EXPLANATION OF SCIENTIFIC TERMS 



MADE USE OF IN THIS VOLUME. 



N.B. Many of the terms are common to both Volumes ; but those explanations that were given in the 

 former Glossary will be merely referred to in the present; except, in a few cases, where the definitions 

 were not supposed to be sufficiently explicit. Several omissions may be supplied by consulting the 

 Indexes. 



ABERRATION. See GLOSSARY I. 



f SPHERICAL. See 



Gloss. I. 



ABSCISSA. See Conic Sections. Gloss. I. 



ACCELERATION. See Gloss. I. 



ACCELERATED FORCE is the in- 

 creased force, or impetus, which a body 

 exerts when stopped, inconsequence of the 

 acceleration of its motion. Some object 

 to the expression, and propose to substi- 

 tute the term Accumulated Force. 



ACCELERATED MOTION. See Ac- 

 celeration. 



ACCIDENTAL COLOURS. See Gloss. 

 I. 



ACHROMATIC. See Gloss. I. 



ACIDS. The term acid was originally 

 confined to denominate those bodies only 

 which have a sour taste ; but recently 

 the name is given to other substances. 

 The present characteristic of an acid is, 

 that it 'changes the blue, green, and 

 purple juices of vegetables to a red 

 colour, and that it unites with alkalis 

 and metallic oxides to form salts. 



ACID, CARBONIC. See Carbon. 



, NITRIC. See Azote. 



ADAMANTINE SPAR. See Corundum, 

 Gloss. I. 



AFFINITY. See Chemical Affinity . 



ACTING POINT. See Machine. 



ACTION. See Gloss. I. 



ACTIVE FORCE. See Gloss. I. 



ACUTE ANGLE. See Angle. 



ADULARIA. See Feldspar, Gloss. I. 



AERIFORM FLUIDS. See Gas, Gloss. I. 



AGATES. See Gloss. I. 



AIR, GENERAL. CONDENSED,ETHE- 

 RIAL, &c. See Gloss. I. 



AIR, PRESSURE OF, a term sometimes 

 used in place of the weight or the pres- 

 sure of the atmosphere. See Atmos- 

 phere. 



AIR, INFLAMMABLE. See Oxygen. 



AIR-TIGHT, that degree of closeness in 

 any vessel or tube, which prevents the 

 passage of air, under the circumstances 

 in which it is placed. 



AIR-VESSEL, a vessel in which air is 

 condensed by pressure, for the purpose of 

 employing the re-action of its elasticity 

 as a moving, or as a regulating power. 



ALCHEMY, the name of that fanciful de- 

 partment of chemical science which, for 

 many centuries, was occupied in the 

 search for the philosopher's stone, and 

 the Elixir Vitce ; by the former of which 



the baser were to be transmuted into the 

 precious metals, and by the latter, human 

 life was to be indefinitely prolonged. 

 Sir Richard Steele was one of the latest 

 of the followers of that phantom. 

 ALCOHOL. That portion of a vegetable 

 substance which is sweet to the taste, or 

 which is capable of becoming sweet under 

 certain circumstances, or by certain ma- 

 nipulations, is termed Succharum or 

 Saccharine matter. This, when sufficiently 

 fluid, readily enters into an intestine 

 motion called the Vinous fermentation, 

 emits Carbonic Acid Gas, and becomes of 

 less and less specific gravity during the 

 action. This lessening of weight is called 

 Attenuation, and the product is a Vinous 

 liquor. From this vinous liquor another 

 liquid is procured by distillation. It is 

 lighter than water, and called spirituous ; 

 and this, by re -distillation, (termed Rec- 

 tification,} is brought to the state of pure 

 spirit, rectified spirit of wine, or Alcohol, 

 which are different names for the same 

 thing. Alcohol always retains a portion 

 of water, and its purity is calculated by 

 its freedom from flavour and its lightness. 

 The strongest alcohol yet procured has 

 the specific gravity of 792, taking water 

 at 1000. 



ALKALIES are substances that have an 

 acrid taste, change blue vegetable colours 

 to green, and form salts by their union with 

 acids. There are three alkalies: Potash, 

 called the Vegetable Alkali, and Soda 

 the Mineral Alkali are said to be Fixed 

 Alkalies ; and Ammonia, which is termed 

 the Volatile Alkali, because it exists in. the 

 form of a gas. Potash and Soda are un- 

 derstood to be the oxides of two substances, 

 called Potassium and Sodium, which are 

 classed among the metals. Lime and 

 certain other minerals, having some of the 

 properties of an alkali, are called Alkaline 

 Substances. 



ALTITUDE of the sun or a star. See 

 Horizon. 



AMALGAM (from the Greek ama, toge- 

 ther, and omeOj I marry) is a chemical 

 term signifying the union of any metal 

 with mercury, which is a solvent to Va- 

 rious metals. 



AMETHYST. See Corundum. 



AMMONIA. See Alkalies. 



AMPLITUDE. See Horizon. 



ANALC1ME is a stone which is found in 

 grouped crystals, deposited by water, in, 



