116 On Gypsum. 



the fact, that, by the mutual decomposition of gypsum and 

 vegetable matter, carbonic acid is produced. I know not 

 if his authority be competent to stand against that of Sir 

 H. Davy ; but the latter has cited it respectfully in his 

 lectures, and that he was an eminent lecturer on chemistry 

 at Paris, is well known* That his theory, or facts, be it 

 either, agrees better with our farmers 1 experience than the 

 other; will appear, I think, from the succtedi) g extract 

 from his book. 



" Le sulfate calcaire est decompo<e par un grand nom- 

 " bre de matieres comuustibles, a l'aide de la chaleur. Le 

 " charbon des ub ance vegetales enleve a Pacide sulfa- 

 " rique l'oxygene avec lequel il a pi d'affinite que nen ? 

 <' a le soufre : il se degage de Pacide carbonique dans 

 " cette decomposition, et le soufre separe de Pacide 

 " sulfurique s'unit a la chaux, et forme ce qu'on appele 

 " hepar calcaire, et ce que nous nommeron:, par la suite 

 " sulphure de chaux. Fourcroy, Elemens de Hist, Nat. 



" et de Chimie, 5 me ed. torn. 2. pag. 125. a Paris." 



" The sulphate of lime, with the aid of heat, is decompo- 

 u sed by a great number of combustible substances The 

 *' carbon of vegetable substances deprives the sulphuric 

 " acid of oxygene, for which it has a stronger affinity than 

 " the sulphur; carbonic acid is disengaged by this decom- 

 « position, and the sulphur separated from the sulphuric 

 " acid, unites with the lime, and forms what has been call- 

 " ed, ' hepar calcaire, and which we will recognize in fu- 

 " ture by the name of sulphite of limey 



It remains to be inquired, if the fermentation of vegeta- 

 bles be sufficient to excite a heat adequate to the decom 

 position. We farmers know, that under favourable cir- 

 cumstances, it will produce fire ; but as I have no preten- 



