88 CALIFORNIA ACADEMY OF SCIENCES. 



both funnels will rest side by side in equal and least possi- 

 ble height above the cork. Both tubes are, now, cut off, so 

 that they reach nearly to the bottom of the flask. They 

 ought to be as narrow as a reasonably fast flow of the liquid 

 from flask to cups will allow. As I could not procure fun- 

 nels to satisfy me in this respect I shoved a narrow tube 

 through the straight tube, flanging it a little so that it found 

 a support in the conical bottom of the cup, and closed the 

 lower opening of the bent tube partially. Thus, when the 

 air is compressed in the flask the liquid will travel in both 

 tubes with tolerably equal speed. The graduated cup with 

 the straight tube serves for fractional titration, the other one 

 to compare the original color with the changes of color pro- 

 duced by the additions from the burette to the graduated 

 cup. 



Everything being prepared, I pour 25 c-c. of my normal 

 solution of potassium bromide through one of the funnels 

 into the flask, raise 5 c.c. or ^ to the correspondiiig mark in 

 the cup, close the clamp and assay in similar manner as 

 described above. 



No. 1. — I add OQe drop of the solution of hypochlorite 

 of sodium of unknown strength. A yelloAvish tint is no- 

 ticed, faint but unmistakable. I am allowed to add four 

 more drops. I do so, and observe deepening of the color 

 with every drop. Having, thus, spent .25 c.c. I am allowed 

 to add 1 c.c. more or 1.25 c.c. in all. I add .25 c.c. at one 

 time, stir and observe that the color becomes more intense 

 by stirring. The next. 25 c.c. do not seem materially to in- 

 crease the color although it does not decrease. Therefore, 

 I add only .10 c.c. at one time, note .85 as doubtful, observe 

 with the next drop a probable decrease of color, which de- 

 crease becomes more marked with the second drop, and 

 quite decided and unmistakable with the third. I know, 

 now, that the assay will be finished between 5 X .75 = 3.75 

 c.c, and 5x1 = 5 c.c, probably already 5 X .90 = 4.5 c.c 

 I lower the stand in the burette to 3.75 c.c, which makes 



