﻿ji6J RIGG, TRUMBULL, LI X COLS — TOXIC SOLUTIOXS 413 



The surface tension of 13 per cent ethyl alcohol was tested with 

 a duplicate of Czapek's apparatus. The average of the tests made 

 was 66, which lies between the results given by Czapek and the 

 results obtained by the writers with the Jolly apparatus. It was 

 thought best to use the Jolly apparatus rather than this duplicate 

 of Czapek's apparatus, since in general more dependable results 

 would thus be obtained. There are at least three sources of error 

 in Czapek's apparatus: (i) the difference in the height of the water 

 in the two sides of the manometer cannot be read any closer than 

 1 mm., owing to the irregular meniscus and the necessity of taking 

 the readings just as a sudden change of height is taking place; 

 (2) the capillary tube is immersed so slightly in the liquid that a 

 small error in the depth to which it is immersed would make a 

 relatively large error in the result; (3) it is an indirect method, the 

 value for each liquid being compared with the value for pure water 

 determined with the same apparatus, thus giving a double chance 

 for error. 



Livingston (5) has published data which he 

 follows: "bog waters do not have an appreciable higher concen- 

 tration of dissolved substances than do the streams and lakes of 

 the same region." The following are the averages of the results 

 of all tests of the lowering of the freezing point of bog waters and 

 of other surface waters reported by Livingston (loc. cit.), and of 



