Page:Experimental researches in chemistry and.djvu/165

150 ammonia, but it soon ceased, and the wire blackened upon its surface; the introduction of a second portion of clean wire caused a second evolution of ammonia. Clean copper wire, in fused potash, caused a very slight evolution of ammonia, and became tarnished.

The following, among other vegetable substances supposed to contain no nitrogen, have been tried with potash in tubes open to the air:—Lignine, prepared by boiling linen in weak solution of-potash, then in water, afterwards in weak acid, and finally in water again; oxalate of potassa, oxalate of lime, tartrate of lead, acetate of lime, asphaltum, gave very striking quantities to turmeric and litmus paper: acetate of potash, acetate of lead, tartrate of potash, bensoate of potash, oxalate of lead, sugar, wax, olive oil, naphtha line, produced ammonia, but in smaller quantity: resin appeared to yield none, nor when potash was heated in the vapour of alcohol or ether, or in olefiant gas, could any ammonia be detected.

It may be remarked, that much appeared to depend upon the quantity of potash used; sugar, for instance, which with a little potash would with difficulty yield traces of ammonia, does so very readily when the quantity of potash is doubled or trebled; and linen, which with potash gives ammonia very readily, yields it the more readily, and in greater quantity, as the proportion of potash is increased.

The experiments with the substances which contain carbon, assimilate, in consequence of the presence of that body, with the one by Mr. Wood house. Whether the substances act exactly as charcoal does, probably cannot be decided until the correct nature of the action is ascertained; but there are apparently some very evident differences. The ammonia in the charcoal experiment does not exist until after the ignition, nor before the addition of water; but in several experiments of the nature of those described in this paper, the ammonia is evolved before the substances acting or acted upon are charred. Thus, if linen fibre, cut small, be mixed in the tube with hydrate of lime, and heated, ammonia is evolved before the heat has risen so high as to render the linen more than slightly brown; and oxalate of potash, in a tube with potash, when heated, gives much ammonia before any blackening is produced.

Mr. Wood house's experiment may be very readily repeated,