30 



the atoms of crystals, had taken their places during their deposi- 

 tion, according to exact laws, and that this idea derived much 

 support from the recent discoveries of Faraday, that all bodies 

 possessed inherent magnetism of a certain intensity. There 

 was no reason to suppose that a grain of silex, forming a portion 

 of a sedimentary rock, should not still be possessed of the original 

 qualities by which it took a crystalline form. 



Prof. Rogers presented a specimen of altered Rock, from New 

 Hope, on the Delaware. At this place a dyke of Greenstone 

 passes through the Argillaceous Red Shale, within an hundred 

 feet of which specks or centres of imperfect crystallization are 

 perceptible, and nuclei of Epidote and Tourmaline. The sedi- 

 mentary rock assumes the appearance of Greenstone. He also 

 spoke of the rocks at Newton Tunnel. An Agillaceous Sandstone 

 is there seen altered to Porphyry. The original bedding is un- 

 effaced. Prof. R. made some remarks on slaty cleavage ; and 

 promised to go more fully into the subject at a future meeting. 



Dr. C. T. Jackson read from his note-book notices of 

 experiments on solutions of Gun-cotton, which had been 

 read at the meeting in January, 1848, but had not been 

 particularly recorded. 



The date of the entry is Dec. 20, 1847, and it is as follows : 

 *' Tried the solubility of my Gun-cotton. That of one hour's 

 immersion will not dissolve in ether, and does not lose its explo- 

 sive quality when dried. That of twelve hours' immersion dis- 

 solves quickly and entirely in sulphuric ether, and numerous 

 bubbles of oxygen disengage from the dissolving mass. The 

 ether solution is an excellent cement and varnish. It dries into 

 a pellucid substance, like horn ; and when dried more, turns 

 white. It is not explosive ; but an immersion in the mixed acids 

 renders it so again readily. Its ethereal solution is precipitated 

 by water, white and flocculent. Acids will not dissolve it, nor will 

 boiling water ; but the latter renders it hard, or rather exces- 

 sively tough. Paper immersed in the ethereal solution, became 

 glazed, and is good for writing." 



Mr. Ayres, on behalf of Dr. Storer, exhibited a figure, 

 with a description, of a new genus of Fish, Blennius ser- 



