546 REVIEWS 
home state. There will, however, be many matters to consider before 
the attempt is made. The present, being a preliminary report, leaves 
this as well as many interesting problems of cost, production, markets, 
and treatment almost untouched. We would like, for example, to 
know more about the fuel and labor costs, the type of dry houses and 
speed of drying found best adapted to the various clays, methods oi 
burning, length of water-soaking, and many other things. These will, 
of course, be discussed in the final report, which will be eagerly antici- 
pated by all interested in the clay industry. 
Among the most valuable things in the present paper are the 
rational analyses and the large number of physical tests. The latter 
include the determination of the percentage of water necessary to give 
a workable paste, the approximate plasticity, the speed of slaking, tex- 
ture, percentage of air and fire shrinkage, average and maximum tensile 
strength per square inch, the point of vitrification, vitrification and 
viscosity temperatures, total fluxes, color when burned, and specific 
gravity. There is nothing new or especially accurate with regard to 
the plasticity determinations, such general expressions as “lean,” 
Co Tianie,” “A rexoyeyal,”” ive. lnomnes wise, It 1S MOE Starec! Inony mney esis 
were used in getting the average tensile strength, nor is the range of 
variation given. In view of the method adopted, a minor variation 
from the standard cement test, the omission is important. For exam- 
ple, the pottery clay (No. 50) from Blackburn in Catawba county, gave 
an average tensile strength of 148 pounds, with a maximum of 200 
pounds per square inch. Assuming that the minimum varied as much 
from the average as the maximum, and we have as the result a clay 
with tensile strength varying from 96 to 200 pounds, over 100 per 
cent. While some of the figures are closer, this is not exceptional 
except in the high strength. Other variations are 84 average to 120 
HMO, Oo WO) Guys wo no, uy Wo US, Cie, Iba Sori, ilne results, 
judging from the imperfect data presented, show as wide or wider vari- 
ation than is common in cements, and there is the same need here for 
an improved and more accurate test that cement users recognize. It 
would be interesting to know more also as to the methods adopted in 
making some of the tests. For example, does the percentage of water 
necessary to give a workable paste have reference to clays dried to a 
uniform state or taken from the bank? ‘The difference might be con- 
siderable. Was the shrinkage measured in bulk on market products 
or along single directions on tests bricklets? Without this data the 
