This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
In diphtheritic inflammation with membranous deposit, I cannot recommend the strong nitrate; if the part be irritated it is more liable to inflame, and if the membrane be roughly detached the absorbents more readily receive morbid material, so that, although this remedy was at one time commended, I am satisfied that the use of a solvent or disinfectant spray is more serviceable, and is far more thoroughly and easily effected. Strong nitrate of silver is not a suitable local remedy for membranous croup (laryngeal diphtheria), or acute congestion of the larynx. I have seen almost fatal suffocative spasm of the vocal cords induced by the application of the solid nitrate in the latter condition. Guillon, however, states that the insufflation of finely powdered nitrate may be very useful (Medical Record, 1877); sometimes a weak spray (1 gr. to 1 oz.) has been of service.