292 True and H unk 61, The Poisonous Effect Exerted etc. 



tration in an easy mathematical ratio to each other and, there- 

 fore, readily comparable. 



Experimental Results. 



In general, the phenols were found to act with less sharpnesS' 

 and precision than acids and metals, and oftentimes some diffi- 

 culty was experienced in determining the desired limit-eoncen- 

 tration. Accordingly, a large part of the work was repeated one 

 or more times. In order to compare more readily some of the- 

 physico-chemical and the toxic properties of the substances under 

 study, the results obtained by Richard Bader,^) who made a 

 study of the electrical conductivity of many phenols, accompany 

 the biological data obtained by the authors. 



In experiraenting on the electrical conductivity of the phe- 

 nols, Bader encountered a number of difficulties which he was 

 unable to overcome. Phenol and some of its homologues, as also^ 

 di- and trioxybenzenes, dissociate to but a very slight degree. 

 The conductivity of the water used has to be determined and 

 corrections made for the same in each instanee. As it was impo-^ 

 sible to foresee how the conductivity ot water would affect the. 

 conductivity of the Compound, the corrections were omitted in the 

 tables of results. It was noticed that some of the Solutions became 

 brown in the measuring flask, owing to the oxidizing effect of the 

 electrodes. The Solutions were removed after each determination. 

 and replaced by the next dilution. By operating rapidly, de- 

 composition was almost entirely obviated. Inasmuch as no suffi- 

 eiently accurate method exists for the titration of these com^ 

 pounds, no other method could be pursued. 



In the tabulated results given below, the following data are tound.. 

 The date designated at the beginning of the experiment indicates- 

 the time at which the radicles, provided with the India ink line 

 15 mm from the tip were, placed in the Solution named. In tha 

 left-hand column is indicated the concentration in fractions of a 

 gram-molecule of the substance in question per liter of water. In^ 

 the second column, the length of the radicles measured from the> 

 India ink line to the tip is given as found by measurement made 

 at the date given at the head of the column, usually about twenty- 

 four hours after the beginning of the experiment. The amount 

 of growth made during this period is obtained by subtraeting 

 15 Irom the lengths given in millimeters. In case column three. 

 is also headed with a date, the numbers given in the column. 

 indicate the lengths from tip to line found when measurements- 

 were made at the date indicated. The column headed „Condition" 

 contains the verdiet rendered on each radicle after its exposure. 

 to the Solution in question. 



Although many trial experiments were made in locating the 

 critical concentration, only those appear in the following tablea 

 which give decisive evidence. 



Phenol, CeHsOH. 



') Bader, R. (Zeitschr. f. physik. Chemie. VI. p. 289.) 



