This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
With regard to the influence of soda salts on diuresis, opinions are divided, partly, perhaps, because of the different doses employed. Usually some increase in the quantity of urine passed is observed in patients taking carbonates, especially in those with acid dyspepsia, but it is not always the same with healthy persons. Munch found, in five subjects, when perspiration or diarrhoea did not occur, increased excretion of water as the principal effect of 3 to 6 or 9-gramme doses of carbonate, but Rabuteau and Constant could not verify any increase with 5-gramme doses, given daily. A continued weak alkalescence of the urine may be secured from about 3-gramme doses of bicarbonate of soda, taken thrice daily at meal-times, while one daily dose of 5 gr. will give alkalinity only for two or three hours - even 1 gramme will do this if taken fasting. Much dilution or warmth of the liquid in which the drug is taken promotes the alkalescence of urine, and it lasts longer in weak or elderly persons.
The chloride will produce the same effect, though not so quickly as the carbonate, and under its use earthy phosphates replace free acids (Munch).