same circumstances and for the same time, I obtained a quantity
of alkali which must have been more than twenty times greater,
but no traces of muriatic acid. There was much probability that
the agate contained some minute portion of saline matter, not
easily detected by chemical analysis, either in combination or
intimate cohesion in its pores. To determine this, I repeated
this a second, a third, and a fourth time. In the second
experiment turbidness was still produced by a solution of nitrate
of silver in the tube containing the acid, but it was less
distinct; in the third process it was barely perceptible; and in
the fourth process the two fluids remained perfectly clear after
the mixture. The quantity of alkaline matter diminished in every
operation; and in the last process, though the battery had been
kept in great activity for three days, the fluid possessed, in a
very slight degree, only the power of acting on paper tinged with
turmeric; but its alkaline property was very sensible to litmus
paper slightly reddened, which is a much more delicate test; and
after evaporation and the process by carbonate of ammonia, a
barely perceptible quantity of fixed alkali was still left. The
acid matter in the other tube was abundant; its taste was sour;
it smelled like water over which large quantities of nitrous gas
have been long kept; it did not effect solution of muriate of
barytes; and a drop of it placed upon a polished plate of silver
left, after evaporation, a black stain, precisely similar to that
produced by extremely diluted nitrous acid.

"After these results I could no longer doubt that some saline
matter existing in the agate tubes had been the source of the
acid matter capable of precipitating nitrate of silver and much
of the alkali. Four additional repetitions of the process,