Photography

Hyposulphite of Soda.--This salt forms one of the important chemicals for the Daguerreotype operator. Its application to this art is of an interesting nature. It is used to dissolve the sensitive salt of silver which remains unchanged during the exposure in the camera. It has the property of readily dissolving the chloride, bromide and iodide of silver. It should be pure and free from sulphuret of sodium; should this last be present, it will cause brown spots of sulphurated silver upon the Daguerreotype impression.

Regarding specks from bad water, I would remark that gilding should be made only with distilled water. Thus made, it produces very little deposit, even by long keeping. It therefore preserves its original strength, and works with great uniformity.

Remarks on the Accelerating substances Used in the Daguerreotype.--I have now arrived at a point in this work, where the eye of the Daguerreotype public will intently search for something new. This search will prove in vain, at least so far as regards those who have enjoyed and embraced the opportunities for studying the principles of our art.

The following is from Humphrey's Journal, vol. 5, and from the pen of Dr. WM. HARRINGTON, one of the most able writers upon the subject of the Daguerreotype in this country:

Hydrate of Lime.--The operation by which water is combined with lime is called slaking. Take a piece of quick lime, common lime used in mortar, and immerse it in warm water for about fifteen seconds; then place it in an iron or tin vessel. It will soon begin to swell, evolving a great deal of heat and emitting steam, and soon falls into a fine powder, hydrate of lime. This should be well stirred and allowed to cool, and then bottled in order to prevent it from giving off the hydrate and recovering the carbonic acid from the atmosphere.

To make Plates for the Daguerreotype--Determining the Time of Exposure in the Camera--Instantaneous Process for Producing Daguerreotype--Galvanizing the Daguerreotype Plate--Silvering Solution--Daguerreotype without Mercury--Management of Chemicals--Hints and Cautions--Electrotyping--Crayon Daguerreotypes--Illuminated Daguerreotypes--Natural Colors in Heliography--Multiplying Daguerreotypes on one Plate--Deposit in Gilding--Practical Hints on the Daguerreotype.

Beyond all doubt this is traceable to dampness. Truly this is not a new thought; but where does this dampness come from? How does it originate, and where is it located? Generally it has been referred to a point entirely remote from its real location.

This dampness exists particularly upon the surface of the plate; is obviously derived immediately from the atmosphere; and is owing to a certain relative temperature of the plate with the hygrometric condition of the atmosphere.