238 DR. ROBERTS ON THE DIURNAL 
XVI.—A Contribution to Urology, embracing Observations 
on the Diurnal Variations in the Acidity of the 
Urine, chiefly in relation to Food. 
By Witi14M Roserts, B.A., M.D., 
Physician to the Manchester Royal Infirmary. 
Read May 3rd, 1859, 
Ir has been the universal belief, until recently, that the 
reaction of the human urine was, in health, invariably 
acid; and that a neutral or alkaline condition of it was 
either a sign of disease, or the consequence of partaking of 
alkaline substances, or of subacid fruits, the vegetable salts 
of which, being broken up in the blood, appeared in the 
urine as alkaline carbonates. 
In 1845 Dr. Bence Jones* called this belief in question, 
and announced that he found that the urine became not 
unfrequently alkaline a few hours after taking food. 
Three years later Dr. Jones investigated the subject 
comprehensively ; and the result of his inquiries were 
published in the Philosophical Transactions for 1849. He 
conducted the inquiry as follows : — The urine was passed 
immediately before breakfast (about nine), and the acidity 
per 1000 grains estimated by a test solution of carbonate 
of soda. After breakfast the urine was passed about every 
hour or hour-and-half, and the products separately ex- 
amined by the test solution. This went on till dinner 
(about six p.m). After dinner the observations were less 
frequent and regular. Generally the first examination was 
* Phil. Trans. 1845, p. 349. 
