39G INKS. 



till it is ht-ld near the fire, rubbed with another liquor, or some 

 other expedient is used to render the characters legible. 



Sympathetic inks are prepared from various substances, such as 

 bismuth, lead, &c. Thus, a solution of common sugar of lead in 

 water, if employed with a clean pen, will remain concealed till it is 

 wetted with a solution of the liver of sulphur, or is exposed to the 

 vapours of such liquid ; in which case it will assume a deeper or 

 lighter brown shade, in proportion to the strength of the sulphu. 

 reous gas. By the same process, words written with a solution of 

 bismuth in spirit of nitre, will appear of a deep black colour. 



Another sympathetic ink may be easily prepared, by diluting oil 

 of vitriol with a sufficient quantity of water, to prevent the paper 

 from being corroded. Letters drawn with this fluid are invisible 

 when dry, but, on being held near the fire, they assume a perfect 

 black colour. The juices of lemons or onions ; a solution of sal 

 ammoniac, &c. will answer a similar purpose, though their appli- 

 cation is more difficult, and they afterwards require a greater de- 

 gree of heat. 



INK, removing the stains of. The stains of ink, on cloth, paper 

 or wood, may be removed by almost all acids; but those acids are 

 to be preferred, which are least likely to injure the texture of the 

 stained substance. The muriatic acid, diluted with five or six 

 times its weight of water, may be applied to the spot, and, after a 

 minute or two, may be.washid oft', repeating the application as 

 often as may be found necessary. But the vegetable aciils are at- 

 tended wi'h less risk, and are equally effectual. A solution of the 

 oxalic, citric (acid of lemons), or tartareous acids, in water, may 

 be applied to the most delicate fabrics without any danger of in- 

 juring them: and the same solutions will discharge writing but not 

 printing-ink. Hence they may be employed in cleaning books 

 which have been df faced by writing on the margin, without impair- 

 ing the text. Lemon-juice, and the juice of sorrel, will also 

 remove ink-stains, but not so easily us the concrete acids of lemons, 

 or citric acid. 



IKK, for marking Linen. M. Ilaussman has given some com- 

 positions for marking pieces of cotton or linen, previous to their 

 being bleached, which are capable of resisting every operation in 

 the processes both of bleaching and dying, and consequently might 

 be employed in marking linen for domestic purposes. One of these 

 consists of asphaltum dissolved in about four parts of oil of turperu 



