INK-MAKING. 307 



dark blue precipitate takes place. This precipitate 

 is the gallic acid of the galls united to the iron of 

 the green vitriol, forming gallat of iron, which is 

 the basis of writing ink. If galls and sulphate of 

 iron only were used, the precipitate would fall 

 down, leaving the water colourless ; and, in order 

 to keep it suspended in the water, forming a per- 

 manently black, or rather very dark blue fluid, gum 

 arabic is added, which, by its viscid nature, pre- 

 vents the precipitate from falling down. 



Various receipts have been given for the compo- 

 sition of writing ink, but very few have been 

 founded upon a knowledge of its real nature. 

 Though so important an article, it is but lately that 

 it has been studied with any attention ; and even 

 still, the principles and theory of its formation do 

 not appear to be so thoroughly understood as might 

 be wished. The receipt given by M. Ribancourt 

 is as follows : Take eight ounces of Aleppo galls, 

 in coarse powder; four ounces of logwood, in thin 

 chips ; four ounces of sulphate of iron (green cop- 

 peras) ; three ounces of gum arabic, in powder ; 

 one ounce of sulphate of copper (blue vitriol) ; and 

 one ounce of sugar-candy. Boil the galls and log- 

 wood together in twelve pounds of water for one 

 hour, or till half the liquid has been evaporated. 

 Strain the decoction through a hair sieve, or linen 

 cloth, and then add the other ingredients. Stir the 

 mixture till the whole is dissolved, more especially 

 the gum ; after which, leave it to subside for 

 twenty-four hours. Then decant the ink, and pre- 

 serve it in bottles of glass or stone-ware, well corked. 



Red writing ink is made in the following manner : 

 Take of the raspings of Brazil wood a quarter of a 

 pound, and infuse them two or three days in vine- 

 gar. Boil the infusion for an hour over a gentle 



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