To crystallized nitrate of silver, dissolved in concentrated aqua ammonia, add gum arabic and soft water. Keep in the dark. Remember to remove all grease from the hair before applying the dye.
There is danger in some of the patent hair dyes, and hence the Scientific American offers what is known as the walnut hair dye. The simplest form is the expressed juice of the bark or shell of green walnuts. To preserve the juice a little alcohol is commonly added to it with a few bruised cloves, and the whole digested together, with occasional agitation, for a week or fortnight, when the clear portion is decanted, and, if necessary, filtered. Sometimes a little common salt is added with the same intention. It should be kept in a cool place. The most convenient way of application is by means of a sponge.