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Photography

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.

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.

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.

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:

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.

I do not give the method employed by our regular plate manufacturers; this is not important, as the operator could not possibly profit by it from the fact of the great expense of manufacturing. The following will be found practical:

In the great catalogue of complaints made by operators, none is more common than that alleged against the quality of plates in general use. Although the greatest diversity of opinion exists upon this subject, nevertheless the plates of every manufactory share in this universal condemnation.

M. Soliel has proposed the use of the chloride of silver to determine the time required to produce a good impression on the iodated plate in the camera. His method is to fix at the bottom of a tube, blackened within, a piece of card, on which chloride of silver, mixed with gum or dextrine, is spread. The tube thus disposed is turned from the side of the object of which we wish to take the image, and the time that the chloride of silver takes to become of a greyish slate color will be the time required for the light of the camera to produce a good effect on the iodated silver.

AN ACCOUNT OF WOLCOTT AND JOHNSON'S EARLY EXPERIMENTS, IN THE DAGUERREOTYPE. BY JOHN JOHNSON.

[From Humphrey's Journal, vol. ii 1851]

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