VOL. LIV.] PHILOSOPHICAL TRANSACTIONS. 121 



Exper. 1. — 14 gr. of the extract of hemlock prepared at Coimbra, digested 

 with 1 oz. of highly rectified spirit of wine for 36 hours in a warm room, gave 

 a brownish yellow tincture; the clear liquor being poured off, a fresh quantity of 

 spirit was added as before, and exposed to digestion for the same space of time; 

 the 2d tincture was considerably less coloured; this, added to the former tincture, 

 was filtered, and exposed to the air in a warm room till the spirit was entirely 

 evaporated: the dry residuum weighed 5 gr. ; on exposing it to the air it became 

 softer, and even moist at the surface. On pouring some water on the residuum 

 now moist, it was soon tinged of a brownish yellow; which being poured off, 

 and a fresh quantity added at different times, till 1-^ oz. of water had been used, 

 there remained some blackish matter not soluble in water, which when dry 

 weighed 1 gr., did not attract the moisture of the air, melted and burned with 

 a bright flame when exposed to the fire, was soluble in spirit of wine, and had 

 every characteristic of a resin. The tinged water, which had been separated 

 from this resin and filtered, was evaporated slowly, till a brown dry matter re- 

 mained, weighing 3 gr., which in a few hours attracted the moisture of the air, 

 and relented into a dark brown thick liquor, of a saline taste, and the smell 

 peculiar to the extract of hemlock. One drop of this liquor, diluted with a little 

 water, destroyed the colour of 10 times the quantity of syrup of violets, without 

 giving it the least red tint; reducing it, on adding some drops of oleum tartari 

 per deliq. it suffered no remarkable change. Spirit of salt did not occasion any 

 alteration in it. But with oil of vitriol there was a strong efftrvescence, without 

 any sensible fume. 



It appears from the above experiment, that the Coimbra extract of hemlock 

 contains -i- soluble in spirit of wine, 4- of which consist of an oily essential salt, 

 the remainder being a resin. 



Exper. 2. — The extract of hemlock from Vienna was softer than that from 

 Coimbra; on breaking it, there appeared small whitish streaks on each surface. 

 24 gr. of it, treated as in the former experiments with spirit of wine, gave a fine 

 deep green tincture, which on evaporation gave a residuum of a dark green to- 

 wards the edges of the cup, and a dark brown towards the middle; the whole 

 residuum when dry weighed 2^ gr. ; on leaving it exposed to the air, the brown 

 matter attracted moisture from it, and relented into a thick brown liquor; on 

 adding water to it, as in the experiments on the Coimbra extract, the solution 

 was of a light green colour ; on evaporation it gave ^ of a grain of dark brown 

 residuum, which ran per deliquium into a brown liquor, differing only in colour 

 from that obtained by a similar process from the Coimbra extract. The undis- 

 solved resinous matter weighed -^ gr., was of a greenish colour, but in other res- 

 pects like the resin of the Coimbra extract. It appears from the green tincture 



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