VOL. LXXIV.] PHILOSOPHICAL TRANSACTIONS. o6l 



retort became hot from the watery steams of the acid. The air receiver was 

 taken away, and a common receiver was luted on, with a little water in it, to 

 condense the vapours, and a quantity of dilute, but highly phlogisticated, acid 

 was caught in the receiver. When the watery vapours had nearly come over, 

 and yellow fumes appeared in the neck of the retort, the common receiver was 

 removed, and the air receiver replaced ; about 4 oz. of very strong nitrous air 

 passed up immediately, the fumes in the retort became red, and dephlogisticated 

 air passed up, which, uniting with the nitrous air in the receiver, produced red 

 fumes in the receiver ; and the 2 kinds of air acting on each other, their bulk 

 was reduced to the 4- oz. measure. At this period the fumes in the retort were 

 of a dark red colour, and dephlogisticated air was produced very fast. After a 

 short time some orange-coloured sublimate appeared in the upper part of the 

 retort, and extended a little way along its neck, the red colour of the fumes 

 gradually disappeared, and the neck of the retort became quite clear. At the 

 time when this happened, small globules of mercury appeared in the neck of the 

 retort, and accumulated there till they ran down in drops. The production of 

 the air was now very rapid, and accompanied with much of the white cloud or 

 powdery matter, which passed up with the air into the receiver, and mixed with 

 the water, but did not dissolve in it. After giving about 36 oz. measures of de- 

 phlogisticated air, it suddenly ceased to give any more ; and the retort being 

 cooled, the bulb was found to be quite empty, excepting a small quantity of 

 black powder, which, on being rubbed on the hand, proved to be mostly running 

 mercury. The orange-coloured sublimate was washed out of the neck of the 

 retort, and what running mercury was in it was separated, and added to that 

 which had run down into the bason among the water. The whole fluid mercury, 

 when dried, weighed 218 grs. ; therefore 22 grs. remained in the form of sub- 

 limate, which I believe would also have been reduced if I could have applied 

 heat in a proper manner to the neck of the retort, as some of it, to which heat 

 could be applied, disappeared. 



10. The l6oz. measures of nitrous air, which had been produced in the solu- 

 tion of the mercury, and had remained confined by water in the receiver, was 

 converted into nitrous acid by the gradual admission of common air, and was 

 taken up by the water ; this water was added to that in the bason, which had 

 served to receive the dephlogisticated air. The whole quantity was about 2 

 quarts, was very acid to the taste, and sparkling with nitrous air. It was im- 

 mediately put into bottles, and well corked, till it had lost the heat gained in the 

 operation. In order to determine the quantity of acid in the receiving water and 

 in the sublimate, I dissolved fixed alkali of tartar in water, and filtered the solu- 

 tion. 352 grs. of this alkaline solution saturated 120 grs. of the nitrous acid I 

 had employed to dissolve the mercury, and 13Q5 grs. of the same alkaline solu- 



vol xv. 4 C 



