Sentence:  A "Saline" liquor therefore, mixt with another <WSD>ting'd</WSD> liquor, may alter the colour of it ſeveral ways, either by altering the refraction of the liquor in which the colour ſwims: or ſecondly by varying the refraction of the coloured particles, by uniting more intimately either with ſome particular "corpuſcles" of the <WSD>tinging</WSD> body, or with all of them, [...] 
Meaning of the word marked with <WSD> tags:  To add a small amount of colour; to tint;  to add a small amount of some other thing.