Stir flour and water together, mixing thoroughly, and add the other ingredients. After the stuff is well mixed, heat it, watching very carefully and removing the instant it stiffens.

This gum (also called gum tragacanth) is usually in the form of curls (i.e., leaf gum), which take a long time to properly dissolve in water—several weeks, in fact—but during the past few years there has been put on the market a powdered gum dragon which does not occupy so many days in dissolving. To make a mucilage from gum dragon a very large volume of water is required. For example, 1 ounce of the gum, either leaf or powder, will swell up and convert 1 gallon of water into a thickish mucilage in the course of 2 or 3 weeks. Only cold water must be used, and before using the mucilage, all whitish lumps (which are particles of undissolved gum) should be picked out or else the mucilage strained. The time of solution can be considerably shortened (to a few hours) by acidifying the water in which the gum is placed with a little sulphuric or oxalic acid; but as the resultant mucilage would contain traces of their presence, such acids are not permissible when the gum-dragon mucilage is to be used for mounting photographs.

Glycerine and gum arabic make a very good adhesive of a fluid nature suited to mounting photographs; and although glycerine is hygroscopic by itself, such tendency to absorb moisture is checked by the reverse nature of the gum arabic; consequently an ideal fluid mucilage is produced. The proportions of the several ingredients are these:

First dissolve the gum in the water, and then stir in the glycerine, and allow all débris from the gum to deposit before using. The following adhesive compound is also one that is free from chemical reactions, and is suited for photographic purposes:

Mix the gum arabic with half the water, and in the remainder of the water dissolve the gum dragon. When both solids are dissolved, mix them together, and then stir in the glycerine.

The following paste will be found a useful mountant:

Dissolve the gum in just sufficient water to completely dissolve it, then add the sugar, and when that has completely dissolved stir in the starch paste, and then boil the mixture until the starch is properly cooked.

A very strong, stiff paste for fastening cardboard mounts to frames, wood, and other materials is prepared by making a bowl of starch paste in the usual way, and then adding 1 ounce of Venice turpentine per pound of paste, and {42} boiling and stirring the mixture until the thick turpentine has become well incorporated. Venice turpentine stirred into flour paste and boiled will also be found a very adhesive cement for fastening cardboard, strawboard, leatherette, and skiver leather to wood or metal; but owing to the resinous nature of the Venice turpentine, such pastes are not suitable for mounting photographic prints. The following half-dozen compounds are suitable mountants to use with silver prints:

Soak the gelatine in water for an hour or two until it is completely softened; take the gelatine out of the water, and allow it to drain, and put it into a bottle and pour alcohol over it; add the glycerine (if the gelatine is soft, use only ¹/₂ ounce; if the gelatine is hard, use 1 ounce of the glycerine), then melt the gelatine by standing the bottle in a vessel of hot water, and shake up very well. For use, remelt by heat. The alcohol prevents the prints from stretching or cockling, as they are apt to, under the influence of the gelatine.

In the following compound, however, only sufficient alcohol is used to serve as an antiseptic, and prevent the agglutinant from decomposing: Dissolve 4 ounces of photographic gelatine in 16 ounces of water (first soaking the gelatine therein for an hour or two until it is completely softened), then remove the gelatine from the water, allow it to drain, and put it into the bottle, and pour the alcohol over it, and put in the glycerine (if the gelatine is soft, use only ¹/₂ ounce; if the gelatine is hard, use 1 ounce of the glycerine), then melt the gelatine by standing the bottle in a vessel of hot water, and shake up well and mix thoroughly. For use, remelt by heat. The alcohol prevents the print from stretching or cockling up under the influence of the gelatine.

