Operations in a chemical laboratory with noxious, inflammable or explosive materials are always attended with risks of personal injury or material destruction. The importance of a due regard for safe methods of work and of taking precautions against accidents, however unlikely, must be instilled as an integral part of the training of the young chemist. Codes of regulations - to be strictly observed - may go some way towards reducing dangers inherent in chemical work, and compilations in book or chart form of the injurious action of various types of chemical are unquestionably useful. Yet it is from the precept and example of his more experienced colleagues that the new recruit will draw the surest guidance. This booklet, compiled primarily to help the new entrant to the National Chemical Laboratory, contains much that even an experienced worker may be glad to know. The previous editions have, indeed, achieved a wide circulation in other laboratories and many letters suggesting amendments or additions have been received and considered.