Henley's Twentieth Century Formulas, Recipes and Processes. Various

with a little benzine or oil of turpentine and applied while still warm. The cement is waterproof.

      III.—The National Druggist says that experience with pasting or cementing parchment paper seems to show that about the best agent is casein cement, made by dissolving casein in a saturated aqueous solution of borax.

      IV.—The following is recommended for paper boxes:

Chloral hydrate	5 parts
Gelatin, white	8 parts
Gum arabic	2 parts
Boiling water	30 parts

      Mix the chloral, gelatin, and gum arabic in a porcelain container, pour the boiling water over the mixture and let stand for 1 day, giving it a vigorous stirring several times during the day. In cold weather this is apt to get hard and stiff, but this may be obviated by standing the container in warm water for a few minutes. This paste adheres to any surface whatever.

      Waterproof Cements For Glass, Stoneware, And Metal.

      —I.—Make a paste of sulphur, sal ammoniac, iron filings, and boiled oil.

      II.—Mix together dry: Whiting, 6 pounds; plaster of Paris, 3 pounds; sand, 3 pounds; litharge, 3 pounds; rosin, 1 pound. Make to a paste with copal varnish.

      III.—Make a paste of boiled oil, 6 pounds; copal, 6 pounds; litharge, 2 pounds; white lead, 1 pound.

      IV.—Make a paste with boiled oil, 3 pounds; brickdust 2 pounds; dry slaked lime, 1 pound.

      V.—Dissolve 93 ounces of alum and 93 ounces of sugar of lead in water to concentration. Dissolve separately 152 ounces of gum arabic in 25 gallons of water, and then stir in 62 ¹/₂ pounds of flour. Then heat to a uniform paste with the metallic salts, but take care not to boil the mass.

      VI.—For Iron and Marble to Stand in Heat.—In 3 pounds of water dissolve first, 1 pound water glass and then 1 pound of borax. With the solution make 2 pounds of clay and 1 pound of barytes, first mixed dry, to a paste.

      VII.—Glue to Resist Boiling Water.—Dissolve separately in water 55 pounds of glue and a mixture of 40 pounds of bichromate and 5 pounds of alum. Mix as wanted.

      VIII. (Chinese Glue).—Dissolve shellac in 10 times its weight of ammonia.

      IX.—Make a paste of 40 ounces of dry slaked lime 10 ounces of alum, and 50 ounces of white of egg.

X.—	Alcohol	1,000 parts
Sandarac	60 parts
Mastic	60 parts
Turpentine oil	60 parts

      Dissolve the gums in the alcohol and add the oil and stir in. Now prepare a solution of equal parts of glue and isinglass, by soaking 125 parts of each in cold water until it becomes saturated, pouring and pressing off the residue, and melting on the water bath. This should produce a volume of glue nearly equal to that of the solution of gums. The latter should, in the meantime, have been cautiously raised to the boiling point on the water bath, and then mixed with the hot glue solution.

      It is said that articles united with this substance will stand the strain of cold water for an unlimited time, and it takes hot water even a long time to affect it. {22}

XI.—	Burgundy pitch	6 parts
Gutta percha	1 part
Pumice stone, in fine powder	3 parts

      Melt the gutta percha very carefully add the pumice stone, and lastly the pitch, and stir until homogeneous.

      Use while still hot. This cement will withstand water and dilute mineral acids.

      Leather And Rubber Cements.

      I.—Use a melted mixture of gutta percha and genuine asphalt, applied hot. The hard-rubber goods must be kept pressed together until the cement has cooled.

      II.—A cement which is effective for cementing rubber to iron and which is especially valuable for fastening rubber bands to bandsaw wheels is made as follows: Powdered shellac, 1 part; strong water of ammonia, 10 parts. Put the shellac in the ammonia water and set it away in a tightly closed jar for 3 or 4 weeks. By that time the mixture will become a perfectly liquid transparent mass and is then ready for use. When applied to rubber the ammonia softens it, but it quickly evaporates, leaving the rubber in the same condition as before. The shellac clings to the iron and thus forms a firm bond between the iron and the rubber.

III.—	Gutta percha white	1 drachm
Carbon disulphide	1 ounce
Dissolve, filter, and add:
India rubber	15 grains
Dissolve.

      Cement For Metal On Hard Rubber.

      —I.—Soak good Cologne glue and boil down so as to give it the consistency of joiners’ glue, and add with constant stirring, enough sifted wood ashes until a homogeneous, moderately thick mass results. Use warm and fit the pieces well together while drying.

      How To Unite Rubber And Leather.

      —II.—Roughen both surfaces, the leather and the rubber, with a sharp glass edge; apply to both a diluted solution of gutta percha in carbon bisulphide and let this solution soak into the material. Then press upon each surface a skin of gutta percha 1/10 of an inch in thickness between rolls. The two surfaces are now united in a press, which should be warm but not hot. This method should answer in all cases in which it is applicable. The other prescription covers cases in which a press cannot be used. Cut 30 parts of rubber into small pieces, and dissolve it in 140 parts of carbon bisulphide, the vessel being placed on a water bath of 30° C. (86° F.). Further, melt 10 parts of rubber with 15 of colophony, and add 35 parts of oil of turpentine. When the rubber has been completely dissolved, the two liquids may be mixed. The resulting cement must be kept well corked.

      To Fasten Rubber To Wood.

      —I.—Make a cement by macerating virgin gum rubber, or as pure rubber as can be had, cut in small pieces, in just enough naphtha or gasoline to cover it. Let it stand in a very tightly corked or sealed jar for 14 days, or a sufficient time to become dissolved, shaking the mixture daily.

      II.—Dissolve pulverized gum shellac, 1 ounce, in 9 ¹/₂ ounces of strong ammonia. This of course must be kept tightly corked. It will not be as elastic as the first preparation.

      III.—Fuse together shellac and gutta percha in equal weights.

IV.—	India rubber	8 ounces
Gutta percha	4 ounces
Isinglass	2 ounces
Bisulphide of carbon	32 ounces
V.—	India rubber	5 ounces
Gum mastic	1 ounce
Chloroform	3 ounces
VI.—	Gutta percha	16 ounces
India rubber	4 ounces
Pitch	4 ounces
Shellac	1 ounce
Linseed oil	1 ounce

      Amalgamate by heat.

      VII.—Mix 1 ounce of oil of turpentine with 10 ounces of bisulphide of carbon in which as much gutta percha as possible has been dissolved.

      VIII.—Amalgamate by heat:

Gutta percha	100 ounces
Venice turpentine	80 ounces
Shellac	8 ounces
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