<'XXIir. 



FIG. 350. 



FIG. 351. 



FI8. 350. From Sutton's Handbook of Volumetric Analysis. The figure to the left shows the elliptical appear, 

 aiice presented by a line round a burette or by the surface of fluid in it, when the eye of the observer is above 

 it. The figure to the right shows the curved surface of fluid in a tube. In raiding off its level, the lower border 

 of the dark zone must coincide with the graduation of the burette as in the figure, where the dark line stretch- 

 ing across the tube indicates one of the graduated lines upon it. 



FIG. 351. Erdmanu's float. (From Button's Handbook of Volumetric Analysis.) 



j 



353- 



FIG. 352. Stand for burettes. (From Button's Handbook of Volumetric Analysis.) 



FIG. 353.--,sv/cvA,m/;;irf,'i-. and 6 are two Nicol's prisms, one of which, 6, is fixed, and the other, a, is movable- 

 !, is an indicator to show the position of it. s *, is a circular graduated disk for measuring the rotation of a. g, it a 

 juartz plate composed of two pieces, /i, is a single plate of quai t/. /and/;, are (lie scale and \crnierofthe compen- 

 sator, r, the screw by which the e. in] ensntor is adjusted, r and r', are the two quartz prisms of which the coui- 

 [H'U>ator consists, i, </, is the space for.contaiuiiig the tube of fluid for examination. 