The following paste agglutinant is one that is very permanent and useful for all purposes required in a photographic studio: Take 5 pints of water, 10 ounces of arrowroot, 1 ounce of gelatine, and a ¹/₂ pint (10 fluidounces) of alcohol, and proceed to combine them as follows: Make arrowroot into a thick cream with a little of the water, and in the remainder of the water soak the gelatine for a few hours, after which melt the gelatine in the water by heating it, add the arrowroot paste, and bring the mixture to the boil and allow to boil for 4 or 5 minutes, then allow to cool, and mix in the alcohol, adding a few drops of oil of cloves.

Perhaps one of the most useful compounds for photographic purposes is that prepared as follows: Soak 4 ounces of hard gelatine in 15 ounces of water for a few hours, then melt the gelatine by heating it in a glue pot until the solution is quite clear and free from lumps, stir in 65 fluidounces of cold water so that it is free from lumps, and pour in the boiling-hot solution of gelatine and continue stirring, and if the starch is not completely cooked, boil up the mixture for a few minutes until it “blows,” being careful to keep it well stirred so as not to burn; when cold add a few drops of carbolic acid or some essential oil as an antiseptic to prevent the compound from decomposing or becoming sour.

A useful photographic mucilage, which is very liquid, is obtained by mixing equal bulks of gum-arabic and gum-dragon mucilages of the same consistence. The mixture of these mucilages will be considerably thinner than either of them when alone.

As an agglutinant for general use in the studio, the following is recommended: Dissolve 2 ounces of gum arabic in 5 ounces of water, and for every 250 parts of the mucilage add 20 parts of a solution of sulphate of aluminum, prepared by dissolving 1 part of the sulphate in 20 parts of water (common alum should not be used, only the pure aluminum sulphate, because common alum is a mixture of sulphates, and usually contaminated with iron salts). The addition of the sulphate solution to the gum mucilage renders the latter less hygroscopic, and practically waterproof, besides being very adhesive to any materials, particularly those exhibiting a smooth surface.

Mucilages:

Dissolve the gums in 1 pint of water, strain and add the glycerine, in which the thymol is suspended; shake well and add sufficient water to make 2 pints. This separates on standing, but a single shake mixes it sufficiently for use.

Rub the rye flour and the acacia to a smooth paste with 8 ounces of cold water; strain through cheese cloth, and pour into 1 pint of boiling water and continue the heat until as thick as desired. When nearly cold add the glycerine and oil of cloves.

IV.—One part, by weight, of tragacanth, when mixed with 95-per-cent alcohol to form 4 fluidounces, forms a liquid in which a portion of the tragacanth is dissolved and the remainder suspended; this remains permanently fluid, never deteriorates, and can be used in place of the present mucilage; 4 to 8 minims to each ounce of mixture is sufficient to suspend any of the insoluble substances usually given in mixtures.

V.—To 250 parts of gum-arabic mucilage add 20 parts of water and 2 parts of sulphate of alumina and heat until dissolved.

VI.—Dissolve ¹/₂ pound gum tragacanth, powdered, ¹/₄ pound gum arabic, powdered, cold water to the desired consistency, and add 40 drops carbolic acid.

II.—Add to 250 parts of concentrated gum solution (2 parts of gum in 5 parts of water) 2 parts of crystallized aluminum sulphate dissolved in 20 parts of water. This mixture glues even unsized paper, pasteboard on pasteboard, wood on wood, glass, porcelain, and other substances on which labels frequently do not adhere well.

The gum arabic is first dissolved in some water, the sugar added, then the starch, after which the mixture is boiled for a few minutes in order to dissolve the starch, after which it is thinned down to the desired consistency.

Cheaper envelope gums can be made by substituting dextrine for the gum arabic, glucose for the sugar, and adding boric acid to preserve and help stiffen it.

ADULTERANTS IN FOODS: See Foods.

ADUROL DEVELOPER: See Photography.

ÆSCO-QUININE: See Horse Chestnut.

AGAR AGAR PASTE: See Adhesives.

AGATE, BUTTONS OF ARTIFICIAL.

