3. A third with one half of the solid acids of the second.

4. Take 1 gallon of water, in which dissolve with heat

1 pound of cream of tartar adding, to facilitate the solution,

1 pound of warm sulphuric acid of spec. grav. 1·7674; after 24

hours mix

4 libs. of pipe or China clay, and three libs. of gum with the

decanted clear liquor.

In some cases British gum is used alone, as a thickener.