48 S. Gruener — Iodometric Determination of Nitrates. 



3SbCl 3 + 2HN0, + 6HC1 = 3SbCl 5 + 2N0 + 4H 2 0. 



Antimony chloride was dissolved in strong hydrochloric acid, 

 and the solution standardized by diluting convenient portions, 

 adding tartaric acid, nearly neutralizing with 25 per cent solu- 

 tion of sodium hydrate, treating with excess of hydrogen 

 sodium carbonate and titrating with decinormal solution of 

 iodine in presence of starch, the blue color being taken as the 

 end reaction. 



Known portions of this solution boiled with potassium nitrate 

 for a considerable length of time, then diluted, neutralized and 

 titrated (all a simple quick process), showed oxidation to the ex- 

 tent of about 90 per cent of the nitrate present. The evidence 

 pointed to the conclusion that the nitrate was broken up, but 

 that the residue failed to register the amount of decomposition. 

 The products of decomposition when passed in a current of 

 carbon dioxide into potassium iodide set free iodine, but had 

 no oxidizing effect upon an alkaline solution of arsenious oxide. 

 The conclusion was drawn that nitrosyl chloride was probably 

 given off, which breaking up on contact with water into hydro- 

 chloric and nitrous acids exerts no effect upon arsenious oxide 

 in alkaline solution. To see if the nitrosyl chloride was set 

 free in exact measure of the nitric acid lost the following ex- 

 periments were made. 



Into a diminutive retort — made from a pipette shaped like a 

 Liebig's drier and connected by a sliding joint covered by 

 rubber into a Kjehdahl tube used as a receiver, and so placed 

 that carbon dioxide passing through the apparatus should enter 

 from below — lifting the air before it — was introduced the 

 nitrate, dry, washed down with a few drops of recently boiled 

 water, or, if more liquid was required, with hydrochloric acid 

 lest the liquid become too dilute. From a burette a definite 

 amount of antimonious chloride solution, somewhat in excess 

 of the nitrate taken, was introduced. The receiver was 

 charged with 0*25 grm. potassium iodide diluted with recently 

 boiled water and was joined to a trap filled with water. After 

 carbon dioxide was passed through the apparatus for about ten 

 minutes, the solution was warmed on a high boiling bath 

 (103°-107°) to ensure the safety of the retort, to keep the 

 antimony pentachloride from breaking up, to retain the bulk 

 of the acid in the retort and to prevent mechanical loss. This 

 method of procedure was found entirely satisfactory. After 

 fifteen minutes digestion the receiver and trap were washed 

 out and at once titrated with sodium thiosulphate. The resi- 

 due in the retort was treated exactly as was the antimonious 

 chloride when it was standardized. The solution here must be 

 kept dilute, lest at the great heat caused by neutralizing strong 