Prepare a mixture or frit of 33 parts of quartz sand, 65 parts calcium phosphate, and 2 parts of potash. The frit, which has been reduced by heat to the fusing point, is finely ground, intimately mingled with a small quantity of kaolin and pressed in molds which yield button-shaped masses. These masses, after having been fired, are given a transparent glaze by any of the well-known processes.

AGATE (IMITATION): See Gems, Artificial.

AGING OF SILK: See Silk.

AGING, SILVER AND GOLD: See Plating.

AIR BATH.

This air bath is employed in cases in which, upon drying or heating substances, acid vapors arise because the walls of the bath are not attacked by them. For the production of the drying apparatus take a flask with the bottom burst off or a bell jar tubulated above. This is placed either upon a sand bath or upon asbestos paper, previously laid upon a piece of sheet iron. The sand bath or the sheet iron is put on a tripod, so that it can be heated by means of a burner placed underneath. The substance to be dried is placed in a glass or porcelain dish, which is put under the bell jar, and if desired the drying dish may be hung on the tripod. For regulating the temperature the tubulure of the jar is closed with a pierced cork, through whose aperture the thermometer is thrust. In order to permit the vapors to escape, the cork is grooved lengthwise along the periphery.

AIR BUBBLES IN GELATINE: See Gelatine.

AIR, EXCLUSION OF, FROM SOLUTIONS: See Photography.

AIR-PURIFYING.

ALABASTER CLEANING: See Cleaning Preparations and Methods.

ALBATA METAL: See Alloys.

ALBUMEN IN URINE, DETECTION OF.

Patein (Pharm. Zeit.) recommends the following test for albumen in urine: Dissolve 250 grams of citric acid in a sufficient quantity of water, add enough ammonia to neutralize, then 50 grams of alcohol, and finally enough water to make 1 liter. To the acid (or acidulated) urine, one-tenth its volume of the ammonium-citrate solution made as above is added, and the whole heated in the usual manner. The appearance of the faintest turbidity is said to indicate with positive certainty the presence of albumen.

ALBUMEN PAPER: See Photography.

ALBUMEN PASTE: See Adhesives.

ALCOHOL

After the manuscript of this book was ready for the press, Congress passed the bill which has since become a law, whereby the prohibitive tax on industrial or denatured alcohol is removed. So important is this legislative measure that the Editor has deemed it wise to insert an article on the sources of alcohol and the manufacture of alcohol from farm products. Because the first portion of the book was in type when this step was decided upon, the Editor was compelled to relegate to a later page a monograph which should properly have appeared here. The reader will find the matter on alcohol referred to under the heading {45} “Spirit”; likewise methods of denaturing and a list of denaturants.

ALCOHOL, DILUTION OF: See Tables.

Absolute alcohol is a clear, colorless, volatile, readily imflammable liquid which burns with a faintly luminous flame. Absolute alcohol has a peculiar odor, a burning taste, and does not affect litmus paper. Boiling point, 78.50. Specific gravity, 0.795 to 0.797. One hundred parts contain 99.7 to 99.4 parts, by volume, or 99.6 to 99.0 parts, by weight, of alcohol.

Absolute alcohol should have no foreign smell and should mix with water without cloudiness.

After the admixture of 5 drops of silver-nitrate solution, 10 cubic centimeters of absolute alcohol should not become turbid or colored even on heating.

A mixture of 10 cubic centimeters of absolute alcohol and 0.2 cubic centimeter of potash lye evaporated down to 1 cubic centimeter should not exhibit an odor of fusel oil after supersaturation with dilute sulphuric acid.

Five cubic centimeters of sulphuric acid, carefully covered, in a test tube, with a stratum of 5 cubic centimeters of absolute alcohol, should not form a rose-colored zone at the surface of contact, even on standing for some time.

The red color of a mixture of 10 cubic centimeters of absolute alcohol and 1 cubic centimeter of potassium-permanganate solution should not pass into yellow before 20 minutes.

Absolute alcohol should not be dyed by hydrogen sulphide water or by aqueous ammonia.

