Sentence:  Twenty leeches were ordered to be applied round the nose every two days; frequent emollient fomentations; the local vapour bath; general bathing; stimulating pedilavia; a strict regimen; vegetables, milk, white meats; demulcent or <WSD>acidulated</WSD> drinks; avoidance of exposure to the sun or to cold air; flannel waistcoat and trousers. This treatment, being strictly observed for two months, caused all the inflammatory symptoms to disappear, ... 
Meaning of the word marked with <WSD> tags:  To make sour in a moderate degree; to sour somewhat.