470 Scientific Intelligence. 



person can read with at lea.-^t fair accuracy and with great rapidity 

 as follows : 



Adjust a Schiebler sacharometer to zero, and insert before the 

 eye-piece a pocket spectroscope, with the slit horizontal or at 

 right angles to the line Insect ing the chromatic field. 



Looking then in the spectroscope and focussing both the eye- 

 piece of the sacharometer and that of the spectroscope, two verti- 

 cally dispersed parallel spectra will he seen separated by a well- 



,-hite-light spectra except that 

 aosorption nand will j 

 orhood oftheDl 



deep black absorption band will appear 



