Conductors and Insulators. In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.onductors and Insulators. In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.
Butterhead lettuce. A type of head lettuce whose botanical name is Lactuca sativa var. heirloom. Two common types are Boston and bibb lettuce. Have small, round, loosely formed heads with soft, buttery-textured leaves ranging from pale green on the outer leaves to pale yellow-green on the inner leaves.
1 Hydroponic lettuce is not grown in soil, but in a nutrient rich liquid. 2  These small heads of lettuce have a buttery, spinach-like texture and delicate taste. 3  Unlike other types of lettuce, the outer leaves do not need to be discarded. Hydroponic lettuce is not grown in soil, but in a nutrient rich liquid. 2  These small heads of lettuce have a buttery, spinach-like texture and delicate taste. 3  Unlike other types of lettuce, the outer leaves do not need to be discarded.