266 SIDE; WALLS AND CONCRETE; BUILDINGS 



mortar composed of I part Portland cement and 2 parts ordinary lime 

 mortar. The lime should be very thoroughly slaked before using as 

 the presence of any free lime will injure the wall. After the first coat 

 has hardened it is thoroughly soaked and a finishing coat composed of 



1 part Portland cement, 2 parts sand and a small quantity of slaked 

 lime is applied and rubbed smooth. 



A method of plastering curtain walls is described by Mr. George 

 Hill in the Transactions of the American Society of Civil Engineers, 

 Vol. -29, as follows : "The external curtain walls were composed of hard 

 plaster, Portland cement and sand in equal parts, the scratch coat being 

 applied to uncoated metallic lath, making the thickness of the scratch 

 coat about I inch; then a surfacing of Portland cement ^2 -inch thick 

 was applied on each side making the curtain walls a total thickness of 



2 inches. Good results were obtained in every case except one, where 

 the scratch coat was alternately frozen and thawed several times, and 

 the outer surfacing of the wall peeled off in patches.^ 



The Northwestern Expanded Metal Co. does not recommend the 

 use of hard or patent plasters for curtain walls. 



Expanded metal and plaster curtain walls are light, strong and 

 efficient. They do not require the heavy foundations required by brick 

 and stone walls and are fireproof. They can be used to advantage 

 where it is desirable to have a large glass area in the sides of buildings. 

 This type of construction is almost ideal for factory construction and 

 will be much used in the future. There are quite a number of different 

 systems but the methods of construction are essentially the same in all. 



Curtain walls are made of wire lath and plaster in the same way 

 as expanded metal and plaster and have all the advantages of the latter. 



The cost of curtain walls made as described above is about $1.50 

 to $1.80 per square yard. 



For a detailed description of the construction of small cement and 

 steel buildings see Engineering Record, March 26, 1898. 



Concrete Slabs. The construction of reinforced concrete slabs 

 patented by Milliken Brothers, New York, is described in Engineering 