Five cubic centimeters of absolute alcohol should not leave behind a weighable residue after evaporation on water bath.

Perfumed Denaturized Alcohol.—

Dissolve the oils in the spirit and add the amyl acetate. The mixture serves for destroying the bad odor of denaturized spirit in distilling. Use 50 parts of the perfume per 1,000 parts of spirit.

II.—Smaragdine is a trade name for solidified alcohol. It consists of alcohol and gun cotton, colored with malachite green. It appears in the market in the form of small cubes.

Alcohol Deodorizer.—

Mix the lime and alum intimately by trituration; add the alcohol and shake well; then add the spirit of nitrous ether; set aside for 7 days and filter through animal charcoal.

I.—Complete denaturization by the German system is accomplished by the addition to every 100 liters (equal to 26 ¹/₂ gallons) of spirits:

(a) Two and one-half liters of the “standard” denaturizer, made of 4 parts of wood alcohol, 1 part of pyridine (a nitrogenous base obtained by distilling bone oil or coal tar), with the addition of 50 grams to each liter of oil of lavender or rosemary.

(b) One and one-fourth liters of the above “standard” and 2 liters of benzol with every 100 liters of alcohol.

II.—Incomplete denaturization—i. e., sufficient to prevent alcohol from being drunk, but not to disqualify it from use for various special purposes, for which the wholly denaturized spirits would be unavailable—is accomplished by several methods as follows, the quantity and nature of each substance given being the prescribed dose for each 100 liters (26 ¹/₂ gallons) of spirits:

(c) Five liters of wood alcohol or ¹/₂ liter of pyridine.

(d) Twenty liters of solution of shellac, containing 1 part gum to 2 parts alcohol of 90-per-cent purity. Alcohol for the manufacture of celluloid and pegamoid is denaturized.

(e) By the addition of 1 kilogram of camphor or 2 liters oil of turpentine or ¹/₂ liter benzol to each 100 liters of spirits. Alcohol to be used in the manufacture of ethers, aldehyde, agaricin, white lead, bromo-silver gelatines, photographic papers and plates, electrode plates, collodion, salicylic acid and salts, aniline chemistry, and a great number of other purposes, is denaturized by the addition of—

(f) Ten liters sulphuric ether, or 1 part of benzol, or ¹/₂ part oil of turpentine, or 0.025 part of animal oil.

For the manufacture of varnishes and inks alcohol is denaturized by the addition of oil of turpentine or animal oil, and for the production of soda soaps by the addition of 1 kilogram of castor oil. Alcohol for the production of lanolin is prepared by adding 5 liters of benzine to each hectoliter of spirits.

Ale.

The ale of the modern brewer is manufactured in several varieties, which are determined by the wants of the consumer and the particular market for which it is intended. Thus, the finer kinds of Burton, East India, Bavarian, and other like ales, having undergone a thorough fermentation, contain only a small quantity of undecomposed sugar and gum, varying from 1 to 5 per cent. Some of these are highly “hopped” or “bittered,” the further to promote their preservation during transit and change of temperature. Mild or sweet ales, on the contrary, are less accentuated by lengthened fermentation, and abound in saccharine and gummy matter. They are, therefore, more nutritious, though less intoxicating, than those previously referred to.

In brewing the finer kinds of ales, pale malt and the best hops of the current season’s growth are always employed; and when it is desired to produce a liquor possessing little color, very great attention is paid to their selection. With the same object, the boiling is conducted with more than the usual precautions, and the fermentation is carried on at a somewhat lower temperature than that commonly allowed for other varieties of beer. For ordinary ale, intended for immediate use, the malt may be all pale; but, if the liquor be brewed for keeping, and in warm weather, when a slight color is not objectionable, one-fifth, or even one-fourth of amber malt may be advantageously employed. From 4 ¹/₂ to 6 pounds of hops is the quantity commonly used to the one-fourth of malt, for ordinary ales; and 7 pounds to 10 pounds for “keeping” ales. The proportions, however, must greatly depend on the intended quality and description of the brewing and the period that will be allowed for its maturation.

