CONTROL OF IN^CUBATIKG TEMPERATURES IX LABORATORIES. ^ 3 
at the walls. The floor was sloped to the center to facilitate cleaning 
and disinfecting. 
Walls and ceiling. — Expanded-metal walls and ceiling were con- 
structed, as shown in figure 2. These consisted of 1-inch channel 
studs, tied at the floor and ceiling and thoroughly crosstied. The 
studs were covered w^ith No. 24 gauge high-rib expancled-metal laths 
which were used instead of channels in order to give greater strength. 
Fi<3. 1. — Chart showing drop in room temperature for one week, with heat supply entirely 
shut off. 
Directly on the expanded metal a J-inch course of cement mortar was 
applied, mixed in the proportion of 1 part of Portland cement to 2 
l^artg clean, sharp sand. 
While the mortar was green a course of 2-inch cork board was 
erected on it and the joints were slushed with hot asphalt. Against 
the exposed surface of the cork board a Portland-cement plaster 
finish about one-half inch in thickness was applied in two coats. 
The first coat, about one-fourth inch in thickness, was mixed in the 
