GENERAL OBSERVATIONS. , 311 OBSERVATIONS ON THE SPECIES IN GENEH.IL. 1. Zeolite was discovered by Cronstedt in the middle of the last century, and he published an account of it in the Memoirs of the Swedish Academy of Sciences for the year 1756. On account of its intumescing and foam- ing verv much before the blowpipe, he named it Zeohth, from the G-reelc word to foam. This name was uni versally adopted by mineralogists until the publication of the system of Hauy. He is of opinion that the zeolite of Cronstedt contains two distinct species; and hence he rejects the name Zeolite altogether, and substitutes in its place the names Mesotype and Stilbilc. Werner, how ever, still retains the original name, and his own division of the species. It is equally distinct with the method of Hauy, and enables us to avoid the introduction of two new species into the system. 2. This species is well characterised. Its most fre quent colour is white: the other colours which it exhibits, viz. yellow, brown, and red occurring but seldom. Its internal lustre is more or less pearly: it is never more than semi-hard; and its specific gravity does not exceed 2.200. Hut we observe diif'erences in the fracture, degree of lustre, transparency, and crystallization. The differences in the fracture, conjoined with other characters, afford us the distinctions for the four subspecies into which zeo lite is subdivided. These subspecies, as W erner observes, pass by almost imperceptible shades into each other; and hence all of them seem to belong to the same species. U 4 3. Apophyllite.
