One of the most popular recipes for ink for typewriter ribbons is as follows. Melt some petrolatum, having a high boiling point, on a water bath. Petrolatum is a soft hydrocarbon obtained from the residues left after the distillation of lighter oils from crude petroleum, or it may be deposited by the latter on standing; its commoner name is vaseline. Incorporate as much lampblack or powdered dropblack as the petrolatum will take up without becoming granular. When the mixture is partly cool, dissolve it, a little at a time, in a mixture of equal parts of petroleum, benzine, and rectified oil of turpentine. Regulate the quantity of the latter solvents to produce a solution of the consistency of fresh oil paint. Try on one end of the ribbon and, if too thin, add wax; if too faint, add colour if too hard, add vaseline. Apply to the ribbon and brush off the excess. Many typewriter inks have glycerine, a very undesirable ingredient, as the vehicle for the colouring matter. The following recipes are typical of the com. position of such inks.

(1) Dissolve 1/4oz. of aniline dye in 4 oz. of glycerine, and add 2 oz. of alcohol and 2 oz. of water.

(2) Dissolve 1 part (by weight) of powdered aniline dye in 6 parts of glycerine, and add 3 parts of soft soap. Warm until the soap dissolves and well mix.

(3) Dissolve 1/2oz. of aniline dye in 15 fl. oz. of alcohol, and add 15 fl. oz. of glycerine.

(4) A good ink is made by dissolving 1 part of aniline dye (soluble in oil) in 6 or 8 parts of oil of cloves; gentle heat assists the solution.

The aniline dye in these four recipes may be of any suitable colour ; black and violet are perhaps the most serviceable. Another method of making a black ink is to grind 1 part of gas black with 5 parts of oil of cloves. All inks containing aniline colouring matter and glycerine are copying inks. Two other recipes for copying inks are here given.

(1) Grind 1 part (by weight) of suitable aniline colouring matter with 6 parts of glycerine.

(2) Dissolve, by the aid of heat, 1 oz. of transparent soap in a mixture of 4 fl. oz. of glycerine and 12fl. oz. of water; mix with a solution of a sufficient quantity of aniline dye in 21 fl. oz. of alcohol. If the ink is too thin, add soap.

The unsatisfactory results given by home-made typewriter inks appear to be caused by the use of glycerine as one of the ingredients, according to Prof. Shuttle-worth. The hygroscopic properties of glycerine make it an undesirable ingredient, and the addition of glucose, soap, alcohol, or water does not improve matters. Vaseline, with or without the addition of wax, gives better results, but its consistence is appreciably affected by temperature. Prof. Shuttleworth proposes castor oil as a more suitable medium; the colouring matter may be any of the salts of the aniline series, and of these methyl violet is practically soluble in the oil mentioned. In preparing the ink, triturate the powdered colour with the oil in the mortar, the work being facilitated by the addition of a very little alcohol A suitable formula for such an ink is that of Higgins. Castor oil, 4oz.; carbolic acid, loz.; oil of cassia, loz.; suitable aniline colour, loz. Printing inks may be modified for service in the typewriter by adding vaseline to make them non-drying on the ribbon; if it is found that they are too soft, add wax also.