14 



in a chemical sense. The discovery of the pos- 

 sibility of dissolving, by means of caustic alkali, the 

 medullary part of the nerve, so that its membrane 

 should remain as a hollow tube, has afforded a 

 good opportunity for separating the membrane, 

 and has given us some information concerning the 

 nature of the channel which the neurilema forms. 



Next to the nervous system, the principal part 

 in the animal body is acted by the blood and the 

 vessels by which it is circulated. The extremi- 

 ties of these vessels are interwoven with the last 

 ramifications of the nerves, and perform in this 

 union, at the expence of the blood, all the pro- 

 cesses of the animal body. The attention of 

 Chemists was very early directed to the blood ; 

 and its different properties in certain diseases, in- 

 duced them to make several experiments with it. 

 HALES tried to determine the quantity of air 

 which is disengaged in the distillation of the blood. 

 LEMERY and MENGHINI burnt it to ashes, 

 found iron amongst its constituent parts, which 

 the latter even believed himself able to extract 

 from dry blood with the magnet. HOFFMAN 

 examined the different matters which are sepa- 

 rated in the coagulation of blood. LANG RISK, 

 CHEYNE, and SCHWENKE, published for their 



