V^OL. X.] PHILOSOPHICAL TRANSACTIONS. 24Q 



after, the compression made by this newly generated air grew, manifestly fainter, 

 and the imprisoned gauge-air drove down the mercury again, till it was depressed 

 within one division of its first station ; so that in this operation there seemed to 

 have been a double compressive power exercised; the one transient, by the brisk 

 agitation of vapours ; the other durable, from the aerial on springy particles, 

 either produced or extricated by the action of the spirit of vinegar on the coral. 



A considerable quantity of spirit of vinegar being put upon minium in a 

 conical glass, furnished with a glass stopple and a mercurial gauge, continued 

 several days without any sensible depression of the mercury in either leg ; nor 

 did any change appear in the gauge, on removing the stopple, though it waS 

 evident by its sweetness, that it had made a solution of a great portion of the 

 minium. 



Exper. IX. Putting some filings of copper into a phial, capable of holding 

 two or three ounces of water, we poured on them strong spirit of sal animoniac 

 made without quicklime, till the liquor reached near an inch above them. In 

 4 days it had acquired a deep blue tincture, but lost again so much of it, that it 

 was pale almost like common water. On unstopping the phial, in less than 

 a minute it acquired a deep blue tincture on the surface to the thickness of the 

 back of a knife, the whole liquor becoming of the like colour in four or five 

 minutes more; and the glass being presently stopped again, it appeared not at 

 the end of nine days to have lost its tincture. 



Exper. X. Putting into a round phial, holding about 8 ounces of water, 

 filings of copper, and the mercurial gauge, we poured on the metal strong spirit 

 of sal ammoniac, till it reached to a good height in the phial ; which then being 

 hermetically sealed, and set by in a south window, it quickly acquired a deep 

 blue tincture. In 12 days the liquor little by little became so diluted that it was 

 pale, and almost like water : during this stay of the glass in the window, the 

 mercury in the open leg appeared to be impelled upward; after 9 o'clock at 

 night the hermetic seal was broken off, on which there was produced a noise, 

 and the mercury in the shorter and closed leg was briskly impelled up near three 

 eighths of an inch ; and though the orifice at which the air had access was scarce- 

 ly wide enough to admit a middle sized pea, yet within a minute and a half the 

 surface of the liquor, being held between the eye and the candle, appeared to 

 have acquired a very lovely and fair colour, that reached downwards a quarter of 

 an inch ; so that the phial seemed to contain two very different liquors swim- 

 ming one on the other ; and the coloration piercing deeper and deeper, with - 

 in five minutes in all the whole liquor had attained a rich blue colour. 



VOL. II. K K 



