18 CEMENT MATERIALS AND INDUSTRY. [bull. 243. 
facturers, and have not felt justified in spending their time in sum- 
marizing the practice for the benefit of competitors. In view of these 
conditions, the present writer has endeavored, in a volume now in 
press,* 7 to describe the technologic and financial features of the lime 
and cement industries. In the present. bulletin, however, considera- 
tion of these features has been subordinated to the discussion of the 
geology and of the distribution of the raw materials. 
Hydraulic Cement; its Properties, Testing, and Use, by F. P. Spald- 
ing, is without doubt the most satisfactory single volume to serve as 
an introduction to the general subject of cement testing and properties. 
As might be inferred from its subtitle, it contains practically nothing 
relative to raw materials or methods of manufacture, but is devoted 
almost entirely to a consideration of the finished product. 
Cements, Mortars, and Concretes, by M. S. Falk, contains valuable 
data on the physical properties of these materials. 
The Cement Industry, a volume containing a number of papers 
which originally appeared in the Engineering Record, is of great serv- 
ice as an introduction to the study of cement-manufacturing methods. 
The Directory of American Cement Industries contains, in addition 
to its lists of plants, many valuable notes on manufacturing and testing 
methods. 
Books devoted to Portland cement exclusively have been written by 
Jameson and Butler, but the}^ contain nothing relative to rotaiy kiln 
practice, and are therefore of little use to American readers. 
To one fairly conversant with the French language, two admirable 
books will be of service. The first of these, Candlot's Ciments et 
Chaux Hydrauliques, is probably the best single book, in any lan- 
guage, on cement technology. In its treatment of the theoretical 
questions involved in cement manufacture it is excellent; but its value 
for American readers is lessened because the mechanical side of the 
cement industry is discussed solely from the standpoint of European 
practice. 
The second, of somewhat different character, is Bonnami's Fabri- 
cation et Controle des Chaux Hydrauliques et des Ciments. This 
volume contains a very detailed description of the manufacture and 
properties of the hydraulic limes, so widely used in Europe, but it 
also contains valuable discussions on the theoretical side of cement 
manufacture in general. 
DEFINITION OF PORTLAND, NATURAL, AND PUZZOLAN CEMENTS. 
Before taking up the subject of the materials and manufacture of 
cements, it is advisable to define the four great classes which are 
included in the group of " hydraulic cements," as that term is used by 
a Cements, Limes, and Plasters: Their Manufacture and Properties. Wiley & Sons, New York. 1905. 
