GENERAL MICROSCOPY 



For synthetic fibers, cellulose lacquer can 

 be used. In these cases it is advisable, after 

 the lacquer has dried, to apply a thin shadow 

 coating to the upper surface of the fibers. 

 This coating is especially necessary if the 

 fibers are matted. 



(3) The normal interference methods can 

 usually be employed for surface examination 

 of fibers. 



(4) A very good method for fibers is the 

 electron scanning method. On the whole the 

 images are much better than those obtained 

 with the reflection electron microscope (q.v.) 

 The foreshortening of the image is not a 

 serious drawback. This method can be par- 

 ticularly important for examining keratin 

 fibers and paper suspensions. 



Staining Methods and Chemical Reactions. 



Of the numerous staining methods and chemical 

 reactions used in textile and paper microscopy, 

 only the most important will be mentioned. A 

 complete list of all the customary reactions can be 

 found in the references. 



Cuoxam (copper oxide ammonia) reagent for 

 cellulose. Ammonia is added to an aqueous solu- 

 tion of copper sulfate. The precipitate is washed 

 and dried and put in as little concentrated am- 

 monia as possible. 



Herzberg's Solution (zinc chloroiodide) (A) 20 g 

 dry zinc chloride in 10 g water; (B) 2.1 g KI and 

 0.1 g iodine in 5 cc water. Solutions A and B are 

 mixed together. Allow precipitate to settle, de- 

 cant and keep in the dark, a crystal of iodine be- 

 ing added. 



I ado --potassium iodide (KI3). 0.6 g KI and 1 g 

 iodine dissolved in 100 cc water. 



Phloroglucine-acid. An approx. 5% solution of 

 phloroglucinol in absolute alcohol. Always used 

 with concentrated HCl. Reagent for lignified cell 

 walls. 



Millon's reagent. 1 part mercxu-y is dissolved, 

 with application of heat, in 2 parts HNO3 (cone). 

 Next 2 parts of water are added. Reagent for 

 proteins. 



Ruthenium Red. 0.1 g ammoniacal oxychloride 

 of ruthenium is dissolved in water (10 cc). After 

 staining, the fibers are mounted in glycerol. Gen- 

 eral reagent for best fibers. 



Victoria Blue B. Reagent for distinguishing raw 

 and bleached cotton. 3% Victoria Blue in 10 cc 

 water. The fibers are boiled in this solution. Wash 

 in cold water until no more stain comes off. 



Colotex B. Stain made by Union Chemical Com- 

 pany, New York; similar to Neocarmine W. The 

 fibers are stained for 3-5 minutes in the solution, 

 washed in water and then washed again in water 

 containing several drops of ammonia, washed 

 once again in distilled water and then dried. 



Shirlastain A (I.C.I.). The fibers are eluated for 

 1 minute at room temperature, stained in the solu- 

 tion, washed in distilled water and examined un- 

 der the microscope. 



lodo-sulfuric acid. 3 g KI is dissolved in 60 cc 

 water, while 1 g iodine is added. 10 parts of water 

 are added. The sulfuric acid solution is prepared 

 by adding together 3 parts glycerin, 1 part water 

 and 1 part concentrated sulfuric acid. After the 

 fibers are stained in the iodine solution they are 

 mounted in the sulfuric acid. 



Allworden's reaction. Reagent for damage to 

 wool (see Fig. lb). The wool fibers are treated with 

 saturated chlorine or bromine solution. Depend- 

 ing upon the thickness of the fiber, the tempera- 

 ture, and the acid or lye damage, a number of 

 small blisters occur on the fiber. The time needed 

 for bringing about the blisters indicates the state 

 of damage. In the case of wool damaged by acid 

 the blisters occur earlier than normal, while in the 

 case of lye-damage the reaction takes longer than 

 normal. The normal reaction times at 17° C are: 



for fine wool 



for wool 



for coarse wool 



20-25 M diam. 

 25-30 M " 

 >.30m " 



30 sec 



70-80 sec 



120 sec 



The reaction time must always be compared 

 with a control to eliminate influences of tempera- 

 ture, reagent and fiber diameter. 



K.M.V. reagent. (Fig. 1.) 20 g KOH is dissolved 

 in 50 cc liquid ammonia; after about 1 hour the 

 liquid is decanted and stored in a stoppered flask. 

 The reagent keeps for 6 to 8 weeks. 



Pieces of wool not longer than 3 mm are treated 

 with the reagent. The moment the reagent begins 

 to act a stopwatch is pressed. The reaction time 

 is the time elapsing before the first blisters ap- 

 pear on the fiber. This depends upon: 



(a) the thickness of the fibers (thinner fibers 

 have a short reaction time). 



(b) temperature (higher temperature — shorter 

 reaction time). 



(c) state of damage (acid-damage shortens re- 

 action time; lye-damage lengthens it). 



(d) age of reagent (the reaction time is in- 

 creased through loss of NH3). 



(e) chroming of wool (chromed wool reacts 

 more slowly than unchromed). 



Factors (a), (b) and (d) can be eliminated by 

 using a control of the same thickness. 



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