2? '2 ANNUAL OF SCIENTIFIC DISCOVERY. 



the bronze was changed into gray sulphuret of copper. In the bricks of 1 !i-? 

 Roman -works, numerous crystals of zeolite minerals were found, wlikli 

 had been formed in the cavities by the action of the mineral-waters; also 

 small crystals of fluor spar. Among the minerals thus formed are Apophyi- 

 lite, Chabasie, Chalcedony, Malachite, Haematite, Opal, Hyalite, Arragonite, 

 Calcareous Spar, and a variety of other minerals. The alkaline mineral- 

 waters acting on the components of the bricks and cement formed double 

 silicates most readily. The Apophyllite was found in the cement, and not in. 

 the bricks, while Chabasie was found in the bricks. 



The conditions required for the formation of zeolite minerals are fulfill^.! 

 most perfectly when trap rocks are thrown in a molten state into beds of 

 new red sandstone strata. The humid sandstones and slates of that series 

 are in the very condition required for the chemical combinations to take 

 place, under the heat of the trap rocks and the influence of heated saline 

 waters. Trap breccia is a mixture of scoriaceous trap rock and sandstone. 

 Amygdaloid is the scoria produced by the interfusion of trap rocks and 

 sandstone. Now, in Nova Scotia, all along the shores of the Bay of Fundy, 

 we find in the utmost profusion the Zeolites, Quartz and Amethyst geodes, 

 Apophyllite, Stilbite, Mesotype, Analcime, Agates, etc., in the Amygdaloid, 

 but not in the compact trap rocks. So on the south shore of Lake Superior, 

 where the trap rocks have been erupted through and between the strata of 

 new red sandstone, we find the Amygdaloid at the point of contact of the 

 trap and the sandstone, and the Amygdaloid is filled with an abundance of 

 Zeolite minerals, Agates, Chalcedony, etc., while the compact trap rocks are 

 not charged with these minerals. Dr. Jackson therefore inferred that these 

 minerals were produced in the Amygdaloid by agencies such as are cited by 

 M. Daubree. 



Sea-water undoubtedly played a conspicuous part in effecting changes in 

 the composition of rocks, and in the formation of minerals contained in the 

 metamorphosed rocks ; and it is probable, in accordance with the views of 

 Forchammcr, Mitschcrlich, Mavignac, Se'narmont, Favre, and Hunt, that the 

 magnesia of the Dolomites came from the decomposition of the chloride of 

 magnesium of sea-water, and that gypsum was also produced by the reac- 

 tion of the sulphate of soda on carbonate of lime. Forchammer found 

 that when sea-water was heated with bicarbonate of lime magnesia was 

 precipitated, and the proportion augments at higher temperatures under 

 pressure. He found also that gypsum was decomposed in fourteen days 

 when in contact with carbonate of magnesia, and sulphate of magnesia and 

 carbonate of lime resulted. Marignac found at two hundred degrees Centi- 

 grade that chloride of magnesium and carbonate of lime, reacted 'on each 

 other, and that double carbonate of magnesia resulted. Se'narmont made a 

 similar experiment. Favre estimates that an ocean pressure of from five 

 hundred to six hundred feet is adequate to effect these changes when the 

 water is heated. 



ON THE ORIGIN OF CERTAIN ELONGATED, FLATTENED, AND 

 CURVED QUARTZ PEBBLES FROM THE CONGLOMERATE OF VER- 

 MONT. 



At a meeting of the Boston Society of Natural History, October, 1800, 

 Professor Kdward Hifchcock, of Amherst, mafic a communication on the 

 conglomerate of Vermont, which contains elongated, flattened, and curved 



