PROCEEDINGS OF SECTION B. 339 



irom leaving the water out of the air chamber. As this reduces the 

 labor in making successive tests, the water was omitted from the air 

 •chamber in subsequent tests, for although the actual duration of the 

 test when water is used, as in table A, is less than that shown in table 

 B, the saving in time is more than compensated for by the fact that 

 the temperature rises too rapidly, and greater care is required in testing 

 to prevent the results obtained being too high. 



In tables C and D a modification is introduced to avoid the neces- 

 sity of waiting for the water bath to cool down, or of emptying it and 

 refilling with cold water. This modification follows the principle of 

 the prescribed test for oil of 73° flash-point, in that the temperature of 

 the water bath at the time the oil cup is inserted is arranged so as to 

 give a result without having the burner going during the test. In 

 table C the temperature chosen is 180°, and in table D it is 160°, and 

 the tables show that this variation does not materially affect the flash- 

 points, and further they show that the results are comparable with 

 those obtained in following the British method (of tables A and B), 

 where the bath is heated throughout the test, starting all cold. It 

 follows, therefore, that the test may be begun with the water bath at 

 any temperature between 160° and 180° when testing this kerosine. 

 As time is saved by heating the bath to 160° F. only, this temperature 

 was adopted in the succeeding tests. 



Throughout these tests (tables A, B, C, and D) it will be seen that 

 the flash-points obtained are not too satisfactory, for although the 

 averages 106°4, 105°-6, 105°-3, and 106°-1 are concordant, the individual 

 tests range from 104° to 109°, and this in spite of the greatest care taken 

 by experienced operators. 



It occurred to us, therefore, that the fault was in the Pensky slide, 

 and an investigation of three of these attachments disclosed the facts 

 that they did not agree amongst themselves, and that they all differed 

 materially from the ordinary hand slide with respect to the times of 

 opening and closing the port holes in the oil cup cover. 



The Abel apparatus described by the British Petroleum Act, 1879, 

 defines the nature of the slide to be used, and the instructions state 

 that the slide is to be slowly and regularly opened during three swings 

 of a pendulum of 24in, in length and quickly closed at the fourth smng. 

 The whole opening and closing occupies, therefore, a total of 3-1416 

 seconds of time. Now, the Pensky clockwork attachment, which is 

 prescribed in Germany, occupies only two seconds, and the variation 

 of time allowed for the slide movement is 0-2 second over or under the 

 prescribed standard. 



Three of these Pensky slides, which are supposed to be standard 

 attachments, were timed and found to take 2-4, 2-4, and 2-6 seconds 

 respectively, thus agreeing neither with the German prescription nor 

 with the Australian one, which requires them to be adjusted " so as 

 to give the same results as the Abel standard." 



That this difference in time is material is shown by a comparison 

 of rabies D and E, from which it will be seen that while the Pensky 



