| LOCKYER | Norman -, astronomer jointly credited with detecting the element helium |
| HE | Symbol for the element helium (2) |
| RHENIUM | Element helium with nickel in strange surroundings (7) |
| LEIBNITZ | Wilhelm ____ is jointly credited for the discovery of calculus |
| APARTHEID | Help about element helium separation |
| RAREGAS | Any of the unreactive elements helium, neon, argon, krypton, radon and xenon (4,3) |
| TEST | In chemistry, what is the process of detecting the presence of an ingredient in a compound? (4) |
| RADAR | System for detecting the direction, presence of aircraft, ships by high-frequency radio waves reflected from the object |
| EUREKA | Archimedes' cry when he had thought of a method of detecting the adulteratjon of the gold for Iliero's crown (6) |
| SONAR | Apparatus for detecting the presence of submarines (5) |
| ASDIC | Apparatus for detecting the presence of submarines (5) |
| GEIGER | ___ counter, instrument for detecting the presence of radiation (6) |
| MERCURY | Named after a talaria-wearing swift-flying Roman messenger god, the first planet from the Sun or, the element with the symbol Hg (7) |
| BRIMSTONE | Old name for the element sulphur, whose yellow colour matches that of the wings of the male lepidopteran in the genus Gonepteryx rhamni, the original "butter-coloured fly" (9) |
| ATOM | (physics and chemistry) The smallest component of an element having the chemical properties of the element. |
| ARSENIC | Featuring in the title of a play adapted into a film by Frank Capra, the element with germanium to its left and selenium to its right on the periodic table (7) |
| THALLIUM | Derived from the Greek meaning "green twig" in reference to its green spectral line, the element with the atomic number 81 (8) |
| IRIDIUM | The element was discovered in 1803 in the acid-insoluble residues of platinum ores by the English chemist Smithson Tennant. The international prototype standard kilogram of mass is made from an alloy |
| CUPS | One of the four suits of the Minor Arcana in tarot, associated with the element of water (4) |
| SOUL | The element of humanity the Little Mermaid wants more than the prince (4) |
