1 By convention a normal lens on a 35mm film camera (and thus a full-frame EOS digital SLR) has a focal length of 50mm or so. 2  A lens with a focal length of 35mm is considered ânormalâ for a cropped-frame EF-S camera.
Aspirin. One of the best known aromatic acetates is acetylsalicylic acid, or aspirin, which is prepared by the esterification of the phenolic hydroxyl group of salicylic acid. Aspirin possesses a number of properties that make it the most often recommended drug.
1 Aspirin is the common name for the compound acetylsalicylic acid, widely used as a fever reducer and as a pain killer. Salicylic acid, whose name comes from Salix, the willow family of plants, was derived from willow bark extracts.In folk medicine, willow bark teas were used as headache remedies and other tonics.n the presence of moisture, aspirin may decompose (hydrolysis) into salicylic acid and acetic acid. This reaction is the reverse of the synthesis reaction. The maximum allowable amount of free salicylic acid in an aspirin sample is 0.15% salicylic acid.