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 for fear they might soak there too long before they could be separated, and so, possibly, give trouble.

The “hydrocarbon varnish” (or India-rubber solution), and the “transferring solution” (or benzine), are very volatile and inflammable; should be kept tightly corked, to prevent waste from evaporation; and must never be used near a naked flame or fire.

The varnish brush, to be kept soft and straight, should be suspended from a hook on the underside of the lid, in a tin brush cup, which should always contain enough of the “transferring solution” to keep the brush saturated.

Pictures technically called “vignettes,” of the size of life, or cartes-de-visite, may be made on the tissue without difficulty.

The utmost care and attention must be used not to allow the tissue to be struck by light, after it is sensitized, either before placing it under the negative or in any of the subsequent manipulations. Remember that the sensitized tissue is much more sensitive to the action of light than any silvered paper, and that any want of care, in this particular, will certainly be punished by the entire failure of the whole operation. Several, who have used the tissue, have lost many pictures by neglecting this often-repeated caution.

As many prefer ascertaining the density of the sensitizing solution by the use of a hydrometer, instead of weighing the crystallized salt, and as the hydrometers in common use, unless of high cost, are not made with much accuracy or uniformity, it is recommended that each photographer who prefers to use the hydrometer, should carefully make one sensitizing solution, as herein directed, from the crystallized salt, and ascertain its density by the particular hydrometer he has in use. By