348 



nftt afFectcd by 

 the air. 

 State of the 

 sulphate unim- 

 portant. 



Sulphuric acid 

 de^tro5's the 

 colour, unless 

 much water 

 present. 



How i?; tlie 

 priiici'il« 

 formed ? 



Qacstlon 1, 



Question 2. 



Question 3. 

 'Question 4. 



Question 5. 



Question 1 

 answered. 



Results of Ion; 

 boiling the 

 simple priis- 

 siato. . 



ON THE pr.ussic and prussous acids. 



acid, even if pure, might also cause this effect, as Table I 

 may convince us. The solutions with which this effect oc- 

 curred to ms were those of bismuth, silver, mercury, lead, 

 csbalt, gold, and platina. 



The liquid B is not altered by exposure to the air. 

 Its effect on oxisulphate of iron is the same, whether 

 this sulphate is neutral, or contains an excess of acid, or is 

 supersaturated with carbonate of ammonia. 



Sulphuric acid destroys the colour produced on oxisul- 

 phate of iron, provided the three liquids are in a concen- 

 trated state. If there is much water present, no change 

 ensues. 



Having obtained the tingeing principle B separate from 

 the other salts with which it was contaminated, I asked my- 

 self, to what was its formation and the simultaneous disap- 

 pearance of the prussic acid, during the second ebullition, 

 ovving? I could imagine but five causes for this that were 

 likely to have been ethcient, concerning each of which I 

 made a question to be resolved by experiment, viz. 



Was it owing to the complete separation of the oxide of 

 iron from the triple prussiate by the sulphur, and the sub- 

 sequent decomposition of the simple prussiate by the heat of 

 ebullition long continued? 



Was it owing to the action of the sulphurous acid pro- 

 duced? 



W^as it owing to the action of the sulphuretted hidrogen ? 

 Was it owing to a combination of the prussiate of potash 

 and sulphur? 



Was it owing to the deoxJdation of the prussic acid by 

 the hidroguretted stilphurct? 



To answer the first question, it is only necessary to at- 

 tend to the results afforded by long-continued boiling of the 

 simple prussiate of potash. I shall state these results as I 

 find them recorded by Professor Proust. 



They are carbonate of ammonia, carbonate of potash, 

 and some simple prussiate that escapes decomposition, even 

 after four or five successive distillations. There is, therefore, 

 no analogy between the products of this experiment and the 

 liquid A ; for had the latter contained carbonate of potash, 

 it must have changed turmeric paper brown; had it contain- 

 ed 



