A plain silver solution, of a strength of 30 grains of nitrate of
silver to the ounce of water in hot weather, increasing to 60
grains in the coldest, with enough bi-carbonate of soda added from
time to time to keep a small sediment of carbonate of silver in
the bottom of [p073] the bottle or dish, is all that can be
desired as a silvering solution for albumen paper. It only needs
to be kept up to the proper strength by the addition of silver
nitrate and water, when required; and when it shows signs of
discoloration a little more soda and an hour's sunlight will keep
it in good order the year round.