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(2) Apparatus and material. The following apparatus and materials are needed and shall comply with the following provisions:

(i) Microprojector. The microprojector shall be capable of giving a precise magnification of at least 500x. This magnification can be accomplished satisfactorily with a vertically installed microscope equipped with a 1015× eyepiece, a 20-21× objective with an aperture of approximately 0.50 centimeter, a fixed body tube, a focusable stage responsive to a coarse and fine adjustment, a focusable substage with condenser and iris diaphragm, and a light source that will give a welldefined fiber image. The microscope must be installed so that the projection distance can be adjusted to produce the required 500× magnification.

(ii) Stage micrometer. Calibrated glass slide used for accurate setting and control of the magnification.

(iii) Cross-sectioning device, heavy duty. An instrument approximately 2 inches (5 cm.) in height; consisting essentially of a metal plate with slot for holding a quantity of fibers, a key for compressing the fibers, and a tonguepropelling arrangement by which the fiber bundle may be extruded for sectioning.

(iv) Microscope slides. 1" by 3" (25×75 mm.).

(v) Cover glasses. No. 1 thickness, %" by 2′′ (22×50 mm.).

(vi) Mounting medium. Colorless mineral oil with a refractive index between 1.53 and 1.43 and of suitable viscosity.

(vii) Wedge scales. Strips of heavy paper or Bristol board imprinted with a wedge for use at a magnification of 500×. The wedge is usually divided into 2.5 micron intervals (cells).

(3) Calibration. The microscope shall be adjusted to give a magnification of 500x in the plane of the projected image. This may be accomplished by placing a stage micrometer on the stage of the microprojector and bringing the microscope into such adjustment that an interval of 0.20 mm. on the stage micrometer will measure 100 mm. when sharply focused in the center of the image plane.

(4) Sampling. The lot shall be sampled by drawing from each 20,000

pounds (9,072 kilograms), or fraction thereof, four sections of sliver (test specimens) each of which shall be at least 1 yard (0.91 meter) in length and taken from different balls of mohair top, selected at random. Only one ball shall be taken from any one bale or carton. For broken mohair top (top not wound into balls), an equivalent length of sliver shall be taken at random. Only one test specimen shall be taken from any one can or package. The four test specimens shall constitute a sample.

(5) Test condition. Test specimens shall be preconditioned to approximate moisture equilibrium in an atmosphere of from 5 to 25 percent relative humidity at a temperature less than 122° F. (50° C.). Then the test specimens shall be conditioned for at least 4 hours in the standard atmosphere for testing, namely, 63 to 67 percent relative humidity at a temperature of 68° to 72° F. (19.9° to 22.1° C.).

(6) Preparation of slides—(i) Filling cross-section device. Each sliver (test specimen) of mohair top making up the sample shall be placed individually in the slot of the cross-sectioning device, positioning each sliver so that it will be cut at its approximate midlength. The sliver shall be compacted firmly with the compression key and the latter secured with the set screw.

(ii) Preliminary section. The gripped fibers shall be cut off at the upper and lower surfaces of the plate. The fiber bundle shall be extruded approximately 0.50 mm. in order to take up slack in the fibers and the propulsion mechanism. The projecting fibers shall be moistened with a few drops of mineral oil. This projecting fiber bundle shall be cut off with a razor blade flush with the upper surface of the fiber holder plate and the section discarded.

(iii) Final section. The fiber bundle shall again be extruded, approximately 0.25 mm., i.e., 250 microns. The fiber bundle shall be moistened with a few drops of mineral oil and the excess blotted off. The projecting fibers shall be cut off with a sharp razor blade flush with the holder plate, leaving the fiber pieces adhering to the razor blade.

(iv) Mounting the fibers. A few drops of mineral oil shall be placed on a

clean glass slide. With a dissecting needle the fiber pieces shall be scraped from the razor blade onto the slide. The fibers shall be thoroughly dispersed in the oil with the dissecting needle and the slide completed with a cover glass. Sufficient oil should be used in the preparation of the slide to insure thorough distribution of the fibers, but an excess must be avoided, as practically no oil should be permitted to flow out or be squeezed out beyond the borders of the cover glass. If the number of fibers is too great to permit proper distribution on the slide, or if an excess of oil has been used, a portion of the mixture, after thorough dispersion of the fibers, may be wiped away with a piece of tissue or cloth. Slides shall be measured the day they are prepared.

(7) Measurement of fibers. The slide shall be placed on the stage of the microprojector, cover glass toward the objective. Fiber diameter measurements shall be made at the approximate mid-length of the fibers. Fiber edges appear as fine lines without borders when they are uniformly in focus. It is unusual, however, for both edges of the fiber to be in focus at the same time. If both edges of the fiber are not uniformly in focus, adjustment shall be made so that one edge of the fiber is in focus and the other shows as a bright line. To record the measurement, it is necessary to mark the point where the wedge corresponds with the fiber image as determined by (i) the fine lines of both edges when they are uniformly in focus, or (ii) the fine line of one edge and the inner side of the bright line at the other edge when they are not uniformly in focus. The slide shall be traversed in planned courses so that fibers on all portions of the slide will be measured. Successive fibers should be measured whose mid-points come within the field (a circle 4 inches in diameter, centrally located in the projected area). Fibers shorter than 200 microns or longer than 300 microns and those having distorted images shall be excluded from measurement. The marks on the wedge scale indicating the diameter of fibers measured are counted and combined into cells for calculation as indicated in para

graph (a)(10) of this section. Occasionally a fiber diameter will be less or greater than the extreme limits of the wedge scale. When this occurs, the image of the fiber is projected onto the border of the wedge scale and lines are drawn on the scale at the edges of the fiber image. The distance between the lines is later measured with a metric ruler to obtain the diameter of the fiber. When measuring fiber diameters in this manner, 1 mm. is equal to 2 microns.

