H. G-ruener — Iodometric Determination of Nitrates. 49 



solutions there be action upon the pentachloride on the part of 

 the small amount of tartaric acid now present. The difference 

 between the trichloride left in the retort and the iodine found 

 in the receiver is the measure of trichloride left unoxidized by 

 the nitrate, and by difference we have the measure of the 

 nitrate present. The results are given in series I and II. In 

 experiments (1) to (8) the receivers were washed with ordinary 

 distilled water ; after that with water recently boiled. 







Series I. 











KNO3 correspond- 



Entire 









KN0 3 



ing to I found in 



KNO3 



Error in 



Error in 





taken. 



receiver. 



found. 



KNO3. 



HN0 3 . 





grata. 



grm. 



grm 



grm. 



grm. 



1 



0-0222 



0-0020 



0-0233 



0-001 1 + 



0-0007 + 



2 



0-0336 



00.026 



0-0333 



0-0003 — 



0-0002 — 



3 



0-0470 



00045 



0-0471 



0-0001 + 



00001 + 



4 



0-0553 



00057 



0-0554 



0-0001 + 



0-0001 4- 



5 



0-0664 



0-0076 



0-0679 



0-0015 + 



0009 + 



6 



0-0759 



0-0082 



0-0752 



00007- 



0-0004— 



7 



0-0837 



0-0103 



0-0841 



0-0004 + 



0-0002 + 



8 



0-0934 



0-0113 



0-0955 



0-0021 + 



0-0013 + 



9 



0-1034 



0-0134 



0-1036 



0-0002 + 



0-0001 + 



10 



00262 



0-0024 



0-0259 



0-0003- 



0-0002- 



11 



0*0127 



0-0007 



0-0130 



0-0003 + 



0-0002 + 



12 



0-0065 



00003 



0067 



0-0002 + 



0-0001 + 



13 



0-0026 



o-oooi 



0-0023 



0-0003- 



0-0002- 



14 



0-1232 



0-0098 



0-1227 



0005- 



0-0003 — 



15 



0-1540 



0-0146 



0-1540 



00000 



o-oooo 



16 



0-1878 



0-0210 



0-1865 



0-0013— 



0-0008 — 



Three more experiments were performed to see if the titra- 

 tion of the iodine set free in the receiver could be accom- 

 plished as well in alkaline solution by means of arsenious oxide. 

 For this purpose the solutions from the receivers were poured 

 into a strong solution of sodium bicarbonate, care being taken 

 to prevent loss during effervescence. 



Series II. 



17 0-0530 



18 0-0547 



19 0-0541 



0-0052 

 0-0065 

 00063 



0533 0-0003 + 

 0-0549 0-0002 + 

 0-0537 0-0004- 



0-0002 + 

 0-0001 + 

 0-0002- 



The results run from extremes of '0021 grm.+ to *0013 grm.— 

 with a mean error of '00016 grm.-f , which tends to emphasize 

 the well known fact that it is impossible to remove every trace 

 of air from reagents and generator. The operation is quick, 

 taking in all three-quarters of an hour and requiring very little 

 watching. The experiments given are all that were performed 

 with the apparatus as described, it not having been found nec- 

 essary to reject a single determination for mechanical mis- 

 chances. 



Am. Jour. Sci.— Third Series, Vol. XLVI. No. 271. 



4 



-July, 1893. 



