1 882. 1-41 Trans. N. V. Ac. Scz. 



quantity of the oil to be tested is introduced, tht cap with the wicks is 

 fitted, and the whole is placed in a vessel of water of the temperature 

 at which the oil should noi flash. When this temperature is nearly 

 reached, the little wick on the side of the cap is lighted ; and when ihe 

 thermometer reaches the standard temperature, a measured quantity 

 of water is poured into the narrow limb of the U tube. By this action 

 the Irvel of the oil in the enlarged portion of the tube is raised, and 

 any vapors that may be there are forced through the tubes around the 

 central jet. These vapors meet the flame of the jet already lighted, 

 they become ignited, and by so doing ignite the central wick. 



It will be seen that as soon as the oil-level is raised, it is not easy to 

 repeat the experiment ; hence the apparatus is only intended to deter- 

 mine at what temperature an oil does not give off vapors, and not to 

 determine its flashing point. One important difficulty in this apparatus' 

 is the fact that the central wick will not ignite with certainty every 

 time that an oil is giving ofif inflammable vapors. For I have repeat- 

 edly failed to ignite the central wick in an experiment, and on remov- 

 ing the cap have immediately obtained a flash with the oil in the cup. 

 When the central wick ignites, this apparatus gives results that are 

 generally h'gher than with open testers, which may be due to the fact 

 that the vapors must have a certain density before their ignition will 

 inflame the central jet. 



One of the best of the recently devised forms of " closed testers " is 

 that used in the State of Wisconsin. Its construction is very simple, 

 but it embodies some features that make it stand before those I have 

 already mentioned. It consists of a copper water-balh, a copper oil 

 vessel, and a cover with two holes in it, through one of which passes a 

 thermometer. 



The oil-cup holds a good quantity of oil, and there is considerable 

 space above the oil-surface for the accumulation of the vapors. Its use 

 is very simple, and consists in heating the oil slowly by means of the 

 water, the flash being obtained by introducing a small flame into the 

 second hole of the cover. The apparatus is not costly ; it is easily used 

 and cleaned, and the results obtained are quite near the truth. 



Some years ago Mr. Mann conceived the idea that the best way to 

 test oil is under the same conditions that obtain in using it. For this 

 purpose he devised a metallic lamp, about the same size as an ordinary 

 kerosene one ; he replaced the usual wick-hokier by a tube, which 

 cculd be loosely closed with a plug. The side of the lamp contained a 

 valve opening inwards, through which a flame could be introduced to 

 ignite the vapors. The thermometer was placed in a c'osed tube fitted 

 into the side cf the lamp. This lamp was placed in a water-bath that 

 fitted it, and the whole heated slowly. A small flame (a gas-jet) was 



