210 ON THE TANNING -MATERIALS AND 



duties, as the custom-house apply to it the the tariff of pharmaceutical 

 substances, it cannot be employed in the Italian tanyards and dyeworks 

 until its price shall be much reduced. 



The Algarobilla is the fruit of a leguminous plant of the genus 

 Mimosa, which grows in abundance in Paraguay. Besides tannin and a 

 yellow colouring matter, I have extracted from it starch, which is con- 

 verted into alcohol during the tanning process, and which can be ob- 

 tained by distilling the water that is left. 



The Bablah, the fruit of the Acacia BablaJi, which is used in Africa, 

 is little known among our tanners. 



The Ou-poci-tse, or Chinese gallnut, is an excrescence growing on the 

 leaves of the Distylum racemosum, according to M. Decaisne. It comes 

 from China and Japan ; it is used for tanning and for dyeing black, and 

 produces a peculiarly beautiful pearl grey colour. 



We now come to the colouring matter, and in this list we include those 

 which are used for dyeing, colouring, and graduating ths shades of the 

 tissues, either by a direct process, or by means of heat, light, or the use of 

 acids. For staining skins mineral substances, such as Prussian blue, or 

 sulphate of iron — vegetable substances, such as the woods of Cuba, Per- 

 nambuco, Campeachy ; indigo, the bark and roots of the berberry tree, the 

 florets of the safflower, and lastly animal substances, such as cochineal are 

 used. Leather dyeing is not altogether dissimilar to silk dyeing, but it is 

 the most difficult branch of the dyeing art, because the nature of the ani- 

 mal tissue must be taken into consideration. This becomes changed at 70 

 degrees of heat, and it therefore recmires skill to adjusc the properties of 

 tanning and colouring matters, and the various effects of all those processes 

 which have for their object to convert raw hides into tanned leather. 



The chief colours produced are yellow, blue, and red ; the principal 

 yellow colouring matters are the following : — The berberry (Berberis 

 vulgaris) is a shrub which grows abundantly in the Piedmontese Alps ; 

 its bark, and especially its roots, impart to hides tanned with alum and 

 sumach, a rather durable tint of light yellow. 



The wood and the roots of the fustic, or the sumach, yield a yellow 

 or scarlet colour when they are mixed with cochineal, even tawny 

 colours when they are mixed with indigo, carmine, orchella, or Cam- 

 peachy wood, &c. 



Woad (Reseda luteola) is occasionally used for dyeing skins which have 

 been steeped in sumach ; it is used principally for sheep skins. It 

 grows in abundance on the hills of Montferrato and the mountains of 

 Ascoli ; and was formerly cultivated at Cortona, in Tuscany. 



The broom used by the dyers (Genista tinctoria) is applied to the 

 same purposes as woad. It is very abundant in the first zones of the 

 Alps. 



Saffron (Crocus sativus) is used in the dyeing of skins, but merely to 

 give more brilliancy to the scarlet of the cochineal. The cultivation of 

 saffron is very general in Italy ; the most celebrated places are those of 



