Muriatic Acid. 213 



acid, although the latter in most cases can be employed. 

 Muriatic acid commonly contains some sulphuric acid. 

 This is injurious in many cases, especially in mixtures of 

 mordants, in which salts of tin and muriatic acid occur 

 at the same time ; such is the case in the Tin Mordant, 

 No. I. We dissolve 1 lb. tin salt in 1 lb. water, and add 

 1 lb. muriatic acid. If any sulphuric acid be present, the 

 liquid asumes a brown colour, and acquires an odour of 

 sulphuretted hydrogen, which does not take place when 

 the muriatic acid is free from sulphuric acid. 



In order to render this tin mordant fit for use, it should 

 be placed in a close flask at rest ; it will then become clear 

 by the deposition of a brown sediment. The disagreeable 

 odour is still retained, but the dye is not injured. 



Muriatic acid corrodes cotton. This takes place more 

 rapidly according as the heat is stronger. It is necessary 

 to employ with precaution the mordants which contain free 

 muriatic acid ; and, pieces which are printed with it, must 

 not be allowed to hang for any length of time. 



But, when the mordants, displaced by muriatic acid, are 

 by preference caustic, which iron, lead, and other colours 

 require, and muriatic acid is the menstruum which dissolves 

 these colours; it loses thereby much of its Injurious pro- 

 perty, because it rather acts upon these dyes than upon the 

 cotton threads. Yet, a piece printed with such caustic 

 mordants must not be allowed to hang up for any length of 

 time ; but it is indispensably necessary to rinse it when the 

 mordant has finished its action. 



Muriatic acid is volatile. This property renders some 

 caution necessary. A mordant containing muriatic acid 

 must be well thickened, and the piece printed with it must 

 not hang in a moist atmosphere, otherwise the muriatic 

 acid escapes by the edges, and the pattern is destroyed. 



Muriatic acid dissolves (lost) easily in water, and thus 

 may still prove injurious to the dyed stuff; namely, in 

 washing the printed pieces with caustic mordant. The 

 acid may be made harmless, either by washing the pieces 

 completely in running water, in which case the acid is 

 quickly carried away, or it may first be passed through 

 chalk water, and afterwards washed in the usual way. 



The muriatic acid salts, as the muriate of alumina, cannot 



