SAND-LIME BRICK. 3821 
meter) gives very satisfactory results. After the steam treat- 
ment, the bricks are ready for immediate use. 
The pest commercial practise results in a very desirable prod- 
uct. The strength is as high as, and more uniform than, a good 
quality of stone, and it increases with age; the absorption of 
moisture is less than that of any other except vitrified brick, and 
it is remarkably little affected by heat. The best commercial 
practise in America produces a sand-lime brick with compres- 
sive and tensile strengths ranging from 4,000 to 6,500 and from 
300 to 370 pounds per square inch (280 to 460 and from 21 
to 26 kilograms per square centimeter) respectively. These 
figures can be increased to 8,500 for compression and 550 for 
tension, but a compressive strength of 4,000 and a tensile 
strength of 300 pounds per square inch are sufficient for all 
ordinary brick construction work. 
The sand-lime brick industry has reached its highest state of 
commercial success in Germany where over 300 factories have 
been in successful operation for many years. Practically no face 
bricks are manufactured, but the largest factory, the Berliner- 
Kalksandsteinwerke near Berlin, operates continuously and pro- 
duces 440,000 bricks daily. The success of the industry in 
Germany is due largely to the control of an association of sand- 
lime brick manufacturers which, since 1903, put its members 
under obligation to manufacture brick having a crushing strength 
of not less than 2,000 pounds per square inch (140 kilograms 
per square centimeter). The sand-lime brick industry has not 
gained much prominence in the British Isles, for the reasons 
that in England there are immense deposits of first-class clay 
which enable clay bricks to be produced and sold at a very low 
price, while in Scotland good stone quarries are plentiful and 
building stone is a cheap commodity. The industry was intro- 
duced into the United States in 1901, but did not make much 
progress until 1903 when 16 plants reported products valued at 
155,040 dollars. During the next four years the industry grew 
rapidly, 94 plants reporting 1,225,679 dollars’ worth of products 
in 1907. Since then it has declined, and in 1911 there were but 
66 firms, and the total value of their production dropped to 
879,664 dollars.» A careful investigation of the cause of this 
decline has led us to believe that it was due to the marketing of an 
improperly prepared product and to the fraudulent practises of 
°U.S. Geol. Surv. Press Bull. (1912), 53, 1. : 
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