ON COLORING. 59 



ry in coloring the former goods, from that which is required for 

 the latter. The fibres of linen or cotton are prepared for dye- 

 ing by being first boiled in water, with a portion of potash, and 

 afterwards bleached. It should then be soaked in water soured 

 with sulphuric acid, to dissolve and remove all eaithy matter, 

 and then be thoroughly rinsed, to free it from the acid. Alum, 

 and not tin, must be used as the mordant, for although tin gives 

 yellows exceeding all others in lustre and beauty, on cotton, 

 they decay very speedily when exposed to the sun and air. 



For one lb. of cotton and linen yarn, or cloth, take alum 3 

 ounces, sugar of lead 1 ounce — dissolve them in cne gallon of 

 water, about blood warm, and soak the stuff two hours; take it 

 out, moderately squeeze or wring it, let it then be dried, and 

 then soaked again in the solution of alum, squeezed and dried 

 as before ; then let it be thoroughly washed in lime water and 

 dried as before. Let it then be well rinsed and put into a ket- 

 tle of cold water with three ounces of quercitron bark tied up 

 in a bag ; stirring it frequently, gradually raise the water to a 

 boiling heat, let it boil a few minutes only, as longer boiling 

 would injure the color, and take it out, rinse and dry as usual. 

 It has been found that by immersing cotton a great number of 

 times, alternately in the solution of alum and lime water, and 

 drying after each immersion, the color acquires greater body 

 and durability. The reason of this seems to be found in the 

 shrinking of the aluminous basis (the clay) in drying, and 

 thereby making room for an additional quantity to penetrate 

 the fibre after each drying, and the larger the quantity of this 

 substance united or incorporated with the cotton, the deeper and 

 more durable will be the color fixed upon it. 



There are other methods of preparing cotton, so that it will 

 take a sufficient quantity of the clay, from alum, without the 

 use of the sugar of lead, and which are, consequently, some- 

 what cheaper than the one described above. 



Take of the roots of our common sumach, (rhus glabrum) 

 dried and chipped, one pound, sal soda four ounces, or barilla 

 half a pound, which is an impure soda used by manufacturers 

 of hard soap, and in two or three gallons of soft water boil them 