The stronger varieties of ale usually contain from 6 to 8 per cent of “absolute alcohol”; ordinary strong ale, 4 ¹/₂ to 6 per cent; mild ale, 3 to 4 percent; and table ale, 1 to 1 ¹/₂ per cent (each by volume); together with some undecomposed saccharine, gummy, and extractive matter, the bitter and narcotic principles of the hop, some acetic acid formed by the oxidation of the alcohol, and very small and variable quantities of mineral and saline matter.

Ordinary ale-wort (preferably pale), sufficient to produce 1 barrel, is slowly boiled with about 3 handfuls of hops, and 12 to 14 pounds of crushed groats, until the whole of the soluble matter of the latter is extracted. The resulting liquor, after being run through a coarse strainer and become lukewarm, is fermented with 2 or 3 pints of yeast; and, as soon as the fermentation is at its height, is either closely bunged up for draft or is at once put into strong stoneware bottles, which are then well corked and wired.

White ale is said to be very nutritious, though apt to prove laxative to those {47} unaccustomed to its use. It is drunk in a state of effervescence or lively fermentation; the glass or cup containing it being kept in constant motion, when removed from the mouth, until the whole is consumed, in order that the thicker portion may not subside to the bottom.

ALE, GINGER: See Beverages.

ALFENIDE METAL: See Alloys.

ALKALI, HOW TO DETECT: See Soaps.

ALKALOIDS, ANTIDOTES TO: See Atropine.

ALLOYS

No general rules can be given for alloying metals. Alloys differing greatly in fusibility are commonly made by adding the more fusible ones, either in the melted state or in small portions at a time, to the other melted or heated to the lowest possible temperature at which a perfect union will take place between them. The mixture is usually effected under a flux, or some material that will promote liquefaction and prevent volatilization and unnecessary exposure to the air. Thus, in melting lead and tin together for solder, rosin or tallow is thrown upon the surface is rubbed with sal ammoniac; and in combining some metals, powdered charcoal is used for the same purpose. Mercury or quicksilver combines with many metals in the cold, forming AMALGAMS, or easily fusible alloys (q. v.).

Alloys generally possess characteristics unshared by their component metals. Thus, copper and zinc form brass, which has a different density, hardness, and color from either of its constituents. Whether the metals tend to unite in atomic proportions or in any definite ratio is still undetermined. The evidence afforded by the natural alloys of gold and silver, and by the phenomena accompanying the cooling of several alloys from the state of fusion, goes far to prove that such is the case (Rudberg). The subject is, however, one of considerable difficulty, as metals and metallic compounds are generally soluble in each other, and unite by simple fusion and contact. That they do not combine indifferently with each other, but exercise a species of elective affinity not dissimilar to other bodies, is clearly shown by the homogeneity and superior quality of many alloys in which the constituent metals are in atomic proportion. The variation of the specific gravity and melting points of alloys from the mean of those of their component metals also affords strong evidence of a chemical change having taken place. Thus, alloys generally melt at lower temperatures than their separate metals. They also usually possess more tenacity and hardness than the mean of their constituents.

Matthiessen found that when weights are suspended to spirals of hard-drawn wire made of copper, gold, or platinum, they become nearly straightened when stretched by a moderate weight; but wires of equal dimensions composed of copper-tin (12 per cent of tin), silver-platinum (36 per cent of platinum), and gold-copper (84 per cent of copper) scarcely undergo any permanent change in form when subjected to tension by the same weight.

