574 abstracts: technology 



Province of Guanacaste, on the Pacific Coast of Costa Rica, and two 

 recently discovered deposits in Panama. The Costa Rican deposits 

 are widespread, but most of them are either of low grade or of small 

 extent, and in October, 191 8, ore was being produced at only three 

 localities. Development of ore bodies of any reasonable size could be 

 done at low cost, but only one other group of prospects seems promising. 

 The two deposits examined in Panama are northeast of the Canal 

 Zone on the Atlantic side, and the ore in sight was estimated at 25,000 

 to 30,000 tons. An assay of the ore from one deposit showed 55 per 

 cent of manganese. J. D. S. 



GEOLOGY. — Peat in the Dismal Swamp, Virginia and North Carolina. 

 C. C. OSBON. U. S. Geol. Survey Bull. 711-C. Pp. 19. (41-59), 

 pis. 3. 1919. 



The peat deposits of the Dismal Swamp lie in shallow basins that 

 originated in an extensive depression of the Columbia group of forma- 

 tions. The Dismal Swamp covers approximately 2,200 square miles, 

 of which a little more than 700 square miles has been permanently 

 drained to a depth of 3 feet or more by Dismal Swamp Canal and smaller 

 ditches. Much of the drained land is farmed. In the remaining 

 1500 square miles peat deposits ranging in depth from i foot to 20 feet 

 are found. The thickest beds lie in the region east and northeast of 

 Lake Drummond, where peat 18 feet deep was exposed by compara- 

 tively recent excavations. The peat in this area is black and low in 

 inorganic impurities and is probably the best in the swamp. In gen- 

 eral, the depth of the peat gradually decreases toward the edge of the 

 swamp, where the peat finally merges into the sands of the adjoining 

 areas. It is estimated that the average thickness of the peat is 7 feet. 

 On the assumption that the uncultivated area of the Dismal Swamp 

 is 1,500 square miles, that about one-half of this area is covered with 

 peat averaging 7 feet in depth, and that 200 tons of dry peat per acre- 

 foot may be obtained, the^j the total available peat in the Dismal 

 Swamp is 672,000,000 tons. R. W. Stone. 



TECHNOLOGY. — The MacMichael torsional viscosimeter. Winslow 



H. Herschel. Journ. Ind. and Eng. Chem. 12: 282. 1920. 



The MacMichael viscosimeter contains a pendulum hanging at the 



center of a motor-driven cup. Near the upper end of the pendulum is a 



disk graduated from zero to 300, on which readings may be made of 



