In 1926 a series of tests on the urine of patients suffering from achlorhydria was reported.1 It was shown that little or no increase in alkalinity developed in such subjects after a standard meal, but that when normal subjects used as controls were studied by the same technic, the urine usually showed an alkaline tide; that is, it became more alkaline than it had been before the meal. The difference between the two types of cases was clearly shown by the average figures. This indicated that the secretion of hydrochloric acid by the stomach was the usual cause of the increase in alkalinity observed, as had been claimed by many observers since Bence-Jones2 first described these variations in acidity.3 Similar work by Ackman4 and Davies5 has furnished confirmation of this thesis.
In addition to these studies of the physiology involved, it was suggested that the test might be adapted to
HUBBARD RS. THE ALKALINE TIDE AS A METHOD OF STUDYING GASTRIC ACIDITY. Arch Intern Med (Chic). 1930;46(6):994-1001. doi:10.1001/archinte.1930.00140180095009