•S2 AMMONIACAL SALTS. 



wheat, oats, and potatoes. There appears to be no doubt, therefore 

 that the sulphur required by plants is supplied abundantly by the soil 

 enriched with ordinary manure, as happens in the culture of the 

 cereals, roots, and tubers. 



In a wcrd, it may be presumed that Paris-plaster acts usefully on 

 artificial meadows by introducing lime into the soil. This is con- 

 sistent both with the analysis of the ashes of the crops produced and 

 of the soil ; for according to the researches of M. Rigaud de I'lsle, 

 gypsum operates only upon soils which do not contain a sufficient 

 dose of lime in the state of carbonate.* 



OF AMMONIACAL SALTS. 



The last products of the putrefaction of azotized matters being 

 ammoniacal combinations, it necessarily follows that salts having 

 ammonia for their base, must act usefully in vegetation. This is 

 confirmed by the employment of guano, and by experiments in which 

 ammoniacal compounds have been directly applied as manure. I 

 have already pointed attention to the observations of Davy relative 

 to the favorable effect of carbonate of ammonia upon the develop- 

 ment of plants, and shall now detail some recent trials made by M. 

 Schattenmann with the sulphate and muriate of the same base. 



These salts were introduced into the soil as a solution marking 

 one degree of Beaume's areometer, and in the dose of 102 bushels 

 per acre. In 1843, the effects produced upon wheat by muriate 

 and sulphate of ammonia were most distinct ; as was also the case 

 with natural meadows, which yielded under the influence of this 

 liquid manure 82 cwts. of hay per acre, precisely double the crop 

 afforded by the same meadow land without the salts of ammonia ; 

 but another important fact, and which M. Schattenmann announces 

 with confidence as having been proved by repeated trials, is this ; 

 that solution of sulphate of ammonia employed in the same dose, and 

 at the same degree of concentration, causes no appreciable meliora- 

 tion upon trefoil and lucerne. The result of a solution of sal-am- 

 moniac was equally negative. 



These observations agree in certain points with those formerly 

 made by Rigaud de I'Isle, and more lately by M. Lecoq, But they 

 are in direct opposition with the experiments of several physiologists 

 who have studied the action of ammoniacal salts presented separate- 

 ly to vegetables, a circumstance very different from that wherein 

 ammoniacal solutions are incorporated with arable land. Thus, M. 

 Bouchardatf has stated that young plants of mentha aquatica and 

 sylvestris, and of mimosa pudica die very soon, when made to ve- 

 getate with the roots plunged in very weak solutions of muriate, 

 nitrate, and sulphate of ammonia. In offering, some years back, 

 divers considerations upon guano, I promulgated the opinion that 

 ammoniacal salts, in order to serve as azotized manure, must alway 

 contain organic acids or carbonic acid. Perhaps the term useftk 



• M*moires de la Soci6t6 d'Agriciilttire, ann6e 1844. 



t Bottch»rdat, Compte* rendus de l'Acad6mle des Sciences, torn. xvi. 



