Absorbent cotton

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. 

In the filtration of small amounts of fine particles from liquid by means of bulky filter media (such as absorbent cotton or felt) it has been found that the preceding equations based upon the resistance of a cake of solids do not hold, since no cake is formed. For these cases, in which filtration takes place on the surface or within the interstices of a medium, analogous equations have been developed [Hermans and Bredee, J. Soc. Chem. Ind., 55T, 1 (1936)]. These are usefully summarized, for both constant-pressure and constant-rate conditions, by Grace [Am. In.st. Chem. Eng. J., 2, 323 (1956)]. These equations often apply to the clarification of such materials as sugar solutions, viscose and other spinning solutions, and film-casting dopes. 

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. 

May be sterile fer use in ceriain circumstances Absorbent cotton wool Swabbing, cleaning. Any method... 

Absorbent cotton gauze Absorbent wound dressing Any method... 

Transfer the sample extract (from Section 6.1) into a 300-mL separatory funnel, add 50 mL of water and extract the sample with 50 mL of n-hexane three times. Separate and dry the n-hexane layer with anhydrous sodium sulfate (plug the funnel with absorbent cotton and 50 g of anhydrous sodium sulfate), and collect the dried extract in a 300-mL of separatory funnel. Add 50 mL of acetonitrile to the separatory funnel and mix well for partitioning with the n-hexane extract three times. Collect the... 

This is very prone to spontaneous oxidative heating. A mixture with absorbent cotton attained a temperature of 230°C 4 min after exposure to air. 

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

DRESSING BURN 24X36 INCHES STERILE ABSORBENT COTTON GAUZE 15S 6510011532S57 PG 104,57 ... 

Absorbent cotton is an excellent drying agent and more convenient for drying tubes than anhydrous calcium chloride.2 It is possible to keep maleic anhydride in a flask closed only by a plug of absorbent cotton, for three weeks without appreciable change in the titration value (F. P. Pingert, private communication). 

Vitrellae are thin walled glass capsules containing volatile substance (drops) (e.g. amyl or octyl nitrite) and protected by absorbent cotton wool and an outer silk bag. This capsule is crushed and the vapours are inhaled in the treatment of angina. 

Purified cotton consists of the fibers of different cultivated varieties of Gossypium sp. The material is freed from adhering impurities, deprived of fatty matter, bleached, and sterilized. The length of cotton fibers is up to about 5 cm, the diameter varies between 9 to 25 pm. A typical cotton fiber is cylindrical when young, but becomes flattened and twisted as it matures. The genuine cellulose wall of the cotton fiber is covered with a waxy cuticule. Delipidation is essential in order to transform the genuine fiber to absorbent cotton wool which is readily wetted by water. 

Oxidized cellulose is very similar to normal cotton but with a defined texture and an acid taste. The material tends to disintegrate on handling. Under the microscope, the fibers are very similar to those of normal absorbent cotton. Oxidized cellulose is used as an absorbable haemostatic in many types of surgery. It is incompatible with penicilline and can not be heat-sterilized. 

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