-7/ and M<n- -Determination of Chlorine. 301 



The fart that nitric acid appears t<» affect bo little the hydro- 

 chloric acid in the solution, suggested the possibility that 



nitrous acid itself might l>c turned to account and used in a 

 similar process instead Of a ferric -alt and nitric acid. Some 

 preliminary experiments were made, therefore, to tot the 

 behavior of hydrochloric acid under the action of nitrous acid, 

 and, as they gave favorable indications, the experiments of 



ies J were undertaken to test the action quantitatively. 

 The general conduct of the test was similar to that followed in 



Ies I. The solution of chloride and iodide containing 

 10 cm 3 of sulphuric acid [1 : 1] was diluted to 400 cm 8 , and agi- 

 tated while the gas developed by the action of sulphuric acid 

 on 2 grm. of sodium nitrite was passed into it. With pure 

 -odium nitrite at hand there is probably no serious objection 

 to introducing that substance directly iuto the solution, but 

 impurities in the article at our disposal made it desirable to 

 generate the gas outside the solution. 



For a generator we used two straight drying tubes connected 

 by a rubber tube and set up after the fashion of the von Babo 

 generator, and regulated the rapidity of the current to a rate 

 of live or six bubbles to the second by changing the relative 

 elevation of the generator tubes. The iodine separates imme- 

 diately upon the introduction of the nitrous fumes and escapes 

 upon boiling in dense fumes, leaving the solution colorless in 

 a very short time. The litmus test was applied as an addi- 

 tional safeguard to indicate the completion of the removal of 

 the iodine. The results of the experiments as given in the 

 accompanying table are evidently satisfactory. 



Series J. 



H 2 S0 4 

 [1 : 1]. 



XaX0 2 



used in 



generator. 



grm. 



cm 3 . 



10 



2 



10 



2 



10 



2 



10 



2 



10 



2 



10 



2 



KC1=HC1. 



grm. 

 0-4953 

 0-4975 

 0-4956 



0-497:; 

 04964 

 0-4969 



grm. 

 0-2421 

 02432 

 0-2423 

 0-2431 

 0-2427 

 0-2429 



KI. 



Initial 



volume. 

 Final 



volume. 



Time in 

 minutes. 



grm. 

 1 



cm :i . cm 3 . 

 400 350 



20 



1 



400 350 



16 



1 



300 250 



15 



.1 



300 250 



15 



1 



300 250 



15 



1 



300 250 



15 



AgCl 

 found. 



HC1. 

 found. 



grm. 

 09524 

 09573 

 0-9530 

 0-9550 

 0-9550 

 0-966 1 ? 



grm. 

 0-2422 

 0-2434 

 02423 

 0-2429 

 02429 

 0-2433 



Error. 



grm. 

 0-0001 + 

 0-0002 + 

 00000 

 0*0002— 

 0-0002 + 

 0-0004 + 



The modes of proceeding to the separation of iodine and the 

 estimation of chlorine according to the processes which we 

 have detailed may be briefly summarized as follow- : 



First Method. — To the solution of the alkaline chloride and 

 iodide diluted to about 400 cm 3 in an Erlenmeyer flask capable 

 of containing a liter, are added 10 cm 1 of sulphuric acid of 



