TWELFTH ANNUAL REPORT 37 



number of pure chemicals heretofore unsuspected. Many new 

 chemical reactions in sunlight and the mechanism concerning a 

 number of old ones have been discovered. 



60. Standardization and testing of supplies. — This Bureau has 

 long maintained a laboratory for the purpose of testing and 

 analyzing the various products purchased under contract for 

 Government supplies. We have tested numerous samples of 

 bituminous and metallic roofing materials for the United States 

 Army; and khaki, shirts, puttees, rain capes, blankets, leather 

 goods, paints, iron and steel, rope, wire, twine, paper, oils, canvas, 

 Babbitt metals, alloys, tiles, bricks, concrete, fabrics, etc. for 

 the local Government. The scope and work of this department 

 have shown a decided increase during recent years, owing largely 

 to a growing realization of the value and necessity of purchasing 

 materials on a basis of quality or, at least, according to specified 

 requirements which will guarantee satisfactory service. Usually, 

 when the testing of a certain class of material is first instituted, 

 the samples submitted give very unsatisfactory results, and im- 

 mediately the manufacturers protest vigorously and complain 

 that the tests are impractical or the testing improperly done and 

 unfair. However, it is a matter of record that when specifica- 

 tions are rigidly enforced, most of the materials subsequently 

 submitted are so uniformly excellent that it is difl^icult to decide 

 in favor of any particular one. The records also show that the 

 improvement in quality is usually obtained without an increase 

 in cost. 



61. Asphalts, bitumen, tars, and oils for road materials. — This 

 Bureau in conjunction with the Bureau of Public Works has 

 given considerable attention to the physical and chemical prop- 

 erties of bituminous road materials. Careful inspection and 

 examination both of the materials employed and their durability 

 under different local conditions of climate and service will give 

 information of much value and will determine their suita- 

 bility for use according to various methods of application and 

 construction. 



62. Portland cement. — For the past five years our investigators 

 have carried on painstaking observations and careful experi- 

 mental work to study the technology of manufacturing, testing, 

 and use of Portland cement. Those characteristics of Portland 

 cement, regarding which there existed the greatest amount of 

 misconception and diversity of opinion, were studied in an en- 

 deavor to assist in the universal eff'ort to formulate cement 

 specifications so drawn as to guarantee the manufacture and use 

 of Portland cement of the quality sought for, and the work of 