(8) Nature of test. One test shall consist of the measurement by two operators of the same four slivers (test specimens) of mohair top. The measurement of both operators shall be combined for calculation of average fiber diameter and fiber diameter dispersion.

(9) Number of slides and fibers. Each operator shall make a slide from each test specimen, making a total of four slides per operator. The number of fibers to be measured per slide shall be determined by dividing the approximate number of fibers to be measured per test by 8 (the total number of slides prepared per test). The minimum number of fiber measurements required for each test shall be the number needed to attain confidence limits of the mean within ±0.40 micron at a probability of 95 percent. Each operator shall measure approximately one-half the required number of fibers. The approximate number of fiber measurements needed for each of the grades-as listed in § 32.100, table 1-may serve as a guide. However, the minimum number of fibers to be measured to attain the prescribed confidence limits can be calculated by using the equation shown below: n=(1.960/0.40) 2

In this equation:

n=Number of fibers to be measured, and σ= =Standard deviation of fiber diameters.

(10) Calculation and report. The measurement of both operators shall be combined and the following calculations made by using the applicable formulae shown below:

(i) The average diameter of fibers (X): X=A+ME,

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EXAMPLE OF CALCULATIONS: AVERAGE FIBER DIAMETER, STANDARD DEVIATION, AND CONFIDENCE

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§ 32.400 Standard samples of grease mohair grades; method of obtaining. Samples certified as representative of the official standards of the United States for grades of grease mohair will be furnished as follows, subject to other conditions of this section, upon filing of an approved application and prepayment of the costs thereof as fixed in § 32.401. The certification will be issued by the U.S. Department of Agriculture and will be signed by the Director of the Livestock Division or other official duly authorized by him.

(a) Samples representative of each of the standard grades of grease mohair:

(1) Complete set. Ten certified samples of grease mohair, grades 40s through 18s.

(2) Individual sample. Individual certified samples of grease mohair.

NOTE: A certified sample consists of grease mohair randomly selected from a bulk sample. The measured average and standard deviation of fiber diameter of the bulk sample were within the limits corresponding to the grade of the standard sample as set forth in § 32.1.

(b) Each application for standard samples of grease mohair shall be upon an application form furnished or approved by the Consumer and Marketing Service, shall be signed by the applicant, and shall be accompanied by certified check, draft, post office money order, or express money order, payable to the "Agricultural Marketing Service," in an amount to cover the cost of the samples requested, and shall incorporate the following agreement.

(1) That no samples representative of the official grease mohair standards shall be considered or used as repre

senting such standards after cancellation in accordance with this section.

(2) That the said standard samples shall be subject to inspection by the Secretary or by any duly authorized officer or agent of the Department of Agriculture during usual business hours of the person having custody of the samples.

(3) That the certificate covering any of the samples representative of the standards may be revoked and canceled by the Director of the Livestock Division, if it is found upon such inspection that the said samples are not representative of the official stand

ards.

§ 32.401 Cost of standard samples for grease mohair grades.

(a) Complete set. $22 each, delivered to any destination within the United States and $25 each, delivered to any destination outside the United States.

(b) Individual sample. $2.50 each, delivered to any destination within the United States, and $3 each, delivered to any destination outside the United States.

§ 32.402 Standard samples of mohair top grades; method of obtaining.

Samples certified as representative of the official standards of the United States for grades of mohair top will be furnished when available as follows, subject to other conditions of this section, upon filing of an approved application and prepayment of the cost thereof as fixed in § 32.403. The certification will be issued by the U.S. Department of Agriculture and will be signed by the Director of the Livestock Division or other official duly authorized by him.

(a) Samples representative of the official grades of mohair top: (1) Complete set. Nine certified samples of mohair top, grades 40s through 20s.

(2) Individual sample. Individual certified samples of mohair top, grades 40s through 20s.

(b) Each application for standard samples of mohair top shall be upon an application form furnished or approved by the Agricultural Marketing Service, shall be signed by the applicant, and shall be accompanied by cer

tified check, draft, postal money order, or express money order, payable

to the " 'Agricultural Marketing Serv

ice," in an amount to cover the cost of the samples requested and shall incorporate the following agreement:

(1) That no samples representative of the official mohair top standards shall be considered or used as representing such standards after cancellation in accordance with this section.

(2) That the said standard samples shall be subject to inspection by the Secretary or by any duly authorized officer or agent of he Department of Agriculture during usual business hours of the person having custody of the samples.

(3) That the certificate covering any of the samples representative of the standards may be revoked and cancelled by the Director of the Livestock Division, if it is found upon such inspection that the said samples are not representative of the official stand

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"Act" and "Export Apple and Pear Act" are synonymous and mean “An act to promote the foreign trade of the United States in apples and/or pears, to protect the reputation of Americangrown apples and pears in foreign markets, to prevent deception or misrepresentation as to the quality of such products moving in foreign commerce, to provide for the commercial inspection of such products entering such commerce, and for other purposes," approved June 10, 1933 (48 Stat. 123; 7 U.S.C. 581 et seq.).

§ 33.2 Person.

"Person" means an individual, partnership, association, corporation, or any other business unit.

§ 33.3 Secretary.

"Secretary" means the Secretary of Agriculture of the United States or any officer or employee of the United States Department of Agriculture to whom authority has heretofore been delegated or to whom authority may hereafter be delegated to act in his stead.

§ 33.4 Carrier.

"Carrier" means any common or private carrier, including, but not being limited to, trucks, railroads, airplanes, vessels, tramp or chartered steamers

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