CHEMISTRY 



1298 



CHEMISTRY 



In this instance one atom of sodium com- 

 bines with one atom of chlorine, but in cases 

 where the number of atoms is not thus equal, 

 figures must be used. These figures are made 

 small and are written to the right of and be- 

 low the letters, thus 03, which means three 

 atoms of oxygen, combined into one molecule 

 of ozone. Water is made up of hydrogen and 

 oxygen in the ratio of two atoms to one, two 

 atoms of hydrogen uniting with one of oxy- 

 gen, and the formula is therefore H^O. 



Branches of Chemistry. The two great 

 branches into which chemistry is divided are 

 commonly known as organic and inorganic 

 chemistry. The names may not be the best 

 that could be devised, but they have been 

 used so long that there is no thought of 

 change. 



Organic chemistry is that division which 

 treats of the carbon compounds. Hundreds of 

 compounds of this element are found in living 

 organisms plants and animals and indeed no 

 living thing is known which does not contain 

 carbon compounds. In the early days of chem- 

 ical study it was believed that all the so- 

 called organic substances existed in living 

 plants and animals only in other words, that 

 they could be produced only in living organ- 

 isms. But in 1828 a chemist produced in his 

 laboratory an organic compound, called urea, 

 from its elements, and later others were pro- 

 duced artificially until the theory of a vital 

 principle was given up. This branch is thus 

 better described as the chemistry of the car- 

 bon compounds. 



Inorganic chemistry treats of those com- 

 pounds which do not have carbon in their 

 make-up. The dividing line is not, however, 

 quite sharp, because carbon itself and some 

 carbon compounds, especially those which are 

 found as minerals, are commonly discussed in 

 books on inorganic chemistry. 



Other special classifications exist, according 

 to the differing purposes of chemical study, as 

 follows: 



Biochemistry, or physiological chemistry, 

 treats of the chemical changes which take 

 place in living plants and animals. 



Agricultural chemistry deals with the prob- 

 lems of the farm and farm products. Al- 

 though of comparatively recent development, 

 it has already assumed great importance. 



Industrial chemistry treats of the applica- 

 tion of chemical knowledge to the manufac- 

 turing of products. These two branches are 

 divisions of applied chemistry. J.F.S. 



Related Subjects. The articles In these vol- 

 umes which have to do with chemistry are nu- 

 merous. To make reference to them easy, the 

 following index is given, which lists all of those 

 closely related to the subject, except the ele- 

 ments. A list of those is given in the article 

 above, and all of the important elements are 

 treated in separate articles. The reader who 

 takes time to study the text-matter of this list 

 will have a good foundation knowledge. 



Acetic Acid 



Acetylene 



Acid 



Affinity 



Air 



Albumen 



Alchemy 



Alcohol 



Alkali 



Alkaloid 



Allotropy 



Alloy 



Alum 



Alumina 



Aluminum 



Ammonia 



Analysis 



Aniline 



Antidote 



Aqua Regia 



Atom 



Atomic Theory 



Atomic Weights 



Base 



Blue Vitriol 



Borax 



Brimstone 



Bromide 



Calcium Carbide 



Carbides 



Carbohydrate 



Carbolic Acid 



Carbonates 



Carbon Disulphide 



Carbonic-acid Gas 



Carbonic Monoxide 



Carborundum 



Caustic 



Chloroform 



Cinnabar 



Citric Acid 



Coal Tar 



Combustion 



Copperas 



Corrosive Sublimate 



Cream of Tartar 



Creosote 



Crystallization 



Cyanogen 



Decomposition 



Dextrin 



Diffusion 



Distillation 



Electro-chemistry 



Electrolysis 



Electron 



Fermentation 



Fulmination 



Gas 



Geissler's Tubes 



Glauber's Salt 



Glycerine 



Hydrates 



Hydrocarbons 



Hydrochloric Acid 



Hydrofluoric Acid 



Hydrogen Dioxide 



Hydrosulphuric Acid 



lodoform 



Lime 



Liquid Air 



Litmus 



Lunar Caustic 



Magnesia 



Metals 



Molecule 



Natural Gas 



Nitrate 



Nitric Acid 



Nitroglycerine 



Oxalic Acid 



Oxidation 



Ozone 



Peroxide of Hydrogen 



Phosphates 



Phosphoric Acid 



Picric Acid 



Potash 



Prussic Acid 



Putrefaction 



Reactions 



Rust 



Sal Ammoniac 



Salicylic Acid 



Salt 



Saltpeter 



Silica 



Soda 



Solution 



Spontaneous 



Combustion 

 Stearic Acid 

 Stearin 

 Sublimation 

 Sulphates 



Sulphureted Hydrogen 

 Sulphuric Acid 

 Tannin 

 Tartaric Acid 

 Vitriol 

 Water 

 Wood Alcohol 



CHEMISTS 



Bunsen, Robert W. E. Crookes, Sir William 



