Drying, use of absorbent cotton

Drying, use of absorbent cotton, 20,8, 9 Dumb-bell vacuum desiccator, 23, 105... 

Absorbent cotton (cotton wool). This material is an excellent drying agent for use in the so-called calcium chloride tubes, i.e., drying tubes, placed at the top of dropping funnels, reflux condensers, etc., to exclude moisture. It is more convenient than calcium chloride, and should preferably be dried in an oven at 100° before use. 

One of the most stringent and most widely accepted test is UL 94 that concerns electrical devices. This test, which involves burning a specimen, is the one used for most flame-retardant plastics. In this test the best rating is UL 94 V-0, which identifies a flame with a duration of 0 to 5 s, an afterglow of 0 to 25 s, and the presence of no flaming drips to ignite a sample of dry, absorbent cotton located below the specimen. Tlie ratings go from V-0, V-l, V-2, and V-5 to HB, based on specific specimen thicknesses. 

Wet wipe sampling is generally not recommended for carpet, upholstery and other fabric-covered or soft surfaces because the solvent may be absorbed into the surface being sampled. Wipes of soft surfaces also are less likely than wipes of hard surfaces to reflect the dermal exposure potential (Ness, 1994). However, Lu and Fenske (1999) recently reported the use of cotton gauze wetted by misting with distilled water to wipe carpets freshly treated with a chlorpyrifos formulation (Dursban L.O.) and found it to be 23 to 24 times more efficient than transfer to dry palm presses. 

---