146 
CHEMICAL ACTION. 
the coast. It is probable that any attentive obser- 
ver vrould not estimate the loss of land there at less 
than this amount. Nearly one half the matter com- 
ing from the degradation of the land is supposed to 
be swept coastwise in a westerly direction. There 
are many evidences that the east end of Long Isl- 
and was once much larger than at present; and it 
is thought probable that it might have been connect- 
ed with Block Island, which lies in the direction of 
the prolongation of Long Island." 
I Chemical action. — Rocks are continually subject to 
decomposition, through the influence of chemical 
changes. Chemical affinity is constantly and suc- 
cessfully acting against the attraction of cohesion ; 
in other words, the forces which strive to separate 
the particles of rocks are superior to those which 
tend to bind them together ; the consequence is a 
silent, but sure, and often a rapid, decay of the solid 
structure of the globe. " It is painful," says Philips, 
" to mark the injuries effected by a few centuries 
on the richly sculptured arches of the Romans, th© 
graceful mouldings of the early Enghsh architects, 
and the rich foliage of the decorated and later Gothic 
styles. The changing temperature and moisture of 
the air communicated to the slowly conducting stone, 
especially on the western and southern fronts of 
buildings, bursts the parts near the surface into pow- 
der, or, by introducing a new arrangement of the 
particles, separates the external from the internal 
parts, and causes the exfoliation or desquamation,^ as 
MacCulloch calls it, of whole sheets of stone paral- 
lel to the ornamental work of the mason. From 
thes^ attacks no shelter can wholly protect^ the 
parts of a building which are below a ledge often 
decay the first ; oiling and painting will only retard 
the destruction ; and stones which resist all watery 
agency, and refuse to burst with changes of temper- 
ature, are secretly eaten away by the chemical forces 
of carbonic acid and other atmospheric influences. 
