In The Horizontal Developing Chambers, Hptlc Plates Can Be Developed From Both Opposing Sides Towards The Middle. This Permits The Number Of Samples To Be Doubled As Compared With Development In A Tank, Provided The Separation Distance Of 45 Mm, I.E. 50 Mm Minus 5 Mm Distance From The Edge, Is Sufficient. This Chamber Type Is Often Used For Screening Purposes. The Obtained Chromatograms Differ From Those Obtained With The Same Mobile Phase System Developed In Vertical Chambers. This Chamber Is Suitable For Plates Up To 20 X 10 Cm In Size.