VOL. LXV.] PHILOSOPHICAL TRANSACTIONS. SQ/ 



when put into the mixture while hot. Soap and water may be perhaps used 

 with advantage, as the solvent for several other colours. 



From the foregoing experiments it appears, that this colouring substance, on 

 which they have been made, is of the resinous kind, and has a good deal of 

 affinity with annotta. 



X. Experiments and Observations on the Gymnotus Electricus, or Electrical 

 Eel. By Hugh JVilliamson, M. D., of Philadelphia, p. 94. 



A sea-faring man brought to this city a large eel, that had been caught in the 

 province of Guiana, a little to the westward of Surinam. It had the extraordi- 

 nary power of communicating a painful sensation, like that of an electrical shock, 

 to people who touched it, and of killing its prey at a distance. The eel was 3 

 feet 7 inches long, and about 2 inches thick near the head. On a transient view 

 it resembled one of our common eels both in shape and colour ; but its head was 

 flat, and its mouth wide, like that of a cat-fish, without teeth. A fin, which 

 was above 2 inches broad, extended along its belly, from the point of its tail to 

 within 6 inches of its head. This fin was almost an inch thick where it adhered 

 to the body ; the upper part of it was muscular, but of a very different texture 

 from the muscular part of the body ; the difference was obvious to the touch, 

 but Dr. W. had no opportunity of making any observations by dissecting the 

 subject. It was a native of fresh water, and breathed at the interval of 3 or 4 

 minutes, by lifting its head to the surface. 



Exper. 1 . On touching the eel with one hand. Dr. W. perceived such a sen- 

 sation in the joints of his fingers as he received on touching a prime conductor 

 or charged phial, when no circle was formed ; or such as he had received, when 

 a few sparks of the electric fluid have been conveyed through his fingers only. 

 2. On touching the eel more roughly, he perceived a similar effect in his wrist 

 and elbow. 3. Touching the eel with an iron rod, 12 inches long, he perceived 

 the like sensation in the joints of the thumb and fingers with which he held the 

 metal. 4. While another person provoked the eel by touching it. Dr. W. put 

 his hand into the water at the distance of 3 feet, and felt such a sensation in the 

 joints of his fingers as when he had touched the eel, but not so painful. 5. Some 

 small fishes were thrown into the water where he was swimming ; he killed them 

 immediately, and swallowed them. 6. A cat-fish,* that was at least I4. inch 

 thick, was thrown into the water where the eel was swimming ; he killed it also, 

 and attempted to swallow it, but could not. 7- To discover whether the eel 

 killed those fish by an emission of the same fluid with which he affected the hand 

 when touched. Dr. W. put his hand into the water, at some distance from the 

 eel ; another cat-fish was thrown into the water ; the eel swam up to it, but 



• The Bayre de Rio of Marcgrave. — Orig. 



