ALKALIES.

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Indeed, it is not long since ammonia has resignedits place amongst the simple bodies, as it was not,till lately, supposed to be a compound ; nor is itimprobable that potash and soda may some dayundergo the same fate, as they are strongly sus-pected of being compounds also.

The general properties of alkalies are, an acridburning taste, a pungent smell, and a caustic ac-tion on the skin and flesh.

CAROLINE.

IIow can they' be caustic, Mrs. B., since they'do not contain oxy'gen?

MRS. B.

Whatever substance has an affinity for anyone of the constituents of animal matter, suf-ficiently powerful to decompose it, is entitled tothe appellation of caustic. The alkalies, in theirpure state, have a very strong attraction forwater, for hydrogen, and for carbone, which, youknow, are the constituent principles of oil, and itis chiefly by absorbing these substances fromanimal matter, that they effect its decomposition ;for, when diluted with a sufficient quantity ofwater, or combined with any oily substance, theylose their causticity.

But, to return to the general properties of alka-lies—they change the colour of syrup of violets,and other blue vegetable infusions, to green ; ando 2