50 On a new Black Di/e. 



of wood of different kinds. All these colours incline eitlicf 

 to red or blue, and they resist but feebly the action of the 

 air, of water, and of acids. The tincture which I have 

 cou;posed, and which I use daily in dyeing all kinds of 

 cotton, silk, or wool stuffs to an unalterable black, embraces 

 an intimate ur^ion of the oxide of iron with that of copper 

 and the pyro-ligneous acid. 



Preparation of t lie Pi/ro-Ugneous Acid. 

 Take a tubulated retort made of plate iron, or of cast iron, 

 which is better, place it in a furnace in such a manner that 

 the neck be perfectly free, and the bottom receive directly 

 the heat of the fire. It nuist be luted carefully, and there 

 must be introduced into the retort some chcstr.ut wood cut 

 into small bits. The distillation then conmiences with a 

 very moderate fire, which is progressivelv increased till no 

 more liquid passes into the receiver. The acid which is 

 found in the receiver, mixed with a kind of oil, may be se- 

 parated from it by a filter of gray paper : the wood will be 

 reduced to charcoal in the retort. 



V 



Preparation of the Oxide of Iron. 

 Dissolve 4 pounds of vitriol (sulphate) of iron, very pure, 

 in 24 pounds of rain water. Dissolve in like manner 4 

 pounds of potash in ItJ pounds of filtered water. These two 

 solutions, when well nnxed, will appear at the beginning of 

 a deep green ; but in a little time the surface exposed to the 

 air will take a dark red colour; then pour the whole on a 

 filter of linen : the oxide which will remain after the water 

 has passed ought to be washed in a great deal of water, to 

 free it from all adhering salt. Leave this oxide exposed on 

 a plate to the action of the atmosphere, which will reduce it 

 to a state of red oxide. 



Preparation f the Oxide of Copper. 

 To prepare this oxide, take a pound of blue vitriol of 

 Cyprus (sulphate of copper), which dissolve in 12 pounds 

 of rainwater: make it boil, and mix with it a pound of 

 water saturated with potnsli, and you will obtain a green 

 jirecipitate, whl:.-;i mu't bo well washed after being filtered. 



Fn.Darutiun 



