580,705. Turbidometers. MAY, K. R., and WELCHMAN, R. M. A. July 18, 1944, No. 13763. [Class 97 (iii)] A fluid carrying suspended particles is passed in succession through a series of jet orifices, each orifice being smaller than the preceding one, and a sampling plate is placed in the path of each jet. As shown in Fig. 2, the largest jet 12 is mounted in the wall of a tube 1 which is closed at one end by a removable cap 11 and carries at the other end the tapered jet tube 13. The latter is soldered into and supports the wall of the second tube 2, which has its axis normal to that of the first tube 1. The third tube 3 is similarly supported by a jet 14 carried by the tube 2 and the fourth tube 4 is supported by a jet 15 carried by the tube 3. A pipe 17 connects the last tube 4 to a suction device. The sampling plates 5, 6, 7, 8 are detachably mounted in the tubes 1, 2, 3, 4 by abutments 9 and leaf springs 10 so as to lie normal to the jets and contain the axes of the tubes. The size of jets and the distance between jet orifice and sampling plate diminishes progressively from tube 1 to tube 4, so that the plates 5, 6, 7, 8 have deposited on them particles of progressively smaller size. In the modification shown in Fig. 3, a series of jets 34, 36, 39 are removably mounted in a block 20 so that their orifices lie near a single sampling plate 32.