——— 
AND DERIVATION OF ROSOLTC ACID. 3 
less, becomes of a dark red colour. This colour arises 
from the rosolate of lime which, on standing, is precipi- 
tated as a highly coloured red powder.” 
From this it appears that Runge did not find its deriva- 
tion, although it has generally been put as an appendix to 
carbolic acid. 
In separating this resin from the lime by means of 
very dilute muriatic acid, there was at first a separation 
of fine light brown flakes; these at last gradually fell and 
united at the bottom of the vessel into a resinous mass. 
When this was dissolved in alcohol or ether, the solution 
had a deep brown colour, but no appearance of the rose 
colour; neither had it in any stage the beautiful orange 
colour mentioned by Runge. It is a question, there- 
fore, whether it is right to give it the same name; but 
in many particulars it is so like it that I have made no 
alteration. When treated with alkalies these shades of 
brown, or reddish-brown, gave way before the peculiar 
rose colour. The finest colour in solution appeared to me 
to be that with ammonia; in a solid state, the finest was 
certainly that of the lime compound. 
In order to find exactly its origin, I purified some car- 
bolic acid made from coal by heating it with caustic soda, 
decomposing with acid and distilling. <A vessel of lime 
was suspended over this under a bell-jar for some days, 
and gradually a rosy colour appeared on the surface. 
Another portion of carbolic acid was mixed with the lime 
and allowed to stand: this became of a very dark brown, 
and although rosolic acid*was formed it was mixed with 
other substances which made it appear very impure. I 
then filled a glass tube with caustic lime and passed the 
vapour of the acid over it, allowing free access of air, 
heating one end of the tube nearly to redness and allow- 
ing the heat gradually to decrease to the other end, so 
as to observe at what temperature the formation of the 
