Blacking, a preparation applied to leather, designed either to preserve or to polish it. Ivory black, vinegar or sour beer, sugar or molasses, and a little sweet oil and sulphuric acid are the common ingredients. The corrosive properties of the acids are neutralized by the lime in the ivory black. It is made in the form of a paste, and also liquid. The following recipe (patented in England) is designed to give the leather somewhat of a waterproof quality: Dissolve 18 oz. of caoutchoucin 9 lbs. of hot rape oil; to this add 00 lbs. ivory black and 45 lbs. molasses, with 1 lb. finely ground gum arabic, previously dissolved in 20 gallons of vinegar, of strength No. 24; the whole to be well triturated in a paint mill till smooth. Then add, in small successive quantities, 12 lbs. sulphuric acid, stirring strongly for half an hour. The stirring is to be continued for half an hour a day during a fortnight, when 3 lbs. of gum arabic, in fine powder, are to be added, and the half hour's daily stirring continued another fortnight, when it is ready for use. For paste blacking the same ingredients and quantities are used, except that instead of 20 gallons of vinegar, 12 gallons will answer, and a week of stirring only is required.

A good blacking is also made more simply by mixing 3 oz. of ivory black, 2 of m dasses, a table-spoonful of sweet oil, 1 oz. of sulphuric acid, and 1 of gum arabic, dissolved in water and a pint of vinegar. - An excellent blacking for harness is prepared by. melting 2 oz. of mutton suet with 0 oz. of beeswax, to which are to be added 6 oz. of sugar candy, 2 oz. of soft soap dissolved in water, and 1 oz. of indigo finely powdered, and, when melted and well mixed, a gill of turpentine. It is to be put on with a sponge and polished with a brush. - Blacking for stoves may be made of finely powdered black lead, of which 1/2 lb. may be mixed with the whites of three eggs well beaten. The mixture is then to be diluted with sour beer or porter well stirred, and heated to simmering for about half an hour.