14 The Colorado Experiment Station. 
the outside as well as to the inside of the mold, which makes it im¬ 
possible for any of the material to cling to it. With the iron molds, 
the oil prevents rusting. In case the molds are made of wood, the 
oil helps to keep out the moisture, thus preventing shrinking and 
swelling, and also making them easier to keep clean. 
As soon as the mold is removed from the post all material 
sticking to it should be scraped off and the inside surface covered 
with a thin coating of oil. In case tamped posts are being made, 
the oil need not be applied oftener than once for ten or twelve posts; 
but with poured posts, the oil should be applied each time the mold 
is removed. Great care should be taken not to allow the molds to 
become bruised or dented, as it not only causes the posts to have a 
bad appearance, but allows the mixture to adhere to the uneven 
spots; thus a great deal of unnecessary trouble is experienced in re¬ 
moving the posts from the molds. 
If the molds are not to be used for a time, they should be 
thoroughly scraped and oiled, inside and out, and carefully laid 
away. When it is understood that the speed of operation and the 
value of the posts depend largely upon the condition of the molds, 
the importance of properly caring for them will be readily under¬ 
stood. 
REINFORCEMENT. 
Cement and concrete work has the property of resisting great 
crushing stresses, but when subjected to tensile stress, the best of it 
breaks very easily. 
For this reason it becomes necessary to put some material pos¬ 
sessing great tensile strength into the post, in order that the full 
crushing strength of the cement or concrete may be utilized. Iron 
is the most satisfactory material from which to make the reinforce¬ 
ment. 
The reinforcement should be placed in the post as near the cor¬ 
ner as possible. This places it as far as possible from the neutral 
axis, thus giving it the greatest advantage in strengthening the 
post. In order that the reinforcements may be properly held and 
protected by the cement, it is a good plan to place it from jks to % 
inch in from each side. This insures a good, firm grip of the ce¬ 
ment upon the reinforcement. 
The material used for reinforcement should be strong, light, 
and rough enough to permit the mixture to get a firm grip upon it. It 
should be very rigid, with little or no tendency to spring or stretch. 
A great many special reinforcements are now being made, but 
the farmer should see to it that the reinforcement which he is to 
use is reliable, rigid, and easily secured. 
The experiment showed that ordinary iron or steel wire was 
cheapest, strongest and easiest to procure. In order to provide a 
