J 6 TANNING MATTER, &C. 



Experiments, ^^^ after having been digested for more than two months, 

 &c. on an arti- were only superficially carbonized, 

 ficial substance ,p, , ,, i. • i, j. • i 



having the cha- ^"® gums and the saccharine substances required many 



ractcr of tan- evaporations and filtrations before the whole of their ear- 

 ning matter, bonaceous residua could be obtained. 



These were the principal eftects observed during the 

 experiments, and I have stated them in this manner, that 

 tedious and useless repetitions may be avoided. 



§11. 



Turpentine, common resin, elemi, tacamahac, mastich, 

 copaiba, copal, camphor, benzoin, balsam of Tolu, bal- 

 sam of Peru, asafcetida, and amber, yielded an abundance 

 of the tanning substance. 



Oil of turpentine also afforded much of it; asphaltum 

 yielded a small portion ; some slight traces of it were even 

 obtained from gum arabic and tragacanth ; but none was 

 produced by guaiacum, dragon's blood, myrrh, gum am- 

 moniac, olibanum, gamboge, caoutchouc, elastic bitumen, 

 liquorice, and manna. I am persuaded, however, that 

 many of these would have afforded the tanning substance 

 had not the digestion been of too long a duration. 



Olive oil was partly converted into the above mentioned 

 substance, and also linseed oil, wax, and animal fat; but 

 the three last appear to merit some attention. 

 Lilnseed Oil. 



This oil with sulphuric acid very soon formed a thick 

 blackish-brown liquid, which after being long digested in 

 a sand-bath, was still partly soluble in cold water, and 

 passed the filter. This solution precipitated gelatine; 

 the residuum was a tough black substance, which became 

 hard on exposure to air. A great part was soluble on 

 alcohol, and formed a brown liquid, which became turbid 

 by the addition of water. When this was evaporated, a 

 brown substance remained, which was partially dissolved 

 by cold water, and the solution thus formed, was rendered 

 turbid by gelatine. 



The undissolved portion left by the alcohol, was of a 

 blackish-brown ; it was soft and tenacious, and appeared 

 to retain many of the properties of an inspissated fat oil. 

 Bleached Wax. 



That which was employed in this experiment, was the 



white 



