Dr. Kane on the Compounds of Ammonia. SS 



of substances, which have their origin in the secondary decompositions of those 

 at first formed ; hence we find very irreconcileable statements put forward as to 

 the nature of the black powder, which is the more immediate product of this 

 action, by one chemist it being looked on as a mere oxide, by another as a sub- 

 nitrate, whilst the analyses of George Mitscherlich, to whose accuracy I have had 

 occasion so often to bear witness, showed that it did really contain ammonia and 

 nitric acid among its elements. I am inclined to believe that Soubeiran himself 

 now admits the incorrectness of his former statements, since in his Nouveau 

 Traite de Pharmacie, he adopts the results of Mitscherlich, without at all 

 adverting to the conclusions which he had advanced in his own paper on the 

 subject. 



When, to a solution of protonitrate of mercury, there is added water of 

 ammonia, the precipitate, which at first is of a velvety black colour, gradually 

 changes, passing through various shades of grey, until it becomes nearly white, 

 and its state of aggregation varies in a similar manner : the portions first formed 

 are heavy, and rapidly deposit, but according as the colour becomes lighter, it 

 remains long suspended, at least the whitish portion, whilst a heavy grey powder 

 falls more quickly down. 



Having satisfied myself, by treating portions of these precipitates, of various 

 shades of black and grey, with sulphuretted hydrogen, that the liquor contained, 

 after separation of the quicksilver as sulphuret, nitrate of ammonia neutral, 

 proving that an equal number of equivalents of nitric acid and ammonia were pre- 

 sent in the precipitate ; and having found, moreover, so great difficulty in decom- 

 posing the last portions as to render this method unavailable in obtaining a 

 quantitative result, I resolved to examine minutely the influence which the 

 variations in shade had on the quantity of mercury which the precipitate might 

 contain ; a result which very simple considerations will show, to lead to a com- 

 plete knowledge of the nature of the body under examination. 



A dilute solution of pure protonitrate of mercury was taken, and there was 

 added to it a quantity of weak water of ammonia, about one-fourth of what 

 would suffice for its complete decomposition. A considerable mass of a fine 

 glossy black powder fell, which was collected on a filter, washed carefully, and 

 dried at a temperature not exceeding 100° F. To the liquor separated from this 

 first portion was added another quantity of water of ammonia, and thus another 



