PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 527 



heavy kerosene and parafine oils, which drain entirely oil and leave 

 the parts dry. 



10. It must not be too thick, like tallow or frozen sperm oil, 

 as those substances will not penetrate to the parts to be lubricated. 

 Even the so boasted of Mecca oil was found defective in this 

 respect at the Brooklyn navy yard, as it was too thick to penetrate 

 between the axes and journals when the pressure on them was 

 considerable ; however, for some heated parts of machinery, as 

 the cylinders of steam engines, tallow or a thicker oil may be 

 preferable ; and in general the oils should be adapted to the 

 machinery on which they are to be used ; and even different parts 

 of the same machine should be lubricated with a different oil, 

 each oil adapted to the functions the part has to perform. 



This summary of the requisites of a good lubricator is, in fact 

 a criticism on the existing oils used for this purpose ; it shows 

 that none are perfect, and that there is great room for impiove- 

 ments. In the future I will give the results of some further 

 investigations, with which I am now occupied. 



Dr. J Hirsh said he found that if petroleum is poured slowly 

 into bone black the temperature will rise instantly; he noticed that 

 it got quite hot in a few days. Petroleum will always heat if 

 absorbed by a porous substance. 



This position Dr. Vanderweyde positively denied. He also 

 remarked that now an axle grease is made of parafine and vevy 

 heavy petroleum. The naturally heavy petroleums arc the true 

 lubricators. 



Mr. L. B. Page said he had a pair of boots that were tanned 

 with petroleum. 



Drs. Parmelee, Rich, Messrs. Overton, Walling, and others, 

 participated in an interesting debate, after which the association 

 adjourned. 



American Institute Polytechnic Association, 



October 18, 1866. 



Prof. S. D. Tillman in the chair; T. D. Stetson, Esq., Secretary. 



Dr. E. Powell exhil)ited indicator cards from the Expansion 

 Steam Engine built by the U. S. Government for the purpose of 

 making experiments regarding the value of the cut-off. Those 

 experiments are still in progress at the Novelty Iron Works. Dr. 

 E. promises to furnish a detailed account of these experiments at 

 some future meeting. 



