BULLETIN 691, U. S. DEPARTMENT OF AGEICULTTJEE. 



from one-third to one-half gallon per square yard. It should be 

 covered with a uniform layer of dustless broken stone all of which 

 will pass a one-inch or three-fourths inch laboratory screen or 

 pea gravel which will pass a one-half inch laboratory screen in 

 an amount just sufficient to absorb the bitumen and to prevent the 

 surface from picking up under traffic. Subsequent applications 

 may be made by a pressure distributor or by brooming the oil 

 uniformly over the road surface. From one-tenth to one-fifth 

 gallon per square yard will usually prove sufficient, and this 

 should be covered with coarse sand or stone chips which will pass 

 a one-half inch laboratory screen. To obtain best results the 

 treatment should be applied in the early summer except in locali- 

 ties where snow and freezing weather are not common. Under 

 favorable conditions with occasional patching of any breaks 

 in the surface a treatment should last for several years. 



