CALICO-PRINTING 627 



to vary in its constituents from difference in the food of the animals, their health, &c. ; 

 the method of using substitutes for it being now -well known, and better colours and 

 whites being more easily obtained from them than with dung, this substance has 

 almost ceased to bo used in calico-printing processes. The dunging operation ought 

 to be a definite chemical decomposition, which cannot be the case with a variable 

 substance like dung. The substitutes for dung in use are : 



1. Phosphate of soda and lime. 



2. Arseniate of soda. 



3. Arsenite of soda. 



4. Silicate of soda. 

 6. Silicate of lime. 



Each of these has its peculiar virtues, and the printer determines for himself which 

 is best adapted for his styles. The first was patented by John Mercer, about 1842, and 

 is made by calcining bones, then decomposing them with sulphuric acid, filtering out 

 the sulphate of lime, and, to the clear superphosphate of lime, adding carbonate of soda 

 till slightly alkaline ; the resulting mixture of phosphate of soda and phosphate of lime 

 is dried down to a powder ; the use of arseniates formed part of the same patent. 

 Arsenite of soda followed as a matter of course, though not so safe in use as phos- 

 phates and arseniates. Silicate of soda was suggested by Adolph Schlieper, of Elber- 

 feld, and patented by Jager in 1852. It is the ordinary soluble glass dissolved in 

 water. It is open to the objection of being too alkaline, and requires care in the use. 

 The silicate of lime was suggested by Higgin with a view to remove this objection. 

 The silicate of lime is formed in the dung cistern, by mixing silicate of soda and 

 muriate of lime, when sparingly soluble silicate of lime is formed ; the quantity in 

 solution at one time being never so much as to be dangerous, and fresh portions 

 being dissolved as wanted. Dunging salts, or liquors, are now made by the manu- 

 facturing chemist, containing various mixtures, arseniates, phosphates, arsenites, &c., 

 which are adapted for every variety of dunging. Great economy of time and mate- 

 rial result from the use of these dung-substitutes. In some of the largest print-works, 

 instead of, as with dung, running off the spent-dung cistern after passing through 

 from 100 to 200 pieces, and having to fill again, and heat to the proper temperature, 

 it is found possible to run pieces through the same cistern charged with substitute, 

 at the rate of two pieces per minute half a day, and with light goods a whole day 

 before letting off; of course, occasionally adding some of the substitute, to make up 

 for that saturated by the mordants. The dunging process is always performed twice : 

 the first time in a cistern with rollers ; and the second, in a beck similar to a dye- 

 beck, washing well between. The first is called fly-dunging ; the other, second 

 dunging. 



The manner of immersing the goods, or passing them through the dung-bath, is an 

 important circumstance. They should be properly extended and free from folds, 

 which is secured by a series of cylinders. The immersion should take place as fast as 

 possible ; for the moment the hot water penetrates the mordanted cloth, the acetic acid 

 quits it, and, therefore, if the immersion was made slowly, or one ply after another, 

 the acid, as well as the uncombined mordant, become free, would spread their 

 influence, and would have time to dissolve the aluminous subsalts now combined with 

 the cloth, whence inequalities and impoverishment of the colours would ensue. 



The fly-dung cistern should be set with about 30 gallons of dung to 1,000 gallons of 

 water; or, to the same quantity, 3 to 4 gallons of dung-substitute liquor; a little chalk 

 is added, to make the cistern slightly milky. The heat varies for different styles 

 from 150 F. to boil. Where there is acid discharge or resist, and the colours are 

 heavy, fly-dunging at boil is necessary, to enable the acid to cut properly through the 

 colour ; the nearer to 150 F. that the bath will give good whites at, the better will 

 be the subsequent dyed colour. With cow-dung, an excess of it is injurious, both to 

 white ground and mordant. 



Figs. 373 and 374 are Furnival's arrangement of first and second dunging vessels. 

 A 1 to A is a smaller cistern provided with rollers, top and bottom, in which a stronger 

 solution of dunging liquor than that in the main vessel is sometimes put ; A A is the 

 main fly-dung vessel, divided into two compartments, made of cast-iron plates bolted 

 together. The whole fly-dung cistern is from 20 to 30 feet long, 4 feet wide, and 5 

 to 6 feet deep. The pieces enter the machine at the end 1, passes over and under 

 the rollers c c, being drawn through by the draw-rollers D, which are placed over the 

 divisions in the cistern ; these rollers being connected and turned by the driving-shaft 

 x ; they then pass through the compartment A B, where they are spirted with water 

 from perforated pipes fixed almost level with the top of tho cistern, and beaten by 

 the square beaters H, which are also connected with and turned by the shaft E ; F are 

 tho steam-pipes for heating the liquid. Tho cistern A A is set with a solution of 

 arseniate of soda, containing from 10 to 50 grains arsenic acid per gallon, according tq 



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