What is "fixed alkali"

Fixed \Fixed\ (f[i^]kst), a.

1. Securely placed or fastened; settled; established; firm; imovable; unalterable.

2. (Chem.) Stable; non-volatile.

   Fixed air (Old Chem.), carbonic acid or carbon dioxide; -- so called by Dr. Black because it can be absorbed or fixed by strong bases. See Carbonic acid, under Carbonic.

   Fixed alkali (Old Chem.), a non-volatile base, as soda, or potash, in distinction from the volatile alkali ammonia.

   Fixed ammunition (Mil.), a projectile and powder inclosed together in a case ready for loading.

   Fixed battery (Mil.), a battery which contains heavy guns and mortars intended to remain stationary; -- distinguished from movable battery.

   Fixed bodies, those which can not be volatilized or separated by a common menstruum, without great difficulty, as gold, platinum, lime, etc.

   Fixed capital. See the Note under Capital, n., 4.

   Fixed fact, a well established fact. [Colloq.]

   Fixed light, one which emits constant beams; -- distinguished from a flashing, revolving, or intermittent light.

   Fixed oils (Chem.), non-volatile, oily substances, as stearine and olein, which leave a permanent greasy stain, and which can not be distilled unchanged; -- distinguished from volatile or essential oils.

   Fixed pivot (Mil.), the fixed point about which any line of troops wheels.

   Fixed stars (Astron.), such stars as always retain nearly the same apparent position and distance with respect to each other, thus distinguished from planets and comets.