no Mr. Hatchett’s Experiments on a Substance , 
The sulphuric acid almost immediately dissolved the resins, 
and formed transparent brown solutions, which progressively 
became black. 
The same effect was produced on most of the other sub- 
stances, but the solutions of the balsams and of guaiacum 
were at first of a deep crimson, slightly inclining to brown. 
Caoutchouc and elastic bitumen were not dissolved, but 
after having been digested for more than two months, were 
only superficially carbonized. 
The gums and the saccharine substances required many 
evaporations and filtrations before the whole of their car- 
bonaceous residua could be obtained. 
These were the principal effects observed during the ex- 
periments, and I have stated them in this manner, that tedious 
and useless repetitions may be avoided. 
§n. 
Turpentine, common resin, elemi, tacamahac, mastich, co- 
paiba, copal, camphor, benzoin, balsam of Tolu, balsam of 
Peru, asa foetida, 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 ammo- 
niac, 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 di- 
gestion been of too long a duration. 
Olive oil was partly converted into the above mentioned 
