If the book to be disinfected is not of much value, burn it. A valuable book may have each page clipped in a solution of bichloride of mercury, blotted and dried, the covers removed and burnt, and the book rebound. Or the book may be passed through a hot-air disinfector, the pages being opened so as to allow the hot air to pass between them; and probably the book will have to be rebound. A steam disinfector is equally effective, but the book will be more damaged than by hot air, and the covers will be completely ruined, making rebiuding a necessity. At Sheffield, a disinfecting apparatus is in use in connection with the free library, the books being placed in a closed chamber in which carbolic acid is vaporised by heat, which it is claimed makes the carbolic acid more potent and active; the vaporisation takes place at 80 F., the vapour being raised to about 200° F aud the books being subjected to this process for about fifteen minutes. It is also stated that books can be disinfected in fifteen minutes in a closed space simply by formaldehyde vapour (or vapour of commercial formalin) by using lcub. centimetre of formalin to 300cub. centimetres, or less, of air.

The books may be placed on their ends, but the better plan is to hang them up; the covers are opened out until they touch each other, and are fastened together, being suspended from the fastener; by this means all the leaves are slightly separated, and free access for the hot air, steam, or disinfecting vapour permitted. They should never be placed flat. These methods are equally suitable for typhoid germs as for tuberculosis.