Make up a weak solution of soap containing a very small quantity of glue, and immerse paper in it until it is wet through. Now take it out, dip it into a solution of alum, and dry it. The alum, gluten, gelatine, and soap unite together, and form an insoluble compound, which coats every fibre of the textile fabric, and when dry repels water like the natural oil in the feathers of a duck. There are various substances which are soluble in water singly, but when combined form insoluble compounds, and _vice versa_. Alum, soap, and gelatine are soluble in water singly, but form insoluble compounds when united chemically. Oil is insoluble in water singly, but combined with caustic soda or potash it forms soluble soap. Such are some of the useful curiosities of chemistry. TO RENDER CANVAS WATER-PROOF. Take 7 lbs. of soap and dissolve it in two gallons of water, and while at the boiling heat add 3½ lbs. of the sulphate of zinc (white copperas). The sulphuric acid of the salt combines with the alkali of the soap, and the oxide of the salt combines with its oil and forms an insoluble metallic soap, which, when cold, rises to the surface and has the appearance of a white hard mass. This is afterwards re-boiled to purify it. The next step to be taken is to boil 2⅛ gallons of linseed oil along with one pound of potash until it assumes a soapy appearance. The whole is now boiled along with two pounds of fine animal charcoal and five quarts of water, which purifies the mixture, after an hour’s boiling, when the whole is filtered and is of a clear color. About one pound of sugar of lead (acetate) and one pound of rosin is mixed with the oil, and boiled for one hour. Into this mixture is stirred at a boiling heat, 2 lbs. of the metallic soap described above, and after it is dissolved, about two quarts of India-rubber dissolved in turpentine is added, and this completes the making of the mixture. This is put on to the canvas with a brush at the heat of 160° Fah. Two coats will be found sufficient to make it water-proof. More however may be applied. Each coat should be allowed to dry before the other is put on. If copperas be employed in this mixture, it will make it of a brown color, and cobalt a blue. To make leather water-proof, take equal quantities of the metallic soap and raw linseed oil, mix them together, and place the liquid in at a heat of 225° and suffer it to cool gradually. The leather should be dried in the atmosphere, when it will be perfectly pliable. Any quantity of the above may be made, so as the proportions are maintained. This is a first rate composition for the purpose stated, and one to which painters should give peculiar attention, so should the manufacturers of glazed and patent leather. JAPANNING LEATHER.