24 vols and supplements. Reference collection 660.03 E56 and incomplete 4th ed. Reference collection 660.03 E56.4 Useful for data on common, industrial or environmental substances. Often includes physical data, reactions, methods, environmental aspects, uses, safety of substances. Has substantial bibliographies after articles often including reports and patents.
Index covers substance names, properties, topics but the indexing of substances can be erratic.
The 3rd edition has an index for all volumes at the end of the set. The 4th edition has indexes for every 4 volumes. Ullmann's encyclopedia of industrial chemistry. Section A covers chemicals, processes etc. Section B covers basic principles.