42 CONDUCTIVITY UF ROSANILINE HYDROCHLORIDE 



The final recrystallization was made from the so-called 

 conductivity water and the sample Avas dried at 120 °C to con- 

 stant weight and preserved in a weighing tube in a desiccator. 



Determination of the Melting Point of Fuchsine. The 

 final sample was tested for its melting point. An ordinary 

 melting point flask with sulphuric acid was used, but it was 

 found difficult to observe the exact temperature of fusion with 

 a capillary tube made as ordinarily described in the text books. 

 The trouble disappeared, however, when the capillary tube, 

 containing the fuchsine, was drawn so as to terminate in a 

 point. Into this tube a little column of fuchsine, about 2 mm. 

 in height was tightly packed. It was then easy to observe when 

 the substance in the very point of the tube began to fuse. The 

 fuchsine melted fairly sharply at 216.8° C. 



The thermometer used was an ordinary one, graduated 

 only to degrees. It was standardized by placing it in a dis- 

 tilling flask, containing boiling naphthalene, according to the 

 method outlined by Gattermann in his "Laboratory Manual of 

 Organic Chemistry," page 66. 



The B. P. of naphthalene is about 217° C, the M. P. of 

 fuchsine is about 216.8°C. 



An attemjDt was ' .also made to find the melting point by 

 having the substance in a capillary tube complete an electric 

 circuit according to the method outlined by Beilstein.^ ISTo 

 change in the resistance could be detected, however, even 

 when the substance became fused. It seems, therefore, even 

 when fused to be a nonconductor. 



Conductivity Measurements. All resistances were measured 

 by means of the Wheatstone bridge. The bridge used was 

 manufactured by Queen &; Co. and the coils were originally 

 (1895) guaranteed to s\ of one per cent, and the bridge 

 wire to too of one per cent. 



. Beilstein : " Organische Chcmie," vol.1, page 37. 



