LXXVIII REPOET OF THE SECRETARY OF AGRICULTURE. 



BXTREAXJ OF CHEMISTRY. 



Examination of Imported Food Products. 



The Bureau of Chemistry has continued the examination of imported 

 food products for the purpose of determining if they contain any 

 added substances injurious to health. The Bureau has also collabo- 

 rated with the Treasur}^ Department in controlling the polarizations 

 of imported sugars and in determining the character of certain other 

 imported products in order to classify them for dutiable purposes. 

 Investigations of the adulteration of food products is one of the impor- 

 tant studies of this Bureau, and the work has been especially devoted 

 during the past year to the adulterations of olive oils, with the object 

 of securing an honest market for the olive oils of domestic manufac- 

 ture which are compelled to compete with cheaper and adulterated oils. 



Investigations of Forest Products. 



Important investigations, in cooperation with the Bureau of For- 

 estry, have been conducted by this Bureau in connection with eco- 

 nomic forest products such as tannin, gums, rubbers, and wood pulps. 



Laboratory Tests of Road Materials. 



The road material laboratory of this Bureau, which was established 

 in December, 1900, in cooperation with the Office of Public Road 

 Inquiries, tests road materials of all descriptions, free of charge, for 

 practical road builders throughout the countr3^ 



Those interested in the construction of a road have only to send 

 samples of their available materials to this laboratory and have the 

 road-making qualities of these materials determined. In the case of 

 materials for macadam roads, the resistance of wear to rock, its 

 cementing value, hardness, toughness, and absorptiveness are deter- 

 mined. After such tests are made it is possible to predict which 

 material will give the best practical results under a given traffic. 



Onl}^ practical road builders of much experience realize the large 

 amount of mone}^ which can be wasted through an improper selection 

 of material. There are generally several materials available in every 

 locality, and the difficult}^ of selecting the most suitable for a particu- 

 lar road is evident. The only way a proper selection can be made 

 within a reasonable time is by means of physical and chemical labora- 

 tory tests. 



The laboratory is now equipped for the testing of road materials of 

 ever}" description, as well as cement and concrete for drains and high- 

 way bridges. 



The large number of samples received from all parts of the country, 

 including our island possessions, attest the value which practical road 

 builders place upon these laboratory tests. 