The same chemist gives the following approximate results upon the tenacity of certain metals and wires hard-drawn through the same gauge (No. 23):

On the other hand, the malleability, ductility, and power of resisting oxygen of alloys is generally diminished. The alloy formed of two brittle metals is always brittle; that of a brittle and a ductile metal, generally so; and even two ductile metals sometimes unite to form a brittle compound. The alloys formed of metals having different fusing points are usually malleable while cold and brittle while hot. The action of the air on alloys is generally less than on their simple metals, unless the former are heated. A mixture of 1 part of tin and 3 parts of lead is scarcely acted on at common temperatures; but at a red heat it readily takes fire, and continues to burn for some time like a piece of bad turf. In like manner, a mixture of tin and zinc, when strongly heated, decomposes both moist air and steam with rapidity.

The specific gravity of alloys is rarely {48} the arithmetical mean of that of their constituents, as commonly taught; and in many cases considerable condensation or expansion occurs. When there is a strong affinity between two metals, the density of their alloy is generally greater than the calculated mean; and vice versa, as may be seen in the following table:

• ALLOYS HAVING A DENSITY
  • Greater than the Mean of their Constituents:
    • Copper and bismuth,
    • Copper and palladium,
    • Copper and tin,
    • Copper and zinc,
    • Gold and antimony,
    • Gold and bismuth,
    • Gold and cobalt,
    • Gold and tin,
    • Gold and zinc,
    • Lead and antimony,
    • Palladium and bismuth,
    • Silver and antimony,
    • Silver and bismuth,
    • Silver and lead,
    • Silver and tin,
    • Silver and zinc.
  • Less than the Mean of their Constituents:
    • Gold and copper,
    • Gold and iridium,
    • Gold and iron,
    • Gold and lead,
    • Gold and nickel,
    • Gold and silver,
    • Iron and antimony,
    • Iron and bismuth,
    • Iron and lead,
    • Nickel and arsenic,
    • Silver and copper,
    • Tin and antimony,
    • Tin and lead,
    • Tin and palladium,
    • Zinc and antimony.

1. Melt the least fusible, oxidizable, and volatile first, and then add the others heated to their point of fusion or near it. Thus, if it is desired to make an alloy of exactly 1 part of copper and 3 of zinc, it will be impossible to do so by putting proportions of the metals in a crucible and exposing the whole to heat. Much of the zinc would fly off in vapor before the copper was melted. First, melt the copper and add the zinc, which has been melted in another crucible. The zinc should be in excess, as some of it will be lost anyway.

2. Some alloys, as copper and zinc, copper and arsenic, may be formed by exposing heated plates of the least fusible metal to the vapor of the other. In making brass in the large way, thin plates of copper are dissolved, as it were, in melted zinc until the proper proportions have been obtained.

3. The surface of all oxidizable metals should be covered with some protecting agent, as tallow for very fusible ones, rosin for lead and tin, charcoal for zinc, copper, etc.

4. Stir the metal before casting and if possible, when casting, with a whitewood stick; this is much better for the purpose than an iron rod.

5. If possible, add a small portion of old alloy to the new. If the alloy is required to make sharp castings and strength is not a very great object, the proportion of old alloy to the new should be increased. In all cases a new or thoroughly well-cleansed crucible should be used.

To obtain metals and metallic alloys from their compounds, such as oxides, sulphides, chlorides, etc., a process lately patented makes use of the reducing qualities of aluminum or its alloys with magnesium. The finely powdered material (e. g., chromic oxide) is placed in a crucible mixed with aluminum oxide. The mixture is set afire by means of a soldering pipe or a burning magnesium wire, and the desired reaction takes place. For igniting, one may also employ with advantage a special priming cartridge consisting of pulverized aluminum to which a little magnesium may be mixed, and peroxide of magnesia, which is shaped into balls and lighted with a magnesium wire. By suitable additions to the pulverized mixture, alloys containing aluminum, magnetism, chromium, manganese, copper, iron, boron, silicic acid, etc., are obtained.

Aluminum Alloys.

M. H. Pecheux has contributed to the Comptes Rendus, from time to time, the results of his investigations into the alloys of aluminum with soft metals, and the following constitutes a brief summary of his observations: