MICROSCOPIC ACCESSORIES. 



45 



lines, enables the chemist to identify different substances. 

 The object of the microspectroscope is different. It en- 

 ables us to distinguish substances by the absence of cer- 

 tain rays in the spectrum, or, in other words, to judge, of 

 substances by a scientific examination of their color. The 

 color of a body seen with the naked eye is the general 

 impression made by the transmitted light, and this may 

 be the same although the compound rays may differ 



Fl i. 25. 



The Sorby-Browning Microspectroscope. 



greatly, so that colors which seem absolutely alike may 

 be distinguished by their spectra. Many solutions are 

 seen to absorb different colors in very definite parts of the 

 spectrum, forming absorption bands or lines, varying in 

 width and intensity according to the strength of the so- 

 lution. The instrument usually employed consists of a 

 direct-vision spectrum apparatus attached to the eye piece 

 of the microscope, which shows the principal Fraunhofer 



