cross 31 so that the cell 30 is of the flow through type a stainless steel tube 36 is shown mounted in the tubing connector 35 by the use of a ferrule 37 and a nut 38 similarly a connector 39 is shown threadably attached to the cross 31 a stainless steel tube 40 is shown mounted in the connector 39 by means of a ferrule 41 and a nut 42 a sapphire window 43 is shown brazed to the tube 36 by brazing compound 44 similarly a sapphire window 45 is shown brazed to the tube 40 by brazing compound 46 the tube assemblies represented by the reference numerals 36 43 44 and 40 45 46 obtained by special order from the eimac division of varian associates supra can be adjusted as to the gap between the window 45 and the window 43 so that the path length of the cell 30 can be adjusted as desired as shown in fig2 the sapphire windows 43 and 45 are brazed into steps in the tubes 36 and 40 so that the windows are more resistant to high pressure in the chamber 32 it should be understood that in the present invention the tubes 36 and 40 are considered to be a portion of the cell 30 and fusion sealing a window to them is considered to be the same as fusion sealing a window directly to a cell body the cell 30 is designed to be placed between a light source 45a and a detector 43a of a photometric analysis system so that a process stream which is directed through the pipe 33 into the chamber 32 between the windows 45 and 43 can be photometrically analyzed it should be understood that optical fibers or any other suitable.