200 Gooch and Browning — Method for Determination, etc. 



tions which shall eliminate errors in the indicated amount of 

 iodine due to the action of these substances. From the aver- 

 ages of Series L it is apparent that the amount to be added in 

 each case may be obtained by multiplying the product of the 

 weights in grins, of sodium chloride and potassium iodide by 

 the constant 0*004 ; and the amount to be subtracted, by multi- 

 plying the weight in grms. of potassium bromide by 0*0016. 

 Thus, for example, the correction in (24) will be 0*0011 grm. + 

 (=0-5 X 0*56x0*004) and 0*0008 grm. - (-0*5x0*0016). The 

 individual results of Series L thus corrected will stand as fol- 

 lows : 



No. of 

 Exp. 



Theory for 

 Iodine. 



Corrected amount 

 of Iodine found. 



Error. 



Mean error. 



0) 



0-4080 grm. 



0-4079 grm. 



00001 grm 







(2) 



0-4091 



0-4086 



0-0005 



— 





(3) 



0-4083 



04086 



00003 



+ 





(4) 



0-0400 



0-0396 



0-0004 



— 





(5) 



0-0400 



0-0391 



0-0009 



— 





(6) 



0-0400 



0-0400 



o-oooo 







CO 



0-0400 



00401 



00001 



+ 





(8) 



0-0040 



0-0037 



0-0003 



— 





(9) 



0-0040 



0-0038 



0002 



— 





(10) 



0-4077 



04077 



0-0000 







(11) 



0-4082 



0-4084 



00002 



+ 





(12). 



0-4086 



0-4084 



0-0002 



— 





(13) 

 (14) 



0-0400 

 0-0400 



00403 

 0-0396 



0-0003 

 00004 



4- 



}. 0-0001 grm.- 



(15) 



00040 



0-0037 



0-0003 



— 





(16) 



■ 00040 



0-0037 



0-0003 



— 





(17) 



0-4082 



04084 



0-0002 



+ 





(18) 



0-4138 



0-4128 



00010 



— 





(19) 



0-4083 



04191 



0-0008 



+ 





(20) 



0-0400 



0-0402 



0-0002 



+ 



i 



(21) 



0-0400 



0-0396 



0-0004 



— 





(22) 



0-0040 



0-0040 



o-oooo 







(23) 



0-0040 



0-0041 



o-oooi 



+ 





(24) 



0-4087 



0-4086 



00001 



— 





(25) 



0-4112 



0-4114 



0-0002 



+ 





(26) 



0-4083 



0-4082 



o-oooi 



.— 



„, 



The mode of proceeding in the analysis of a mixture of alka- 

 line chlorides, bromides and iodides, according to this method 

 may be briefly summarized as follows : 



The substance (which should not contain of chloride more 

 than an amount corresponding to 0*5 grm. of sodium chloride, 

 nor of bromide more than corresponds to 0*5 grm. of potassium 

 bromide, nor of iodide much more than the equivalent of 0*5 

 grm. of potassium iodide) is dissolved in water in an Erlen- 

 meyer beaker of 300 cm 3 capacity, and to the solution are added 

 2 grms. of dihydrogen potassium arseniate dissolved in water, 

 20 cm 3 of a mixture of sulphuric acid and water in equal vol- 



i 



