REPORT OF THE SECRETARY. 157 



The corrosion experiments have been extended to the use of paints 

 in the protection of structures of iron and steel, and as a result of 

 these paint experiments the entire science of protective paints has 

 been placed on a firmer foundation. It is now possible to design 

 and specify a protective paint which will not only cover the metal, 

 but will act as a rust inhibitor. It has been shown that the life of 

 wire fencing can be prolonged by painting it, at an expense of about 

 1 cent per rod. 



OIL-CEMENT CONCRETE. 



The Office has conducted important investigative work during the 

 past 3'^ear in the development of oil-cement concrete. Portland- 

 cement concrete is rapidly becoming a universal building material. 

 The principal objection to the present use of cement concrete is that 

 it is extremely porous and absorbs water. It has been found 

 during the laboratory investigations that it is possible to mingle 

 mineral oils A\ath concrete while it is still wet and before it is laid or 

 molded in the forms, so that the material may thus be rendered 

 waterproof. Several pieces of road surface have already been 

 improved by oil-cement concrete. In addition to this, a bridge 

 surface has been constructed of this material in New Jersey. Up 

 to the present time these surfaces are giving entire satisfaction. 

 Oil-cement concrete is now being given a practical application on a 

 series of new vaults at the United States Treasury. From the 

 results already obtained, the experiments indicate that it would be 

 practicable to use this material for floors, cellars, foundation walls, 

 tanks, silos, manure pits, and similar construction, where strength, 

 solidity, and waterproof quahties are required. Varying amounts 

 of oil have been used in these experiments, the best results having 

 been obtained when the amount of oil represents about 10 to 15 per 

 cent of the weight of the cement used. The projecjt is. yet in an 

 experimental stage and the results obtained should not be considered 

 conclusive. 



THE HANDLING OF PERISHABLE PRODUCTS. 



It will be observed that more and more attention is being directed 

 to the study of the handling of perishable products, that waste may 

 be lowered and quality and condition improved. Such investiga- 

 tions as have been conducted in California on the handling of citrus 

 fruits and table grapes; in Georgia on the handling of peaches; the 

 handling of poultry and eggs, oysters, corn, wheat, flaxseed, milk, 

 codfish, sweet ciders, etc., indicate the breadth of the work now in 

 progress. The results already obtained show the great value and 

 importance of such studios in the conservation of our finished prod- 

 ucts — the most valuable asset of any people. 



