Modern chemists know that alchemists were their historical predecessors, yet they are not proud of this relationship, which chemists today tend to hide or forget. However, no discontinuity exists between alchemy and chemistry and we still use laboratory techniques that were invented by alchemists hundreds or thousands of years ago. Alchemists used a secret language and made an extended use of symbols to indicate substances and procedures. When--in the second half of the 18th century--alchemy became quantitative and evolved into the discipline of chemistry, symbols were abandoned and replaced by abbreviations and formulas. However, the nature of the communication about matter by chemists remains mysterious to the uninitiated. (Contains 18 figures and 5 notes.)