172 PLYMOUTH INSTITUTION. 



of commerce; in affording the greatest facilities, from its insular 

 situation, and its numerous natural and improveable harbours. 



From the numerous highly interesting, novel and useful facts, 

 brought forward by the lecturer in the course of his paper, we find 

 that to give an abstract would be to curtail a subject, on the impor- 

 tance of which there can be but one opinion ; we therefore at an 

 early day, purpose giving in as compact a space as possible the 

 entire of this interesting paper. 



MARCH 13th. Mr. HARRIS' Lectur^ on Combustion. 

 The Lecturer began by defining the term combustion, which he 

 described as being the disengagement of heat and light, during the 

 chemical combination of certain substances which possess the pe- 

 culiar property of exhibiting these phenomena. He then proceeded to 

 give a brief account of some of the earlier theories which had 

 been advanced to explain these appearances ; he remarked on the 

 experiments of Lavoisier who first showed that the air which we 

 breathe contained a principle essentially necessary, not only to com- 

 bustion but also to animal life; this principle he exhibited in a dis- 

 tinct form, and found that with it combustion would go on with 

 much greater rapidity than in the atmospheric air : to this principle 

 he gave the name of oxygen ; several experiments were shewn in illus- 

 tration of the action of this gas; metals burned in it readily, throwing 

 out beautiful scintillations, sulphur burned with an intense blue flame, 

 and phosphorus with a white flame, so brilliant as to distress the eye 

 by its glare, while the heat produced cracked the glass receiver con- 

 taining it ; he then called the attention of the society, to a number 

 of elementary substances, the names of which were arranged on the 

 diagram board, these he described as the probable elements to which 

 all known bodies were capable of being resolved : but that these were 

 only considered simple so far as that they had hitherto resisted all 

 attempts to decompose them. After having described the properties 

 of some of the principle ones which were engaged in the phenomena 

 of combustion, and explained the difference between combustibles 

 and supporters of combustion, he went on to describe that modifica- 

 cation designated flame; this was illustrated by the analysis of the 

 flame of a candle, which is found to consist of three parts ; first, a 

 dark hollow centre where all the volatilized parts are collected; 

 second, a white flame, where these particles enter into combustion, and 

 thirdly, a thin, pale, red film, surrounding the whole ; this being the part 

 which receives the oxygen immediately from the atmosphere, was 

 consequently the part of greatest heat, as the combustion here wa? 



