392 Proceedings of the British Association. 



organic substances exhibit in a dark place a pale lambent flame, 

 similar to that exhibited by dry phosphorus when heated in the air 

 to a temperature below incandescence, (as low as 300°), and that 

 this flame bursts out into that known to attend ordinary combustion, 

 when the substance is plunged into oxygen gas. This feeble com- 

 bustion commences in organic substances when vapours begin to 

 be evolved. This feeble flame has little heating power, and passes 

 to ordinary flame by a rapid transition, accompanied by a feeble de- 

 tonation. Some metals, as zinc and potassium, shew the same 

 phenomenon, though of shorter duration, probably from the forma- 

 tion of a coating of oxide. — As a practical result from his observa- 

 tions, he remarked on the danger of many manufactures, as those 

 of soap and candle-making, in which vapours are driven off from 

 organic substances, and this low combustion actually goes on dur- 

 ing the whole process of manufacture. 



Dr Daubeny next brought before the meeting the economical 

 employment of coal-tar in connection with water as fuel, according 

 to the method lately suggested by Mr Rutter. A discussion then 

 arose as to whether the water in this case acts chemically or me- 

 chanically, or both, in facilitating tlie combustion of the tar. Mr 

 Macintosh stated, that by repeated experiments he had found, 

 that coal-tar gave no more heat when burned than an equal weight 

 oi splint codXy the kind preferred, where a long continued heat is re- 

 quired. Mr Low also stated, that from long experience he could af- 

 firm, that the use of water along with coal-tar was productive of no 

 benefit whatever, and that 3 gallons, or 33 lb. of coal-tar, give an 

 equal amount of heating effect fully to 40 lb. of coke, made from 

 the Newcastle coal of the Hutton seam. 



From the discussion on this subject, which was protracted for 

 some time, it appears to be established, 1. That tar may be used as 

 fuel, but that it does not give much more heat than the same 

 weight of the best coal. 2. That when mixed with water, it flows 

 more easily through tubes, but does not appear to evolve more 

 heat than when used alone. 



The next communication was an abstract of the discoveries of 

 Reichenbach, in regard to the products of the destructive distilla- 

 tion of organic substances. In this paper Dr Gregory detailed 

 the properties of Paraffine, Eupion, Kreosote, Pittakall, Pica- 

 mar, and Kapnomor, and exhibited specimens of several of them. 

 He also made some observations regarding the more common 

 products of destructive distillation, and stated that several of these 



