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The tide at tahiti
394
CURRENT TOPICS.
[J. F. I.
T h e T i d e at Tahiti. H. A. MARME~. (Jour. Washington Acad. Sci., 17, No. 7 . ) - - A t Tahiti, it is said, high tide comes at the same time every day. Now there is definite knowledge of this matter, for Mr. H. W. Smith, acting for the U. S. H y d r o graphic Office, has secured tide records covering a period of several years. The tide gauge with automatic registration was set up in Papeari H a r h o r on the south coast of Tahiti. The mean range of the tide is .78 ft., the spring range is .97 ft., and the neap range .58 ft. The interval between high waters is 12 h. 09 m., and between low waters 5 h. 53 m. The progression at the time of spring tides is much less than the usual 50 min. and at neap tides is considerably more. " At spring tides high water comes about noon and midnight, and low water about six o'clock both morning and afternoon. At spring tides the tide has its greatest range and is therefore most noticeable while at neap tides the times of high and low water are difficult to determine. Apparently, therefore, the characteristics of the spring tides have heen taken as the average characteristics." G.F.S. N e w U n i v e r s a l I n d i c a t o r . - - E M I L BOGEN, of the University of Cincinnati (Jour. Am. Med. Asso., 1927, 89, ~99), has devised the following universal indicator for use in the colorimetric determination of hydrogen-ion concentration: Phenolphthalein o.Ioo gram, methyl red o.2oo gram, dimethylaminoazobenzene 0.30o gram, bromthymol blue 0.400 gram, thymol blue 0.500 gram, absolute alcohol 500 c.c. The indicators are dissolved in the alcohol; and tenth-normal sodium hydroxide is added to the resulting solution until it becomes yellow in color. In order to determine the hydrogenion concentration of a solution, one drop of the universal indicator is added to one cubic centimetre of the solution; a red indicates p H 2.0, orange p H 4.0, yellow p H 6.0, green p H 8.0, blue pI-t IO.O. These values are approximate; more exact values may be obtained by comparison with bnffer solution of known p H to which the universal indicator has been added. Differences as low as 0.2 of a p H unit may be distinguished. J.S.H. C u l t u r e d B u t t e r m i l k . - - M i l k , which has been inoculated with lactic acid bacteria, such as Bacillus acidophilus, Bacillus bulgaricus, etc., is used on a large scale as a food and as a therapeutic agent. F o r this reason, the following definition and standard for cultured buttermilk, adopted by the Secretary of Agriculture for the enforcement of the Federal Food and Drugs Act (Food Inspection Decision 2IO, I927), is of general interest: " Cultured buttermilk is the product obtained by souring pasteurized skimmed, or partially skimmed, milk by means of a suitable culture of lactic bacteria. It contains not less than eight and five-tenths per cent. (8. 5 per cent.) of milk solids not fat." J.S.H.
CURRENT TOPICS.
[J. F. I.
T h e T i d e at Tahiti. H. A. MARME~. (Jour. Washington Acad. Sci., 17, No. 7 . ) - - A t Tahiti, it is said, high tide comes at the same time every day. Now there is definite knowledge of this matter, for Mr. H. W. Smith, acting for the U. S. H y d r o graphic Office, has secured tide records covering a period of several years. The tide gauge with automatic registration was set up in Papeari H a r h o r on the south coast of Tahiti. The mean range of the tide is .78 ft., the spring range is .97 ft., and the neap range .58 ft. The interval between high waters is 12 h. 09 m., and between low waters 5 h. 53 m. The progression at the time of spring tides is much less than the usual 50 min. and at neap tides is considerably more. " At spring tides high water comes about noon and midnight, and low water about six o'clock both morning and afternoon. At spring tides the tide has its greatest range and is therefore most noticeable while at neap tides the times of high and low water are difficult to determine. Apparently, therefore, the characteristics of the spring tides have heen taken as the average characteristics." G.F.S. N e w U n i v e r s a l I n d i c a t o r . - - E M I L BOGEN, of the University of Cincinnati (Jour. Am. Med. Asso., 1927, 89, ~99), has devised the following universal indicator for use in the colorimetric determination of hydrogen-ion concentration: Phenolphthalein o.Ioo gram, methyl red o.2oo gram, dimethylaminoazobenzene 0.30o gram, bromthymol blue 0.400 gram, thymol blue 0.500 gram, absolute alcohol 500 c.c. The indicators are dissolved in the alcohol; and tenth-normal sodium hydroxide is added to the resulting solution until it becomes yellow in color. In order to determine the hydrogenion concentration of a solution, one drop of the universal indicator is added to one cubic centimetre of the solution; a red indicates p H 2.0, orange p H 4.0, yellow p H 6.0, green p H 8.0, blue pI-t IO.O. These values are approximate; more exact values may be obtained by comparison with bnffer solution of known p H to which the universal indicator has been added. Differences as low as 0.2 of a p H unit may be distinguished. J.S.H. C u l t u r e d B u t t e r m i l k . - - M i l k , which has been inoculated with lactic acid bacteria, such as Bacillus acidophilus, Bacillus bulgaricus, etc., is used on a large scale as a food and as a therapeutic agent. F o r this reason, the following definition and standard for cultured buttermilk, adopted by the Secretary of Agriculture for the enforcement of the Federal Food and Drugs Act (Food Inspection Decision 2IO, I927), is of general interest: " Cultured buttermilk is the product obtained by souring pasteurized skimmed, or partially skimmed, milk by means of a suitable culture of lactic bacteria. It contains not less than eight and five-tenths per cent. (8. 5 per cent.) of milk solids not fat." J.S.H.