Previous to the Greek invasion, ancient Egyptians knew nothing whatever of the valuable uses of iron; the peculiar formation of the soil of Egypt produced none of that mineral, but they were adepts in the manipulation of copper and tin to make bronze, tempered in a certain manner, with which they cut and carved rocks of adamantine properties.<br><br>In Mexico there are mountains of iron, but the highly civilized and progressive Toltecs knew none of its uses; not one bar, blade or bolt of iron can be found in the ancient ruins of Mexico, Central or South America. They also knew the secret of preparing a cement impervious to decay known only to the ancient Egyptians (which with the above mentioned bronze is now a lost art) with which they lined mammoth reservoirs or zonotes which were first paved with cobble-tones, then cemented together, which remain as the beds of lakes in Mexico today.