232 C. F. Roberts — Estimation of Chlorates and Nitrates. 



chloric acid, the liberated chlorine being conducted into potas- 

 sium iodide, and the iodine set free determined by titration 

 with sodium thiosulphate. This method is entirely analogous 

 to the first mentioned method of determining nitrates, the 

 only difference being that in the latter case a solution of man- 

 ganous chloride in hydrochloric acid is used instead of the acid 

 alone. In case of the nitrate, however, there is a second 

 product, nitric oxide, which may be collected and measured. 

 It would then seem possible, with the use of the apparatus 

 heretofore described, to treat a mixture of a chlorate and 

 nitrate with manganous chloride, pass the resulting gases 

 through potassium iodide, and then into the Hempel's burette. 

 The amount of nitric oxide will give at once the amount of 

 nitrate present. The iodine liberated will give the total chlo- 

 rine set free by the reduction of the nitrate and chlorate. 

 After that which is due to the nitrate determined has been 

 deducted, we have an exact measure of the chlorate present. 



To verify these presumptions, a few preliminary experi- 

 ments were first made with potassium chlorate alone. In 

 these, and all of the following experiments, great care was 

 taken that the escaping gases should only come in contact 

 with glass. Between the condenser and Hempel's burette were 

 two Will and Varrentrapp tubes sealed together and contain- 

 ing potassium iodide, and generally a Geissler bulb containing 

 potassium iodide was also added to make sure that no chlorine 

 escaped absorption. The potassium chlorate was weighed out 

 and introduced into the retort, air driven out by carbon 

 dioxide, and then manganous chloride added through the 

 funnel-tube. The liquid became dark at once, and a short 

 heating sufficed to restore it to its original clear, light-green 

 color. When this was accomplished, a current of carbon di- 

 oxide was passed through the apparatus, the bulbed tubes were 

 disconnected, and their contents titrated with sodium thiosul- 

 phate. The following results were obtained from five trials : 



wt. 



KC10 3 taken. 



Wt. KCJ0 3 found. 



Difference. 



0) 



o-iooo 



0-0990 



o-ooio 



(2) 



o-iooo 



0-0995 



0-0005 



(3) 



0-0500 



0-0484 



0-0016 



4) 



0-0500 



0-0498 



0-0002 



(5) 



0*0500 



0-0496 



0-0004 



Working in the same way with a mixture of potassium 

 chlorate and potassium nitrate, and estimating the amount of 

 nitrate first from the nitric oxide produced, the following 

 results were obtained : 



