BAIRD &TATLOCK (LOM)ON) LTD. 



A MODIFIED FORM OF POLARIMETER FOR SCIENTIFIC PURPOSES. 



This apparatus, which has been fully described by H. Landolt (Ber., 1895, 28, 3102-3104), is similar in 

 principle to Landolt's apparatus with a Lippich polariser. This new instrument, which is fitted with a triple 

 field polariser, is made to take tubes not more than 220 millimetres long. 



The following illustration will explain its construction : 



5838 T 



5839 T 

 5840 T 



5838 



Polariscope, Landolt's, half-shadow, with divided circle, Lippich's triple field polariser, 

 graduated to read to 0.01, to take tubes up to 220 millimetres long. Price, with tubes 

 100, 200, and 220 millimetres on Bock stand 



Landolt's Gas Lamp, for sodium flame . . . . . . . . . . extra 



Landolt's Heating Apparatus, G, for 100 cm. tube, with thermometer, asbestos cased 

 jacket, so that tube can be heated while under observation . . . . extra 



The metal jacket is made so that the observation tube may be heated, or a convenient freezing mixture may 

 be introduced. For such experiments only a 100 centimetre tube can be used, as there are arrangements at each 

 end for preventing the deposition of moisture on the outside of the glasses of the tube. The inner surface of the 

 tube is gilded, and a vertical tubular limb of small bore allows for the contraction or expansion of the contents of 

 the observation tube. 



The analyser is controlled by the simple lever c and a micrometer screw for fine adjustments ; the scale 6 is 

 divided into degrees, and the readings are accurate to o.oi degree. The instrumen t is constructed for homogeneous 

 light. 



39 10 

 3 13 





 



3 15 



Fig. E. 



DESCRIPTION OF HALF-SHADOW APPARATUS. 



Fig. E shows the parts of an apparatus for the determination of specific rotatory power. (F. Lippich upon " Polaristrobometric 

 Methods, with especial reference to the Half-Shadow Apparatus," Sitzungsber. d. k. Akad. d. Wiss. Wien. Math.-naturiv.Klassc, 

 | 1885, 91, Ila, 1059-1906 ; also O. Schonrock, " Apparatus and Methods for the Estimation of Specific Rotation," Part IV. in 

 H. Landolt's work, Das optische Drehungsvermogen, 2nd edition, 1898. Brunswick, F. Vieweg & Son.) The diaphragm A 1 and 

 the lens K are portions of the illuminating arrangement ; the lamp is situated near the diaphragm A 1 . The Nicol prisms N, and 

 N,, together with the diaphragm D, comprise the polariser. The diaphragm A, the Nicol prism N,, and the small astronomical 

 telescope Q R form the analyser' 



CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS. 



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