New Bark /or Dyeing, called Paraguatan. 93 



eient to leave a certain quantity in the bafons expofed to the cold during the winter. It 

 would not indeed be proper to extraft the common fait from thefe waters, after having 

 feparated the fulphate of foda, becaufe they would then contain too great a quantity of mu- 

 riate of magnefia. It would be more advantageous to add fulphate of iron to prepare the 

 fulphates of foda and of magnefia. 



With regard to fuch waters as do not contain any fulphate of magnefia, which is very 

 rare, it would (till be of advantage to purify them by thefe means ; becaufe the water mull 

 be very bad, and highly charged with deliquefcent falts, to require more than fifty or fe- 

 venty-five pounds of fulphate of foda for thirty quintals of fait obtained by evaporation. 



In order to make ufe of this method, it is proper to be well acquainted with the prin- 

 ciples which enter into the compofition of the water intended to be purified. It then will 

 be known whether lime alone, or fulphate of foda, or both fubllances together, ought to be 

 ufed. Immediate experiment muft afterwards determine what quantity ought to be ufcd 

 to infure the mod perfeft fuccefs. 



A Report made to the Council of Trade and Mines in Spain, on a new Kind of Wood for Dyeing, 

 named Paraguatan. By D. DOMINI^E Garcia PERNANDEZy InfpeElor of Coinage *. 



I 



N compliance with the order of the Supreme Council of Commerce and Mines I have 

 undertaken a chemical examination of the wood known at Guiana by the name of Para- 

 guatan j which I have carried as far as appeared neceflary to afcertain the nature of the 

 wood, and the advantages to be derived from it. In the firfl place I obferved that the 

 bark, the wood properly fo called, and the leaves of paraguatan afford different colourSr 

 The leaves do not deferve notice, becaufe they produce only a falfe and difagreeable co- 

 lour. My refearches were chieHy diredled to the bark, which is the part mod deferving 

 of attention. But my remarks upon the bark may alfo be extended to the wood ; for, 

 though this affords a different colour, it prefents nearly the fame phenomena as the bark 

 itfelf. 



When the bark is boiled in water it affords a coloured extraft, which, when expofed to 

 the a£tion of the fulphuric, muriatic or nitric acid, refills their agency for a longer time 

 than brazil or logwood does. The colour may be revived by means of alkalis, after it has 

 been deftroyed by combination with acids. 



Vinegar, lemon juice and tartar render this colour more brilliant. They give rt a fine 

 rofe colour ; whereas thefe acids entirely deflroy the colours of brazil and logwood. 



The fecula of the bark of paraguatan fixes and attaches itfelf to wool, cotton, and filk. 

 The colour is brighter on filk than on wool, and brighter on wool than on cotton. 



The fame fecula dried is afterwards foluble in alcohol. It communicates to it a tinge 

 fimilar to that afforded by cochenille. : 



By mixing alum with a very concentrated decoftion of the fame fubftance, a kind 6£ 



* Tranflated from the Spanifh by Cit. Venturi, Annales dc Chimie, XXlH. 3«o. 



lac 



