| Hydronium, e.g. | 15 |
| Hydrometer scale | 16 |
| Hydromassage facility | 21 |
| Hydromassage facilities | 23 |
| Hydrolysis product | 18 |
| Hydrolysis atom | 15 |
| Hydrologist's field: Abbr. | 30 |
| HydrogenÂ’s lack | 19 |
| Hydrogenated oil | 16 |
| Hydrogen, for one | 17 |
| Hydrogen, e.g. | 14 |
| Hydrogen's number | 21 |
| Hydrogen's atomic number | 28 |
| Hydrogen sulfide smell-alike | 28 |
| Hydrogen sulfide characteristic | 31 |
| Hydrogen or neon | 16 |
| Hydrogen or helium | 18 |
| Hydrogen has one | 16 |
| HYDROGEN GAS | 12 |
| Hydrogen compound | 17 |
| Hydrogen bomb, for short | 24 |
| Hydrogen bomb physicist Edward | 30 |
| Hydrogen atom's lack | 24 |
| Hydrogen and oxygen, e.g. | 25 |
| Hydrogen and oxygen | 19 |
| Hydrogen and methane (Var.) | 27 |
| Hydrogen and methane | 20 |
| Hydrogen and helium | 19 |
| Hydroforming machine part | 25 |
| Hydrofluoric ___ | 16 |
| Hydroelectricity suppliers? | 27 |
| Hydroelectricity structure | 26 |
| Hydroelectricity sources | 24 |
| Hydroelectricity providers? | 27 |
| Hydroelectric structures | 24 |
| Hydroelectric structure | 23 |
| Hydroelectric project | 21 |
| Hydroelectric power site | 24 |
| Hydroelectric power projects | 28 |
| Hydroelectric power agcy. | 25 |
| Hydroelectric org. | 18 |
| Hydroelectric option | 20 |
| Hydroelectric facility | 22 |
| Hydroelectric dam-building agcy. | 32 |
| Hydroelectric agcy. | 19 |
| Hydrodynamic duo | 16 |
| Hydrocortisone target | 21 |
| Hydrocortisone producer | 23 |
| Hydrocortisone cream from Palindromic Products, Inc.? | 53 |
| Hydrocortisone additive | 23 |
| Hydrochloric, for one | 21 |
| Hydrochloric, e.g. | 18 |
| Hydrochloric ___ | 16 |
| Hydrochloric solution | 21 |
| Hydrochloric or amino, e.g. | 27 |
| Hydrochloric or amino | 21 |
| Hydrochloric and others | 23 |
| Hydrochloric and boric | 22 |
| Hydrochloric e.g. | 18 |
| Hydrocarbons: suffix | 20 |
| Hydrocarbons used in making plastics | 36 |
| Hydrocarbons used in lighters | 29 |
| Hydrocarbons | 12 |
| Hydrocarbon: Suffix | 19 |
| Hydrocarbon's suffix | 24 |
| Hydrocarbon with two carbons | 28 |
| Hydrocarbon with one double bond | 32 |
| Hydrocarbon used as a solvent | 29 |
| Hydrocarbon type: Suffix | 24 |
| Hydrocarbon suffixes | 20 |
| Hydrocarbon suffix | 18 |
| Hydrocarbon source | 18 |
| Hydrocarbon radicals with six parts carbon | 42 |
| Hydrocarbon obtained from petroleum | 35 |
| Hydrocarbon in petroleum | 24 |
| Hydrocarbon in gasoline | 23 |
| Hydrocarbon groups | 18 |
| Hydrocarbon group | 17 |
| Hydrocarbon gas | 15 |
| Hydrocarbon fuel | 16 |
| Hydrocarbon from resins | 23 |
| Hydrocarbon from evergreens | 27 |
| Hydrocarbon found in coal gas | 29 |
| Hydrocarbon finish | 18 |
| Hydrocarbon endings | 19 |
| Hydrocarbon ending | 18 |
| Hydrocarbon derived from petroleum | 34 |
| Hydrocarbon derivative | 22 |
| Hydrocarbon | 11 |
| Hydroacoustic tool | 18 |
| Hydroacoustic technology | 24 |
| Hydroacoustic device | 20 |
| Hydro-mattress support? | 23 |
| Hydro-carbon suffix | 19 |
| Hydro- or electro- follower | 27 |
| Hydrindene | 10 |
| Hydraulic system makeup | 23 |
| Hydraulic press' piston | 27 |
| Hydration from underground | 26 |
| Hydration amounts | 17 |