1885.] NEW YORK ACADEMY OF SCIENCES. 69' 



Dr. N. L. Britton, fromliis own microscopical observations, 

 confirmed Mr. Dudley's statements as to the nature of the vege- 

 table growth. 



President Newberry said that brownstone was upon the 

 whole a ])oor building stone, and some preservative treatment 

 was most desirable and necessary. To find a substitute would be 

 a good thing, even on aesthetic grounds, as a relief from the 

 monotony of color in our streets. Some varieties were of fair 

 quality, as the Long Meadow stone. A specimen of tlie Belle- 

 ville stone had yielded eleven per cent of lime, a soluble constitu- 

 ent. New York had grown up like a mushroom; the buildings 

 were comparatively new, yet were already showing much decay. 

 The marble roof of the Assay office shows well the result of 

 weathering; about one-fourth of an inch of the more soluble 

 material has been removed, while the siliceous and less soluble 

 parts are left projecting. The building of the State Cabinet of 

 Natural History in Albany, only fifty years old, built of West- 

 chester marble, looks as if about to crumble. ]\[any buildings 

 in New York, the Cathedral for example, are of the same stone. 

 In the city, the disintegration of stone work goes on more 

 rapidly because of the greater quantity of sulphur fumes and 

 carbonic acid in the air. But even in the pure air of the coun- 

 try, the limestone and the marble of burial grounds shows the 

 soluble effect of atmospheric gases and water.- Siliceous rocks 

 endure better, but no kind of rock can long withstand, in our 

 climate, the combined attack of acidulated water as a physical 

 and chemical agsnt. 



The speaker had no doubt that the obelisk was in a bad con- 

 dition when it arrived here. Other specimens of Egyptian 

 granite which he had examined showed that after an ex])osure, 

 even in the dry climate of Egypt, of two or three thousand years 

 the rock becomes shaky. The disintegration is interstitial, and 

 is not very evident to the eye. A fresh or recently quarried 

 specimen of good granite, like the Aberdeen, would not in 

 many years show any such decay as the obelisk has suffered. In 

 the flakes from the obelisk exhibited this evening, the feldspar 

 crystals are broken and the hornblende is quite gone. Some 

 preservative should have been applied as soon as the monolith 

 was erected here. 



The President further said that lie had knowledge of other 

 processes of j^reserving stone, and that he had most confidence 

 in a process using paraffine. It was .certainly more efficacious 

 than the silica treatment. The name of the substance signified 

 its chemical inertness. It is most unchangeable, yet managea- 

 ble. It is simple, and easily renewed, and not expensive. Ap- 



