In this article is tried to come to a definition of the word 'drugs'. This has not been done for medical, juridical, psychological and sociological purposes but to define a general conception.
The following substances are subjected to closer inspection: alcohol, barbituraten, ether, laughing-gas, trichlorethylene, and other solvents, marihuanha, LSD, cocaine, amphetamine (weckamines) and opium-alkaloids.
From a pharmacological point of view drugs form a very heterogenous group of substances which have not much in common but have widely different properties.
These aspects and the pharmacology of the above mentioned substances are discussed.
At the same time is indicated whether the use of a certain substance might lead to addiction or dependence.