied that sulphric acid 

 was the active ingredient in plaster. He showed from the observa- 

 tions of Berard, that lands near Catanea, in Silicy, abounding in vol- 

 canic matter, including sulphur,* v/ere very fertile^ and from an ex- 

 periment by the same person, that brimstone, pounded, sifted and mix- 

 ed with ashes, had a surprising effect on lucerne and clover. Sulphu- 

 ric acid, greatly diluted with water, had a similar effect. 



As a further confirmation of the eflfect^ of sulphur or sulphuric 

 acid, when Chancellor Livingston was traveling in Flanders, he saw 

 the farmers preparing pyrites for manure. This mineral is a combi- 

 nation of sulphur and iron, and when partially burnt is employed in 

 the same manner, and for the same purpose as we use plaster. Dr. 

 Chapman of Pennsylvania, found a similar result from sulphuret of 

 barytes. 



Last summer, a new work called Organic Chemistry^ by Profes- 

 sor Liebig of Germany, was first published in this country, and it has 

 been considered by those best qualified to judge, as constituting a new 

 era in agriculture. It is not my intention, however, to detain you 

 with any of its details, except his explanation of the effect of plaster 

 on growing plants. 



Ammonia is an essential part of the food of plants. It affords all 

 vegetables, without exception, with the nitrogen that enters into their 

 composition. It is very volatile, but sulphuric acid (furnished by the 

 plaster) can prevent its flight, and fix it in the soil. This can only 

 be done, however, when the plaster is dissolved. The sulphuric acid 

 then unites with the ammonia, and the carbonic acid of the ammonia 

 unites with the lime. 



Such is the purport of Professor Liebig's explanation of this great 

 mystery. If he is correct in ascribing allJ the effect of plaster to 

 this new combination, its importance in the economy of our farms, 

 must be evident. All our fields, pastures and meadows ought to be 

 strewed with it, and in accordance with his suggestion, it ought to 

 be scattered in all our stables, and over all our barn-yards. The 

 quantity required is not great, and many experiments may be institut- 

 ed at a trifling expense. 



I ought to say, however, that this theory appears insufficient for 

 explaining all the phenomena in connexion with the use of plaster. 

 Why is its effect on clover so extraordinary, and on wheat so insigni- 

 ficant? Judge Peters, after using it forty years, said he never found 

 it beneficial on winter grain; and others, after long trials, thought it 



* A late traveler writing from Italy, says of the peasants residing in the neighborhood of Vesu- 

 vius — " If their houses are burned, they return, when the lava^cools, to build new ones, and culti- 

 Tate a soil inexhaustibly fertile." 



t " The evident influence of gypsum upon the growth of grasseS) depends owlt upon its fixing 

 in the soil the ammonia of the atmosphere."— Liebig, p. 145. 



