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.
Field greens, baby lettuces, lamb's lettuce, arugula...chic gardeners and gastronomes (sorry, I can't stand the word foodie) everywhere want every leaf imaginable in their salad bowl except one: iceberg lettuce.he biggest difference between these two lettuce traditions is the stage of maturity at harvest and the manner of harvesting. In France, batavias are harvested young, with the dense head at the center unformed or just beginning to form. All the skirt (outer) leaves are cut along with the head.