Sentence:  As soon as that operation has taken place, the food is passed down to the stomach, and there it is mixed with the chemical fluid called the gastric juice, a substance which has the <WSD>peculiar</WSD> property of making soluble and dissolving out the nutritious matter in the grass, and leaving behind those parts which are not nutritious; 
Meaning of the word marked with <WSD> tags:  Common or usual for a certain place or circumstance; specific or particular.