466 



KEROSENE, TEST FOR. 



KNIT CLOTHS. 



cock e. The best results by this method are 

 obtained when the diameter of the cylinder is 

 between 2-J- and 4 centimetres. The length is 

 of no consequence, provided the cylinder is al- 

 ways filled with oil to within the same distance 

 of the top ; but different results are given when 

 the distance of the oil, or rather of the foam 

 into which its surface is broken by the air- 

 current, is allowed to vary. Prof. John T. 

 Stoddard, of Smith College, makes in " The 

 Popular Science Monthly " the following state- 

 ments and directions concerning the use of this 

 method : 1. The oil-cylinder should have a di- 

 ameter of from 2 to 4 centimetres.* It may 

 be of any convenient length, provided it holds, 

 when filled for the tests, not less than 50 c. c. 

 of oil. "With a diameter of 2 centimetres, the 

 length should be at least 16 centimetres; with 

 a diameter of 3 centimetres, the least length 

 should be 13 centimetres. A good tester may 

 be made from the chimney of a student-lamp 

 by cutting off the lower part a little above the 

 contraction; or the whole chimney may be 

 made to serve as an oil-cylinder by corking 

 the large end. 2. The cylinder is filled with 

 oil to a point where, when the air-current is 

 running, the top of the foam is 4 or 6 centi- 

 metres below the mouth. 3. The oil is heat- 

 ed by means of a water-bath, into which the 

 cylinder is plunged to the end of the oil. The 

 temperature of the oil should not rise faster 

 than two degrees a minute. 4. Air is forced 

 through the oil with such velocity that about 

 (and not less than) one centimetre of foam is 

 maintained on the surface, and a flash- jet is 

 brought to the mouth of the cylinder at every 

 half degree, or oftener, in the vicinity of the 

 flashing-point. The approach of the flashing- 

 point is announced by the appearance of a faint 

 blue halo of burning vapor around the flash- 

 jet ; this finally detaches itself and runs down 

 to the surface of the oil. The reading of the 

 temperature at this instant gives a trial flash- 

 ing-point, which may be a little too high if the 

 current of air has been running too long, or 

 not long enough. The test should now be re- 

 peated with a fresh sample of oil, the air-cur- 

 rent being started in full strength, not less 



than one nor more than three or four minutes 

 before the flash occurs. It is well, however, 

 to let a very slow current of air bubble through 

 the oil from the time that the tester is put in 

 the water-bath, so as to secure regularity in 

 the heating of the oil. This method has the 

 advantages of simplicity in apparatus and ma- 

 nipulation, and of securing a trustworthy de- 

 termination of the lowest flashing-point, inde- 

 pendently of arbitrary conditions. We have 

 seen that 116 Fahr. is the very lowest flash- 

 ing-point consistent with safety. The state- 

 ments so often put forth, that our best kero- 

 senes are " 150 or 160 test" oils, are mislead- 

 ing; for it has reference, not to the flashing- 

 point, but to the fire-test, or burning-point, 

 which, as has been shown, gives little indica- 

 tion of- the character of the oil. The best 

 oils sold flash at about 109 Fahr., while the 

 cheaper grades have much lower flashing-points 

 at least as low as 85 Fahr. 



KNIT CLOTHS. The idea of knitting other fab- 

 rics than hosiery is not new, but the application 

 of the process to the production of certain kinds 

 of cloth has been, by improved machinery, 

 brought apparently to perfection very recently. 



Fig. 1 (see page 467) gives a good idea of a 

 machine imported from England in 1883, and 

 set up in Philadelphia by John E. Hanifen & 

 Co. Portions of it were patented in England 

 by Joseph Belshaw, as long ago as 185V ; and 

 virtually the same thing was produced by two 

 other English inventors, and by them assigned 



FIG. 2. 



to John Kent, who patented it in the United 



States in 1 872, but his patent has been contested. 



Fig. 2 shows (enlarged) a section of the 



