1902] 



ELECTRICAL CONDUCTIVITY OF PLANT JUICES 



85 



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the constant for the cell, can be determined. If now the solu- 

 tion of potassium chloride be replaced by the juice which has an 



unknown 



conductivity, and the minimum again found for the 



telephone, we have the new value from which the specific con- 

 ductivity can be determined : 



Specific conductivit}' 



>^X 



M 



R -ad' 



MEASUREMr:NTS. 



With the apparatus and according to the method just 

 described measurements were made to determine the con- 

 ductivity of the juice obtained from different parts of plants. 

 The following list represents those species used : Bela vulgaris, 

 Solaimrn tuberosum, Allium cepa, Raphanus sativus, Nuphar advena, 

 Cucumts sativuSy Amarantus retrojlcxus, Portulaca oleracea, 



I. Beta vulgaris, 



r 



A number of preliminary measurements were made with the 

 juice extracted from the blades of the leaves, the petioles, and 

 the roots, with the following result as an example : 



Blades of leaves 



Petioles 



Root - 



specific cond. of juice 

 - 0.03652 



0.03652 

 O.OI89I 



It will be noted from these results that the specific con- 

 ductivity for blades of leaves and petioles is the same, hence in 

 the subsequent measurements leaf-blades and petioles are taken 

 together. In order to determine if there was any relation 

 between the conductivity and the amount of ash present in the 

 juice, the crude ash present in 5" of the juice was found. The 

 crude ash was afterwards dissolved in distilled water, diluted up to 

 the original volume of the juice and the specific conductivity of 

 this solution determined. The result is shown by the following : 











^^^^^^^^^™-^^^^^^^^^^^^^^^^^^^ 



Sp. cond. of juice 



Cnide ash from 5 cc 



1 



1 



Sp. cond. of ash soL 



Leaves . 



Root ... ■ ' 



0.02676 

 0.01349 



0.0626 



0.0296 



0. 01 10^ 



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