The British Association opened its business in the sections yesterday,
when several interesting papers were read : among others, by Sir David Brewster, on the "radiant spectrum " ; by Dr. Shaw, on African explo- rations; by Dr. Dickie, on the effects of winter upon vegetation at Aberdeen ; and by Professor George Wilson of Edinburgh, on the changes of artificial sea-water in marine vivariums, where living plants and animals had been kept in full vigour for periods respectively of ten and six months.
"On analysis, it appeared that whereas magnesia, sulphuric acid, potas- sium, sodium, and chlorine were the only substances originally present in solution in the artificial sea-water, lime, phosphoric acid, silica, iodine, and Iron now occurred in it. The lime was probably dissolved by carbonic acid evolved from the animals ; the phosphoric acid was taken up as phosphate of lime by the same gas, along with water ; the iodine was separated from the sea-weeds; the silica from the infusoria and fragments of rock within the vivarium, and the iron from many sources. It was further stated, that certain important substances which were likely to be present could not be detected, owing, as the author believed, solely to the small amount of water Which could be spared from the vivaria, not permitting a minute amount of such bodies as bromine, fluorine, ammonia, or nitric acid, to be discovered. The success of Mr. Gosse's artificial sea-water was shown to be complete. The substances not originally purposely dissolved in the water gradually separated from the stones, plants, and animals, and passed into a state of so- lution ; so that, ultimately, every ingredient to plant life or animal life, as these are developed in the open ocean, was found in the water of the viva- rium- It might be better to add all the needful ingredients from the first, and to leave none to chance ; but these were in part supplied from the be- ginning by the sea-water adhering to the living things transferred from the ocean to the vivarium, and in part were slowly added to its contents as a result of the chemical changes which these underwent." The first conversazione had been held on Thursday evening, at the- M4Lellan Rooms.
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