4SSS On the Oxidation of the Constituents of Ammonia. 



sence of nitrite of ammonia. The simplest way of doing so is to 

 add to the water some dilute sulphuric acid, and paste of starch 

 containing a little pure iodide of potassium (free even from the 

 slightest trace of iodate) ; nitrite being present, the mixture will 

 become dark blue. 



Assisted a little by heat, even compact platinum is capable of 

 causing common oxygen to produce a nitrite with ammonia. 

 Put some drops of a strong solution of ammonia into a bottle 

 containing air, introduce into the vessel the heated coil of a thick 

 platinum wire, hold over this coil a strip of filtering-paper to 

 which sticks starch paste containing some iodide of potassium, 

 and on being acidulated with dilute sulphuric acid, you will per- 

 ceive the paste instantaneously turn dark blue. Whilst the hot 

 platinum coil remains within the bottle, whitish vapours make 

 their appearance, which, on being taken up by distilled water, 

 give to that fluid all the properties of a nitrite solution. On 

 acidulation with dilute sulphuric acid, it deeply and instantane- 

 ously blues the starch paste containing the iodide, and a strong 

 reaction will be obtained, though the heated coil may have 

 remained in the bottle but for a few seconds. The platinum coil 

 does not require to be heated to redness to produce this effect, 

 but those of iron wire, &c. must have that temperature to enable 

 oxygen to produce a nitrite with ammonia. 



I mentioned above copper as another substance which was 

 capable of causing ordinaiy oxygen to oxidize both the elements 

 of ammonia at the common temperature, and I may add that its 

 action even surpassed that of platinum. To convince yourself 

 of the truth of my statement, put about 50 grms. of minutely 

 divided copper (such as is obtained by reducing oxide of copper 

 by hydrogen) into a bottle containing oxygen or air, moisten the 

 metallic powder with a solution of ammonia, close or cover the 

 bottle, and you will soon see the vessel fill with whitish fumes, 

 which are nitrite of ammonia ; for if you introduce into the bottle 

 a strip of paper covered with acidulated starch paste contain- 

 ing some iodide of potassium, it will rapidly be coloured blue. 

 Or if strips of filtering- paper impregnated with distilled water be 

 suspended in it but for a shopt time, they will contain perceptible 

 quantities of nitrite of ammonia, as you may easily satisfy your- 

 self by applying the above-mentioned test. Even a moistened 

 glass plate or watch-glass used to cover the vessel will receive 

 within a very few minutes so much of the nitrite formed as to 

 enable you to ascertain its presence by the most striking reactions. 

 To complete my statement, I must not omit to mention that 

 copper powder, soon after having been moistened with liquid am- 

 monia, exhibits a rise of temperature, no doubt resulting from 

 the fonnatioil of the nitrite of ammonia. 



