Much has been written praising the versatility of concrete as a material of construction. Practically every kind of construction known makes use of concrete. Since concrete is used for such widely contrasting purposes, it is only natural that there has developed a need for types of cement especially adapted to specific applications. Type 1(1A) cement is the backbone of the American cement industry. It is used wherever the special characteristics of the other cements are not needed. Type II (IIA) is similar in application to Type I but it is manufactured to somewhat closer tolerances and offers (1) greater resistance to sulfate attack; (2) somewhat less heat of hydration; (3) lower permeability; and (4) less tendency to bleed. Type III (IIIA) cement is usually referred to as the early strength cement. It gains strength during the first month at a considerable faster rate than other cements because it is ground finer and has an altered chemical composition. Type IV cement is used almost exclusively in mass concrete, such as dams. Its very low rate of generating heat of hydration helps prevent the cracks resulting from the high internal temperatures which develop with ordinary cements. Type V cement has a high sulfate resistance and finds favor in area afflicted with the problem of sulfate soils. The use of various raw materials in the manufacture of cement has introduced still other type variations. White cement is used for such applications of white or colored walls and exposed aggregate work. The manufacture of white cement is a highly exacting task and requires special raw materials and hence the higher price. Portland blast furnace slag cement (IS and ISA) is the outcome of research by the steel industry aimed at creating new markets for its byproducts. Slag cement is a combination of Type I clinker and granulated blast furnace slag. Portland-pozzolan cement (IP and IPA) is intended for general construction usage, but tests indicate that it does not develop early strengths as great as Type I. Natural cement is generally mixed with portland cement and used for general construction, especially in masonry cement works. Masonry cements (both gray and white) vary greatly in chemical composition, but most are a combination of portland cement or portland blast furnace slag cement with a burned lime, combined in many cases with an air-entraining agent, gypsum to control setting time and a water repellent. The article goes on the mention six more special types.