Which file format is recommended for black and white photographs

The original scanned image should be saved as a TIFF(whether they are black and white or color makes no difference). TIFF files do not compress or other wise loose any of the information you just scanned into your computer. Later you can re-size, adjust levels, add to the file information and all the things that Photoshop can do and then save them as a JPEG under a new name that will describe the subject in some way. 

JPEG files are the most commonly used on the Internet and while they loose data every time something is modified in them, they do have the ability to bring the most information to the viewer while still being a compressed..