Sentence:  When the juice of the poppy has been properly dried, that is rapidly, in a cool shade, and protected from dust, it possesses, at the <WSD>spissitude</WSD> of 70 per cent. (this is 30 of water) the following properties:... 
Meaning of the word marked with <WSD> tags:  Density, thickness; the state or quality of being inspissated or thickened.