No abstract

The crystal structure of the monoclhtic modification of n-propylamine clathrate hydrate has been determined at -lOOT. The space group is P 21 / n with cell dimensions. a = 12.43, b = 20,73. c = 17.28 A, and ,8=89.3°. The water framework is described as a packing of small unoccupied II hedra and large concave polyhedra. The disordered amine molecules occupy convex regions of the concave polyhedra with the amine nitrogens hydrogen bonding to the framework.

No abstract

No abstract

The national responsibilities assigned to the National Bureau of Standards (NBS) early in the last century for providing measurement assistance and service are carried out today by the four programs that comprise the National Institute of Standards and Technology (NIST) Office of Measurement Services (OMS). They are the Calibration Program (CP), the Standard Reference Materials Program (SRMP), the Standard Reference Data Program (SRDP), and the Weights and Measures Program (W&MP). Organized when the U.S. Congress changed the NBS name to NIST, the OMS facilitates access to the measurement and standards activities of NIST laboratories and programs through the dissemination of NIST products, data, and services. A brief historical introduction followed by a perspective of pivotal measurement developments from 1901 to the present and concluding with a look to the future of NIST measurement services in the next decade of the new millennium are presented for each OMS program.