MICROSCOPE IN MANUFACTURES 



former markings are natural to the fibres, the 

 latter are caused by one fibre being pressed against 

 the other. In countries where the production of 

 silk is of great importance, the microscope is not 

 only pressed into service for examining the product 

 of these useful little insects, but also in keeping 

 watch for a very deadly disease which attacks the 

 caterpillars. It is called " pebrine " and the great 

 scientist Pasteur, whose name is world famous for 

 his work on bacteriology, discovered that it was 

 caused by a tiny fungus. 



Artificial silk is an important article of commerce. 

 It is made in several different ways and of various 

 substances. Some artificial silk is made of col- 

 lodion, some again is made of cellulose the substance 

 of which the cell walls of young plants is com- 

 posed; gelatine is also used in making this com- 

 modity. As a rule it is easy to distinguish artificial 

 from real silk, for usually the imitation consists of 

 flat fibres or at least fibres quite different to the 

 smooth rods of real silk. The iodine test is often 

 sufficient indication, for with this chemical true 

 silk is coloured brown. 



Space or lack of it does not allow us to describe 

 how the microscope may be and is applied to other 

 manufactures, even the miller uses the instrument, 

 for it will tell him if his flour is of pure wheat, and 

 in this manner. He puts a little flour in a drop of 

 water on a slide and covers with a cover slip ; then, 

 for a moment or two, he rubs the cover glass to 

 and fro over the water and flour and examines his 



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