ACETATES AND THEIR MANUFACTURE. 273 



which impairs very much the beauty and gloss of the color given 

 to the cloth. 



A better mordant is made by decomposing alum by lead acetate. 

 Since lead sulphate is insoluble the decomposition of the alum 

 solution is more perfect than when it is acted upon by acetate of 

 lime ; nevertheless, red liquor is not a true acetate, but a mixture 

 of aluminium acetate, sulphate and hydrate, with potassium sul- 

 phate, as will be seen from the receipts in general use for its 

 manufacture. In practice it is found advantageous to employ 

 equal parts of alum and sugar of lead, or even a rather less 

 quantity of the latter. The alum is dissolved in boiling water, 

 and the powdered lead acetate added to the solution. About 

 one-tenth of crystallized carbonate of soda, or a little carbonate 

 of lime, is added to the alum to combine with the free acid. 

 The three following receipts serve to indicate the proportions 

 employed : 



I. Dissolve 100 pounds of alum in 50 gallons of boiling water, 

 and add 10 pounds of acetate of lead in fine powder, stirring the 

 mixture well at first, and likewise several times during cooling. 



II. Dissolve 100 pounds of alum in 50 gallons of boiling 

 water, add slowly 10 pounds of crystallized carbonate of soda, 

 and then stir in 50 pounds of acetate of lead in powder. 



III. Dissolve 100 pounds of alum in 50 gallons of boiling 

 water, and add in small portions 6 pounds of crystallized carbon- 

 ate of soda, and then stir in 50 pounds of acetate of lead, in 

 powder, as before. 



When used by the calico printer the red liquor is thickened 

 with gum or some other suitable material, and with it the design 

 is impressed upon the cloth by a wood block, or by any other 

 means; on subsequently submitting the goods to the drying-bath, 

 acetic acid is partly volatilized, and the aluminous basic compound 

 remains perfectly combined with the cloth. 



Grace Calvert states, from practical observations, that a sulpli- 

 acetate of alumina is to be preferred as giving the most satisfac- 

 tory results. He considers that a mordant of such a composition 

 is best adapted for fixing the colors, on account of the excess of 

 alumina in such a solution above those which contain, besides the 

 .18 



