RESUMO
2,4-Bis(4-nitrobenzazo)resorcinol-6-sulphonic acid is suggested as a new visual acid-base indicator, which because of its colour sharpness and other qualities is useful in titrations of weak acids. There are two colour transitions, one from yellow to red at pH 6.8-8.2, the other from red to blue-violet at 10.5-13.0. The corresponding dissociation constants are pK(1) 7.64, and pK(2) 11.64.
RESUMO
During a 24-hr period (12-13 April, 1966) continuous records of temperature, relative humidity, wind speed, wind direction, salt spray, and evaporative power of the air were made at Nungua beach, Ghana. Water loss from emersed plants of Sargassum vulgare, Bryocladia thyrsigera, and Ulva fasciata was measured during the same period. The daily march of desiccation in these seaweeds follows the curve for evaporative power of the air. At night the 3 species lose relatively little water and very nearly the same percentage in each case. During the day Ulva is most resistant to water loss, Bryocladia next, and Sargassum is least resistant. This behavior is correlated with the upper limits of the zones they occupy on the shore.
