288 ANNUAL OP SCIENTIFIC DISCOVERY. 



The sample from New Jersey is a grayish-white sandstone, two or 

 three shades ligher than the above. It is less uniform in its general 

 appearance, but is about the same in hardness and. frangibility. It con- 

 tains a few minute spangles of mica, but no carbonate of lime or sul- 

 phuret of iron, though under the microscope there are seen a few dark 

 spots, apparently arising from the decomposition of the latter. The 

 specific gravity is 2.37. A mass exposed under the same circumstan- 

 ces as that from New Brunswick absorbed 5.8 per cent, of pure rain- 

 water. Its absorption was more rapid, and attended with a hissing 

 sound, as if hot-air bubbles were escaping from the pores of the 

 stone. As it takes up water more readily, it will probably part with 

 it sooner than the first sample, thus being more liable to crumble 

 from sudden expansion and contraction, caused by changes of temper- 

 ature in the atmosphere. The weight of a cubic foot, estimated as 

 before, is 149 pounds. 



The Connecticut specimen is of a darker shade than the first, and of 

 a coarser texture, not at all uniform, some parts being fine and granu- 

 lar, while others are formed of nodules of flint or quartz. It contains 

 more oxide of iron than the first specimen, and is largely impregnated 

 with mica and carbonate of lime, less frequently with felspar and sul- 

 phuret of iron. The lime may have an injurious effect in two ways. 

 By the escape of its carbonic acid gas in case of fire, the walls of a 

 building constructed of this stone would speedily crumble, or the 

 same effect might be more slowly produced by the decomposition of 

 its pyrites, and the formation of sulphuric acid, which would seize 

 the lime. Its specific gravity is 2.51. Exposed as before, it absorbed 

 2.3 per cent, of water. This less susceptibility to absorb water is 

 owing to the numerous quartz pebbles contained in the stone. Some 

 samples contain 15 per cent, of peroxide of iron, which gives addi- 

 tional hardness to the stone. A cubic foot weighs 156 pounds. 



All these sandstones belong to the sedimentary group of rocks, 

 known as new red and old red sandstone. They are similar to the 

 sandstone grits or carboniferous sandstones of Scotland, and of York- 

 shire and Derbyshire in England, of which buildings erected as long 

 ago as 1142 are composed, and whose ornamental portions even are 

 said to be still in a perfect condition. The same quarry produces 

 stone of very different qualities and colors, so that some of the 

 Scotch buildings erected within the present century are already be- 

 ginning to crumble. The sandstones of Great Britain generally con- 

 tain carbonate of lime and mica, and, excepting that they are of a 

 lighter color, have the same lithological character as those of Amer- 

 ica. It is evident that great care should be exercised in the selection 

 of sandstone for building material. That which is good will resist 

 fire better than marble, or granite, or even brick, for the reason that it 

 is a fire-proof material. In our climate the prolific cause of decay 

 arises from the expansion and contraction of the stone, by the gain or 

 loss of water, which may be prevented to some extent by painting. 

 In all cases the blocks of stone should be placed in the building with 

 their planes of stratification horizontal, conformably to their geological 

 position in their native beds, otherwise the layers will be thrown off 



