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 9.5 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

India rubber..... 2 ounces

Liquid storax..... 10 ounces

IX

Amalgamate by heat:

India rubber..... 100 ounces

Rosin........... 15 ounces

Shellac.......... 10 ounces

Then dissolve in bisulphide of carbon.

X

Make the following solutions separately and mix:

(a)  India rubber......      5 ounces

Chloroform......   140 ounces

(b)  India rubber.....       5 ounces

Rosin...........       2 ounces

Venice turpentine.       1 ounce

Oil of turpentine..     20 ounces