214 Practical Hints. 
exerting any pressure on the picture ; it appears that by pressing 
down the fingers the collodion film is displaced and allows the 
gelatine to come in contact with the plate, and of course causes it 
to stick.’ Since I have observed this caution, I have never had 
any trouble. Louis REINHARDT. 
Sauga La Grand, Cuba. 
Photographs of the Sun and Weather Predictions.—One of 
the Photographic Journals relates that the photographs of the 
sun, taken daily at Prague by Professor Zenger since 1877, have 
proved very useful for making meteorological reports and predic- 
tions regarding the weather. In these prints are often seen 
circular or elliptical rings, white or grey, around the disc ; some- 
times these zones, as they are called, spread over the disc itself, 
and impart to it a greyish appearance. Observation has shown, 
since several years, that these zones are more dense and more 
wide-spread before the electric or magnetic storms at the surface 
of the earth, and they enable the prediction to be made of a 
coming storm. It is evident, therefore, that the cause of this 
appearance on the photographic plate is to be found in the 
terrestrial atmosphere. According to the author, these zones 
indicate a storm twenty-four hours in advance.—Dr. Phepson in 
Philadelphia Photographer. 
Practical Hints. 
To tell Fresh Eggs.—The following, says Zhe Boston Journal 
of Commerce, is a simple French test for telling whether eggs are 
fresh or not. Dissolve two ounces of kitchen salt in a pint of 
water. When a fresh egg is put in this solution, it will descend to 
the bottom of the vessel, while one which has been laid the day 
previously will not quite reach the bottom. If the egg be three 
days old, it will float in the liquid, and if more than three days 
old it will float on the surface, projecting above the water more 
and more as it happens to be lighter with increased age. 
Ink for Rubber Stamps.—Take aniline rose or violet, 90 
grains ; boil this in r ounce of distilled water; then add halfa- 
teaspoonful of glycerine and half as much molasses. The crys- 
tals of the aniline dye must be worked up with the boiling water, 
and the other ingredients added in succession. This ink does not 
readily smear, and yet does not easily dry upon the pad. 
Microtome.—To make a microscope take the place of a micro- 
tome, use the tube to carry the imbedded object and the movable 
