Boston, Mass. : Photo Era Publishing Co. · leaf 92
Potassium Metabisulphite (12), and the product is 360 seconds or 6 minutes. Development will therefore be completed in six minutes. Potassium metabisulphite is made chiefly for photo- For the benefit of those members of our Guild, who graphic uses, for it is one of the best preservatives for have…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
![An illustration from St. Nicholas [serial] (1873)](https://img.insideoutlibrary.com/img/200/ia-stnicholasserial4921dodg-439-515.webp)
![An illustration from St. Nicholas [serial] (1873)](https://img.insideoutlibrary.com/img/200/ia-stnicholasserial4721dodg-125-162.webp)
