260 



crals — Actinolitc, Asbestos, Dolomite, Talc, Chromic Iron, 

 and Magnetic Iron Ore — from the quarries at Roxbury, 

 Vermont. 



At the request of Dr. Brewer, Dr. A. A. Hayes gave the 

 Society an account of the characters of the so-called Verd- 

 Antique Marble, polished specimens of which were on the 

 table. 



IIo remarked, that considerable interest having of late been 

 attached to this material, as an ornamental stone, a committee of 

 the Franklin Monument Association, had requested him to ex- 

 amine it in relation to the action of atmospheric agents, purpos- 

 ing to adopt it as the base of the monument to be erected. It is 

 well known, that the extremes of heat and cold, tlie alternate 

 dryness and humidity of our climate soon deface and even dis- 

 integrate the less compact stones, leaving us but a limited number 

 of materials, for ornamental workmanship exposed to the air. 

 Ordinary marble suffers not only a superficial degradation of 

 surface rapidly, but the new surface produced, becomes a hot- 

 bed for cryptogamous plants, which in turn disfigure it, and 

 greatly aid further corrosion. The classic and beautiful sepul- 

 chral monument, over the remains of Spurzheim, at Mt. Auburn, 

 exhibits the defacement due to combined action of lichen growth 

 and moisture, while near by is a monument to one whose mem- 

 ory is revered by us, of imperfect bronze, also attesting the 

 activity of atmospheric agents, when this metal is freely exposed 

 to them. 



The samples subjected to trials were sawed, not polished sur- 

 faces ; choice being made of the former, because the natural 

 (laws existing in the material might become filled by the fine 

 powders used in polishing. 



The stone was first subjected to Braads's test, which, as is well 

 known, quickly shows the unenduring character of sandstones, 

 bricks, and some marbles. The activity of this test was in- 

 creased, but under any mode of application it failed to show any 

 disposition in the material to absorb moisture or disintegrate. 

 Finally, hot diluted hydrochloric acid was applied, and the 



