290 Journal of Applied Microscopy. 



Sample No. 590, a very extreme case, yielded only 20 per cent, of wool 

 fiber. The index of strength and elasticity may vary from normal to practically 

 nothing. 



It is intended in this series of articles to describe the Museum's work in the 

 practical examination and investigation of fibers, this first paper being restricted 

 to some hints regarding the application of the microscope to commercial fiber 

 investigation. 



The study of the minute structural features of any material must, of necessity, 

 be attended with considerable difficulty, and, in this respect, the examination of 

 wool fibers offers no exception to the rule. 



There are but few existing rules, laws, methods, and processes to serve as 

 o-uides in the work. In a few isolated cases some facts have been recorded 

 concerning tests made in Germany, England, France, and Russia, but these 

 facts have not been definitely correlated, and only stray references have been 

 made to the methods and instruments of research. The Technological labora- 

 tories of the Philadelphia Commercial Museum were established for the purpose 

 of furnishing impartial and reliable tests, not only of wool, but of all other kinds 

 of fibers, whether of animal or vegetable origin. 



Work of this kind, especially when made the basis of a guarantee of absolute 

 reliability, has been accompanied by serious difficulties, the most prominent of 

 which has been the absence of precedents in this country, and the consequent 

 lack of reliable testing instruments and approved methods of conducting an 

 investigation intended to supply manufacturers and others with accurate data 

 relating to the essential and actual value of wool and other fibers and textile 

 materials. 



It was, in fact, necessary to devise special machinery and apparatus for the 

 testing, treating, and measuring of the fibers; and instruments designed for 

 the one class of fibers will not do for all, since each kind requires a different 

 method of investigation. 



The most valuable instrument in studying the special forms and structures 

 of fibers is the microscope, with its various attachments for obtaining exact 

 views and accurate measurements. The fibers of wool, when seen through a 

 microscope, are seemingly so uniform and transparent that, in order to become 

 familiar with the characteristics and variations of the diverse types and breeds, 

 it is advisable to use a microscope of high power and clear definition. Optical 

 conditions being favorable, some wools, hairs, and furs will show numerous 

 irregular lines crossing the fiber. The edges of the fiber may appear perfectly 

 regular, or they may be more or less serrated, the number and size of the teeth 

 varying according to the breeds from which the samples are selected. This 

 slight variation, and the nearly amorphous and transparent appearance of the 

 wool render it necessary to make repeated tests upon each class of wool, until 

 the observer becomes fitted by experience to identify the various breeds, 

 qualities, and stages of manufacture. 



The color, resulting from pigment contained in the center of the fiber of 

 certain breeds, furnishes a fairly reliable test, when the observer has learned by 

 experience and practice to distinguish the slight, yet distinct, differences in the 



