9. 

 might be attributed to starvation rather than to the toxioitr of the water. 

 Powers (unpublished) has ohown th.it two goldfishes lived In thie water ninety-five 

 and ninety-nine days, whsreas in the chemistry distilled w*ter, the length of 

 life was tiros hundred fifty-two and five hundred ninety-seven eiinutee. 



All chemicals ueed were either Marks or Baker's analysed oharaicals. 

 The acids and basee were standardised at a/lOO, except H3PO4, Na2C03, HaHC0 3 , 

 which were ^100 tnol. 



For the determi:./tion of CO2 production,! pt clamp-top fruit Jars 

 were used. The capacity of one of thesa J are is about 500 c.c. 400 c.e. of 

 water or the solution under investigation was put in a jar, then a test tube 

 containing 10 c.c. n /50 Ba (OH) 2 was inserted so thct the top of the test tube 

 etood above the level of the vrater, ths rubber ring was adjusted, tho tadpole 

 put in, and the lid olaapsd down. A stronger solution of Ba(0H)2 *■** used 



where acid had been added to tne water or nhnre more CO2 was expected. To 

 correct for the CO2 in the *ater and in the air above, a control Jsr was prepared 

 at the same tins and in precisely the same manner, sxoept th"t no tadpole was 

 put in it, and placed beside the experiment. At intervals, usually 24 hours, 



the Ba(0H)2 was nixed aith the ^ster by inverting and rotating the Jar. The 

 tadpole was quickly reaioved, and the excess Ba(0H)2 titrated with n /l00 HgSOb 

 using Phenolpthaleir as indicator. The difference li tM amount of acid 



required to neutralise the experiment and the control was recorded as the amount 

 of CO2 (ob a /l00 H2CO3) . produced by the tadpole during the givan tins* 



The hydrogen ion concentration was determined by the method of 

 MeClendon (1916). The solution to be tested w^e placed in a test tube 1 cm. 

 bore and l/lO o.c. of the indicator solution added. It was then compared with 

 the color chart by looking down into the tube against a white background. The 

 indicators used were Butter yellow (Dlmatfcyl amido azobenzene)methyl orange, 



