Graphology - the study of handwritings; autograph - written with one's own hand; seismograph - a machine noting strength and duration of earthquakes. marina - a harbor for pleasure boats; maritime - relating to the sea; submarine - an undersea boat; aquamarine - color of sea water.
Chemicals are classified into various hazard classifications in accordance with their physiochemical properties and health hazards. Each class of chemical has a pictorial symbol called a danger symbol.
There are 7 'Chemical' classes [1]. 1  Amino acids in each class are in the order of Table 2 2  : Aliphatic (A, G, I, L, P, V) 3  Aromatic (F, W, Y) 4  Sulfur (C, M) 5  Hydroxyl (S, T) 6  Basic (R, H, K) 7  Acidic (D, E) 8  Amide (N, Q)