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the Nitrous Acid.

quite colourless, but a fly, or any smallsubstance containing phlogiston, falling intoit, would colour the surface of it again fora considerable time, though at length theseaccidents had less effect upon it. This acidkept increasing in bulk to the April follow-ing, when the quantity was considerablymore than doubled ; but from that time itbegan to decrease, and continued so to do tillmore than half that it had gained was gone,after which it continued very much thesame for several months,

The circumstances relating to the whitematter, which I have observed was formedby the nitrous acid in glass tubes hermeticcally sealed, and exposed to a continuedheat, I am not able to explain. I first ob-served it in that short tube in which thephenomena of the colour of the acid were sovery remarkable, and indeed singular; butafterwards it never failed to make its appear-ance whenever the acid had been long con-fined, and exposed to much heat, but thequantity procured was too inconsiderableto make many experiments upon it.

C3

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