[ 165 ] 



XXVII. Process employed to oh tarn a Black Liquid, invented 

 by Mr. Clarke, an Englishman, and introduced into 

 Commerce ; its Use in marking Linen in a solid and dura- 

 hie Manner, and its Application for printing Cotto?is or 

 Stuffs. By M. Hermbstadt, of Berlin. 



jC or these two or three years past, ablack tinclure has been 

 sold for the purpose of marking Unen. 



A glass polisher and directions for using the tincture 

 accompany the two bottles which contain the ingredients, 

 and the whole is sealed up in a case. 



One of the bottles contains the mordant. The other con- 

 tains the iuk, which is of a deep brown colour, and which 

 must be well shaken before making use of it, because it 

 subsides when left to rest. 



The part of the linen intended to be marked must be in 

 the first place impregnated with the mordant, which is al- 

 lowed to dry on the linen. The place which had been wetted 

 is then rubbed with the polisher; an ordinary pen is then 

 dipped in the ink, and the writing is performed on the linen 

 the same as on paper. Neither soap nor any chemical pre- 

 paration will destroy this writing, which, when well dried, 

 is of a very fine black. 



Having chemically analysed these two liquids, I am able 

 to give an account of the ingredients whi.ch compose them. 



Preparation cf the Ink. 



Dissolve in iiitric acid (aquafortis) what quantity of silver 

 you please. This solution, if the silver has been alloyed 

 with copper, will be of a sapphire blue. 



In order to separate the copper from the silver add to the 

 solution twelve times its weight of distilled water, or, for 

 want of it, rain water^ and suspend in it a thin plate of cop- 

 per. In proportion as this plate dissolves, the silver will 

 precipitate itself, perfectly pure, in the form of a white pow- 

 der. When no more of this powder will precipitate itself, 

 the liquor should be decanted. The powder is then washed 

 in 3 great quantity of water, until the water thrown upon it 

 » L 3 is 



