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BACKGROUND
Fiber is composed of plants which resist human digestive enzymes, a definition that includes lignin and polysaccharides, are of two types water soluble and insoluble. Fibers are natural and synthetic. Natural fibers are collected from plant sources.
Aim of this experiment is to determine length and width of fibers.
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REQUIREMENTS
Microscope with mechanical stage
Eyepiece and stage micrometer
Glycerin water
Phloroglucinol
Concentrated hydrochloric acid
Chloral hydrate solution
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PROCEDURE
Calibration of eyepiece micrometer with the help of stage micrometer
- Stage micrometer
- Take the micrometer slide in hand and feel the sides of the slide.
- The correct sides shows a slight elevation on one side.
- Place it on the stage of the microscope. View the scale through the eyepiece at 10 x 10 magnification to find the position of the scale on the micrometer.
- To locate the scale, start viewing from the edge of the cover glass containing the engraved micrometer scale and then move to the centre and locate the scale on the equatorial plane.1
- Eyepiece micrometer
- Remove the eyepiece and unscrew the part A
- Place the eyepiece micrometer at level B of the eye piece where there is a hinge or diaphragm (it is the support on which the eyepiece micrometer rests).
- Screw part A back and see whether the numbering on the eyepiece micrometer is in correct position, i,e zero to hundred. If numbers are reverse, remove the scale and place it in a correct manner.
- The eye-piece can be rotated to make adjustments.
- Do not introduce the eyepiece micrometer into the draw tube.
- Calibration of eyepiece micrometer
- View through the eyepiece with the required optical combinations.
- Adjust the scales of the two micrometers such that both the scales are superimposed. Rotate the eyepiece to place the scales in a parallel position or remove the stage micrometer till the lines coincide with eyepiece scale.
- Move the stage micrometer such that the “0” readings of both the micrometer scales coincide or one of the larger division of the stage micrometer coincides with one of the lines of the eyepiece micrometer scale. Note the initial readings.
- Carefully scan the scales to see, which of the two scale readings exactly coincide on the right side. Note the final readings and calculate the factor for 1 division of the eyepiece micrometer.
Now the microscope is ready for taking measurements.
Using stage micrometer calibrate the eyepiece micrometer. Calculate the factor (average distance between two lines in microns). Take a little quantity of powder drug (Ceylon cinnamon, Cassia bark or Cinchona bark) in a test tube and boil with clearing agent, chloral hydrate solution. Transfer the cleared powder in a watch glass. Stain the lignified fibers with the staining reagent (phloroglucinol and concentrated hydrochloric acid). Mount this treated powder in glycerin water and observe the slide under low power. (Power should be thinly, uniformly scattered, without overlapping of particles). Focus a stained fiber (intact fiber). By rotating the scale of eyepiece micrometer, note the numbers of divisions of the eye piece micrometer covered by the length of the fiber. Again rotate the eyepiece micrometer without disturbing the slide and find the numbers of division of the eyepiece micrometer covered by the width of the same fiber. Similarly calculate the length and width of about 25 fibers, and write the readings in two separate columns.
Multiply each value by the factor calculated in the first step to get the value in microns. Then calculate the average value and write the range for the length and the width fiber.
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CONCLUSION
Length and width of the fibre is ___________
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REFERENCES
- Khandelwal KR. Practical Pharmacognosy: Techniques and experiments, 9th edition, Nirali Prakashan. Pune; 2002: 159.
