ALBERT

Description: These data suggest that calcium may be lost during heavy sweating conditions (up to 20 mg calcium/hour) and that this loss should be considered in establishing recommended allowances for calcium. It was observed that 7 men consuming 441 mg of calcium a day in a study extending for 48 days, excreted 8.1, 11.6 and 20.2 mg/hour of calcium when living at 70, 85 and 100°F. This accounted for 21.8, 25.1 and 33.2% of the total calcium excreted. These observations are important since they show an additional calcium loss, which has not been reported in previous calcium balance studies in the literature. It is questionable whether an individual, consuming a low calcium diet, ever really attains calcium balance (equilibrium), under heavy sweating conditions. It was observed that (a) the calcium excreted in sweat, in men working at a moderate rate in extreme heat (100°F), was still fairly high after acclimatization, averaging 17 mg/hour after the first 4 days, and (b) that the daily total calcium in sweat increased as the sweat rate increased. Therefore it appears that the calcium requirements may be increased under these conditions. It was shown that even after acclimatization the urinary calcium did not decrease in compensation for the losses of calcium in sweat. It is recognized that changes in the urinary excretion of calcium in adjusting to different levels of dietary calcium and the various other metabolic factors, may require months to achieve.

Description: in a recent publication von Brandt (1) gives a survey of all determinations of the calcium content of Baltic water hitherto published. He records in all 39 analyses made during the last century, which give us an idea of the order of magnitude of the calcium concentration; they cannot, however, serve for comparative purposes as in many cases chlorine determinations on the same water samples are lacking. Neither have we any clue for judging the accuracy of these analyses, the latest of which date from 1884. Fifty years later, in 1935, Za rin s and O z o 1 ins (8) published an extensive investi­gation of the water in the Bay of Riga and in the Baltic off the Latvian coast, their most westerly station nearly coinciding with the Finnish station F81 (Lat. 57° 22'N., Long. 19°57'E.) above the central depression of the Baltic. Their material comprised about 70 calcium analyses on water from all depths. Finally v o n B r a n d t in the above-mentioned paper publishes nearly 300 analyses of surface water collected in 1935 and 1936 during several voyages from Pillau to Helsingfors and back, and along the German coast as far as Kiel and back. The present material comprises analyses of only 48 samples of surface and bottom water collected during the summer cruise, in July 1935, of the s.s. "Nautilus" from the Gulf of Finland, the Gulf of Bothnia, and the northern half of the Baltic proper. In spite of the smaller number of samples this material is more comprehensive than the two preceding investigations in so far as it covers a greater area of the sea. I t was originally meant as a survey of the calcium content in these parts of the Baltic, but the surprisingly simple relationships between calcium content and chlorinity which it revealed, give the results far more scope than was expected.