188 ANNUAL REPORT 
of white plaster one-half inch or less in thickness, apparently carrying 
some plaster of Paris, was spread upon the forms and then the iron 
bars and concrete were put in place. The white mortar acted as a 
plaster or surface coat for the underside of the roof. 
Within the building heavy machinery, crushers, filter presses, 
tanks, etc., were set upon the floor or hung from the ceiling with no 
extra strengthening attempted. Borax, weighing 340 pounds per barrel, 
was stacked three barrels high over large areas. In fact, much of the 
floor, so the general manager said, had been tested in actual service by 
loads of 1,000 to 1,650 pounds per square foot. 
Baltimore Fire.—The Engineering News* employed several experts 
to investigate and report upon the fire proof construction within the area 
swept by the great Baltimore fire of February 7, 1904. Extracts from 
these various papers read: “Comparing the efficiency of concrete and the 
hollow blocks as fire-proofing materials, there is no doubt but that the 
concrete made from steam boiler cinders and Portland cement, made 
the best showing.” 
“Generally speaking concrete and terra cotta protected successfully 
the steel columns.” | 
“As fire and water resisting materials, terra cotta and concrete 
have given a very good account of themselves.” 
“The buildings were all gutted, but the concrete floors were all 
apparently in first-class condition. The iron work was not exposed 
and’ the concrete did not appear to be disintegrated.” 
“The concrete construction? (speaking of the Fidelity and Guar- 
anty Company’s building) endured the fire practically uninjured, a 
notable demonstration being the fact that the cantilever extensions 
of the floors in front and rear remained intact, and the attic floor 
carried a tier of columns reaching to the roof which it had never been 
designed to support.” 
“In a few cases where the heat was the greatest, fine surface cracks 
were seen in the beams and ceilings and small portions of the concrete had 
flaked off, but nowhere sufficient to indicate serious injury to the structure.” 
One of the floors in this building was afterward tested by loading it 
with a uniformly distributed load of 225 Ibs. per square foot and it only 
showed 1-16 inch deflection under the load. The concrete used in the 
United States Fidelity and Guaranty Company’s building was composed 
of 1 cement, 3 sand and 5 crushed granite. Two other buildings were of 
so called fire proof construction. 
*EHnaineering News March 8, 1904. 
+Hngineering Record March 18, 1904 
