1835.] Calico- Printing. 5 



PRELIMINARY PROCESSES. 



The cotton cloth, after being woven, is subjected to seve- 

 ral preliminary processes, before it is fit for calico-printing. 

 It will be sufficient merely to allude to them. They are 

 singeing and bleaching. The singeing is intended to remove 

 the fibres of cotton which protrude on the surface of the 

 cloth. This is done, by passing the cloth rapidly over the 

 surface of a red-hot iron cylinder, which burns off all the 

 hairs, or protruding fibres of the cotton, without injuring 

 the cloth. Of late years, an ingenious coal-gas apparatus 

 has been substituted for the red-hot iron, both in Manches- 

 ter and Glasgow. 



The bleaching of cotton consists essentially of four dif- 

 ferent processes. 1. The cloth is boiled with lime and 

 water; it is then washed clean. 2. It is steeped for some 

 hours in a solution of chloride of lime, or bleaching powder, 

 as it is usually called. From this steep also it is washed 

 clean. 3. It is boiled in a solution of American potash. 

 After the duty was taken off common salt, carbonate of 

 soda (and consequently caustic soda) became so cheap, 

 that it gradually took the place of pearl ashes * 4. The 

 cloth is now almost bleached; it requires only to be 

 steeped in water holding in solution about four per cent, 

 of sulphuric acid, to complete the process. 



Cotton cloth at an average, takes about two days to 

 bleach. But, when there happens to be occasion for greater 

 dispatch, it is no uncommon thing to complete the bleach- 

 ing and callendring in twenty- four hours. 



PRINTING. 



There are two modes of printing, namely, block-printing, 

 and cylinder-printing. The former has been practised from 

 time immemorial; the latter is a modern invention, and 

 originated, probably, after the introduction of the art of 

 printing into Great Britain. 



The block is a piece of sycamore, (or, more commonly, a 



* An impure Soda ash is now very generally used by Bleachers. For, 

 as every hundred pounds of crystallized carbonate of Soda contains 62£ of 

 water, the expense of carriage is more than double, and although the form indi- 

 cates in some measure the purity of this salt, every Bleacher knows how to 

 estimate the value of the drier preparation. 



