112 



The tube containing the fluid -- 200 mm (8 in.) in length -- slides in a 

 brass tube which carries a polarizer and double quartz plate at one end, the 

 other end being fitted with a circle divided in 1 / l degrees, over which an ana- 

 lyzer with vernier can be rotated. Observation is made by adjusting the so-called 

 transition colour in both halves of the quartz plate, the tube being directed by 

 hand upon a white surface. (See directions for using the instrument.) 



Also supplied in conjunction with a small telescope for the more exact 

 observation of the quartz plate. 



If a support be desired, we recommend for the purpose our simple Sacchari- 

 meter Stand provided with a joint, No. 206 a . 



Prices : Code-words : 



No. 205: Hand-Saccliarimeter, without telescope, in case . . Marks go. . Pereza. 

 206: with . . 108. . Perfecto. 



206 a : Saccharimeter Stand provided ivilh joint .... jo. . Perfldia. 



207: Glass Tubes separately, with stopper-plates, each , 7.50. Perfil. 



208: without 3. . Perforar. 



If desired, tubes of wo mm (4 in.) length may be obtained at the same 

 price as 200 mm tubes. 



Heating Apparatus, 



L. PPEIFFER'S Warm Chamber for heating microscopical objects during 

 observation, Fig. 65. (See L. PFEIFFER "Protozoen als Krankheitserreger &c.", 

 2^S edition, Jena, 1891.) 



The chamber consists of a mahogany box encasing the whole of the micros- 

 cope, with a window in the front to admit the necessary light. On either side 

 is a closely fitting door through which the specimen can be moved with the 

 fingers. The side walls may also be completely folded back, carrying with them 

 the halves of the back wall, which is divided down the centre. 



The whole (chamber and microscope stand) rests upon a thick metal plate 

 on three legs. The metal plate is heated from below by a micro-burner, con- 

 trolled by a thermo-regulator, No. 215, and should be adjusted so as to burn 

 with smokeless flame. 



By this means the whole stand and the air surrounding it are gradually 

 brought to the same temperature, so that after a reasonable lapse of time the 

 readings of the thermometer placed in the air space indicate the actual tempera- 

 ture of the object on the stage. 



The temperature may be raised to 45* C (//j F) without risk of injury 

 to the stand or lenses. 



