456 Bihliograpliical ^oticea. 



or pottery, since the various phj-sical conditions directly influence 

 its fusibility. 



Chapter IV. di'scribes processes in tlie manufacture of clay-wares. 

 Firstly, the method of getting and preparing the raw material 

 (pp. 148-184) ; with illustrations of machinery and apparatus. The 

 making of bricks, tiles, pipes, and pottery follows ; with remarks 

 on glazings (pp. 185-234). The methods of drying, heating, and 

 burning are described, with notes on fuel and the types of kilns. 

 Chapter V., "The Chemistry of Clays" (pp. 322-345), gives the 

 methods, results, and value of different analj'tical processes ; the 

 quantitative analyses of samples from seventy-two places in the 

 State are tabulated, pp. 344 & 345. Chapter YI. (pp. 347-370) 

 is concerned with the " Selection, Installation, and Care of Plant 

 Power," giving clear and useful reports on the engines, boilers, and 

 associated machinery used in the clay-works — how they should be 

 chosen, fixed, and utilized to the best advantage. ^Vith severa.1 

 illustrative plates and diagrams. 



Chapter VII. (pp. 379-534), " The Geology of Clay," deals with 

 the topographical and geological distribution of clays and shales in 

 Iowa. Plate I. defines the 101 Counties of the State. Plate II. 

 shows the outcrop of nine regular geological formations, with a 

 N.W.-S.E. strike and a general N.E. dip. Plate III. indicates 

 the distribution of seven superficial Drift-deposits and 220 localities 

 of special clay-pits. 



The Map, PI. II., recognizes the Cretaceous (see also p. 409), the 

 Carboniferous (Missourian, Des-Moines, Alississippian), Devonian 

 (p. 325), Silurian, Ordovician, Cambrian, and Alongkian Formations. 

 At pages 403 &c., after a notice of the Devonian Shales, the Lower 

 Carboniferous series, including the Kinderhook shales, are described 

 as being of some value. In the Upper Carboniferous (pp. 410-549), 

 including the Coal-measures, argillaceous beds, especially the fire- 

 clays, are very valuable and extensive. These fire-clays or under- 

 clays (pages 411 &c., also p. 32-3), because of their having lost (by 

 leaching chiefly) most of their original alkaline constituents, do not 

 readily fuse, and, being resistant to fire, are well-known as " fire- 

 claj's." The characters and uses of these and other clays are carefully 

 noticed according to localities and Counties. The seventy illustra- 

 tions (in plates and text-figures) given for the geological sections, 

 the local works, machinery, and apparatus, are of first-rate quality, 

 and fit well into their right places, both for artistic and economic 

 effect. This may also be said of the numerous other illustrations in 

 the volume, enhancing its value to all engaged in scientific studies 

 or business pursuits concerned with the handling of clays or with 

 the trading of its products. 



The larger portion of the north-western third of the State of Iowa 

 consists geologically of Cretaceous deposits (p. 509). In the upper 

 series argillaceous beds predominate, and near the top the marls and 

 limestones of the Xiobrara Chalk appear. In the ' Iowa Geological 

 Survey,' vol. iii. 18'j5, this formation and its fossils were reported 

 on ; and its Foraminifera were especially noticed in the ' Geological 

 Magazine,' 1895, pp. 425-428. 



