Bilbao almonds), rice cakes and "bollos de mantequilla" (butter buns). Bilbao, as other Basque cities, is known for a variety of appetizers and snacks, being prominent among them the "pintxos", which are typically eaten in bars and that consist of small slices of bread on top of which is placed an ingredient or mixture of ingredients, generally of many different types and usually including elements typical of Basque cuisine. Other snacks include "rabas" (fried or battered calamari rings, usually served with lemon slices), Spanish omelette (omelette made with eggs and potatoes, sometimes including onions and peppers), "txampis" (stuffed mushrooms), "triángulos" (Bilbao-style
Vegetable oil and dammar resin), for example, is used almost exclusively in treating the hulls of wooden boats. Vegetable oils are increasingly being used in the electrical industry as insulators as vegetable oils are not toxic to the environment, biodegradable if spilled and have high flash and fire points. However, vegetable oils are less stable chemically, so they are generally used in systems where they are not exposed to oxygen, and they are more expensive than crude oil distillate. Synthetic tetraesters, which are similar to vegetable oils but with four fatty acid chains compared to the normal three found in a natural