"David Scheidt" wrote in message
news
Joy Beeson wrote:
:On Wed, 03 May 2017 07:30:42 +0700, John B Slocomb
wrote:

: You mean there were no rusty roofs until acid rain was invented?

:Rain has always been acid. That's why southern Indiana is hollow.

Limestone is soluable in distilled water.

Most people seem to believe the exact opposite - pollution is most widely
blamed for erosion of decorative limestone architecture.

It was among the first "proper" building materials - some remains still
exist from ancient times.