Wisconsin and Missouri Lead Region. 35 
Analysis of Pyrochlore, by Wohler. 
Titanic acid, ; ; : 5 : 62.75 
ime, 3 ; : : : : 12.85 
Protoxide of manganese, . ‘sgn 2.75 
Oxide of iron, . : ; : i 2.16 
Oxide of uranium, . : ; pene ie 
Oxide of cerium, ee ee 
wreeo tn,  .  . °.. te 
4.20 
ater, ’ ; : : : 
Fluoric acid and magnesia, : : traces 
97.30 
Arr. IV.—On the Wisconsin and Missouri Lead Region; by 
James T. Hopee. 
Tur following observations upon some of the mineral resources 
of Wisconsin and Missouri, were made in the course of a tour 
through parts of the western country the last season. My at- 
tention having been directed by the company by whom I was 
employed, to ascertain the probable importance of a few mines 
only, I was unable to devote much time to the elucidation of 
the general geology of that country; this I am happy to see 
in the last number of the American Journal, is taken up by one 
well able to connect its formations with those of our eastern 
states. wo Gia tees aerate ests od ans ob steams. calc 
This region, according to Messrs. Owen and Locke, compre- 
hends sixty two townships in Wisconsin, eight in Iowa, and ten 
in Illinois, its extreme length from east to west being eighty seven 
miles, and width from north to south fifty four miles. Though 
the “cliff” limestone, the rock formation that contains the lead 
ore, occupies a greater extent of country, it is in this portion 
only that circumstances seem to have been favorable for the pro- 
duction of fissures containing the ore. This rock is not broken 
through by granite or other rock of igneous origin, as the lime- 
stone of Missouri is, that there produces lead ore ; and its calca- 
reous character is more constant than this, which frequently 
passes into a true siliceous rock. Its strata appear uniformly 
