ON MANGANESE 83 



of sal ammoniac, when a liquid volatile alkali came over, the 

 same as that which is prepared by means of quicklime. 

 There likewise sublimed a little sal ammoniac ; the residuum 

 was put into water, but there remained a good deal of 

 manganese undissolved. As manganese is not soluble in 

 acids without being combined with phlogiston, a question 

 arises, whence the manganese obtains the phlogiston in this 

 process ? (d) If finely pounded manganese be exposed with 

 pure nitrous acid and some volatile alkali to digestion for 

 several weeks, you will observe a great number of air-bubbles 

 rise to its surface. This kind of air, collected in a bladder 

 tied to the neck of the flask, is not aerial acid, but of a quite 

 different nature. During the digestion, the volatile alkali 

 is entirely decomposed ; for if the solution be mixed and 

 distilled with a sufficient quantity of quicklime, not the 

 least smell of volatile alkali appears in the receiver. In 

 this process, the phlogiston, one of the constituent parts of 

 volatile alkali, has combined with the manganese, and thus 

 rendered the acid of nitre capable of acting upon the 

 manganese. The elastic fluid, collected in the bladder, has 

 been either separated from the volatile alkali, and is then 

 its other constituent part, or it is a product arising from its 

 decomposition. That the nitrous acid has no share here, 

 is clearly proved by the following process : (e) I repeated 

 the very same distillation with manganese and sal ammoniac, 

 as in (c) ; but instead of the receiver, I applied an empty 

 bladder, which in these experiments is always to be fastened 

 very exactly to the neck of the retort. It happened here 

 as I expected ; I obtained the same kind of air in the 

 bladder as in the preceding experiment ; and now I under- 

 stand the nature of the process in (e), and how this process 

 is to be explained. The manganese had combined with the 

 phlogiston of the sal ammoniac (resolved by the heat into 



