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with sulphur, but as disseminated in the muria- 

 tiferous gypsum, and in the alpine limestone, 

 we were almost obliged to suppose, that in every 

 part of the Globe the volcanic fire acted on rocks 

 of floetz or secondarv formation ; but recent 

 observations have proved, that sulphur exists 

 in great abundance in those primitive rocks, 

 which so many phenomena indicate as the 

 centre of the volcanic action. Near Alausi, on 

 the summit of the Andes of Quito, I found an 

 immense quantity in a bed of quartz, which 

 formed a layer of mica-slate * ; and this fact is 

 so much the more important, as it is in strict 

 conformity with the observation of those frag- 

 ments of ancient rocks which are thrown out 

 untouched by the volcanoes. 



* In geognosy we must distinguish seven formations of 

 sulphur, which are of a very different relative antiquity. The 

 first belongs to the mica slate (Cordilleras of Quito) ; the se- 

 cond, to the transition gypsum (Bex in Switzerland) ; the 

 third to the trappean porphyries (Antisana in America, Mont 

 Serrat in the archipelago of the smaller Antilles, Mont d'Or 

 in France) ; the fourth, to the Alpine limestone (Sicily) 5 

 the fifth, to the muriatiferous gypsum, placed between the 

 sand -stone and the alpine limestone (Thuringia) ; the sixth, 

 to the gypsum which is more recent than chalk (Montmartre, 

 near Paris); and the seventh, to clayey alluvions (Venejuelo, 

 Lower Oroonoko, Mexico) . It is scarcelynecessary to observe, 

 that, in this nomenclature, those small masses of sulphur, 

 which are not contained in strata, but in the veins that 

 traverse rocks of different formations, are left out of the 

 question. 



