26 PROCEEDINGS OF THE ASSOCIATION OF 



periments of Mr. Fox, of England, on the lamination of clay by 

 galvanism, seem to explain this structure. 



B. SiLLiMAN, Jr. had found this rhombic structure in great 

 perfection in the argillaceous sandstone of the Connecticut valley 

 at Hartford, in Connecticut, where this variety of sandstone is 

 used for flag-stone. Many of the joints parallel to this rhombic 

 structure are filled with carbonate of lime. 



Dr. C. T. Jackson stated that the great trap dykes of Nova 

 {?cotia had the perpendicular columnar structure in a high degree 

 — in the smaller dykes this structure prevails from side to side of 

 the dyke, perpendicular to the walls. He thought that in all c^es 

 these phenomena were referable to the way in which the dykes 

 cooled — the structure being perpendicular to the cooling sur- 

 face ; thus the narrow dykes cooled from side to side, and the 

 heavy ones from the upper surface downward. 



Prof Henry D. Rogers remarked, that the trap dykes of 

 Pennsylvania and the magnetic iron ore of New Jersey were 

 abundantly characterized by the columnar structure. He viewed 

 the horizontal columnar structure of the magnetic iron ore, as a 

 very important indication of its igneous origin. 



This discussion was here suspended to give an opportunity 

 for Prof. Bailey to read his paper on recent and fossil Infusoria. 



Dr. Jackson stated that the mass of infusorial deposit found 

 under peat bogs is hydrate of silica, which loses by being heated 

 to redness from 12 to 15 per cent., principally vegetable matter. 

 Great abundance of this material occurs at Newfield, in Maine, 

 where it covers many hundred acres, and is five or six feet thick. 

 After burning, it is so white and beautiful that it has been fraud- 

 ulently sold for magnesia alba. The ammonia which is evolved 

 in its destructive distillation, is probably derived from the crenic 

 and apocrenic acids which it contains. Phosphate of lime and 

 manganese are found in it in small quantities. As a fertilizer of 

 land, it is considered of use when containing in large quantity 

 the juices of plants. 



A memoir from M. Alexandre Vattemare was presented, pro- 

 posing a general system of exchange of objects of nature and art 

 among all nations. It was by motion laid on the table. 



The subject of bowlders and diluvial scratches was then 

 brought up for discussion by Prof. Mather, and a protracted 

 debate ensued, in which many of the members joined. 



Prof. Mather inferred from the facts in the case, that the 

 bowlders and diluvial scratches had, in general, come from the 



