OFFICE OF PUBLIC ROADS. 785 



During the past fiscal 3'ear the working force of the laboratory was 

 increased by the appointment of two assistant chemists who had 

 qualified for these positions under a civil-service examination dealing 

 mainly with the chemistry of the bitumens. The quarters of the 

 laboratory in the new building consist of an office, two modern chem- 

 ical laboratories, and a petrographic la})oratory. The permanent 

 equipment of the laboratories is thoroughl}^ up-to-date and the best 

 that could be obtained for the limited amount of money available for 

 this purpose. 



It has invariably been the policy of the Office to broaden the 

 experience of its employees to the fullest extent consistent with an 

 economical administration of its duties. Thus the engineermg force 

 is given a course of instruction in the laboratories and each engineer 13 

 encouraged to familiarize himself, both through lectures and labora- 

 tory tests, with the chemical and physical properties of the materials 

 which he has or will have occasion to use in practice. In like manner 

 the laboratory men are allowed to inspect and assist in the experi- 

 mental treatment and construction of roads with various types of dust 

 preventives and road binders in order that they may obtain a thor- 

 oughly practical idea of the value of their laboratory work and, 

 through a study of results, be enabled to modify and improve their 

 methods of examination, and intelligently to investigate certain 

 phases of the work which would be impossible for men confined solely 

 to laborator}" analysis. The wisdom of this policy has been made 

 manifest in many ways, among which may be mentioned the advance 

 made in regard to specifications for bituminous dust preventives and 

 road binders to be used under various known local conditions. 



Routine tests or analyses of bituminous road materials made in the 

 chemical laboratory during the past year numbered 154, over double 

 the number examined during the preceding year. Of these, 61 were 

 tars, 72 oils and asphaltic preparations, 3 bituminous emulsions, and 

 18 rock asphalts and bituminous aggregates. The total number of 

 routine tests, mcluding the examination of materials other than 

 bituminous, amounted to 167, excluding the petrographic analyses of 

 rocks, which are reported among the physical tests. A number of 

 these examinations were made in conjunction with experimental field 

 work of the Oflice, and were reported, together with descriptions of 

 these experiments, in Circular No. 92. It is expected that these 

 examinations will be of great service in determining the value of 

 certain classes of binders. 



Through its laboratory work the Office has been able to offer 

 valuable advice in regard to specifications for bituminous road 

 binders and in many instances to frame such specifications upon the 

 request of various public-service bodies. Tliis opportunity has 

 been used by a numoer of the state highway commissions, among 

 which may be mentioned the highway commissions of Maine, New 

 Jersey, Delaware, Illinois, and Iowa. In the District of Columbia 

 practically all of the bituminous nuiterials employed in the treatment 

 of roads under the jurisdiction of the Office of Public Buihfings and 

 Grounds are examined and selected in accordance with specifications 

 furnished by this Office. 



Many worthless road preparations have been and are at present 

 being manufactured and sold to the public through ignorance on the 

 part of both producer and consumer with regard to the requisite 



73477°— AGB 1910 50 



