382 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



draft is created through the annular spaces, and as the flame is spread out 

 by the vessel above, over these spaces, the air comes in contact with it 

 and completes the combustion. There is no smoke. 



"Paper and its Manufacture" was selected as the subject for the next 

 week, and the Association adjourned. 



C. W. Smith, Secretary pro tern. 





American Institute Polytechnic Association, ) 

 October 23, 1862. \ 

 The Chairman, Mr. Samuel D. Tillman, presiding. 



Improved Coal Oil Lamp. 



Dr. Coburn, of Newark, presented several improvements in lamps. One 

 improvement exhibited was a modification in the mode of interposing some 

 slow conductor of heat between the burner and the collar of the lamp to 

 prevent the heat from being conveyed into the oil. The speaker stated 

 that the Hard Rubber company had purchased several patents for different 

 modifications of this plan, but he thought his was better than any of the 

 others, for the reason especially that in his the screw is formed of metal, 

 while in others it is formed directly on the rubber, and as the rubber is 

 softened by the oil, the screw is very quickly destroyed. 



Dr. Coburn also exhibited an excellent device for attaching a concave 

 mirror to a lamp, so as to turn on a horizontal axis, designed for reading 

 and sewing. 



Mr. J. H. Churchill, and others, remarked on the milky appearance 

 induced in coal oils under certain circumstances. He had observed it 

 particularly in heating oil by jets of steam thrown into it, and believed it 

 to be due generally to the presence of water with heat. 



Instruments for Testing the Explosiveness of Rock Oils. 



Mr. J. H. Churchill exhibited and explained Mr. G. Tagliabue's appa- 

 ratus for testing the volatility of coal oil. A lamp heated a dish of oil, and 

 a thermometer, carefully and peculiarly mounted, showe^ the temperature 

 induced. The great novelty was in the means of igniting and shielding 

 ,from currents of air the combustible vapor when the temperature is so 

 high as to generate it. 



Mr. John Tagliabue described an invention of his own, about to be intro- 

 duced, which has a constant flame above it, with provision for a perfect 

 non-conduction of heat, and with provision, by waste holes, for securing 

 a uniform level of the water in which the oil to be tested is immersed. 

 The effect of the whole he claimed, when properly managed, by withdraw- 

 ing the heating lamp after a short period, so as to allow the final healing 

 to proceed very slowly, is to secure much more uniform results than any 

 other. 



We test any oil in this particular by holding a lighted taper over it, then 



