| Petroleum has been used to some extent both as a fuel and as an illuminant. |
| The Argand burner became the principal lighthouse illuminant for more than 100 years. |
| For the illuminant used in enlarging, we may employ either daylight or artificial light. |
| The term metamerism is used when two colours, identical underneath a given illuminant, appear different under another illuminant. |
| If the illuminant was acetylene gas, the lens rotation could be driven by gas pressure. |
| The owner of the illuminant system was Mr WK Hardacre, of Hellifield House. |
