Part 255

The last advice (to use low-priced preparations) seems sensible since according to recent experiments, none of the oils experimented upon possess any especial advantages over the others.

An overwhelming majority of the laboratories for examination have given a verdict in favor of oil as a dust-suppressing application for floors, and have expressed a desire to see it in universal use. The following is a suggestion put forth for the use of various preparations:

This dust-absorbing agent has for its object to take up the dust in sweeping floors, etc., and to prevent its development. The production is as follows: Mix in an intimate manner 12 parts, by weight, of mineral sperm oil with 88 parts, by weight, of Roman or Portland cement, adding a few drops of mirbane oil. Upon stirring a uniform paste forms at first, which then passes into a greasy, sandy mass. This mass is sprinkled upon the surface to be swept and cleaned of dust, next going over it with a broom or similar object in the customary manner, at which operation the dust will mix with the mass. The preparation can be used repeatedly.

HUNYADI WATER: See Water.

HYDROCHINON DEVELOPER: See Photography.

HYDROGEN, AMALGAMS AS A SOURCE OF NASCENT: See Amalgams.

HYDROGEN PEROXIDE AS A PRESERVATIVE: See Preserving.

«HYDROMETER AND ITS USE.»

Fill the tall cylinder or test glass with the spirit to be tested and see that it is of the proper temperature (60° F.). Should the thermometer indicate a higher temperature wrap the cylinder in cloths which have been dipped in cold water until the temperature falls to the required degree. If too low a temperature is indicated, reverse the process, using warm instead of cold applications. When 60° is reached note the specific gravity on the floating hydrometer. Have the cylinder filled to the top and look across the top of the liquid at the mark on the hydrometer. This is to preclude an {402} incorrect reading by possible refraction in the glass cylinder.

«HYGROMETERS AND HYGROSCOPES:»

«Paper Hygrometers.»—Paper hygrometers are made by saturating white blotting paper with the following liquid and then hanging up to dry:

Cobalt chloride 1 ounce Sodium chloride 1⁠/⁠2 ounce Calcium chloride 75 grains Acacia 1⁠/⁠4 ounce Water 3 ounces

The amount of moisture in the atmosphere is roughly indicated by the changing color of the papers, as follows:

Rose red rain Pale red very moist Bluish red moist Lavender blue nearly dry Blue very dry

«Colored Hygroscopes.»—These instruments are often composed of a flower or a figure, of light muslin or paper, immersed in one of the following solutions:

I.—Cobalt chloride 1 part Gelatin 10 parts Water 100 parts

The normal coloring is pink; this color changes into violet in medium humid weather and into blue in very dry weather.

II.—Cupric chloride 1 part Gelatin 10 parts Water 100 parts

The color is yellow in dry weather.

III.—Cobalt chloride 1 part Gelatin 20 parts Nickel oxide 75 parts Cupric chloride 25 parts Water 200 parts

The color is green in dry weather.

HYOSCYAMUS, ANTIDOTE TO: See Atropine.

«ICE:»

See also Refrigeration.

«Measuring the Weight of Ice.»—A close estimate of the weight of ice can be reached by multiplying together the length, breadth, and thickness of the block in inches, and dividing the product by 30. This will be very closely the weight in pounds. Thus, if a block is 10 x 10 x 9, the product is 900, and this divided by 30 gives 30 pounds as correct weight. A block 10 x 10 x 6 weighs 20 pounds. This simple method can be easily applied, and it may serve to remove unjust suspicions, or to detect short weight.

«To Keep Ice in Small Quantities.»—To keep ice from melting, attention is called to an old preserving method. The ice is cracked with a hammer between 2 layers of a strong cloth. Tie over a common unglazed flower-pot, holding about 2 to 4 quarts and placed upon a porcelain dish, a piece of white flannel in such a manner that it is turned down funnel-like into the interior of the pot without touching the bottom. Placed in this flannel funnel the cracked ice keeps for days.

«ICE FLOWERS.»

Make a 2 per cent solution of the best clear gelatin in distilled water, filter, and flood the filtrate over any surface which it is desired to ornament. Drain off slightly, and if the weather is sufficiently cold, put the plate, as nearly level as possible, out into the cold air to freeze. In freezing, water is abstracted from the colloidal portion, which latter then assumes an efflorescent form, little flowers, with exuberant, graceful curves of crystals, showing up as foliage, from all over the surface. To preserve in permanent form all that is necessary is to flood them with absolute alcohol. This treatment removes the ice, thus leaving a lasting framework of gelatin which may be preserved indefinitely. In order to do this, as soon as the gelatin has become quite dry it should be either varnished, flowed with an alcoholic solution of clear shellac, or the gelatin may be rendered insoluble by contact, for a few moments, with a solution of potassium bichromate, and subsequent exposure to sunlight.