i MILK 41 



objective a scale, divided from 100, is placed. The box con- 

 taining the prisms is hollow and divided in half, and is affixed 

 to the lower end of the telescope tube. It contains two right- 

 angled prisms, the hypotenuse faces of which are placed parallel 

 to one another with only a small space between them. One 

 half of the box (A), which contains one prism, is immovably 

 fixed to the tube, but the other half (B), in which the second 



FIG. 13. Wollny-Zeiss Milk Fat Refractometer. 



prism is placed, can be moved on the hinge ((7) and opened by 

 means of the fastening (F). The two parts of the prism box 

 are hollow, so that a stream of water can be passed round the 

 prisms by means of the short piece of rubber tubing which 

 connects them. On the foot of the stand there is fastened a 

 plain mirror (J) which sends light through the prisms. The 

 apparatus is also provided with a specially constructed thermo- 

 meter, which is placed in part (A) of the prism box, for the 



